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USER MANUAL ATmega325PA Microchip

AVR® Instruction Set Manual

Introduction

This manual gives an overview and explanation of every instruction available for 8-bit AVR ^® devices. Each instruction has its own section containing functional description, it's opcode, and syntax, the end state of the status register, and cycle times.

The manual also contains an explanation of the different addressing modes used by AVR devices and an appendix listing all modern AVR devices and what instruction it has available.

Table of Contents

Introduction....1

1. Instruction Set Nomenclature....6

2. CPU Registers Located in the I/O Space....8

2.1. RAMPX, RAMPY, and RAMPZ....8
2.2. RAMPD....8
2.3. EIND....8

1. The Program and Data Addressing Modes....9

3.1. Register Direct, Single Register Rd....9
3.2. Register Direct - Two Registers, Rd and Rr....9
3.3. I/O Direct....10
3.4. Data Direct.... 10
3.5. Data Indirect....11
3.6. Data Indirect with Pre-decrement....11
3.7. Data Indirect with Post-increment.... 12
3.8. Data Indirect with Displacement....12
3.9. Program Memory Constant Addressing using the LPM, ELPM, and SPM Instructions.... 13
3.10. Program Memory with Post-increment using the LPM Z+ and ELPM Z+ Instruction.... 13
3.11. Store Program Memory Post-increment....14
3.12. Direct Program Addressing, JMP and CALL....14
3.13. Indirect Program Addressing, IJMP and ICALL....15
3.14. Extended Indirect Program Addressing, EIJMP and EICALL....15
3.15. Relative Program Addressing, RJMP and RCALL.... 16

1. Conditional Branch Summary...... 17
2. Instruction Set Summary......18
3. Instruction Description....24

6.1. ADC – Add with Carry....24
6.2. ADD – Add without Carry.... 25
6.3. ADIW – Add Immediate to Word....26
6.4. AND – Logical AND....27
6.5. ANDI – Logical AND with Immediate....28
6.6. ASR – Arithmetic Shift Right.... 29
6.7. BCLR – Bit Clear in SREG....30
6.8. BLD – Bit Load from the T Bit in SREG to a Bit in Register.... 31
6.9. BRBC – Branch if Bit in SREG is Cleared....32
6.10. BRBS – Branch if Bit in SREG is Set....33
6.11. BRCC - Branch if Carry Cleared....34
6.12. BRCS – Branch if Carry Set....35
6.13. BREAK-Break 36
6.14. BREQ - Branch if Equal....36
6.15. BRGE – Branch if Greater or Equal (Signed)....37
6.16. BRHC – Branch if Half Carry Flag is Cleared....38

6.17. BRHS – Branch if Half Carry Flag is Set....39

6.18. BRID – Branch if Global Interrupt is Disabled....40

6.19. BRIE – Branch if Global Interrupt is Enabled....41

6.20. BRLO – Branch if Lower (Unsigned)....42

6.21. BRLT – Branch if Less Than (Signed)......43

6.22. BRMI – Branch if Minus....44

6.23. BRNE - Branch if Not Equal 45

6.24. BRPL – Branch if Plus....46

6.25. BRSH – Branch if Same or Higher (Unsigned)...... 47

6.26. BRTC - Branch if the T Bit is Cleared....48

6.27. BRTS - Branch if the T Bit is Set....49

6.28. BRVC - Branch if Overflow Cleared.... 50

6.29. BRVS – Branch if Overflow Set....51

6.30. BSET-Bit Set in SREG 52

6.31. BST – Bit Store from Bit in Register to T Bit in SREG....53

6.32. CALL – Long Call to a Subroutine....54

6.33. CBI – Clear Bit in I/O Register....55

6.34. CBR – Clear Bits in Register....56

6.35. CLC – Clear Carry Flag....57

6.36. CLH – Clear Half Carry Flag.... 57

6.37. CLI – Clear Global Interrupt Enable Bit....58

6.38. CLN - Clear Negative Flag.... 59

6.39. CLR - Clear Register....60

6.40. CLS – Clear Sign Flag....61

6.41. CLT - Clear T Bit....62

6.42. CLV - Clear Overflow Flag....62

6.43. CLZ – Clear Zero Flag....63

6.44. COM – One's Complement.... 64

6.45. CP – Compare....65

6.46. CPC - Compare with Carry....66

6.47. CPI – Compare with Immediate.... 67

6.48. CPSE – Compare Skip if Equal....68

6.49. DEC - Decrement....69

6.50. DES – Data Encryption Standard....71

6.51. EICALL - Extended Indirect Call to Subroutine.... 72

6.52. EIJMP - Extended Indirect Jump....73

6.53. ELPM – Extended Load Program Memory....73

6.54. EOR – Exclusive OR....75

6.55. FMUL - Fractional Multiply Unsigned.... 76

6.56. FMULS - Fractional Multiply Signed....77

6.57. FMULSU - Fractional Multiply Signed with Unsigned....79

6.58. ICALL – Indirect Call to Subroutine....80

6.59. IJMP – Indirect Jump....81

6.60. IN - Load an I/O Location to Register....82

6.61. INC – Increment....83

6.62. JMP – Jump....84

6.63. LAC – Load and Clear....85

6.64. LAS – Load and Set....86

6.65. LAT – Load and Toggle....86

6.66. LD - Load Indirect from Data Space to Register using X....87

6.67. LD (LDD) – Load Indirect from Data Space to Register using Y.... 89

6.68. LD (LDD) – Load Indirect From Data Space to Register using Z.... 90

6.69. LDI – Load Immediate....92

6.70. LDS – Load Direct from Data Space....93

6.71. LDS (AVRrc) – Load Direct from Data Space.... 94

6.72. LPM – Load Program Memory....95

6.73. LSL - Logical Shift Left.... 96

6.74. LSR – Logical Shift Right.... 97

6.75.MOV-CopyRegister 98

6.76. MOVW – Copy Register Word....99

6.77. MUL - Multiply Unsigned.... 100

6.78. MULS – Multiply Signed....101

6.79. MULSU - Multiply Signed with Unsigned....102

6.80. NEG - Two's Complement.... 103

6.81. NOP – No Operation.... 104

6.82. OR - Logical OR.... 105

6.83. ORI - Logical OR with Immediate....106

6.84. OUT – Store Register to I/O Location.... 107

6.85. POP – Pop Register from Stack....108

6.86. PUSH – Push Register on Stack....109

6.87. RCALL - Relative Call to Subroutine.... 110

6.88. RET – Return from Subroutine.... 111

6.89. RETI – Return from Interrupt.... 112

6.90. RJMP - Relative Jump.... 113

6.91. ROL – Rotate Left trough Carry....114

6.92. ROR - Rotate Right through Carry....115

6.93. SBC – Subtract with Carry....116

6.94. SBCI – Subtract Immediate with Carry SBI – Set Bit in I/O Register.... 117

6.95. SBI – Set Bit in I/O Register.... 118

6.96. SBIC - Skip if Bit in I/O Register is Cleared.... 119

6.97. SBIS - Skip if Bit in I/O Register is Set.... 120

6.98. SBIW – Subtract Immediate from Word.... 121

6.99. SBR – Set Bits in Register.... 122

6.100. SBRC - Skip if Bit in Register is Cleared....123

6.101. SBRS - Skip if Bit in Register is Set.... 124

6.102. SEC – Set Carry Flag....125

6.103. SEH – Set Half Carry Flag.... 126

6.104. SEI – Set Global Interrupt Enable Bit....127

6.105. SEN – Set Negative Flag.... 128

6.106. SER – Set all Bits in Register....128

6.107. SES - Set Sign Flag.... 129

6.108. SET – Set T Bit.... 130

6.109. SEV – Set Overflow Flag.... 131

6.110. SEZ – Set Zero Flag....132

6.111.SLEEP 132

6.112. SPM (AVRe) – Store Program Memory....133

6.113. SPM (AVRxm, AVRxt) – Store Program Memory....135
6.114. ST – Store Indirect From Register to Data Space using Index X.... 136
6.115. ST (STD) – Store Indirect From Register to Data Space using Index Y.... 138
6.116. ST (STD) – Store Indirect From Register to Data Space using Index Z....140
6.117. STS – Store Direct to Data Space....141
6.118. STS (AVRrc) – Store Direct to Data Space.... 142
6.119. SUB – Subtract Without Carry....143
6.120. SUBI – Subtract Immediate....144
6.121. SWAP – Swap Nibbles....145
6.122. TST - Test for Zero or Minus.... 146
6.123.WDR-Watchdog Reset 147
6.124. XCH – Exchange....148

7. Appendix A Device Core Overview....149

7.1. Core Descriptions....149
7.2. Device Tables....150

8. Revision History.... 161

8.1. Rev. DS40002198B - 02/2021....161
8.2. Rev. DS40002198A - 05/2020....161
8.3. Rev.0856L - 11/2016.... 161
8.4. Rev.0856K - 04/2016....161
8.5. Rev.0856J - 07/2014.... 161
8.6. Rev.0856I - 07/2010.... 161
8.7. Rev.0856H - 04/2009....162
8.8. Rev.0856G - 07/2008....162
8.9. Rev.0856F - 05/2008....162

The Microchip Website....163

Product Change Notification Service....163

Customer Support....163

Microchip Devices Code Protection Feature....163

Legal Notice....164

Trademarks....164

Quality Management System.... 165

Worldwide Sales and Service....166

1. Instruction Set Nomenclature

Status Register (SREG)

SREG Status Register

C Carry Flag

Z Zero Flag

N Negative Flag

V Two's Complement Overflow Flag

S Sign Flag

H Half Carry Flag

T Transfer Bit

I Global Interrupt Enable Bit

Registers and Operands

Rd: Destination (and source) register in the Register File

Rr: Source register in the Register File

R: Result after instruction is executed

K: Constant data

k: Constant address

b: Bit position (0..7) in the Register File or I/O Register

s: Bit position (0..7) in the Status Register

X,Y,Z: Indirect Address Register (X=R27:R26, Y=R29:R28, and Z=R31:R30 or X=RAMPX:R27:R26, Y=RAMPY:R29:R28, and Z=RAMPZ:R31:R30 if the memory is larger than 64 KB)

A: I/O memory address

q: Displacement for direct addressing

UU Unsigned × Unsigned operands

SS Signed × Signed operands

SU Signed × Unsigned operands

Memory Space Identifiers

DS() Represents a pointer to address in data space

PS() Represents a pointer to address in program space

I/O(A) I/O space address A

I/O(A,b) Bit position b of the byte in I/O space address A

Rd(n) Bit n in register Rd

Operator

✗ Arithmetic multiplication

• Arithmetic addition
• Arithmetic subtraction
  ^ Logical AND
  v Logical OR
  ⊕ Logical XOR

  Shift right
  << Shift left
  == Comparison
  ← Assignment
  ↔ Swap
  Logical complement of x (NOT x)

Stack

STACK Stack for return address and pushed registers

SP The Stack Pointer

Flags

Flag affected by instruction

0 Flag cleared by instruction

1 Flag set by instruction

- Flag not affected by instruction

2. CPU Registers Located in the I/O Space

2.1 RAMPX, RAMPY, and RAMPZ

Registers concatenated with the X-, Y-, and Z-registers enabling indirect addressing of the whole data space on MCUs with more than 64 KB data space, and constant data fetch on MCUs with more than 64 KB program space.

2.2 RAMPD

Register concatenated with the Z-register enabling direct addressing of the whole data space on MCUs with more than 64 KB data space.

2.3 EIND

Register concatenated with the Z-register enabling indirect jump and call to the whole program space on MCUs with more than 64K words (128 KB) program space.

3. The Program and Data Addressing Modes

The AVR ^® Enhanced RISC microcontroller supports powerful and efficient addressing modes for access to the program memory (Flash) and Data memory (SRAM, Register file, I/O Memory, and Extended I/O Memory). This section describes the various addressing modes supported by the AVR architecture. In the following figures, OP means the operation code part of the instruction word. To simplify, not all figures show the exact location of the addressing bits. To generalize, the abstract terms RAMEND and FLASHEND have been used to represent the highest location in data and program space, respectively.

Note: Not all addressing modes are present in all devices. Refer to the device specific instruction summary.

3.1 Register Direct, Single Register Rd

Figure 3-1. Direct Single Register Addressing

graph TD
    A["OP"] --> B["Rd"]
    B --> C["REGISTER FILE"]
    C --> D["d"]
    C --> E["31"]

The operand is contained in the destination register (Rd).

3.2 Register Direct - Two Registers, Rd and Rr

Figure 3-2. Direct Register Addressing, Two Registers

graph TD
    A["OP Rr"] --> B["Rd"]
    B --> C["REGISTER FILE"]
    C --> D["d"]
    C --> E["r"]
    C --> F["31"]

Operands are contained in the sources register (Rr) and destination register (Rd). The result is stored in the destination register (Rd).

3.3 I/O Direct

Figure 3-3. I/O Direct Addressing

graph TD
    A["OP"] --> B["Rr/Rd A"]
    B --> C["I/O MEMORY"]
    C --> D["63"]
    style C fill:#f9f,stroke:#333
    style D fill:#ccf,stroke:#333

Operand address A is contained in the instruction word. Rr/Rd specify the destination or source register.
Note: Some AVR microcontrollers have more peripheral units than can be supported within the 64 locations reserved in the opcode for I/O direct addressing. The extended I/O memory from address 64 and higher can only be reached by data addressing, not I/O addressing.

3.4 Data Direct

Figure 3-4. Direct Data Addressing

graph TD
    A["OP"] --> B["Data Address"]
    C["Rr/Rd"] --> B
    B --> D["Data Space 0x0000"]

A 16-bit Data Address is contained in the 16 LSBs of a two-word instruction. Rd/Rr specify the destination or source register. The LDS instruction uses the RAMPD register to access memory above 64 KB.

3.5 Data Indirect

Figure 3-5. Data Indirect Addressing

graph TD
    A["X, Y OR Z - POINTER"] --> B["Data Space"]
    B --> C["0x0000"]

The operand address is the contents of the X-, Y-, or the Z-pointer. In AVR devices without SRAM, Data Indirect Addressing is called Register Indirect Addressing.

3.6 Data Indirect with Pre-decrement

Figure 3-6. Data Indirect Addressing with Pre-decrement

graph TD
    A["X, Y OR Z - POINTER"] --> B["+"]
    C["-1"] --> B
    B --> D["Data Space 0x0000"]
    D --> E["Feedback to +"]

The X,- Y-, or the Z-pointer is decremented before the operation. The operand address is the decremented contents of the X-, Y-, or the Z-pointer.

3.7 Data Indirect with Post-increment

Figure 3-7. Data Indirect Addressing with Post-increment

graph TD
    A["X, Y OR Z - POINTER"] --> B["+"]
    C["1"] --> B
    B --> D["Data Space 0x0000"]
    D --> E["Output"]

The X-, Y-, or the Z-pointer is incremented after the operation. The operand address is the content of the X-, Y-, or the Z-pointer before incrementing.

3.8 Data Indirect with Displacement

Figure 3-8. Data Indirect with Displacement

graph TD
    A["Y OR Z - POINTER"] --> C["+"]
    B["OP"] --> C
    D["Rr/Rd"] --> C
    E["q"] --> C
    C --> F["Data Space 0x0000"]

The operand address is the result of the q displacement contained in the instruction word added to the Y- or Z-pointer. Rd/Rr specify the destination or source register.

3.9 Program Memory Constant Addressing using the LPM, ELPM, and SPM Instructions

Figure 3-9. Program Memory Constant Addressing

graph TD
    A["Z - POINTER"] --> B["LSb"]
    B --> C["PROGRAM MEMORY"]
    C --> D["0x0000"]
    C --> E["FLASHEND"]

Constant byte address is specified by the Z-pointer contents. The 15 MSbs select word address. For LPM, the LSb selects low byte if cleared (LSb == 0) or high byte if set (LSb == 1). For SPM, the LSb should be cleared. If ELPM is used, the RAMPZ Register is used to extend the Z-register.

3.10 Program Memory with Post-increment using the LPM Z+ and ELPM Z+ Instruction

Figure 3-10. Program Memory Addressing with Post-increment

graph TD
    A["Z- POINTER"] -->|LSb| B["Program Memory"]
    C["1"] --> D["+"]
    D --> B
    B --> E["0x0000"]
    E --> F["FLASHEND"]

Constant byte address is specified by the Z-pointer contents. The 15 MSbs select word address. The LSb selects low byte if cleared (LSb == 0) or high byte if set (LSb == 1). If ELPM Z+ is used, the RAMPZ Register is used to extend the Z-register.

3.11 Store Program Memory Post-increment

Figure 3-11. Store Program Memory

graph TD
    A["Z - POINTER"] --> B["+"]
    C["2"] --> B
    B --> D["PROGRAM MEMORY"]
    D --> E["0x0000"]
    D --> F["FLASHEND"]

The Z-pointer is incremented by 2 after the operation. Constant byte address is specified by the Z-pointer contents before incrementing. The 15 MSbs select word address and the LSb should be left cleared.

3.12 Direct Program Addressing, JMP and CALL

Figure 3-12. Direct Program Memory Addressing

graph TD
    A["OP"] --> B["k"]
    B --> C["PC"]
    D["0x0000"] --> E["Flashend"]
    F["PROGRAM MEMORY"] --> G["0x0000"]

Program execution continues at the address immediate in the instruction word.

3.13 Indirect Program Addressing, IJMP and ICALL

Figure 3-13. Indirect Program Memory Addressing

graph TD
    A["Z - REGISTER"] --> B["PC"]
    B --> C["PROGRAM MEMORY"]
    C --> D["0x0000"]
    C --> E["FLASHEND"]

Program execution continues at the address contained by the Z-register (i.e., the PC is loaded with the contents of the Z-register).

3.14 Extended Indirect Program Addressing, EIJMP and EICALL

Figure 3-14. Extended Indirect Program Memory Addressing

graph TD
    A["EIND"] --> C["PC"]
    B["Z - REGISTER"] --> C["PC"]
    C --> D["PROGRAM MEMORY"]
    D --> E["0x0000"]
    D --> F["FLASHEND"]

Program execution continues at the address contained by the Z-register and the EIND-register (i.e., the PC is loaded with the contents of the EIND and Z-register).

3.15 Relative Program Addressing, RJMP and RCALL

Figure 3-15. Relative Program Memory Addressing

graph TD
    A["PC"] --> C["+"]
    B["OP k"] --> C
    C --> D["0x0000 FLASHEND"]
    E["1"] --> C
    F["PROGRAM MEMORY"] --> D

Program execution continues at the address PC + k + 1. The relative address k is from -2048 to 2047.

1. Conditional Branch Summary

One Form Complement Form Comment
Mnemonic	Common Test	Status Register Mnemonic		Common Test	Status Register
BRGE	Rd ≥ Rr	S == 0 BRLT		Rd < Rr	S == 1 Signed
BRSH C == 0 BRLO C == 1 Unsigned
BRNE Rd ≠ Rr Z == 0 BREQ Rd == Rr Z == 1 Unsigned/Signed
BRBC	-	SREG(s) == 0 BRBS		-	SREG(s) == 1 -
BRCC C == 0		BRCS C == 1 Simple
BRPL		N == 0	BRMI		N == 1 Simple
BRVC V == 0		BRVS	V == 1		Simple

Note: The Status Register status is a result of the preceding instruction, for further information see instruction description. If the preceding instruction is CP, CPI, SUB, or SUBI, the branch will occur according to column 'Common Test'.

5. Instruction Set Summary

Several updates of the AVR CPU during its lifetime has resulted in different flavors of the instruction set, especially for the timing of the instructions. Machine code level of compatibility is intact for all CPU versions with very few exceptions related to the Reduced Core (AVRrc), though not all instructions are included in the instruction set for all devices. The table below contains the major versions of the AVR 8-bit CPUs. In addition to the different versions, there are differences depending on the size of the device memory map. Typically these differences are handled by a C/EC++ compiler, but users that are porting code should be aware that the code execution can vary slightly in the number of clock cycles.

Table 5-1. Versions of AVR® 8-bit CPU

Name Description
AVR Original instruction set from 1995
AVRe AVR instruction set extended with the Move Word (MOVW) instruction, and the Load Program Memory (LPM) instruction has been enhanced. Same timing as AVR.
AVRe+ AVRe instruction set extended with the Multiply (xMULxx) instructions, and if applicable with the extended range instructions EICALL, EIJMP and ELPM. Same timing as AVR and AVRe. Thus, tables listing number of clock cycles do not distinguish between AVRe and AVRe+, and use AVRe to represent both.
AVRxm AVRe+ instruction set extended with the Read Modify Write (RMW) and Data Encryption Standard (DES) instructions. SPM extended to include SPM Z+2. Significantly different timing compared to AVR, AVRe, AVRe+.
AVRxt A combination of AVRe+ and AVRxm. Available instructions are the same as AVRe+, but the timing has been improved compared to AVR, AVRe, AVRe+ and AVRxm.
AVRrc AVRrc has only 16 registers in its register file (R31-R16), and the instruction set is reduced. The timing is significantly different compared to the AVR, AVRe, AVRe+, AVRxm and AVRxt. Refer to the instruction set summary for further details.

Table 5-2. Arithmetic and Logic Instructions

Mnemonic	Operands	Description Operation Flags						#Clocks AVRe	#Clocks AVRxm	#Clocks AVRxt	#Clocks AVRrc
ADD	Rd, Rr	Add without Carry	Rd	←	Rd + Rr	Z,C,N,V,S,H	1	1	1	1	1
ADC	Rd, Rr	Add with Carry	Rd	←	Rd + Rr + C	Z,C,N,V,S,H	1	1	1	1	1
ADIW	Rd, K	Add Immediate to Word	R[d + 1]:Rd	←	R[d + 1]:Rd + K	Z,C,N,V,S	2	2	2	N/A	N/A
SUB	Rd, Rr	Subtract without Carry	Rd	←	Rd - Rr	Z,C,N,V,S,H	1	1	1	1	1
SUBI	Rd, K	Subtract Immediate	Rd	←	Rd - K	Z,C,N,V,S,H	1	1	1	1	1
SBC	Rd, Rr	Subtract with Carry	Rd	←	Rd - Rr - C	Z,C,N,V,S,H	1	1	1	1	1
SBCI	Rd, K	Subtract Immediate with Carry	Rd	←	Rd - K - C	Z,C,N,V,S,H	1	1	1	1	1
SBIW	Rd, K	Subtract Immediate from Word	R[d + 1]:Rd	←	R[d + 1]:Rd - K	Z,C,N,V,S	2	2	2	N/A	N/A
AND	Rd, Rr	Logical AND	Rd	←	Rd ∧ Rr	Z,N,V,S	1	1	1	1	1
ANDI	Rd, K	Logical AND with Immediate	Rd	←	Rd ∧ K	Z,N,V,S	1	1	1	1	1
OR	Rd, Rr	Logical OR	Rd	←	Rd v Rr	Z,N,V,S	1	1	1	1	1
ORI	Rd, K	Logical OR with Immediate	Rd	←	Rd v K	Z,N,V,S	1	1	1	1	1
EOR	Rd, Rr	Exclusive OR	Rd	←	Rd ⊕ Rr	Z,N,V,S	1	1	1	1	1

......continued
Mnemonic Operands Description Operation Flags							#Clocks AVRe	#Clocks AVRxm	#Clocks AVRxt	#Clocks AVRrc
COM Rd One's Complement Rd ← 0xFF - Rd Z,C,N,V,S 1 1 1 1
NEG Rd Two's Complement Rd ← 0x00 - Rd Z,C,N,V,S,H 1 1 1 1
SBR	Rd,K	Set Bit(s) in Register	Rd	←	Rd v K	Z,N,V,S	1	1	1	1
CBR	Rd,K	Clear Bit(s) in Register	Rd	←	Rd ∧ (0xFFh - K)	Z,N,V,S	1	1	1	1
INC	Rd	Increment	Rd	←	Rd + 1	Z,N,V,S	1	1	1	1
DEC	Rd	Decrement	Rd	←	Rd - 1	Z,N,V,S	1	1	1	1
TST	Rd	Test for Zero or Minus	Rd	←	Rd ∧ Rd	Z,N,V,S	1	1	1	1
CLR	Rd	Clear Register	Rd	←	Rd ⊕ Rd	Z,N,V,S	1	1	1	1
SER	Rd	Set Register	Rd	←	0xFF	None	1	1	1	1
MUL	Rd,Rr	Multiply Unsigned	R1:R0	←	Rd x Rr (UU)	Z,C	2	2	2	N/A
MULS	Rd,Rr	Multiply Signed	R1:R0	←	Rd x Rr (SS)	Z,C	2	2	2	N/A
MULSU	Rd,Rr	Multiply Signed with Unsigned	R1:R0 ← Rd x Rr (SU)		Z,C	2 2 2 N/A
FMUL	Rd,Rr	Fractional Multiply Unsigned	R1:R0 ← Rd x Rr<<1 (UU)		Z,C	2 2 2 N/A
FMULS	Rd,Rr	Fractional Multiply Signed	R1:R0	←	Rd x Rr<<1 (SS)	Z,C	2	2	2	N/A
FMULSU	Rd,Rr	Fractional Multiply Signed with Unsigned	R1:R0 ← Rd x Rr<<1 (SU)		Z,C	2 2 2 N/A
DES K	Data Encryption if (H == 0), R15:R0 ← Encrypt(R15:R0, K)						N/A	1 / 2	N/A	N/A

Table 5-3. Change of Flow Instructions

Mnemonic	Operands	Description	Operation			Flags	#Clocks AVRe	#Clocks AVRxm	#Clocks AVRxt	#Clocks AVRrc
RJMP	k	Relative Jump	PC	←	PC + k + 1	None	2	2	2	2
IJMP		Indirect Jump to (Z)	PC(15:0)	←	Z	None	2	2	2	2
			PC(21:16)	←	0
EIJMP		Extended Indirect Jump to (Z)	PC(15:0)	←	Z	None	2	2	2	N/A
			PC(21:16)	←	EIND
JMP	k	Jump	PC	←	k	None	3	3	3	N/A
RCALL	k	Relative Call Subroutine	PC	←	PC + k + 1	None	3/4^(1)	2/3^(1)	2/3	3
ICALL		Indirect Call to (Z)	PC(15:0)	←	Z	None	3/4^(1)	2/3^(1)	2/3	3
			PC(21:16)	←	0
EICALL		Extended Indirect Call to (Z)	PC(15:0)	←	Z	None	4^(1)	3^(1)	3	N/A
			PC(21:16)	←	EIND
CALL	k	Call Subroutine	PC	←	k	None	4/5^(1)	3/4^(1)	3/4	N/A
RET		Subroutine Return	PC	←	STACK	None	4/5^(1)	4/5^(1)	4/5	6
RETI		Interrupt Return	PC	←	STACK	I	4/5^(1)	4/5^(1)	4/5	6
CPSE	Rd,Rr	Compare, skip if Equal	if (Rd == Rr) PC	←	PC + 2 or 3	None	1/2/3	1/2/3	1/2/3	1/2
CP	Rd,Rr	Compare	Rd - Rr			Z,C,N,V,S,H	1	1	1	1
CPC	Rd,Rr	Compare with Carry	Rd - Rr - C			Z,C,N,V,S,H	1	1	1	1

......continued
Mnemonic Operands Description Operation Flags							#Clocks AVRe	#Clocks AVRxm	#Clocks AVRxt
CPI Rd,K Compare with Immediate Rd - K Z,C,N,V,S,H 1 1 1 1
SBRC	Rr, b	Skip if Bit in Register Cleared	if (Rr(b) == 0) PC	←	PC + 2 or 3	None	1/2/3	1/2/3	1/2/3
SBRS	Rr, b	Skip if Bit in Register Set	if (Rr(b) == 1) PC	←	PC + 2 or 3	None	1/2/3	1/2/3	1/2/3
SBIC	A, b	Skip if Bit in I/O Register Cleared	if (I/O(A,b) == 0) PC	←	PC + 2 or 3	None	1/2/3	2/3/4	1/2/3
SBIS	A, b	Skip if Bit in I/O Register Set	If (I/O(A,b) == 1) PC	←	PC + 2 or 3	None	1/2/3	2/3/4	1/2/3
BRBS	s, k	Branch if Status Flag Set	if (SREG(s) == 1) then PC	←	PC + k + 1	None	1/2	1/2	1/2
BRBC s, k	Branch if Status Flag Cleared	if (SREG(s) == 0) then PC	←	PC + k + 1	None	1/2	1/2	1/2	1/2
BREQ	k	Branch if Equal	if (Z == 1) then PC	←	PC + k + 1	None	1/2	1/2	1/2
BRNE	k	Branch if Not Equal	if (Z == 0) then PC	←	PC + k + 1	None	1/2	1/2	1/2
BRCS	k	Branch if Carry Set	if (C == 1) then PC	←	PC + k + 1	None	1/2	1/2	1/2
BRCC	k	Branch if Carry Cleared	if (C == 0) then PC	←	PC + k + 1	None	1/2	1/2	1/2
BRSH	k	Branch if Same or Higher	if (C == 0) then PC	←	PC + k + 1	None	1/2	1/2	1/2
BRLO	k	Branch if Lower	if (C == 1) then PC	←	PC + k + 1	None	1/2	1/2	1/2
BRMI	k	Branch if Minus	if (N == 1) then PC	←	PC + k + 1	None	1/2	1/2	1/2
BRPL	k	Branch if Plus	if (N == 0) then PC	←	PC + k + 1	None	1/2	1/2	1/2
BRGE	k	Branch if Greater or Equal, Signed	if (S == 0) then PC	←	PC + k + 1	None	1/2	1/2	1/2
BRLT	k	Branch if Less Than, Signed	if (S == 1) then PC	←	PC + k + 1	None	1/2	1/2	1/2
BRHS	k	Branch if Half Carry Flag Set	if (H == 1) then PC	←	PC + k + 1	None	1/2	1/2	1/2
BRHC	k	Branch if Half Carry Flag Cleared	if (H == 0) then PC	←	PC + k + 1	None	1/2	1/2	1/2
BRTS	k	Branch if T Bit Set	if (T == 1) then PC	←	PC + k + 1	None	1/2	1/2	1/2
BRTC	k	Branch if T Bit Cleared	if (T == 0) then PC	←	PC + k + 1	None	1/2	1/2	1/2
BRVS	k	Branch if Overflow Flag is Set	if (V == 1) then PC	←	PC + k + 1	None	1/2	1/2	1/2
BRVC k	Branch if Overflow Flag is Cleared	if (V == 0) then PC	←	PC + k + 1	None	1/2	1/2	1/2	1/2
BRIE	k	Branch if Interrupt Enabled	if (I == 1) then PC	←	PC + k + 1	None	1/2	1/2	1/2
BRID	k	Branch if Interrupt Disabled	if (I == 0) then PC	←	PC + k + 1	None	1/2	1/2	1/2

Table 5-4. Data Transfer Instructions

Mnemonic	Operands Description Operation Flags						#Clocks AVRe	#Clocks AVRxm	#Clocks AVRxt	#Clocks AVRrc
MOV	Rd, Rr	Copy Register	Rd	←	Rr	None	1	1	1	1
MOVW	Rd, Rr	Copy Register Pair	R[d + 1]:Rd	←	R[r + 1]:Rr	None	1	1	1	N/A
LDI	Rd, K	Load Immediate	Rd	←	K	None	1	1	1	1
LDS	Rd, k	Load Direct from Data Space	Rd	←	DS(k)	None	2(1)	3(1)(3)	3(2)	2
LD	Rd, X	Load Indirect	Rd	←	DS(X)	None	2(1)	2(1)(3)	2(2)	1/2
LD Rd, X+	Load Indirect and Post-Increment		Rd	←	DS(X)	None	2(1)	2(1)(3)	2(2)	2/3
			X	←	X + 1
LD Rd, -X	Load Indirect and Pre-Decrement		X	←	X - 1	None	2(1)	3(1)(3)	2(2)	2/3
			Rd	←	DS(X)
Mnemonic Operands Description Operation Flags							#Clocks AVRe	#Clocks AVRxm	#Clocks AVRxt	#Clocks AVRrc
LD Rd, Y Load Indirect Rd ← DS(Y) None 2							(1)	2(1)(3)	2(2)	1/2
LD Rd, Y+ Load Indirect and Post-Increment Rd				←	DS(Y)	None 2	(1)	2(1)(3)	2(2)	2/3
			Y	←	Y + 1
LD Rd, -Y Load Indirect and Pre-Decrement Y				←	Y - 1	None 2	(1)	3(1)(3)	2(2)	2/3
			Rd	←	DS(Y)
LDD Rd, Y+q	Load Indirect with Displacement Rd ← DS(Y + q)		None 2				(1)	3(1)(3)	2(2)	N/A
LD Rd, Z	Load Indirect Rd ← DS(Z)	None 2					(1)	2(1)(3)	2(2)	1/2
LD Rd, Z+	Load Indirect and Post-Increment Rd			←	DS(Z)	None 2	(1)	2(1)(3)	2(2)	2/3
			Z	←	Z+1
LD Rd, -Z	Load Indirect and Pre-Decrement		Z	←	Z - 1	None 2	(1)	3(1)(3)	2(2)	2/3
			Rd	←	DS(Z)
LDD Rd, Z+q	Load Indirect with Displacement Rd ← DS(Z + q)		None 2				(1)	3(1)(3)	2(2)	N/A
STS	k, Rr	Store Direct to Data Space		DS(k)	←	Rd	None	2(1)	2(1)	2(2)
ST	X, Rr	Store Indirect		DS(X)	←	Rr	None	2(1)	1(1)	1(2)
ST X+, Rr Store Indirect and Post-Increment			DS(X)		←	Rr	None 2	(1)	1(1)	1(2)
				X	←	X + 1
ST -X, Rr	Store Indirect and Pre-Decrement		X	←	X - 1	None 2	(1)	2(1)	1(2)	2
			DS(X)	←	Rr
ST	Y, Rr	Store Indirect		DS(Y)	←	Rr	None	2(1)	1(1)	1(2)
ST Y+, Rr Store Indirect and Post-Increment			DS(Y)		←	Rr	None 2	(1)	1(1)	1(2)
				Y	←	Y + 1
ST -Y, Rr Store Indirect and Pre-Decrement			Y		←	Y - 1	None 2	(1)	2(1)	1(2)
				DS(Y)	←	Rr
STD	Y+q, Rr	Store Indirect with Displacement		DS(Y + q)	←	Rr	None	2(1)	2(1)	1(2)
ST	Z, Rr	Store Indirect		DS(Z)	←	Rr	None	2(1)	1(1)	1(2)
ST Z+, Rr Store Indirect and Post-Increment			DS(Z)		←	Rr	None 2	(1)	1(1)	1(2)
				Z	←	Z + 1
ST -Z, Rr	Store Indirect and Pre-Decrement		Z		←	Z - 1	None 2	(1)	2(1)	1(2)
				DS(Z)	←	Rr
STD Z+q,Rr Store Indirect with Displacement			DS(Z + q) ← Rr			None 2		(1)	2(1)	1(2)
LPM		Load Program Memory		R0	←	PS(Z)	None	3	3	3
LPM	Rd, Z	Load Program Memory		Rd	←	PS(Z)	None	3	3	3
LPM	Rd, Z+	Load Program Memory and Post-Increment		Rd	←	PS(Z)	None	3 3 3	N/A
				Z	←	Z + 1
ELPM		Extended Load Program Memory		R0	←	PS(RAMPZ:Z)	None	3	3	3
ELPM	Rd, Z	Extended Load Program Memory		Rd	←	PS(RAMPZ:Z)	None	3	3	3
ELPM	Rd, Z+	Extended Load Program Memory and Post-Increment		Rd (RAMPZ:Z)	←	PS(RAMPZ:Z) (RAMPZ:Z) + 1	None	3	3 3	N/A
SPM		Store Program Memory		PS(RAMPZ:Z)	←	R1:R0	None	-(4)	-(4)	-(4)
SPM	Z+	Store Program Memory and Post-Increment by 2		PS(RAMPZ:Z) Z	← ←	R1:R0 Z + 2	None	N/A -	(4)	-(4)
......continued
Mnemonic Operands Description Operation Flags							#Clocks AVRe	#Clocks AVRxm	#Clocks AVRxt	#Clocks AVRrc
IN Rd, A In From I/O Location Rd ← I/O(A) None 1 1 1 1
OUT A, Rr Out To I/O Location I/O(A) ← Rr None 1 1 1 1
PUSH	Rr	Push Register on Stack	STACK	←	Rr	None	2	1^(1)	1	1
POP	Rd	Pop Register from Stack	Rd	←	STACK	None	2	2^(1)	2	3
XCH	Z, Rd	Exchange	DS(Z)	↔	Rd	None	N/A	2	N/A	N/A
LAS	Z, Rd	Load and Set	DS(Z)	←	Rd v DS(Z)	None	N/A	2	N/A	N/A
			Rd	←	DS(Z)
LAC	Z, Rd	Load and Clear	DS(Z)	←	(0xFF - Rd) ∧ DS(Z)	None	N/A	2	N/A	N/A
			Rd	←	DS(Z)
LAT	Z, Rd	Load and Toggle	DS(Z)	←	Rd ⊕ DS(Z)	None	N/A	2	N/A	N/A
			Rd	←	DS(Z)

Table 5-5. Bit and Bit-Test Instructions

Mnemonic	Operands Description Operation Flags						#Clocks AVRe	#Clocks AVRxm	#Clocks AVRxt	#Clocks AVRrc
LSL	Rd Logical Shift Left		C	←	Rd(7)	Z,C,N,V,H	1 1 1 1
			Rd(n+1)	←	Rd(n), n=6...0
			Rd(0)	←	0
LSR	Rd Logical Shift Right		C	←	Rd(0)	Z,C,N,V	1 1 1 1
			Rd(n)	←	Rd(n+1), n=0...6
			Rd(7)	←	0
ROL	Rd Rotate Left Through Carry		temp	←	C	Z,C,N,V,H	1 1 1 1
			C	←	Rd(7)
			Rd(n+1)	←	Rd(n), n=6...0
			Rd(0)	←	temp
ROR	Rd Rotate Right Through Carry		temp	←	C	Z,C,N,V	1 1 1 1
			C	←	Rd(0)
			Rd(n)	←	Rd(n+1), n=0...6
			Rd(7)	←	temp
ASR	Rd Arithmetic Shift Right		C	←	Rd(0)	Z,C,N,V	1 1 1 1
			Rd(n)	←	Rd(n+1), n=0..6
			Rd(7)	←	Rd(7)
SWAP	Rd Swap Nibbles		Rd(3..0) ↔ Rd(7..4) None 1 1 1 1
SBI	A, b	Set Bit in I/O Register	I/O(A, b)	←	1	None	2	1	1	1
CBI	A, b	Clear Bit in I/O Register	I/O(A, b)	←	0	None	2	1	1	1
BST	Rr, b	Bit Store from Register to T	T	←	Rr(b)	T	1	1	1	1
BLD	Rd, b	Bit load from T to Register	Rd(b)	←	T	None	1	1	1	1
BSET	s	Flag Set	SREG(s)	←	1	SREG(s)	1	1	1	1
BCLR	s	Flag Clear	SREG(s)	←	0	SREG(s)	1	1	1	1
SEC		Set Carry	C	←	1	C	1	1	1	1
CLC		Clear Carry	C	←	0	C	1	1	1	1
SEN		Set Negative Flag	N	←	1	N	1	1	1	1

......continued
Mnemonic Operands Description Operation Flags						#Clocks AVRe	#Clocks AVRxm	#Clocks AVRxt	#Clocks AVRrc
CLN Clear Negative Flag N ← 0 N 1 1 1 1
SEZ Set Zero Flag Z ← 1 Z 1 1 1 1
CLZ Clear Zero Flag Z ← 0 Z 1 1 1 1
SEI		Global Interrupt Enable		I ← 1	I	1	1	1	1
CLI		Global Interrupt Disable		I ← 0	I	1	1	1	1
SES Set Sign Bit			S ← 1 S	1 1 1 1
CLS Clear Sign Bit			S ← 0 S	1 1 1 1
SEV Set Two's Complement Overflow			V ← 1 V	1 1 1 1
CLV Clear Two's Complement Overflow				V ← 0 V	1 1 1 1
SET Set T in SREG			T ← 1 T 1 1 1 1
CLT		Clear T in SREG		T ← 0 T 1 1 1 1
SEH		Set Half Carry Flag in SREG		H ← 1 H 1 1 1 1
CLH Clear Half Carry Flag in SREG			H ← 0 H 1 1 1 1

Table 5-6. MCU Control Instructions

Mnemonic	Operands	Description	Operation	Flags	#Clocks AVRe	#Clocks AVRxm	#Clocks AVRxt	#Clocks AVRrc
BREAK		Break	See the debug interface description	None	1	1	1	1
NOP		No Operation		None	1	1	1	1
SLEEP		Sleep	See the power management and sleep description	None	1	1	1	1
WDR		Watchdog Reset	See the Watchdog Controller description	None	1	1	1	1

Notes:

1. Cycle times for data memory access assume internal RAM access and are not valid for accessing external RAM.
2. Cycle time for data memory access assumes internal RAM access, and are not valid for access to NVM. A minimum of one extra cycle must be added when accessing NVM. The additional time varies dependent on the NVM module implementation. See the NVMCTRL section in the specific devices data sheet for more information.
3. If the LD instruction is accessing I/O Registers, one cycle can be deducted.
4. Varies with the programming time of the device.

6. Instruction Description

6.1 ADC - Add with Carry

6.1.1 Description

Adds two registers and the contents of the C flag and places the result in the destination register Rd.

Operation:

(i) Rd ← Rd + Rr + C

Syntax: Operands: Program Counter:

(i) ADC Rd, Rr 0 ≤ d ≤ 31, 0 ≤ r ≤ 31 PC ← PC + 1

16-bit Opcode:

0001 11rd dddd rrrr

6.1.2 Status Register (SREG) and Boolean Formula

H Rd3 ∧ Rr3 ∨ Rr3 ∧ R3 ∨ R3 ∧ Rd3

Set if there was a carry from bit 3; cleared otherwise.

S N ⊕ V, for signed tests.

V Rd7 ∧ Rr7 ∧ R7 ∨ Rd7 ∧ Rr7 ∧ R7

Set if two's complement overflow resulted from the operation; cleared otherwise.

N R7

Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x00; cleared otherwise.

C Rd7 ∧ Rr7 ∨ Rr7 ∧ R7 ∨ R7 ∧ Rd7

Set if there was a carry from the MSB of the result; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

	; Add R1:R0 to R3:R2
add	r2,r0	; Add low byte
adc	r3,r1	; Add with carry high byte

Words

1 (2 bytes)

Table 6-1. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.2 ADD – Add without Carry

6.2.1 Description

Adds two registers without the C flag and places the result in the destination register Rd.

Operation:

(i) (i) Rd ← Rd + Rr

Syntax: Operands: Program Counter:

(i) ADD Rd, Rr 0 ≤ d ≤ 31, 0 ≤ r ≤ 31 PC ← PC + 1

16-bit Opcode:

0000 11rd dddd rrrr

6.2.2 Status Register (SREG) and Boolean Formula

H Rd3 ∧ Rr3 ∨ Rr3 ∧ R3 ∨ R3 ∧ Rd3

Set if there was a carry from bit 3; cleared otherwise.

S N ⊕ V, for signed tests.

V Rd7 ∧ Rr7 ∧ R7 ∨ Rd7 ∧ Rr7 ∧ R7

Set if two's complement overflow resulted from the operation; cleared otherwise.

N R7

Set if MSB of the result is set; cleared otherwise.

Set if the result is 0x00; cleared otherwise.

C Rd7 ∧ Rr7 ∨ Rr7 ∧ R7 ∨ R7 ∧ Rd7

Set if there was a carry from the MSB of the result; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

add r1,r2 ; Add r2 to r1 (r1=r1+r2)
add r28,r28 ; Add r28 to itself (r28=r28+r28) 

Words 1 (2 bytes)

Table 6-2. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.3 ADIW - Add Immediate to Word

6.3.1 Description

Adds an immediate value (0-63) to a register pair and places the result in the register pair. This instruction operates on the upper four register pairs and is well suited for operations on the Pointer Registers.

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) R[d+1]:Rd ← R[d+1]:Rd + K

Syntax: Operands: Program Counter:

(i) ADIW Rd, K d ∈ {24, 26, 28, 30}, 0 ≤ K ≤ 63 PC ← PC + 1

16-bit Opcode:

1001 0110 KKdd

KKKK

6.3.2 Status Register (SREG) and Boolean Formula

S N ⊕ V, for signed tests.

V Rdh7 ∧ R15

Set if two's complement overflow resulted from the operation; cleared otherwise.

N R15

Set if MSB of the result is set; cleared otherwise.

Z R15 ∧ R14 ∧ R13 ∧ R12 ∧ R11 ∧ R10 ∧ R9 ∧ R8 ∧ R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x0000; cleared otherwise.

C R15 ∧ Rdh7

Set if there was a carry from the MSB of the result; cleared otherwise.

R (Result) equals R[d+1]:Rd after the operation.

Example:

adiw r24,1 ; Add 1 to r25:r24
adiw ZL,63 ; Add 63 to the Z-pointer(r31:r30) 

Words 1 (2 bytes)

Table 6-3. Cycles

Name Cycles
AVRe 2
AVRxm 2
AVRxt 2
AVRrc N/A

6.4 AND - Logical AND

6.4.1 Description

Performs the logical AND between the contents of register Rd and register Rr, and places the result in the destination register Rd.

Operation:

(i) Rd ← Rd ∧ Rr

Syntax: Operands: Program Counter:

(i) AND Rd, Rr 0 ≤ d ≤ 31, 0 ≤ r ≤ 31 PC ← PC + 1

16-bit Opcode:

0010 00rd dddd rrrr 

6.4.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-		0			-

S N ⊕ V, for signed tests.

v 0

Cleared.

N R7

Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x00; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

and r2,r3 ; Bitwise and r2 and r3, result in r2
ldi r16,1 ; Set bitmask 0000 0001 in r16
and r2,r16 ; Isolate bit 0 in r2 

Words 1 (2 bytes)

Table 6-4. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.5 ANDI – Logical AND with Immediate

6.5.1 Description

Performs the logical AND between the contents of register Rd and a constant, and places the result in the destination register Rd.

Operation:

(i) Rd ← Rd ∧ K

Syntax: Operands: Program Counter:

(i) ANDI Rd, K 16 ≤ d ≤ 31, 0 ≤ K ≤ 255 PC ← PC + 1

16-bit Opcode:

0111 KKKK dddd

KKKK

6.5.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-		0			-

S N ⊕ V, for signed tests.

v 0

Cleared.

N R7

Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x00; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

andi r17,0x0F ; Clear upper nibble of r17
andi r18,0x10 ; Isolate bit 4 in r18
andi r19,0xAA ; Clear odd bits of r19 

Words 1 (2 bytes)

Table 6-5. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.6 ASR – Arithmetic Shift Right

6.6.1 Description

Shifts all bits in Rd one place to the right. Bit 7 is held constant. Bit 0 is loaded into the C flag of the SREG. This operation effectively divides a signed value by two without changing its sign. The Carry flag can be used to round the result.

graph TD
    A["b7"] --> B["b0"]
    B --> C["C"]
    style A fill:#f9f,stroke:#333
    style B fill:#ccf,stroke:#333
    style C fill:#cfc,stroke:#333

Syntax: Operands: Program Counter:
(i) ASR Rd 0 ≤ d ≤ 31 PC ← PC + 1

16-bit Opcode:

1001 010d dddd 0101

6.6.2 Status Register (SREG) and Boolean Formula

S N ⊕ V, for signed tests.

V N ⊕ C, for N and C after the shift.

N R7. Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x00; cleared otherwise.

C Rd0

Set if, before the shift, the LSB of Rd was set; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

ldi r16,0x10 ; Load decimal 16 into r16
asr r16 ; r16=r16 / 2
ldi r17,0xFC ; Load -4 in r17
asr r17 ; r17=r17/2 

Words 1 (2 bytes)

Table 6-6. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.7 BCLR - Bit Clear in SREG

6.7.1 Description

Clears a single flag in SREG.

Operation:

(i) SREG(s) ← 0

Syntax: Operands: Program Counter:

(i) BCLR s 0 ≤ s ≤ 7 PC ← PC + 1

16-bit Opcode:

1001 0100 1sss 1000

6.7.2 Status Register (SREG) and Boolean Formula

If (s == 7) then I ← 0, else unchanged.

T If (s == 6) then T ← 0, else unchanged.

H If (s == 5) then H ← 0, else unchanged.

S If (s == 4) then S ← 0, else unchanged.

V If (s == 3) then V ← 0, else unchanged.

N If (s == 2) then N ← 0, else unchanged.

Z If (s == 1) then Z ← 0, else unchanged.

C If (s == 0) then C ← 0, else unchanged.

Example:

bclr 0 ; Clear Carry flag
bclr 7 ; Disable interrupts 

Words 1 (2 bytes)

Table 6-7. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.8 BLD - Bit Load from the T Bit in SREG to a Bit in Register

6.8.1 Description

Copies the T bit in the SREG (Status Register) to bit b in register Rd.

Operation:

(i) Rd(b) ← T

Syntax: Operands: Program Counter:

(i) BLD Rd, b 0 ≤ d ≤ 31, 0 ≤ b ≤ 7 PC ← PC + 1

16 bit Opcode:

1111 100d dddd 0bbb

6.8.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

; Copy bit
bst r1,2 ; Store bit 2 of r1 in T bit
bld r0,4 ; Load T bit into bit 4 of r0 

Words 1 (2 bytes)

Table 6-8. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1

......continued

Name Cycles

AVRrc 1

6.9 BRBC - Branch if Bit in SREG is Cleared

6.9.1 Description

Conditional relative branch. Tests a single bit in SREG and branches relatively to the PC if the bit is cleared. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form.

Operation:

(i) If SREG(s) == 0 then PC ← PC + k + 1, else PC ← PC + 1

Syntax: Operands: Program Counter:

(i) BRBC s,k 0 ≤ s ≤ 7, -64 ≤ k ≤ +63 PC ← PC + k + 1

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111 01kk kkkk ksss

6.9.2 Status Register (SREG) and Boolean Formula

i) If the condition is false.
ii) If the condition is true.

6.10 BRBS - Branch if Bit in SREG is Set

6.10.1 Description

Conditional relative branch. Tests a single bit in SREG and branches relatively to the PC if the bit is set. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form.

Operation:

(i) If SREG(s) == 1 then PC ← PC + k + 1, else PC ← PC + 1

Syntax: Operands: Program Counter:

(i) BRBS s,k 0 ≤ s ≤ 7, -64 ≤ k ≤ +63 PC ← PC + k + 1

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111 00kk kkkk ksss

6.10.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

bst r0,3 ; Load T bit with bit 3 of r0
brbs 6,bitset ; Branch T bit was set
...
bitset: nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-10. Cycles

Name	Cycles
	i	ii
AVRe	1	2
AVRxm	1	2
AVRxt	1	2
AVRrc	1	2

i) If the condition is false.
ii) If the condition is true.

6.11 BRCC – Branch if Carry Cleared

6.11.1 Description

Conditional relative branch. Tests the Carry (C) flag and branches relatively to the PC if C is cleared. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form. (Equivalent to instruction BRBC 0,k.)

Operation:

(i) If C == 0 then PC ← PC + k + 1, else PC ← PC + 1

Syntax: Operands: Program Counter:

(i) BRCC k -64 ≤ k ≤ +63 PC ← PC + k + 1

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111 01kk kkkk k000

6.11.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

add r22,r23 ; Add r23 to r22
brcc nocarry ; Branch if carry cleared
...
nocarry: nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-11. Cycles

Name	Cycles
	i	ii
AVRe	1	2
AVRxm	1	2
AVRxt	1	2
AVRrc	1	2

i) If the condition is false.
ii) If the condition is true.

6.12 BRCS – Branch if Carry Set

6.12.1 Description

Conditional relative branch. Tests the Carry (C) flag and branches relatively to the PC if C is set. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form. (Equivalent to instruction BRBS 0,k.)

Operation:

(i) If C == 1 then PC ← PC + k + 1, else PC ← PC + 1

Syntax: Operands: Program Counter:

(i) BRCS k -64 ≤ k ≤ +63 PC ← PC + k + 1

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111 00kk kkkk k000

6.12.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

cpi r26,0x56 ; Compare r26 with 0x56
brcs carry ; Branch if carry set
...
carry: nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-12. Cycles

Name	Cycles
	i	ii
AVRe	1	2
AVRxm	1	2
AVRxt	1	2
AVRrc	1	2

i) If the condition is false.
ii) If the condition is true.

6.13 BREAK - Break

6.13.1 Description

The BREAK instruction is used by the On-chip Debug system and not used by the application software. When the BREAK instruction is executed, the AVR CPU is set in the Stopped state. This gives the On-chip Debugger access to internal resources.

If the device is locked, or the on-chip debug system is not enabled, the CPU will treat the BREAK instruction as a NOP and will not enter the Stopped state.

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) On-chip Debug system breakpoint instruction.

Syntax: Operands: Program Counter:

(i) BREAK None PC ← PC + 1

16-bit Opcode:

1001 0101 1001 1000

6.13.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Words 1 (2 bytes)

Table 6-13. Cycles

Name Cycles
AVRe 1
AVRxm	1
AVRxt	1
AVRrc	1

6.14 BREQ – Branch if Equal

6.14.1 Description

Conditional relative branch. Tests the Zero (Z) flag and branches relatively to the PC if Z is set. If the instruction is executed immediately after any of the instructions CP, CPI, SUB, or SUBI, the branch will occur only if the unsigned or signed binary number represented in Rd was equal to the unsigned or signed binary number represented in Rr. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form. (Equivalent to instruction BRBS 1,k.)

Operation:

(i) If Rd == Rr (Z == 1) then PC ← PC + k + 1, else PC ← PC + 1

Syntax: Operands: Program Counter:

(i) BREQ k -64 ≤ k ≤ +63 PC ← PC + k + 1

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111 00kk kkkk k001

6.14.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

cp r1,r0 ; Compare registers r1 and r0
breq equal ; Branch if registers equal
...
equal: nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-14. Cycles

Name Cycles
	i	ii
AVRe 1 2
AVRxm	1 2
AVRxt	1 2
AVRrc	1 2

i) If the condition is false.
ii) If the condition is true.

6.15 BRGE – Branch if Greater or Equal (Signed)

6.15.1 Description

Conditional relative branch. Tests the Sign (S) flag and branches relatively to the PC if S is cleared. If the instruction is executed immediately after any of the instructions CP, CPI, SUB, or SUBI, the branch will occur only if the signed binary number represented in Rd was greater than or equal to the signed binary number represented in Rr. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form. (Equivalent to instruction BRBC 4,k.)

Operation:

(i) If Rd ≥ Rr (S == 0) then PC ← PC + k + 1, else PC ← PC + 1

Syntax:

Operands:

Program Counter:

(i) BRGE k -64 ≤ k ≤ +63 PC ← PC + k + 1

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111 01kk kkkk k100

6.15.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

cp r11,r12 ; Compare registers r11 and r12
brge greateq ; Branch if r11 ≥ r12 (signed)
...
greateq: nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-15. Cycles

Name Cycles
	i	ii
AVRe 1 2
AVRxm	1 2
AVRxt	1 2
AVRrc	1 2

i) If the condition is false.
ii) If the condition is true.

6.16 BRHC – Branch if Half Carry Flag is Cleared

6.16.1 Description

Conditional relative branch. Tests the Half Carry (H) flag and branches relatively to the PC if H is cleared. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form. (Equivalent to instruction BRBC 5,k.)

Operation:

(i) If H == 0 then PC ← PC + k + 1, else PC ← PC + 1

Syntax:

Operands:

Program Counter:

(i) BRHC k -64 ≤ k ≤ +63 PC ← PC + k + 1

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111 01kk kkkk k101

6.16.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

brhc hclear ; Branch if Half Carry flag cleared
...
hclear: nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-16. Cycles

Name Cycles
	i	ii
AVRe 1 2
AVRxm 1 2
AVRxt 1 2
AVRrc 1 2

i) If the condition is false.
ii) If the condition is true.

6.17 BRHS – Branch if Half Carry Flag is Set

6.17.1 Description

Conditional relative branch. Tests the Half Carry (H) flag and branches relatively to the PC if H is set. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form. (Equivalent to instruction BRBS 5,k.)

Operation:

(i) If H == 1 then PC ← PC + k + 1, else PC ← PC + 1

Syntax: Operands:

Program Counter:

(i) BRHS k -64 ≤ k ≤ +63

PC ← PC + k + 1

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111 00kk kkkk k101

6.17.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

brhs hset ; Branch if Half Carry flag set
...
hset: nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-17. Cycles

Name Cycles
	i	ii
AVRe 1 2
AVRxm 1 2
AVRxt 1 2
AVRrc 1 2

i) If the condition is false.
ii) If the condition is true.

6.18 BRID – Branch if Global Interrupt is Disabled

6.18.1 Description

Conditional relative branch. Tests the Global Interrupt Enable (I) bit and branches relatively to the PC if I is cleared. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form. (Equivalent to instruction BRBC 7,k.)

Operation:

(i) If I == 0 then PC ← PC + k + 1, else PC ← PC + 1

Syntax: Operands:

Program Counter:

(i) BRID k -64 ≤ k ≤ +63

PC ← PC + k + 1

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111

01kk

kkkk

k111

6.18.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

brid intdis ; Branch if interrupt disabled
...
intdis: nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-18. Cycles

Name Cycles
	i	ii
AVRe 1 2
AVRxm 1 2
AVRxt 1 2
AVRrc 1 2

i) If the condition is false.
ii) If the condition is true.

6.19 BRIE – Branch if Global Interrupt is Enabled

6.19.1 Description

Conditional relative branch. Tests the Global Interrupt Enable (I) bit and branches relatively to the PC if I is set. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form. (Equivalent to instruction BRBS 7,k.)

Operation:

(i) If I == 1 then PC ← PC + k + 1, else PC ← PC + 1

Syntax: Operands: Program Counter:

(i) BRIE k -64 ≤ k ≤ +63

PC ← PC + k + 1

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111

00kk

kkkk

k111

6.19.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

brie inten ; Branch if interrupt enabled
...
inten: nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-19. Cycles

Name Cycles
	i	ii
AVRe 1 2
AVRxm 1 2
AVRxt 1 2
AVRrc 1 2

i) If the condition is false.
ii) If the condition is true.

6.20 BRLO – Branch if Lower (Unsigned)

6.20.1 Description

Conditional relative branch. Tests the Carry (C) flag and branches relatively to the PC if C is set. If the instruction is executed immediately after any of the instructions CP, CPI, SUB, or SUBI, the branch will occur only if the unsigned binary number represented in Rd was smaller than the unsigned binary number represented in Rr. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form. (Equivalent to instruction BRBS 0,k.)

Operation:

(i) If Rd < Rr (C == 1) then PC ← PC + k + 1, else PC ← PC + 1

Syntax: Operands: Program Counter:

(i) BRLO k -64 ≤ k ≤ +63

$$ \mathrm{PC} \leftarrow \mathrm{PC} + k + 1 $$

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111

00kk

kkkk

k000

6.20.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

eor r19,r19 ; Clear r19
loop: inc r19 ; Increase r19
...
cpi r19,0x10 ; Compare r19 with 0x10
brlo loop ; Branch if r19 < 0x10 (unsigned)
nop ; Exit from loop (do nothing) 

Words 1 (2 bytes)

Table 6-20. Cycles

Name Cycles
	i	ii
AVRe 1 2
AVRxm 1 2
AVRxt 1 2
AVRrc 1 2

i) If the condition is false.
ii) If the condition is true.

6.21 BRLT – Branch if Less Than (Signed)

6.21.1 Description

Conditional relative branch. Tests the Sign (S) flag and branches relatively to the PC if S is set. If the instruction is executed immediately after any of the instructions CP, CPI, SUB, or SUBI, the branch will occur only if the signed binary number represented in Rd was less than the signed binary number represented in Rr. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form. (Equivalent to instruction BRBS 4,k.)

Operation:

(i) If Rd < Rr (S == 1) then PC ← PC + k + 1, else PC ← PC + 1

Syntax: Operands: Program Counter:

(i) BRLT k -64 ≤ k ≤ +63 PC ← PC + k + 1

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111

00kk

kkkk

k100

6.21.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

cp r16,r1 ; Compare r16 to r1
brlt less ; Branch if r16 < r1 (signed)
...
less: nop ; Branch destination (do nothing) 

Words

1 (2 bytes)

Table 6-21. Cycles

Name Cycles
	i	ii
AVRe 1 2
AVRxm 1 2
AVRxt 1 2
AVRrc 1 2

i) If the condition is false.
ii) If the condition is true.

6.22 BRMI – Branch if Minus

6.22.1 Description

Conditional relative branch. Tests the Negative (N) flag and branches relatively to the PC if N is set. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form. (Equivalent to instruction BRBS 2,k.)

Operation:

(i) If N == 1 then PC ← PC + k + 1, else PC ← PC + 1

Syntax: Operands: Program Counter:

(i) BRMI k -64 ≤ k ≤ +63 PC ← PC + k + 1

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111

00kk

kkkk

k010

6.22.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

subi r18,4	; Subtract 4 from r18
brmi negative	; Branch if result negative
...
negative: nop	; Branch destination (do nothing)

Words

1 (2 bytes)

Table 6-22. Cycles

Name Cycles
	i	ii
AVRe 1 2
AVRxm 1 2
AVRxt 1 2
AVRrc 1 2

i) If the condition is false.
ii) If the condition is true.

6.23 BRNE – Branch if Not Equal

6.23.1 Description

Conditional relative branch. Tests the Zero (Z) flag and branches relatively to the PC if Z is cleared. If the instruction is executed immediately after any of the instructions CP, CPI, SUB, or SUBI, the branch will occur only if the unsigned or signed binary number represented in Rd was not equal to the unsigned or signed binary number represented in Rr. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form. (Equivalent to instruction BRBC 1,k.)

Operation:

(i) If Rd ≠ Rr (Z == 0) then PC ← PC + k + 1, else PC ← PC + 1

Syntax: Operands: Program Counter:

(i) BRNE k -64 ≤ k ≤ +63

$$ \mathrm{PC} \leftarrow \mathrm{PC} + k + 1 $$

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111

01kk

kkkk

k001

6.23.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

eor r27,r27 ; Clear r27
loop: inc r27 ; Increase r27
...
cpi r27,5 ; Compare r27 to 5
brne loop ; Branch if r27<>5
nop ; Loop exit (do nothing) 

Words

1 (2 bytes)

Table 6-23. Cycles

Name Cycles
	i	ii
AVRe 1 2
AVRxm 1 2
AVRxt 1 2
AVRrc 1 2

i) If the condition is false.
ii) If the condition is true.

6.24 BRPL – Branch if Plus

6.24.1 Description

Conditional relative branch. Tests the Negative (N) flag and branches relatively to the PC if N is cleared. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form. (Equivalent to instruction BRBC 2,k.)

Operation:

(i) If N == 0 then PC ← PC + k + 1, else PC ← PC + 1

Syntax: Operands: Program Counter:

(i) BRPL k -64 ≤ k ≤ +63 PC ← PC + k + 1

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111

01kk

kkkk

k010

6.24.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

subi	r26,0x50	; Subtract 0x50 from r26
brpl	positive	; Branch if r26 positive
...
positive: nop		; Branch destination (do nothing)

Words

1 (2 bytes)

Table 6-24. Cycles

Name Cycles
	i	ii
AVRe 1 2
AVRxm 1 2
AVRxt 1 2
AVRrc 1 2

i) If the condition is false.
ii) If the condition is true.

6.25 BRSH – Branch if Same or Higher (Unsigned)

6.25.1 Description

Conditional relative branch. Tests the Carry (C) flag and branches relatively to the PC if C is cleared. If the instruction is executed immediately after execution of any of the instructions CP, CPI, SUB, or SUBI, the branch will occur only if the unsigned binary number represented in Rd was greater than or equal to the unsigned binary number represented in Rr. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form. (Equivalent to instruction BRBC 0,k.)

Operation:

(i) If Rd ≥Rr (C == 0) then PC ← PC + k + 1, else PC ← PC + 1

Syntax: Operands: Program Counter:

(i) BRSH k -64 ≤ k ≤ +63

$$ \mathrm{PC} \leftarrow \mathrm{PC} + k + 1 $$

$$ \begin{array}{l} \text {PC} \leftarrow \text {PC} + 1, \text {if the condition is} \ \text {false} \end{array} $$

16-bit Opcode:

1111

01kk

kkkk

k000

6.25.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

subi r19,4 ; Subtract 4 from r19
brsh highsm ; Branch if r19 >= 4 (unsigned)
...
highsm: nop ; Branch destination (do nothing) 

Words

1 (2 bytes)

Table 6-25. Cycles

Name Cycles
	i	ii
AVRe 1 2
AVRxm 1 2
AVRxt 1 2
AVRrc 1 2

i) If the condition is false.
ii) If the condition is true.

6.26 BRTC - Branch if the T Bit is Cleared

6.26.1 Description

Conditional relative branch. Tests the T bit and branches relatively to the PC if T is cleared. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form. (Equivalent to instruction BRBC 6,k.)

Operation:

(i) If T == 0 then PC ← PC + k + 1, else PC ← PC + 1

Syntax: Operands: Program Counter:

(i) BRTC k -64 ≤ k ≤ +63 PC ← PC + k + 1

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111

01kk

kkkk

k110

6.26.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

bst	r3,5	; Store bit 5 of r3 in T bit
brtc	tclear	; Branch if this bit was cleared
...
tclear:	nop	; Branch destination (do nothing)

Words

1 (2 bytes)

Table 6-26. Cycles

Name Cycles
	i	ii
AVRe 1 2
AVRxm 1 2
AVRxt 1 2
AVRrc 1 2

i) If the condition is false.
ii) If the condition is true.

6.27 BRTS - Branch if the T Bit is Set

6.27.1 Description

Conditional relative branch. Tests the T bit and branches relatively to the PC if T is set. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form. (Equivalent to instruction BRBS 6,k.)

Operation:

(i) If T == 1 then PC ← PC + k + 1, else PC ← PC + 1

Syntax: Operands: Program Counter:

(i) BRTS k -64 ≤ k ≤ +63 PC ← PC + k + 1

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111

00kk

kkkk

k110

6.27.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

bst	r3,5	; Store bit 5 of r3 in T bit
brts	tset	; Branch if this bit was set
...
tset: nop		; Branch destination (do nothing)

Words

1 (2 bytes)

Table 6-27. Cycles

Name Cycles
	i	ii
AVRe 1 2
AVRxm 1 2
AVRxt 1 2
AVRrc 1 2

i) If the condition is false.
ii) If the condition is true.

6.28 BRVC – Branch if Overflow Cleared

6.28.1 Description

Conditional relative branch. Tests the Overflow (V) flag and branches relatively to the PC if V is cleared. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form. (Equivalent to instruction BRBC 3,k.)

Operation:

(i) If V == 0 then PC ← PC + k + 1, else PC ← PC + 1

Syntax: Operands: Program Counter:

(i) BRVC k -64 ≤ k ≤ +63 PC ← PC + k + 1

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111

01kk

kkkk

k011

6.28.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

add	r3,r4	; Add r4 to r3
brvc	noover	; Branch if no overflow
...
noover:	nop	; Branch destination (do nothing)

Words

1 (2 bytes)

i) If the condition is false.
ii) If the condition is true.

Table 6-28. Cycles

Name Cycles
	i	ii
AVRe 1 2
AVRxm 1 2
AVRxt 1 2
AVRrc 1 2

6.29 BRVS - Branch if Overflow Set

6.29.1 Description

Conditional relative branch. Tests the Overflow (V) flag and branches relatively to the PC if V is set. This instruction branches relatively to the PC in either direction (PC - 63 ≤ destination ≤ PC + 64). Parameter k is the offset from the PC and is represented in two's complement form. (Equivalent to instruction BRBS 3,k.)

Operation:

(i) If V == 1 then PC ← PC + k + 1, else PC ← PC + 1

Syntax: Operands: Program Counter:

(i) BRVS k -64 ≤ k ≤ +63 PC ← PC + k + 1

PC ← PC + 1, if the condition is false

16-bit Opcode:

1111

00kk

kkkk

k011

6.29.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

add r3,r4 ; Add r4 to r3
brvs overfl ; Branch if overflow
...
overfl: nop ; Branch destination (do nothing) 

Words

1 (2 bytes)

Table 6-29. Cycles

Name Cycles
	i	ii
AVRe 1 2
AVRxm 1 2
......continued
Name Cycles
	i	ii
AVRxt 1 2
AVRrc 1 2

i) If the condition is false.
ii) If the condition is true.

6.30 BSET - Bit Set in SREG

6.30.1 Description

Sets a single flag or bit in SREG.

Operation:

(i) SREG(s) ← 1

Syntax: Operands: Program Counter:

(i) BSET s 0 ≤ s ≤ 7 PC ← PC + 1

16-bit Opcode:

1001 0100 0sss 1000

6.30.2 Status Register (SREG) and Boolean Formula

If (s == 7) then I ← 1, else unchanged.

T If (s == 6) then T ← 1, else unchanged.

H If (s == 5) then H ← 1, else unchanged.

S If (s == 4) then S ← 1, else unchanged.

V If (s == 3) then V ← 1, else unchanged.

N If (s == 2) then N ← 1, else unchanged.

Z If (s == 1) then Z ← 1, else unchanged.

C If (s == 0) then C ← 1, else unchanged.

Example:

bset 6 ; Set T bit
bset 7 ; Enable interrupt 

Words

1 (2 bytes)

Table 6-30. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.31 BST - Bit Store from Bit in Register to T Bit in SREG

6.31.1 Description

Stores bit b from Rd to the T bit in SREG (Status Register).

Operation:

(i) T ← Rd(b)

Syntax: Operands: Program Counter:

(i) BST Rd, b 0 ≤ d ≤ 31, 0 ≤ b ≤ 7 PC ← PC + 1

16-bit Opcode:

1111 101d dddd 0bbb

6.31.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-		-	-	-	-	-	-

T '0' if bit b in Rd is cleared. Set to '1' otherwise.

Example:

	; Copy bit
bst r1,2	; Store bit 2 of r1 in T bit
bld r0,4	; Load T into bit 4 of r0

Words

1 (2 bytes)

Table 6-31. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.32 CALL – Long Call to a Subroutine

6.32.1 Description

Calls to a subroutine within the entire program memory. The return address (to the instruction after the CALL) will be stored on the Stack. (See also RCALL.) The Stack Pointer uses a post-decrement scheme during CALL.

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) PC ← k Devices with 16-bit PC, 128 KB program memory maximum.
(ii) PC ← k Devices with 22-bit PC, 8 MB program memory maximum.

Syntax: Operands: Program Counter: Stack:

(i) CALL k 0 ≤ k < 64K PC ← k STACK ← PC + 2

SP ← SP-2, (2 bytes, 16 bits)

(ii) CALL k 0 ≤ k < 4M PC ← k STACK ← PC + 2

SP ← SP-3 (3 bytes, 22 bits)

32-bit Opcode:

1001 010k kkkk 111k
kkkk kkkk kkkk kkkk

6.32.2 Status Register (SREG) and Boolean Formula

ITHSV		NZC
-	-	-	-	-	-	-	-

Example:

mov r16,r0 ; Copy r0 to r16
call check ; Call subroutine
nop ; Continue (do nothing)
...
check:
cpi r16,0x42 ; Check if r16 has a special value
breq error ; Branch if equal
ret ; Return from subroutine
...
error:
rjmp error ; Infinite loop 

Words

2 (4 bytes)

Table 6-32. Cycles

Name	Cycles
	16-bit PC	22-bit PC
AVRe	4^(1)	5^(1)
AVRxm	3^(1)	4^(1)
......continued
Name Cycles
	16-bit PC 22-bit PC
AVRxt 3 4
AVRrc N/A N/A

Note:

1. Cycle times for data memory access assume internal RAM access and are not valid for accessing external RAM.

6.33 CBI - Clear Bit in I/O Register

6.33.1 Description

Clears a specified bit in an I/O Register. This instruction operates on the lower 32 I/O Registers – addresses 0-31.

Operation:

(i) I/O(A,b) ← 0

Syntax: Operands: Program Counter:

(i) CBI A, b 0 ≤ A ≤ 31, 0 ≤ b ≤ 7 PC ← PC + 1

16-bit Opcode:

1001 1000 AAAA

Abbb

6.33.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

cbi 0x12,7 ; Clear bit 7 at address 0x12

Words

1 (2 bytes)

Table 6-33. Cycles

Name	Cycles
AVRe	2
AVRxm	1
AVRxt	1
AVRrc	1

6.34 CBR - Clear Bits in Register

6.34.1 Description

Clears the specified bits in register Rd. Performs the logical AND between the contents of register Rd and the complement of the constant mask K. The result will be placed in register Rd. (Equivalent to ANDI Rd,(0xFF - K).)

Operation:

(i) Rd ← Rd ∧ (0xFF - K)

Syntax: Operands: Program Counter:

(i) CBR Rd, K 16 ≤ d ≤ 31, 0 ≤ K ≤ 255 PC ← PC + 1

16-bit Opcode: (see ANDI with K complemented)

6.34.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
--- ⇔ 0 ⇔ ⇔ -

S N ⊕ V, for signed tests.

v0

Cleared.

N R7

Set if MSB of the result is set; cleared otherwise.

Z 7 6 5 4 3 2 1 0

Set if the result is 0x00; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

cbr r16,0xF0 ; Clear upper nibble of r16
cbr r18,1 ; Clear bit 0 in r18 

Words

1 (2 bytes)

Table 6-34. Cycles

Name	Cycles
AVRe	1
AVRxm	1
AVRxt	1
AVRrc	1

6.35 CLC – Clear Carry Flag

6.35.1 Description

Clears the Carry (C) flag in SREG (Status Register). (Equivalent to instruction BCLR 0.)

Operation:

(i) C ← 0

Syntax: Operands: Program Counter:

(i) CLC None PC ← PC + 1

16-bit Opcode:

1001 0100 1000 1000

6.35.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----0

C0

Carry flag cleared.

Example:

add r0,r0 ; Add r0 to itself
clc ; Clear Carry flag 

Words 1 (2 bytes)

Table 6-35. Cycles

Name Cycles
AVRe	1
AVRxm	1
AVRxt	1
AVRrc	1

6.36 CLH – Clear Half Carry Flag

6.36.1 Description

Clears the Half Carry (H) flag in SREG (Status Register). (Equivalent to instruction BCLR 5.)

Operation:

(i) H 0

Syntax: Operands: Program Counter:

(i) CLH None PC ← PC + 1

16-bit Opcode:

1001 0100 1101 1000

6.36.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
--0----

H0

Half Carry flag cleared.

Example:

clh ; Clear the Half Carry flag 

Words 1 (2 bytes)

Table 6-36. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt	1
AVRrc	1

6.37 CLI – Clear Global Interrupt Enable Bit

6.37.1 Description

Clears the Global Interrupt Enable (I) bit in SREG (Status Register). The interrupts will be immediately disabled. No interrupt will be executed after the CLI instruction, even if it occurs simultaneously with the CLI instruction. (Equivalent to instruction BCLR 7.)

Operation:

(i) 1 0

Syntax:

Operands:

Program Counter:

(i) CLI

None PC ← PC + 1

16-bit Opcode:

1001 0100 1111

1000

6.37.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
0----

10

Global Interrupt Enable bit cleared.

Example:

in temp, SREG ; Store SREG value (temp must be defined by user)
cli ; Disable interrupts during timed sequence
sbi EECR, EEMWE ; Start EEPROM write
sbi EECR, EEWE
out SREG, temp ; Restore SREG value (I-flag) 

Words 1 (2 bytes)

Table 6-37. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.38 CLN – Clear Negative Flag

6.38.1 Description

Clears the Negative (N) flag in SREG (Status Register). (Equivalent to instruction BCLR 2.)

Operation:

(i) N 0

Syntax: Operands: Program Counter:

(i) CLN None PC ← PC + 1

16-bit Opcode:

1001 0100 1010 1000

6.38.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	0	-	-

N 0

Negative flag cleared.

Example:

add r2,r3 ; Add r3 to r2
cln ; Clear Negative flag 

Words 1 (2 bytes)

Table 6-38. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.39 CLR - Clear Register

6.39.1 Description

Clears a register. This instruction performs an Exclusive OR between a register and itself. This will clear all bits in the register. (Equivalent to instruction EOR Rd,Rd.)

Operation:

(i) Rd ← Rd ⊕ Rd

Syntax: Operands: Program Counter:

(i) CLR Rd 0 ≤ d ≤ 31 PC ← PC + 1

16-bit Opcode: (see EOR Rd,Rd)

0010 01dd dddd dddd

6.39.2 Status Register (SREG) and Boolean Formula

ITHSV		NZC
-	-	-	0	0	0	1	-

S	0
	Cleared.
V	0
	Cleared.
N	0
	Cleared.
Z	1
	Set.

R (Result) equals Rd after the operation.

Example:

clr r18 ; clear r18
loop: inc r18 ; increase r18
...
cpi r18,0x50 ; Compare r18 to 0x50
brne loop 

Words 1 (2 bytes)

Table 6-39. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.40 CLS – Clear Sign Flag

6.40.1 Description

Clears the Sign (S) flag in SREG (Status Register). (Equivalent to instruction BCLR 4.)

Operation:

(i) S 0

Syntax: Operands: Program Counter:

(i) CLS None PC ← PC + 1

16-bit Opcode:

1001 0100 1100 1000

6.40.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	0	-	-	-	-

s 0

Sign flag cleared.

Example:

add r2,r3 ; Add r3 to r2
cls ; Clear Sign flag 

Words 1 (2 bytes)

Table 6-40. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.41 CLT - Clear T Bit

6.41.1 Description

Clears the T bit in SREG (Status Register). (Equivalent to instruction BCLR 6.)

Operation:

(i) T 0

Syntax: Operands: Program Counter:

(i) CLT None PC ← PC + 1

16-bit Opcode:

1001 0100 1110 1000

6.41.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
-0----

T0

T bit cleared.

Example:

clt ; Clear T bit 

Words

1 (2 bytes)

Table 6-41. Cycles

Name	Cycles
AVRe	1
AVRxm	1
AVRxt	1
AVRrc	1

6.42 CLV - Clear Overflow Flag

6.42.1 Description

Clears the Overflow (V) flag in SREG (Status Register). (Equivalent to instruction BCLR 3.)

Operation:

(i) V ← 0

Syntax: Operands: Program Counter:

(i) CLV

None PC ← PC + 1

16-bit Opcode:

1001 0100 1011 1000

6.42.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----0----

v0

Overflow flag cleared.

Example:

add r2,r3 ; Add r3 to r2
clv ; Clear Overflow flag 

Words 1 (2 bytes)

Table 6-42. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.43 CLZ - Clear Zero Flag

6.43.1 Description

Clears the Zero (Z) flag in SREG (Status Register). (Equivalent to instruction BCLR 1.)

Operation:

(i) Z 0

Syntax: Operands:

Program Counter:

(i) CLZ

None

PC ← PC + 1

16-bit Opcode:

1001 0100 1001 1000

6.43.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----0-

z 0

Zero flag cleared.

Example:

add r2,r3 ; Add r3 to r2
clz ; Clear zero 

Words 1 (2 bytes)

Table 6-43. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.44 COM – One's Complement

6.44.1 Description

This instruction performs a One's Complement of register Rd.

Operation:

(i) Rd ← 0xFF - Rd

Syntax: Operands: Program Counter:

(i) COM Rd 0 ≤ d ≤ 31 PC ← PC + 1

16-bit Opcode:

1001 010d dddd 0000

6.44.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	⇔	0	⇔	⇔	1

S N ⊕ V, for signed tests.

v 0

Cleared.

N R7

Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x00; cleared otherwise.

C 1

Set.

R (Result) equals Rd after the operation.

Example:

com r4 ; Take one's complement of r4
breq zero ; Branch if zero
...
zero: nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-44. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.45 CP - Compare

6.45.1 Description

This instruction performs a compare between two registers Rd and Rr. None of the registers are changed. All conditional branches can be used after this instruction.

Operation:

(i) Rd - Rr

Syntax: Operands: Program Counter:

(i) CP Rd, Rr 0 ≤ d ≤ 31, 0 ≤ r ≤ 31 PC ← PC + 1

16-bit Opcode:

0001 01rd dddd rrrr

6.45.2 Status Register (SREG) and Boolean Formula

H Rd3 ∧ Rr3 ∨ Rr3 ∧ R3 ∨ R3 ∧ Rd3

Set if there was a borrow from bit 3; cleared otherwise.

S N ⊕ V, for signed tests.

V Rd7 ∧ Rr7 ∧ R7 ∨ Rd7 ∧ Rr7 ∧ R7

Set if two's complement overflow resulted from the operation; cleared otherwise.

N R7

Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x00; cleared otherwise.

C 7 Rr7 Rr7 R7 R7 7

Set if the absolute value of the contents of Rr is larger than the absolute value of Rd; cleared otherwise.

R (Result) after the operation.

Example:

cp r4,r19 ; Compare r4 with r19
brne noteq ; Branch if r4 <> r19
...
noteq:
nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-45. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.46 CPC - Compare with Carry

6.46.1 Description

This instruction performs a compare between two registers Rd and Rr and also takes into account the previous carry. None of the registers are changed. All conditional branches can be used after this instruction.

Operation:

(i) Rd - Rr - C

Syntax: Operands: Program Counter:

(i) CPC Rd, Rr 0 ≤ d ≤ 31, 0 ≤ r ≤ 31 PC ← PC + 1

16-bit Opcode:

0000

01rd

dddd

rrrr

6.46.2 Status Register (SREG) and Boolean Formula

Set if there was a borrow from bit 3; cleared otherwise.

S N ⊕ V, for signed tests.

V Rd7 ∧ Rr7 ∧ R7 ∨ Rd7 ∧ Rr7 ∧ R7

Set if two's complement overflow resulted from the operation; cleared otherwise.

N R7

Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0 ∧ Z

The previous value remains unchanged when the result is zero; cleared otherwise.

C 7 ∧ Rr7 ∨ Rr7 ∧ R7 ∨ R7 ∧ 7

Set if the absolute value of the contents of Rr plus previous carry is larger than the absolute value of Rd; cleared otherwise.

R (Result) after the operation.

Example:

; Compare r3:r2 with r1:r0
cp r2,r0 ; Compare low byte
cpc r3,r1 ; Compare high byte
brne noteq ; Branch if not equal
...
noteq:
nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-46. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.47 CPI – Compare with Immediate

6.47.1 Description

This instruction performs a compare between register Rd and a constant. The register is not changed. All conditional branches can be used after this instruction.

Operation:

(i) Rd - K

Syntax: Operands: Program Counter:

(i) CPI Rd, K 16 ≤ d ≤ 31, 0 ≤ K ≤ 255 PC ← PC + 1

16-bit Opcode:

0011 KKKK dddd KKKK

6.47.2 Status Register (SREG) and Boolean Formula

H Rd3 ∧ K3 ∨ K3 ∧ R3 ∨ R3 ∧ Rd3

Set if there was a borrow from bit 3; cleared otherwise.

S N ⊕ V, for signed tests.

V Rd7 ∧ K7 ∧ R7 ∨ Rd7 ∧ K7 ∧ R7

Set if two's complement overflow resulted from the operation; cleared otherwise.

N R7

Set if MSB of the result is set; cleared otherwise.

Set if the result is 0x00; cleared otherwise.

C Rd7 ∧ K7 ∨ K7 ∧ R7 ∨ R7 ∧ Rd7

Set if the absolute value of K is larger than the absolute value of Rd; cleared otherwise.

R (Result) after the operation.

Example:

cpi r19,3 ; Compare r19 with 3
brne error ; Branch if r19<>3
...
error:
nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-47. Cycles

Name Cycles
AVRe	1
AVRxm	1
AVRxt	1
AVRrc	1

6.48 CPSE – Compare Skip if Equal

6.48.1 Description

This instruction performs a compare between two registers Rd and Rr and skips the next instruction if Rd == Rr.

Operation:

(i) If Rd == Rr then PC ← PC + 2 (or 3) else PC ← PC + 1

Syntax: Operands: Program Counter:

(i) CPSE Rd, Rr 0 ≤ d ≤ 31, 0 ≤ r ≤ 31 PC ← PC + 1, Condition false - no

skip

PC ← PC + 2, Skip a one word instruction

PC ← PC + 3, Skip a two word instruction

16-bit Opcode:

0001 00rd dddd rrrr

6.48.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

inc r4 ; Increase r4
cpse r4,r0 ; Compare r4 to r0
neg r4 ; Only executed if r4<>r0
nop ; Continue (do nothing) 

Words 1 (2 bytes)

Table 6-48. Cycles

Name Cycles
	i ii	iii
AVRe	1	2	3
AVRxm	1	2	3
AVRxt	1	2	3
AVRrc	1	2	N/A

i) If the condition is false (no skip).

ii) If the condition is true (skip is executed) and the instruction skipped is one word.

iii) If the condition is true (skip is executed) and the instruction skipped is two words.

6.49 DEC - Decrement

6.49.1 Description

Subtracts one -1- from the contents of register Rd and places the result in the destination register Rd.

The C flag in SREG is not affected by the operation, thus allowing the DEC instruction to be used on a loop counter in multiple-precision computations.

When operating on unsigned values, only BREQ and BRNE branches can be expected to perform consistently. When operating on two's complement values, all signed branches are available.

Operation:

(i) Rd ← Rd - 1

Syntax: Operands: Program Counter:

(i) DEC Rd 0 ≤ d ≤ 31 PC ← PC + 1

16-bit Opcode:

1001 010d dddd 1010

6.49.2 Status Register and Boolean Formula

ITHSVNZC
--- ⇔ ⇔ ⇔ ⇔ -

S N ⊕ V, for signed tests.

V R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if two's complement overflow resulted from the operation; cleared otherwise. Two's complement overflow occurs only if Rd was 0x80 before the operation.

N R7

Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x00; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

ldi r17,0x10 ; Load constant in r17
loop:
add r1,r2 ; Add r2 to r1
dec r17 ; Decrement r17
brne loop ; Branch if r17<>0
nop ; Continue (do nothing) 

Words

1 (2 bytes)

Table 6-49. Cycles

Name	Cycles
AVRe	1
AVRxm	1
AVRxt	1
AVRrc	1

6.50 DES – Data Encryption Standard

6.50.1 Description

The module is an instruction set extension to the AVR CPU, performing DES iterations. The 64-bit data block (plaintext or ciphertext) is placed in the CPU Register File, registers R0-R7, where the LSB of data is placed in the LSB of R0 and the MSB of data is placed in the MSB of R7. The full 64-bit key (including parity bits) is placed in registers R8-R15, organized in the Register File with the LSB of the key in the LSB of R8 and the MSB of the key in the MSB of R15. Executing one DES instruction performs one round in the DES algorithm. Sixteen rounds must be executed in increasing order to form the correct DES ciphertext or plaintext. Intermediate results are stored in the Register File (R0-R15) after each DES instruction. The instruction's operand (K) determines which round is executed, and the Half Carry (H) flag determines whether encryption or decryption is performed.

The DES algorithm is described in “Specifications for the Data Encryption Standard” (Federal Information Processing Standards Publication 46). Intermediate results in this implementation differ from the standard because the initial permutation and the inverse initial permutation are performed in each iteration. This does not affect the result in the final ciphertext or plaintext but reduces the execution time.

Operation:

(i) If H == 0 then Encrypt round (R7-R0, R15-R8, K)

If H == 1 then Decrypt round (R7-R0, R15-R8, K)

Syntax: Operands: Program Counter:

(i) DES K 0x00≤K≤0x0F PC ← PC + 1

16-bit Opcode:

1001 0100 KKKK 1011

Example:

Name Cycles
AVRe N/A
AVRxm 1 / 2
AVRxt N/A
AVRrc N/A

Note: If the DES instruction is succeeding a non-DES instruction, it requires two cycles otherwise one.

6.51 EICALL – Extended Indirect Call to Subroutine

6.51.1 Description

Indirect call of a subroutine pointed to by the Z (16-bit) Pointer Register in the Register File and the EIND Register in the I/O space. This instruction allows for indirect calls to the entire 4M (words) program memory space. See also ICALL. The Stack Pointer uses a post-decrement scheme during EICALL.

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) PC(15:0) ← Z(15:0)

PC(21:16) ← EIND

Syntax: Operands: Program Counter: Stack:

(i) EICALL None See Operation STACK ← PC + 1

SP ← SP - 3 (3 bytes, 22 bits)

16-bit Opcode:

1001 0101 0001 1001

6.51.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

ldi r16,0x05 ; Set up EIND and Z-pointer

out EIND,r16

ldi r30,0x00

ldi r31,0x10

eicall ; Call to 0x051000

Words 1 (2 bytes)

Table 6-51. Cycles

Name	Cycles
AVRe	4^(2)
AVRxm	3^(2)
AVRxt	3
AVRrc	N/A

Notes:

1. The instruction is only implemented on devices with 22-bit PC
2. Cycle times for data memory access assume internal RAM access and are not valid for accessing external RAM.

6.52 EIJMP - Extended Indirect Jump

6.52.1 Description

Indirect jump to the address pointed to by the Z (16-bit) Pointer Register in the Register File and the EIND Register in the I/O space. This instruction allows for indirect jumps to the entire 4M (words) program memory space. See also IJMP.

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) PC(15:0) ← Z(15:0)

PC(21:16) ← EIND

Syntax: Operands: Program Counter: Stack:

(i) EIJMP None See Operation Not Affected

16-bit Opcode:

1001 0100 0001 1001

6.52.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

ldi	r16,0x05	; Set up EIND and Z-pointer
out	EIND,r16
ldi	r30,0x00
ldi	r31,0x10
eijmp		; Jump to 0x051000

Words 1 (2 bytes)

Table 6-52. Cycles

Name	Cycles
AVRe	2
AVRxm	2
AVRxt	2
AVRrc	N/A

6.53 ELPM - Extended Load Program Memory

6.53.1 Description

Loads one byte pointed to by the Z-register and the RAMPZ Register in the I/O space, and places this byte in the destination register Rd. This instruction features a 100% space-effective constant initialization or constant data fetch. The program memory is organized in 16-bit words while the Z-pointer is a byte address. Thus, the least significant bit of the Z-pointer selects either low byte ( Z_LSB == 0 ) or high byte ( Z_LSB == 1 ). This instruction can address the

entire program memory space. The Z-Pointer Register can either be left unchanged by the operation, or it can be incremented. The incrementation applies to the entire 24-bit concatenation of the RAMPZ and Z-Pointer Registers.

Devices with self-programming capability can use the ELPM instruction to read the Fuse and Lock bit value. Refer to the device documentation for a detailed description.

This instruction is not available on all devices. Refer to Appendix A.

The result of these combinations is undefined:

ELPM r30, Z+

ELPM r31, Z+

Operation: Comment:

(i) R0 ← PS(RAMPZ:Z) RAMPZ:Z: Unchanged, R0

implied destination register

(ii) Rd ← PS(RAMPZ:Z) RAMPZ:Z: Unchanged

(iii) Rd ← PS(RAMPZ:Z) (RAMPZ:Z) ← (RAMPZ:Z)

+ 1 RAMPZ:Z: Post incremented

Syntax: Operands: Program Counter:

(i) ELPM None, R0 implied PC ← PC + 1
(ii) ELPM Rd, Z 0 ≤ d ≤ 31 PC ← PC + 1
(iii) ELPM Rd, Z+ 0 ≤ d ≤ 31 PC ← PC + 1

16 bit Opcode:

(i) 1001 0101 1101 1000
(ii)	1001 000d dddd 0110
(iii)	1001 000d dddd 0111

6.53.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

ldi ZL, byte3(Table_1 << 1) ; Initialize Z-pointer
out RAMPZ, ZL
ldi ZH, byte2(Table_1 << 1)
ldi ZL, byte1(Table_1 << 1)
elpm r16, Z+ ; Load constant from Program
; memory pointed to by RAMPZ:Z (Z is r31:r30)
...
Table_1:
dw 0x3738 ; 0x38 is addressed when Z_LSB == 0
; 0x37 is addressed when Z_LSB == 1
... 

Words

1 (2 bytes)

Table 6-53. Cycles

Name Cycles
AVRe 3
AVRxm 3
AVRxt 3
AVRrc N/A

6.54 EOR – Exclusive OR

6.54.1 Description

Performs the logical EOR between the contents of register Rd and register Rr and places the result in the destination register Rd.

Operation:

(i) Rd ← Rd ⊕ Rr

Syntax: Operands: Program Counter:

(i) EOR Rd, Rr 0 ≤ d ≤ 31, 0 ≤ r ≤ 31 PC ← PC + 1

16-bit Opcode:

0010 01rd dddd rrrr

6.54.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-		0			-

S N ⊕ V, for signed tests.

v 0

Cleared.

N R7

Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x00; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

eor	r4,r4	; Clear r4
eor	r0,r22	; Bitwise exclusive or between r0 and r22

Words

1 (2 bytes)

Table 6-54. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.55 FMUL - Fractional Multiply Unsigned

6.55.1 Description

This instruction performs 8-bit × 8-bit → 16-bit unsigned multiplication and shifts the result one bit left.

Rd Rr R1 R0

Multiplicand

×

Multiplier

→

Product High Product Low

8 8 16
Let (N.Q) denote a fractional number with N binary digits left of the radix point, and Q binary digits right of the radix point. A multiplication between two numbers in the formats (N1.Q1) and (N2.Q2) results in the format ((N1+N2). (Q1+Q2)). For signal processing applications, the format (1.7) is widely used for the inputs, resulting in a (2.14) format for the product. A left shift is required for the high byte of the product to be in the same format as the inputs. The FMUL instruction incorporates the shift operation in the same number of cycles as MUL.
The (1.7) format is most commonly used with signed numbers, while FMUL performs an unsigned multiplication. This instruction is, therefore, most useful for calculating one of the partial products when performing a signed multiplication with 16-bit inputs in the (1.15) format, yielding a result in the (1.31) format.

Note: The result of the FMUL operation may suffer from a 2's complement overflow if interpreted as a number in the (1.15) format. The MSB of the multiplication before shifting must be taken into account and is found in the carry bit. See the following example.
The multiplicand Rd and the multiplier Rr are two registers containing unsigned fractional numbers where the implicit radix point lies between bit 6 and bit 7. The 16-bit unsigned fractional product with the implicit radix point between bit 14 and bit 15 is placed in R1 (high byte) and R0 (low byte).
This instruction is not available on all devices. Refer to Appendix A.
Operation:
(i) R1:R0 ← Rd × Rr (unsigned (1.15) ← unsigned (1.7) × unsigned (1.7))

Syntax:	Operands:	Program Counter:
(i) FMUL Rd,Rr	16 ≤ d ≤ 23, 16 ≤ r ≤ 23	PC ← PC + 1

(i) PC ← PC + 1

16-bit Opcode:

0000

0011

0ddd

1rrr

6.55.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-

C R16

Set if bit 15 of the result before the left shift is set; cleared otherwise.

Z R15 ∧ R14 ∧ R13 ∧ R12 ∧ R11 ∧ R10 ∧ R9 ∧ R8 ∧ R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x0000; cleared otherwise.

R (Result) equals R1,R0 after the operation.

Example:

;**********************************************************************
;* DESCRIPTION
;* Signed fractional multiply of two 16-bit numbers with 32-bit result.
;* USAGE
;* r19:r18:r17:r16 = ( r23:r22 * r21:r20 ) << 1
;**********************************************************************
fmuls16x16_32:
    clr    r2
    fmuls    r23, r21    ; ((signed)ah * (signed)bh) << 1
    movw    r18, r0
    fmul    r22, r20    ; (al * bl) << 1
    adc    r18, r2
    movw    r16, r0
    fmulsu   r23, r20    ; ((signed)ah * bl) << 1
    sbc    r19, r2
    add    r17, r0
    adc    r18, r1
    adc    r19, r2
    fmulsu   r21, r22    ; ((signed)bh * al) << 1
    sbc    r19, r2
    add    r17, r0
    adc    r18, r1
    adc    r19, r2
    ret 

Words 1 (2 bytes)

Table 6-55. Cycles

Name Cycles
AVRe 2
AVRxm 2
AVRxt 2
AVRrc N/A

6.56 FMULS - Fractional Multiply Signed

6.56.1 Description

This instruction performs 8-bit × 8-bit → 16-bit signed multiplication and shifts the result one bit left.

Rd Rr R1 R0

graph LR
    A["Multiplicand"] -->|×| B["Multiplier"]
    B --> C["Product High Product Low"]
    D["88"] --> E["16"]

Let (N.Q) denote a fractional number with N binary digits left of the radix point, and Q binary digits right of the radix point. A multiplication between two numbers in the formats (N1.Q1) and (N2.Q2) results in the format ((N1+N2). (Q1+Q2)). For signal processing applications, the format (1.7) is widely used for the inputs, resulting in a (2.14)

format for the product. A left shift is required for the high byte of the product to be in the same format as the inputs. The FMULS instruction incorporates the shift operation in the same number of cycles as MULS.

The multiplicand Rd and the multiplier Rr are two registers containing signed fractional numbers where the implicit radix point lies between bit 6 and bit 7. The 16-bit signed fractional product with the implicit radix point between bit 14 and bit 15 is placed in R1 (high byte) and R0 (low byte).

Note: That when multiplying 0x80 (-1) with 0x80 (-1), the result of the shift operation is 0x8000 (-1). The shift operation thus gives a two's complement overflow. This must be checked and handled by software.

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) R1:R0 ← Rd × Rr (signed (1.15) ← signed (1.7) × signed (1.7))

Syntax: Operands: Program Counter:

(i) FMULS Rd, Rr 16 ≤ d ≤ 23, 16 ≤ r ≤ 23 PC ← PC + 1

16-bit Opcode:

0000 0011 1ddd 0rrr

6.56.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
---- ⇔ ⇔

C R16

Set if bit 15 of the result before the left shift is set; cleared otherwise.

Z R15 ∧ R14 ∧ R13 ∧ R12 ∧ R11 ∧ R10 ∧ R9 ∧ R8 ∧ R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x0000; cleared otherwise.

R (Result) equals R1,R0 after the operation.

Example:

fmuls r23,r22 ; Multiply signed r23 and r22 in (1.7) format, ; result in (1.15) format
movw r22,r0 ; Copy result back in r23:r22 

Words

1 (2 bytes)

Table 6-56. Cycles

Name	Cycles
AVRe	2
AVRxm	2
AVRxt	2
AVRrc	N/A

6.57 FMULSU - Fractional Multiply Signed with Unsigned

6.57.1 Description

This instruction performs 8-bit × 8-bit → 16-bit signed multiplication and shifts the result one bit left.

Rd Rr R1 R0

Multiplicand

×

Multiplier

→

Product High Product Low

8 8 16

Let (N.Q) denote a fractional number with N binary digits left of the radix point, and Q binary digits right of the radix point. A multiplication between two numbers in the formats (N1.Q1) and (N2.Q2) results in the format ((N1+N2). (Q1+Q2)). For signal processing applications, the format (1.7) is widely used for the inputs, resulting in a (2.14) format for the product. A left shift is required for the high byte of the product to be in the same format as the inputs. The FMULSU instruction incorporates the shift operation in the same number of cycles as MULSU.

The (1.7) format is most commonly used with signed numbers, while FMULSU performs a multiplication with one unsigned and one signed input. This instruction is, therefore, most useful for calculating two of the partial products when performing a signed multiplication with 16-bit inputs in the (1.15) format, yielding a result in the (1.31) format.

Note: The result of the FMULSU operation may suffer from a 2's complement overflow if interpreted as a number in the (1.15) format. The MSB of the multiplication before shifting must be taken into account and is found in the carry bit. See the following example.

The multiplicand Rd and the multiplier Rr are two registers containing fractional numbers where the implicit radix point lies between bit 6 and bit 7. The multiplicand Rd is a signed fractional number, and the multiplier Rr is an unsigned fractional number. The 16-bit signed fractional product with the implicit radix point between bit 14 and bit 15 is placed in R1 (high byte) and R0 (low byte).

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) R1:R0 ← Rd × Rr (signed (1.15) ← signed (1.7) × unsigned (1.7))

Syntax: Operands: Program Counter:

(i) FMULSU Rd, Rr 16 ≤ d ≤ 23, 16 ≤ r ≤ 23 PC ← PC + 1

16-bit Opcode:

0000 0011 1ddd 1rrr

6.57.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-

C R16

Set if bit 15 of the result before the left shift is set; cleared otherwise.

Z R15 ∧ R14 ∧ R13 ∧ R12 ∧ R11 ∧ R10 ∧ R9 ∧ R8 ∧ R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0×0000; cleared otherwise.

R (Result) equals R1,R0 after the operation.

Example:

;**********************************************************************
;* DESCRIPTION
;* Signed fractional multiply of two 16-bit numbers with 32-bit result.
;* USAGE
;* r19:r18:r17:r16 = ( r23:r22 * r21:r20 ) << 1
;**********************************************************************
fmuls16x16_32:
    clr    r2
    fmuls    r23, r21    ; ((signed)ah * (signed)bh) << 1
    movw    r18, r0
    fmul    r22, r20    ; (al * bl) << 1
    adc    r18, r2
    movw    r16, r0
    fmulsu    r23, r20    ; ((signed)ah * bl) << 1
    sbc    r19, r2
    add    r17, r0
    adc    r18, r1
    adc    r19, r2
    fmulsu    r21, r22    ; ((signed)bh * al) << 1
    sbc    r19, r2
    add    r17, r0
    adc    r18, r1
    adc    r19, r2
    ret 

Words 1 (2 bytes)

Table 6-57. Cycles

Name Cycles
AVRe 2
AVRxm 2
AVRxt 2
AVRrc N/A

6.58 ICALL – Indirect Call to Subroutine

6.58.1 Description

Indirect call of a subroutine pointed to by the Z (16-bit) Pointer Register in the Register File. The Z-Pointer Register is 16 bits wide and allows a call to a subroutine within the lowest 64K words (128 KB) section in the program memory space. The Stack Pointer uses a post-decrement scheme during ICALL.

This instruction is not available on all devices. Refer to Appendix A.

Operation: Comment:

(i) PC(15:0) ← Z(15:0) Devices with 16-bit PC, 128 KB program memory maximum.

(ii) PC(15:0) ← Z(15:0) Devices with 22-bit PC, 8 MB program memory maximum.

PC(21:16) ← 0

Syntax: Operands: Program Counter: Stack:

(i) ICALL None

See Operation

STACK ← PC + 1

SP ← SP - 2 (2 bytes, 16 bits)

(ii) ICALL None See Operation STACK ← PC + 1

SP ← SP - 3 (3 bytes, 22 bits)

16-bit Opcode:

1001 0101 0000 1001

6.58.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

mov r30,r0 ; Set offset to call table
icall ; Call routine pointed to by r31:r30 

Words 1 (2 bytes)

Table 6-58. Cycles

Name Cycles
	9/16-bit PC 22-bit PC
AVRe 3	(1)	4(1)
AVRxm 2	(1)	3(1)
AVRxt	2	3
AVRrc	3	N/A

Note:

1. Cycle times for data memory access assume internal RAM access and are not valid for accessing external RAM.

6.59 IJMP – Indirect Jump

6.59.1 Description

Indirect jump to the address pointed to by the Z (16-bit) Pointer Register in the Register File. The Z-Pointer Register is 16 bits wide and allows jump within the lowest 64K words (128 KB) section of program memory.

This instruction is not available on all devices. Refer to Appendix A.

Operation: Comment:

(i) PC ← Z(15:0) Devices with 16-bit PC, 128 KB program memory maximum.

(ii) PC(15:0) ← Z(15:0) Devices with 22-bit PC, 8 MB program memory maximum.

PC(21:16) ← 0

Syntax: Operands: Program Counter: Stack:

(i), (ii) IJMP None See Operation Not Affected

16-bit Opcode:

1001 0100 0000 1001

6.59.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

mov r30,r0 ; Set offset to jump table
ijmp ; Jump to routine pointed to by r31:r30 

Words 1 (2 bytes)

Table 6-59. Cycles

Name Cycles
AVRe 2
AVRxm 2
AVRxt 2
AVRrc 2

6.60 IN - Load an I/O Location to Register

6.60.1 Description

Loads data from the I/O space into register Rd in the Register File.

Operation:

(i) Rd ← I/O(A)

Syntax: Operands:

Program Counter:

(i) IN Rd,A

0 ≤ d ≤ 31, 0 ≤ A ≤ 63

PC ← PC + 1

16-bit Opcode:

1011

0AAd

dddd AAAA

6.60.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

in r25,0x16 ; Read Port B
cpi r25,4 ; Compare read value to constant
breq exit ; Branch if r25=4 

exit:
nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-60. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.61 INC - Increment

6.61.1 Description

Adds one -1- to the contents of register Rd and places the result in the destination register Rd.

The C flag in SREG is not affected by the operation, thus allowing the INC instruction to be used on a loop counter in multiple-precision computations.

When operating on unsigned numbers, only BREQ and BRNE branches can be expected to perform consistently. When operating on two's complement values, all signed branches are available.

Operation:

(i) Rd ← Rd + 1

Syntax: Operands: Program Counter:

(i) INC Rd 0 ≤ d ≤ 31 PC ← PC + 1

16-bit Opcode:

1001 010d dddd 0011 

6.61.2 Status Register and Boolean Formula

S N ⊕ V, for signed tests.

V R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if two's complement overflow resulted from the operation; cleared otherwise. Two's complement overflow occurs only if Rd was 0x7F before the operation.

N R7

Set if MSB of the result is set; cleared otherwise.

Z 7 6 5 4 3 2 1 0

Set if the result is 0x00; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

clr r22 ; clear r22
loop:
inc r22 ; increment r22
...
cpi r22,0x4F ; Compare r22 to 0x4f
brne loop ; Branch if not equal
nop ; Continue (do nothing) 

Words 1 (2 bytes)

Table 6-61. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.62 JMP - Jump

6.62.1 Description

Jump to an address within the entire 4M (words) program memory. See also RJMP.

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) PC ← k

Syntax: Operands: Program Counter: Stack:

(i) JMP k 0 ≤ k < 4M PC ← k Unchanged

32-bit Opcode:

1001	010k	kkkk	110k
kkkk	kkkk	kkkk	kkkk

6.62.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

mov r1,r0 ; Copy r0 to r1
jmp farplc ; Unconditional jump
...
farplc:
nop ; Jump destination (do nothing) 

Words 2 (4 bytes)

Table 6-62. Cycles

Name Cycles
AVRe 3
AVRxm 3
AVRxt 3
AVRrc N/A

6.63 LAC - Load and Clear

6.63.1 Description

Load one byte indirect from data space to register and stores and clear the bits in data space specified by the register. The instruction can only be used towards internal SRAM.

The data location is pointed to by the Z (16-bit) Pointer Register in the Register File. Memory access is limited to the current data segment of 64 KB. To access another data segment in devices with more than 64 KB data space, the RAMPZ in the register in the I/O area has to be changed.

The Z-Pointer Register is left unchanged by the operation. This instruction is especially suited for clearing status bits stored in SRAM.

Operation:

(i) DS(Z) ← (0xFF - Rd) ∧ DS(Z), Rd ← DS(Z)

Syntax: Operands: Program Counter:

(i) LAC Z,Rd 0 ≤ d ≤ 31 PC ← PC + 1

16-bit Opcode:

1001 001r rrrr

0110

6.63.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Words

1 (2 bytes)

Table 6-63. Cycles

Name Cycles
AVRe N/A
AVRxm 2
AVRxt N/A
AVRrc N/A

6.64 LAS - Load and Set

6.64.1 Description

Load one byte indirect from data space to register and set bits in the data space specified by the register. The instruction can only be used towards internal SRAM.

The data location is pointed to by the Z (16-bit) Pointer Register in the Register File. Memory access is limited to the current data segment of 64 KB. To access another data segment in devices with more than 64 KB data space, the RAMPZ in the register in the I/O area has to be changed.

The Z-Pointer Register is left unchanged by the operation. This instruction is especially suited for setting status bits stored in SRAM.

Operation:

(i) DS(Z) ← Rd v DS(Z), Rd ← DS(Z)

Syntax: Operands: Program Counter:

(i) LAS Z,Rd 0 ≤ d ≤ 31 PC ← PC + 1

16-bit Opcode:

1001 001r rrrr 0101

6.64.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Words

1 (2 bytes)

Table 6-64. Cycles

Name	Cycles
AVRe	N/A
AVRxm	2
AVRxt	N/A
AVRrc	N/A

6.65 LAT - Load and Toggle

6.65.1 Description

Load one byte indirect from data space to register and toggles bits in the data space specified by the register. The instruction can only be used towards SRAM.

The data location is pointed to by the Z (16-bit) Pointer Register in the Register File. Memory access is limited to the current data segment of 64 KB. To access another data segment in devices with more than 64 KB data space, the RAMPZ in the register in the I/O area has to be changed.

The Z-Pointer Register is left unchanged by the operation. This instruction is especially suited for changing status bits stored in SRAM.

Operation:

(i) DS(Z) Rd DS(Z), Rd DS(Z)

Syntax: Operands: Program Counter:

(i) LAT Z,Rd 0 ≤ d ≤ 31 PC ← PC + 1

16-bit Opcode:

1001 001r rrrr 0111

6.65.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Words 1 (2 bytes)

Table 6-65. Cycles

Name Cycles
AVRe	N/A
AVRxm	2
AVRxt	N/A
AVRrc	N/A

6.66 LD - Load Indirect from Data Space to Register using X

6.66.1 Description

Loads one byte indirect from the data space to a register. The data space usually consists of the Register File, I/O memory, and SRAM, refer to the device data sheet for a detailed definition of the data space.

The data location is pointed to by the X (16-bit) Pointer Register in the Register File. Memory access is limited to the current data segment of 64 KB. To access another data segment in devices with more than 64 KB data space, the RAMPX in the register in the I/O area has to be changed.

The X-Pointer Register can either be left unchanged by the operation, or it can be post-incremented or pre-decremented. These features are especially suited for accessing arrays, tables, and Stack Pointer usage of the X-Pointer Register. Note that only the low byte of the X-pointer is updated in devices with no more than 256 bytes of data space. For such devices, the high byte of the pointer is not used by this instruction and can be used for other purposes. The RAMPX Register in the I/O area is updated in parts with more than 64 KB data space or more than 64 KB program memory, and the increment/decrement is added to the entire 24-bit address on such devices.

Not all variants of this instruction are available on all devices.

In the Reduced Core AVRc, the LD instruction can be used to achieve the same operation as LPM since the program memory is mapped to the data memory space.

The result of these combinations is undefined:

LD r26, X+

LD r27, X+

LD r26, -X

LD r27, -X

Using the X-pointer:

Operation: Comment:

(i) Rd ← DS(X) X: Unchanged
(ii) Rd ← DS(X) X ← X + 1 X: Post incremented
(iii) X ← X - 1 Rd ← DS(X) X: Pre decremented

Syntax: Operands: Program Counter:

(i) LD Rd, X 0 ≤ d ≤ 31 PC ← PC + 1
(ii) LD Rd, X + 0 ≤ d ≤ 31 PC PC + 1
(iii) LD Rd, -X 0 ≤ d ≤ 31 PC ← PC + 1

16-bit Opcode:

(i) 1001 000d dddd 1100
(ii)	1001 000d dddd 1101
(iii)	1001 000d dddd 1110

6.66.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

clr r27 ; Clear X high byte
ldi r26,0x60 ; Set X low byte to 0x60
ld r0,X+ ; Load r0 with data space loc. 0x60(X post inc)
ld r1,X ; Load r1 with data space loc. 0x61
ldi r26,0x63 ; Set X low byte to 0x63
ld r2,X ; Load r2 with data space loc. 0x63
ld r3,-X ; Load r3 with data space loc. 0x62(X pre dec) 

Words

1 (2 bytes)

Table 6-66. Cycles

Name	Cycles
	i	ii	iii
AVRe	2^(1)	2^(1)	2^(1)
AVRxm	2^(1)(3)	2^(1)(3)	3^(1)(3)
AVRxt	2^(2)	2^(2)	2^(2)
AVRrc	1 / 2	2 / 3	2 / 3

Notes:

1. Cycle times for data memory access assume internal RAM access and are not valid for accessing external RAM.
2. Cycle time for data memory access assumes internal RAM access, and are not valid for access to NVM. A minimum of one extra cycle must be added when accessing NVM. The additional time varies dependent on the NVM module implementation. See the NVMCTRL section in the specific devices data sheet for more information.
3. If the LD instruction is accessing I/O Registers, one cycle can be deducted.

6.67 LD (LDD) - Load Indirect from Data Space to Register using Y

6.67.1 Description

Loads one byte indirect with or without displacement from the data space to a register. The data space usually consists of the Register File, I/O memory and SRAM, refer to the device data sheet for a detailed definition of the data space.

The data location is pointed to by the Y (16-bit) Pointer Register in the Register File. Memory access is limited to the current data segment of 64 KB. To access another data segment in devices with more than 64 KB data space, the RAMPY in the register in the I/O area has to be changed.

The Y-Pointer Register can either be left unchanged by the operation, or it can be post-incremented or pre-decremented. These features are especially suited for accessing arrays, tables, and Stack Pointer usage of the Y-Pointer Register. Note that only the low byte of the Y-pointer is updated in devices with no more than 256 bytes of data space. For such devices, the high byte of the pointer is not used by this instruction and can be used for other purposes. The RAMPY Register in the I/O area is updated in parts with more than 64 KB data space or more than 64 KB program memory, and the increment/decrement/displacement is added to the entire 24-bit address on such devices.

Not all variants of this instruction are available on all devices.

In the Reduced Core AVRc, the LD instruction can be used to achieve the same operation as LPM since the program memory is mapped to the data memory space.

The result of these combinations is undefined:

LD r28, Y+

LD r29, Y+

LD r28, -Y

LD r29, -Y

Using the Y-pointer:

Operation: Comment:

(i) Rd ← DS(Y) Y: Unchanged
(ii) Rd ← DS(Y), Y ← Y + 1 Y: Post incremented
(iii) Y ← Y - 1, Rd ← DS(Y) Y: Pre decremented
(iv) Rd ← DS(Y+q) Y: Unchanged, q: Displacement

Syntax: Operands: Program Counter:

(i) LD Rd, Y 0 ≤ d ≤ 31
(ii) LD Rd, Y+ 0 ≤ d ≤ 31
(iii) LD Rd, -Y 0 ≤ d ≤ 31

PC ← PC + 1

PC ← PC + 1

PC ← PC + 1

(iv) LDD Rd, Y+q 0 ≤ d ≤ 31, 0 ≤ q ≤ 63 PC ← PC + 1

16-bit Opcode:

(i) 1000 000d dddd 1000
(ii) 1001 000d dddd 1001
(iii) 1001 000d dddd 1010
(iv) 10q0 qq0d dddd 1qqq

6.67.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

clr	r29	; Clear Y high byte
ldi	r28,0x60	; Set Y low byte to 0x60
ld	r0,Y+	; Load r0 with data space loc. 0x60(Y post inc)
ld	r1,Y	; Load r1 with data space loc. 0x61
ldi	r28,0x63	; Set Y low byte to 0x63
ld	r2,Y	; Load r2 with data space loc. 0x63
ld	r3,-Y	; Load r3 with data space loc. 0x62(Y pre dec)
ldd	r4,Y+2	; Load r4 with data space loc. 0x64

Words 1 (2 bytes)

Table 6-67. Cycles

Name Cycles
	i	ii	iii	iv
AVRe	2^(1)	2^(1)	2^(1)	2^(1)
AVRxm	2^(1)(3)	2^(1)(3)	3^(1)(3)	3^(1)(3)
AVRxt	2^(2)	2^(2)	2^(2)	2^(2)
AVRrc	1 / 2	2 / 3	2 / 3	N/A

Notes:

1. Cycle times for data memory access assume internal RAM access and are not valid for accessing external RAM.
2. Cycle time for data memory access assumes internal RAM access, and are not valid for access to NVM. A minimum of one extra cycle must be added when accessing NVM. The additional time varies dependent on the NVM module implementation. See the NVMCTRL section in the specific devices data sheet for more information.
3. If the LD instruction is accessing I/O Registers, one cycle can be deducted.

6.68 LD (LDD) – Load Indirect From Data Space to Register using Z

6.68.1 Description

Loads one byte indirect with or without displacement from the data space to a register. The data space usually consists of the Register File, I/O memory, and SRAM, refer to the device data sheet for a detailed definition of the data space.

The data location is pointed to by the Z (16-bit) Pointer Register in the Register File. Memory access is limited to the current data segment of 64 KB. To access another data segment in devices with more than 64 KB data space, the RAMPZ in the register in the I/O area has to be changed.

The Z-Pointer Register can either be left unchanged by the operation, or it can be post-incremented or pre-decremented. These features are especially suited for Stack Pointer usage of the Z-pointer Register. However, because the Z-Pointer Register can be used for indirect subroutine calls, indirect jumps, and table look-up, it is often more convenient to use the X- or Y-pointer as a dedicated Stack Pointer. Note that only the low byte of the Z-pointer is updated in devices with no more than 256 bytes of data space. For such devices, the high byte of the pointer is not used by this instruction and can be used for other purposes. The RAMPZ Register in the I/O area is updated in parts with more than 64 KB data space or more than 64 KB program memory, and the increment/decrement/displacement is added to the entire 24-bit address on such devices.

Not all variants of this instruction are available on all devices.

In the Reduced Core AVRc, the LD instruction can be used to achieve the same operation as LPM since the program memory is mapped to the data memory space.

For using the Z-pointer for table look-up in program memory, see the LPM and ELPM instructions.

The result of these combinations is undefined:

LD r30, Z+

LD r31, Z+

LD r30, -Z

LD r31, -Z

Using the Z-pointer:

Operation: Comment:

(i) Rd ← DS(Z) Z: Unchanged
(ii) Rd ← DS(Z), Z ← Z + 1 Z: Post incremented
(iii) Z ← Z - 1, Rd ← DS(Z) Z: Pre decremented
(iv) Rd ← DS(Z+q) Z: Unchanged, q: Displacement

Syntax: Operands: Program Counter:

(i) LD Rd, Z 0 ≤ d ≤ 31 PC ← PC + 1
(ii) LD Rd, Z + 0 ≤ d ≤ 31 PC PC + 1

(iii) LD Rd, -Z 0 ≤ d ≤ 31 PC PC + 1

(iv) LDD Rd, Z+q 0 ≤ d ≤ 31 , 0 ≤ q ≤ 63 PC PC + 1

16-bit Opcode:

(i)	1000	000d	dddd	0000
(ii)	1001	000d	dddd	0001
(iii)	1001	000d	dddd	0010
(iv)	10q0	qq0d	dddd	0qqq

6.68.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

clr r31 ; Clear Z high byte
ldi r30,0x60 ; Set Z low byte to 0x60
ld r0,Z+ ; Load r0 with data space loc. 0x60(Z post inc)
ld r1,Z ; Load r1 with data space loc. 0x61
ldi r30,0x63 ; Set Z low byte to 0x63
ld r2,Z ; Load r2 with data space loc. 0x63
ld r3,-Z ; Load r3 with data space loc. 0x62(Z pre dec)
ldd r4,Z+2 ; Load r4 with data space loc. 0x64 

Words 1 (2 bytes)

Table 6-68. Cycles

Name Cycles
	i ii iii iv
AVRe 2	(1)	2^(1)	2^(1)	2^(1)
AVRxm 2	^(1)(3)	2^(1)(3)	3^(1)(3)	3^(1)(3)
AVRxt 2	(2)	2^(2)	2^(2)	2^(2)
AVRrc 1 / 2 2 / 3 2 / 3 N/A

Notes:

1. Cycle times for data memory access assume internal RAM access and are not valid for accessing external RAM.
2. Cycle time for data memory access assumes internal RAM access, and are not valid for access to NVM.
   A minimum of one extra cycle must be added when accessing NVM. The additional time varies dependent on the NVM module implementation. See the NVMCTRL section in the specific devices data sheet for more information.
3. If the LD instruction is accessing I/O Registers, one cycle can be deducted.

6.69 LDI - Load Immediate

6.69.1 Description

Loads an 8-bit constant directly to register 16 to 31.

Operation:

(i) Rd ← K

Syntax: Operands:

Program Counter:

(i) LDI Rd, K

16 ≤ d ≤ 31, 0 ≤ K ≤ 255

PC ← PC + 1

16-bit Opcode:

1110

KKKK

dddd

KKKK

6.69.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

clr r31 ; Clear Z high byte
ldi r30,0xF0 ; Set Z low byte to 0xF0
lpm ; Load constant from Program
; memory pointed to by Z 

Words 1 (2 bytes)

Table 6-69. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.70 LDS – Load Direct from Data Space

6.70.1 Description

Loads one byte from the data space to a register. The data space usually consists of the Register File, I/O memory, and SRAM, refer to the device data sheet for a detailed definition of the data space.

A 16-bit address must be supplied. Memory access is limited to the current data segment of 64 KB. The LDS instruction uses the RAMPD Register to access memory above 64 KB. To access another data segment in devices with more than 64 KB data space, the RAMPD in the register in the I/O area has to be changed.

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) Rd ← DS(k)

Syntax: Operands: Program Counter:

(i) LDS Rd, k 0 ≤ d ≤ 31, 0 ≤ k ≤ 65535 PC ← PC + 2

32-bit Opcode:

1001 000d dddd 0000
kkkk	kkkk	kkkk	kkkk

6.70.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

lds r2,0xFF00 ; Load r2 with the contents of data space location 0xFF00
add r2,r1 ; add r1 to r2
sts 0xFF00,r2 ; Write back 

Words 2 (4 bytes)

Table 6-70. Cycles

Name Cycles
AVRe 2	(1)
AVRxm 3	(1)(3)
AVRxt 3	(2)
AVRrc N/A

Notes:

1. Cycle times for data memory access assume internal RAM access and are not valid for accessing external RAM.
2. Cycle time for data memory access assumes internal RAM access, and are not valid for access to NVM. A minimum of one extra cycle must be added when accessing NVM. The additional time varies dependent on the NVM module implementation. See the NVMCTRL section in the specific devices data sheet for more information.
3. If the LD instruction is accessing I/O Registers, one cycle can be deducted.

6.71 LDS (AVRrc) - Load Direct from Data Space

6.71.1 Description

Loads one byte from the data space to a register. The data space usually consists of the Register File, I/O memory, and SRAM, refer to the device data sheet for a detailed definition of the data space.

A 7-bit address must be supplied. The address given in the instruction is coded to a data space address as follows:

ADDR[7:0] ← (INST[8], INST[8], INST[10], INST[9], INST[3], INST[2], INST[1], INST[0])

Memory access is limited to the address range 0x40...0xbf.

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) Rd ← (k)
Syntax: Operands: Program Counter:
(i) LDS Rd, k 16 ≤ d ≤ 31, 0 ≤ k ≤ 127 PC ← PC + 1

16-bit Opcode:

1010 0kkk

dddd kkkk

6.71.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

lds	r16,0x00	; Load r16 with the contents of data space location 0x00
add	r16,r17	; add r17 to r16
sts	0x00,r16	; Write result to the same address it was fetched from

Words 1 (2 bytes)

Table 6-71. Cycles

Name Cycles
AVRe N/A
AVRxm N/A
AVRxt N/A
AVRrc 2

Note: Registers r0...r15 are remapped to r16...r31.

6.72 LPM – Load Program Memory

6.72.1 Description

Loads one byte pointed to by the Z-register into the destination register Rd. This instruction features a 100% space-effective constant initialization or constant data fetch. The program memory is organized in 16-bit words while the Z-pointer is a byte address. Thus, the least significant bit of the Z-pointer selects either low byte ( Z_LSb == 0 ) or high byte ( Z_LSb == 1 ). This instruction can address the first 64 KB (32K words) of program memory. The Z-Pointer Register can either be left unchanged by the operation, or it can be incremented. The incrementation does not apply to the RAMPZ Register.

Devices with self-programming capability can use the LPM instruction to read the Fuse and Lock bit values. Refer to the device documentation for a detailed description.

The LPM instruction is not available on all devices. Refer to Appendix A.

The result of these combinations is undefined:

LPM r30, Z+

LPM r31, Z+

Operation: Comment:

(i) R0 ← PS(Z) Z: Unchanged, R0 implied

destination register

(ii) Rd ← PS(Z) Z: Unchanged
(iii) Rd ← PS(Z) Z ← Z + 1 Z: Post incremented

Syntax: Operands:
Program Counter:

(i) LPM	None, R0 implied	PC ← PC + 1
(ii) LPM Rd, Z	0 ≤ d ≤ 31	PC ← PC + 1
(iii) LPM Rd, Z+	0 ≤ d ≤ 31	PC ← PC + 1

16-bit Opcode:

(i)	1001	0101	1100	1000
(ii)	1001	000d	dddd	0100
(iii)	1001	000d	dddd	0101

6.72.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

ldi ZH, high(Table_1<<1) ; Initialize Z-pointer
ldi ZL, low(Table_1<<1)
lpm r16, Z ; Load constant from Program
; Memory pointed to by Z (r31:r30)
...
Table_1:
dw 0x5876 ; 0x76 is addresses when Z_LSB == 0
; 0x58 is addresses when Z_LSB == 1 

Words 1 (2 bytes)

Table 6-72. Cycles

Name Cycles
AVRe 3
AVRxm 3
AVRxt 3
AVRrc N/A

6.73 LSL - Logical Shift Left

6.73.1 Description

Shifts all bits in Rd one place to the left. Bit 0 is cleared. Bit 7 is loaded into the C flag of the SREG. This operation effectively multiplies signed and unsigned values by two.

Operation:

(i)

graph LR
    C --> b7
    b7 -.-> b0
    b0 <-- 0

Syntax: Operands: Program Counter:

(i) LSL Rd 0 ≤ d ≤ 31

PC ← PC + 1

16-bit Opcode: (see ADD Rd,Rd)

0000

11dd

dddd

dddd

6.73.2 Status Register (SREG) and Boolean Formula

S N ⊕ V, for signed tests.

V N C , for N and C after the shift.

N R7

Set if MSB of the result is set; cleared otherwise.

Z 7 6 5 4 3 2 1 0

Set if the result is 0x00; cleared otherwise.

C Rd7

Set if, before the shift, the MSB of Rd was set; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

add r0,r4 ; Add r4 to r0
ls1 r0 ; Multiply r0 by 2 

Words 1 (2 bytes)

Table 6-73. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.74 LSR – Logical Shift Right

6.74.1 Description

Shifts all bits in Rd one place to the right. Bit 7 is cleared. Bit 0 is loaded into the C flag of the SREG. This operation effectively divides an unsigned value by two. The C flag can be used to round the result.

Operation:

(i)

graph LR
    A["0"] --> B["b7"]
    B --> C["b0"]
    C --> D["C"]

Syntax: Operands: Program Counter:

(i) LSR Rd 0 ≤ d ≤ 31 PC ← PC + 1

16-bit Opcode:

1001

010d

dddd

0110

6.74.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
--- ⇔ ⇔ 0 ⇔ ⇔

S N ⊕ V, for signed tests.

V N C , for N and C after the shift.

N0

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x00; cleared otherwise.

C Rd0

Set if, before the shift, the LSB of Rd was set; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

add r0,r4 ; Add r4 to r0
lsr r0 ; Divide r0 by 2 

Words 1 (2 bytes)

Table 6-74. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.75 MOV - Copy Register

6.75.1 Description

This instruction makes a copy of one register into another. The source register Rr is left unchanged, while the destination register Rd is loaded with a copy of Rr.

Operation:

(i) Rd ← Rr

Syntax:

Operands:

Program Counter:

(i) MOV Rd, Rr

0 ≤ d ≤ 31, 0 ≤ r ≤ 31

PC ← PC + 1

16-bit Opcode:

0010

11rd

dddd

rrrr

6.75.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

mov r16,r0 ; Copy r0 to r16
call check ; Call subroutine
...
check: cpi r16,0x11 ; Compare r16 to 0x11
...
ret ; Return from subroutine 

Words 1 (2 bytes)

Table 6-75. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.76 MOVW - Copy Register Word

6.76.1 Description

This instruction makes a copy of one register pair into another register pair. The source register pair Rr+1:Rr is left unchanged, while the destination register pair Rd+1:Rd is loaded with a copy of Rr + 1:Rr .

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) R[d+1]:Rd ← R[r+1]:Rr

Syntax: Operands: Program Counter:

(i) MOVW Rd, Rr

$$ d \in {0, 2, \dots , 3 0 }, r \in {0, 2, \dots , 3 0 } $$

$$ \mathrm{PC} \leftarrow \mathrm{PC} + 1 $$

16-bit Opcode:

0000

0001

dddd

rrrr

6.76.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

movw r17:16,r1:r0 ; Copy r1:r0 to r17:r16
call check ; Call subroutine
... 

check: cpi r16,0x11 ; Compare r16 to 0x11
...
cpi r17,0x32 ; Compare r17 to 0x32
...
ret ; Return from subroutine 

Words 1 (2 bytes)

Table 6-76. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc N/A

6.77 MUL - Multiply Unsigned

6.77.1 Description

This instruction performs 8-bit × 8-bit → 16-bit unsigned multiplication.

Rd Rr R1 R0

Multiplicand

×

Multiplier

→

Product High Product Low

8 8 16

The multiplicand Rd and the multiplier Rr are two registers containing unsigned numbers. The 16-bit unsigned product is placed in R1 (high byte) and R0 (low byte). Note that if the multiplicand or the multiplier is selected from R0 or R1, the result will overwrite those after multiplication.

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) R1:R0 ← Rd × Rr (unsigned ← unsigned × unsigned)

Syntax:

Operands:

Program Counter:

(i) MUL Rd, Rr

0 ≤ d ≤ 31, 0 ≤ r ≤ 31

PC ← PC + 1

16-bit Opcode:

1001

11rd

dddd

rrrr

6.77.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-

C R15

Z R15 ∧ R14 ∧ R13 ∧ R12 ∧ R11 ∧ R10 ∧ R9 ∧ R8 ∧ R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x0000; cleared otherwise.

R (Result) equals R1,R0 after the operation.

Example:

mul r5,r4 ; Multiply unsigned r5 and r4
movw r4,r0 ; Copy result back in r5:r4 

Words 1 (2 bytes)

Table 6-77. Cycles

Name Cycles
AVRe 2
AVRxm 2
AVRxt 2
AVRrc N/A

6.78 MULS - Multiply Signed

6.78.1 Description

This instruction performs 8-bit × 8-bit → 16-bit signed multiplication.

Rd Rr R1 R0

graph LR
    A["Multiplicand"] --> B["×"]
    B --> C["Multiplier"]
    C --> D["→"]
    D --> E["Product High Product Low"]
    F["8 8 16"] --> A

The multiplicand Rd and the multiplier Rr are two registers containing signed numbers. The 16-bit signed product is placed in R1 (high byte) and R0 (low byte).

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) R1:R0 ← Rd × Rr (signed ← signed × signed)

Syntax:

Operands:

Program Counter:

(i) MULS Rd, Rr

16 ≤ d ≤ 31, 16 ≤ r ≤ 31

PC ← PC + 1

16-bit Opcode:

0000

0010

dddd

rrrr

6.78.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-

C R15

Z R15 ∧ R14 ∧ R13 ∧ R12 ∧ R11 ∧ R10 ∧ R9 ∧ R8 ∧ R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x0000; cleared otherwise.

R (Result) equals R1,R0 after the operation.

Example:

muls r21,r20 ; Multiply signed r21 and r20
movw r20,r0 ; Copy result back in r21:r20 

Words 1 (2 bytes)

Table 6-78. Cycles

Name Cycles
AVRe 2
AVRxm 2
AVRxt 2
AVRrc N/A

6.79 MULSU - Multiply Signed with Unsigned

6.79.1 Description

This instruction performs 8-bit × 8-bit → 16-bit multiplication of a signed and an unsigned number.

Rd Rr R1 R0

Multiplicand Multiplier

→

Product High Product Low

8 8 16

The multiplicand Rd and the multiplier Rr are two registers. The multiplicand Rd is a signed number, and the multiplier Rr is unsigned. The 16-bit signed product is placed in R1 (high byte) and R0 (low byte).

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) R1:R0 ← Rd × Rr (signed ← signed × unsigned)

Syntax:

Operands:

Program Counter:

(i) MULSU Rd, Rr

16 ≤ d ≤ 23, 16 ≤ r ≤ 23

PC ← PC + 1

16-bit Opcode:

0000

0011

0ddd

0rrr

6.79.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-

C R15

Z R15 ∧ R14 ∧ R13 ∧ R12 ∧ R11 ∧ R10 ∧ R9 ∧ R8 ∧ R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x0000; cleared otherwise.

R (Result) equals R1,R0 after the operation.

Example:

;**********************************************************************
;* DESCRIPTION
;* Signed multiply of two 16-bit numbers with 32-bit result.
;* USAGE
;* r19:r18:r17:r16 = r23:r22 * r21:r20
;**********************************************************************
muls16x16_32:
    clr    r2
    muls    r23, r21    ; (signed)ah * (signed)bh
    movw    r18, r0
    mul    r22, r20    ; al * bl
    movw    r16, r0
    mulsu    r23, r20    ; (signed)ah * bl
    sbc    r19, r2
    add    r17, r0
    adc    r18, r1
    adc    r19, r2
    mulsu    r21, r22    ; (signed)bh * al
    sbc    r19, r2
    add    r17, r0
    adc    r18, r1
    adc    r19, r2
    ret 

Words 1 (2 bytes)

Table 6-79. Cycles

Name Cycles
AVRe 2
AVRxm 2
AVRxt 2
AVRrc N/A

6.80 NEG - Two's Complement

6.80.1 Description

Replaces the contents of register Rd with its two's complement; the value 0x80 is left unchanged.

Operation:

(i) Rd ← 0×00 - Rd

Syntax: Operands: Program Counter:

(i) NEG Rd 0 ≤ d ≤ 31 PC ← PC + 1

16-bit Opcode:

1001 010d dddd 0001

6.80.2 Status Register (SREG) and Boolean Formula

Set if there was a borrow from bit 3; cleared otherwise.

S N ⊕ V, for signed tests.

V R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if there is a two's complement overflow from the implied subtraction from zero; cleared otherwise. A two's complement overflow will occur only if the contents of the Register after the operation (Result) is 0x80.

N R7

Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x00; cleared otherwise.

Set if there is a borrow in the implied subtraction from zero; cleared otherwise. The C flag will be set in all cases except when the contents of the Register after the operation is 0x00.

R (Result) equals Rd after the operation.

Example:

sub r11,r0 ; Subtract r0 from r11
brpl positive ; Branch if result positive
neg r11 ; Take two's complement of r11
positive:
nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-80. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.81 NOP - No Operation

6.81.1 Description

This instruction performs a single cycle No Operation.

Operation:

(i) No

Syntax: Operands: Program Counter:

(i) NOP None

PC ← PC + 1

16-bit Opcode:

0000 0000 0000 0000

6.81.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

clr r16 ; Clear r16
ser r17 ; Set r17
out 0x18,r16 ; Write zeros to Port B
nop ; Wait (do nothing)
out 0x18,r17 ; Write ones to Port B 

Words 1 (2 bytes)

Table 6-81. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.82 OR - Logical OR

6.82.1 Description

Performs the logical OR between the contents of register Rd and register Rr, and places the result in the destination register Rd.

Operation:

(i) Rd ← Rd v Rr

Syntax: Operands:

Program Counter:

(i) OR Rd, Rr

$$ 0 \leq d \leq 3 1, 0 \leq r \leq 3 1 $$

$$ \mathrm{PC} \leftarrow \mathrm{PC} + 1 $$

16-bit Opcode:

0010 10rd

dddd rrrr

6.82.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
-	-	-	⇔	0	⇔	⇔	-

S N ⊕ V, for signed tests.

v 0

Cleared.

N R7

Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x00; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

or r15,r16 ; Do bitwise or between registers
bst r15,6 ; Store bit 6 of r15 in T bit
brts ok ; Branch if T bit set
...
ok:
nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-82. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.83 ORI - Logical OR with Immediate

6.83.1 Description

Performs the logical OR between the contents of register Rd and a constant, and places the result in the destination register Rd.

Operation:

(i) Rd ← Rd v K

Syntax: Operands: Program Counter:

(i) ORI Rd, K 16 ≤ d ≤ 31, 0 ≤ K ≤ 255 PC ← PC + 1

16-bit Opcode:

0110 KKKK

dddd

KKKK

6.83.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-		0			-

S N ⊕ V, for signed tests.

v 0

Cleared.

N R7

Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x00; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

ori r16,0xF0 ; Set high nibble of r16
ori r17,1 ; Set bit 0 of r17 

Words 1 (2 bytes)

Table 6-83. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.84 OUT – Store Register to I/O Location

6.84.1 Description

Stores data from register Rr in the Register File to I/O space.

Operation:

(i) I/O(A) ← Rr

Syntax: Operands: Program Counter:

(i) OUT A, Rr 0 ≤ r ≤ 31, 0 ≤ A ≤ 63 PC ← PC + 1

16-bit Opcode:

1011 1AAr

rrrr

AAAA

6.84.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

clr r16 ; Clear r16
ser r17 ; Set r17
out 0x18,r16 ; Write zeros to Port B 

nop ; Wait (do nothing)
out 0x18,r17 ; Write ones to Port B 

Words 1 (2 bytes)

Table 6-84. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.85 POP – Pop Register from Stack

6.85.1 Description

This instruction loads register Rd with a byte from the STACK. The Stack Pointer is pre-incremented by 1 before the POP.

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) Rd ← STACK

Syntax: Operands: Program Counter: Stack:

(i) POP Rd 0 ≤ d ≤ 31 PC ← PC + 1 SP ← SP + 1

16-bit Opcode:

1001

000d

dddd

1111

6.85.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

call routine ; Call subroutine
...
routine:
push r14 ; Save r14 on the Stack
push r13 ; Save r13 on the Stack
...
pop r13 ; Restore r13
pop r14 ; Restore r14
ret ; Return from subroutine 

Words 1 (2 bytes)

Table 6-85. Cycles

Name Cycles
AVRe 2
AVRxm 2	(1)
AVRxt 2
AVRrc 3

Note:

1. Cycle times for data memory access assume internal RAM access and are not valid for accessing external RAM.

6.86 PUSH – Push Register on Stack

6.86.1 Description

This instruction stores the contents of register Rr on the STACK. The Stack Pointer is post-decremented by 1 after the PUSH.

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) STACK ← Rr

Syntax: Operands: Program Counter: Stack:

(i) PUSH Rr 0 ≤ r ≤ 31 PC ← PC + 1 SP ← SP - 1

16-bit Opcode:

1001

001d

dddd

1111

6.86.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

call routine ; Call subroutine
...
routine:
push r14 ; Save r14 on the Stack
push r13 ; Save r13 on the Stack
...
pop r13 ; Restore r13
pop r14 ; Restore r14
ret ; Return from subroutine 

Words

1 (2 bytes)

Table 6-86. Cycles

Name Cycles
AVRe 2
AVRxm 1	(1)
AVRxt 1
AVRrc 1

Note:

1. Cycle times for data memory access assume internal RAM access and are not valid for accessing external RAM.

6.87 RCALL – Relative Call to Subroutine

6.87.1 Description

Relative call to an address within PC - 2K + 1 and PC + 2K (words). The return address (the instruction after the RCALL) is stored onto the Stack. See also CALL. For AVR microcontrollers with program memory not exceeding 4K words (8 KB), this instruction can address the entire memory from every address location. The Stack Pointer uses a post-decrement scheme during RCALL.

Operation: Comment:

(i) PC ← PC + k + 1 Devices with 16-bit PC, 128 KB program memory maximum.
(ii) PC ← PC + k + 1 Devices with 22-bit PC, 8 MB program memory maximum.

Syntax: Operands: Program Counter: Stack:

(i) RCALL k -2K ≤ k < 2K PC ← PC + k + 1 STACK ← PC + 1

SP ← SP - 2 (2 bytes, 16 bits)

(ii) RCALL k -2K ≤ k < 2K PC ← PC + k + 1 STACK ← PC + 1

SP ← SP - 3 (3 bytes, 22 bits)

16-bit Opcode:

1101

kkkk

kkkk

kkkk

6.87.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

rcall routine ; Call subroutine

...

routine:

push r14 ; Save r14 on the Stack

...

pop r14 ; Restore r14

ret ; Return from subroutine

Words 1 (2 bytes)

Table 6-87. Cycles

Name Cycles
	9/16-bit PC 22-bit PC
AVRe 3	(1)	4(1)
AVRxm 2	(1)	3(1)
AVRxt 2 3
AVRrc 3 N/A

Note:

1. Cycle times for data memory access assume internal RAM access and are not valid for accessing external RAM.

6.88 RET - Return from Subroutine

6.88.1 Description

Returns from the subroutine. The return address is loaded from the STACK. The Stack Pointer uses a pre-increment scheme during RET.

Operation:

Operation: Comment:

(i) PC(15:0) ← STACK Devices with 16-bit PC, 128 KB program memory maximum.
(ii) PC(21:0) ← STACK Devices with 22-bit PC, 8 MB program memory maximum.

	Syntax:	Operands: Program Counter:	Stack:
(i)	RET	None	See Operation	SP← SP + 2, (2 bytes,16 bits)
(ii)	RET	None	See Operation	SP← SP + 3, (3 bytes,22 bits)

16-bit Opcode:

1001

0101

0000

1000

6.88.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

call routine ; Call subroutine
...
routine:
push r14 ; Save r14 on the Stack
...
pop r14 ; Restore r14
ret ; Return from subroutine 

Words 1 (2 bytes)

Table 6-88. Cycles

Name Cycles
	9/16-bit PC 22-bit PC
AVRe 4	(1)	5(1)
AVRxm 4	(1)	5(1)
AVRxt 4 5
AVRrc 6 N/A

Note:

1. Cycle times for data memory access assume internal RAM access and are not valid for accessing external RAM.

6.89 RETI – Return from Interrupt

6.89.1 Description

Returns from the interrupt. The return address is loaded from the STACK, and the Global Interrupt Enable bit is set. Note that the Status Register is not automatically stored when entering an interrupt routine, and it is not restored when returning from an interrupt routine. This must be handled by the application program. The Stack Pointer uses a pre-increment scheme during RETI.

Operation: Comment:

(i) PC(15:0) ← STACK Devices with 16-bit PC, 128 KB program memory maximum.
(ii) PC(21:0) ← STACK Devices with 22-bit PC, 8 MB program memory maximum.

Syntax: Operands: Program Counter: Stack:

(i) RETI None See Operation SP ← SP + 2 (2 bytes, 16
(ii) RETI None See Operation SP ← SP + 3 (3 bytes, 22

bits)

16-bit Opcode:

1001

0101

0001

1000

6.89.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
1	-	-	-	-	-	-	-

1

The I flag is set.

Example:

+ + +

extint:
    push r0 ; Save r0 on the Stack
    ...
    pop r0 ; Restore r0
    reti ; Return and enable interrupts 

Words 1 (2 bytes)

Table 6-89. Cycles

Name Cycles
	9/16-bit PC 22-bit PC
AVRe 4	(2)	5(2)
AVRxm 4	(2)	5(2)
AVRxt 4 5
AVRrc 6 N/A

Notes:

1. RETI behaves differently in AVRe, AVRxm, and AVRxt devices. In the AVRse series of devices, the Global Interrupt Enable bit is cleared by hardware once an interrupt occurs, and this bit is set when RETI is executed. In the AVRxm and AVRxt devices, RETI will not modify the Global Interrupt Enable bit in SREG since it is not cleared by hardware while entering ISR. This bit should be modified using SEI and CLI instructions when needed.

2. Cycle times for data memory access assume internal RAM access and are not valid for accessing external RAM.

6.90 RJMP - Relative Jump

6.90.1 Description

Relative jump to an address within PC - 2K +1 and PC + 2K (words). For AVR microcontrollers with pogram memory not exceeding 4K words (8 KB), this instruction can address the entire memory from every address location. See also JMP.

Operation:

(i) PC ← PC + k + 1

Syntax: Operands: Program Counter: Stack:

(i) RJMP k -2K ≤ k < 2K PC ← PC + k + 1 Unchanged

16-bit Opcode:

1100

kkkk

kkkk

kkkk

6.90.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

cpi r16,0x42 ; Compare r16 to 0x42
brne error ; Branch if r16 <> 0x42 

rjmp ok ; Unconditional branch
error:
add r16,r17 ; Add r17 to r16
inc r16 ; Increment r16
ok:
nop ; Destination for rjmp (do nothing) 

Words 1 (2 bytes)

Table 6-90. Cycles

Name Cycles
AVRe 2
AVRxm 2
AVRxt 2
AVRrc 2

6.91 ROL - Rotate Left trough Carry

6.91.1 Description

Shifts all bits in Rd one place to the left. The C flag is shifted into bit 0 of Rd. Bit 7 is shifted into the C flag. This operation, combined with LSL, effectively multiplies multi-byte signed and unsigned values by two.

Operation:

C b7 b0 ← ← C

Syntax: Operands: Program Counter:

(i) ROL Rd 0 ≤ d ≤ 31 PC ← PC + 1

16-bit Opcode: (see ADC Rd,Rd)

0001 11dd dddd dddd

6.91.2 Status Register (SREG) and Boolean Formula

S N ⊕ V, for signed tests.

V N ⊕ C, for N and C after the shift.

N R7

Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x00; cleared otherwise.

C Rd7

Set if, before the shift, the MSB of Rd was set; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

ls1 r18 ; Multiply r19:r18 by two
rol r19 ; r19:r18 is a signed or unsigned two-byte integer
brcs oneenc ; Branch if carry set
...
oneenc:
nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-91. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.92 ROR – Rotate Right through Carry

6.92.1 Description

Shifts all bits in Rd one place to the right. The C flag is shifted into bit 7 of Rd. Bit 0 is shifted into the C flag. This operation, combined with ASR, effectively divides multi-byte signed values by two. Combined with LSR, it effectively divides multi-byte unsigned values by two. The Carry flag can be used to round the result.

Operation:

graph LR
    C --> b7
    b7 -.-> b0
    b0 --> C

Syntax: Operands: Program Counter:

(i) ROR Rd 0 ≤ d ≤ 31 PC ← PC + 1

16-bit Opcode:

1001

010d

dddd

0111

6.92.2 Status Register (SREG) and Boolean Formula

S N ⊕ V, for signed tests.

V N ⊕ C, for N and C after the shift.

N R7

Set if MSB of the result is set; cleared otherwise.

Z 7 6 5 4 3 2 1 0

Set if the result is 0x00; cleared otherwise.

C Rd0

Set if, before the shift, the LSB of Rd was set; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

lsr r19 ; Divide r19:r18 by two
ror r18 ; r19:r18 is an unsigned two-byte integer
brcc zeroenc1 ; Branch if carry cleared
asr r17 ; Divide r17:r16 by two
ror r16 ; r17:r16 is a signed two-byte integer
brcc zeroenc2 ; Branch if carry cleared
...
zeroenc1:
nop ; Branch destination (do nothing)
...
zeroenc1:
nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-92. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.93 SBC - Subtract with Carry

6.93.1 Description

Subtracts two registers and subtracts with the C flag, and places the result in the destination register Rd.

Operation:

(i) Rd ← Rd - Rr - C

Syntax: Operands: Program Counter:

(i) SBC Rd, Rr 0 ≤ d ≤ 31, 0 ≤ r ≤ 31 PC ← PC + 1

16-bit Opcode:

0000 10rd

dddd rrrr

6.93.2 Status Register (SREG) and Boolean Formula

H Rd3 ∧ Rr3 ∨ Rr3 ∧ R3 ∨ R3 ∧ Rd3

Set if there was a borrow from bit 3; cleared otherwise.

S N ⊕ V, for signed tests.

V Rd7 ∧ Rr7 ∧ R7 ∨ Rd7 ∧ Rr7 ∧ R7

Set if two's complement overflow resulted from the operation; cleared otherwise.

N R7

Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0 ∧ Z

The previous value remains unchanged when the result is zero; cleared otherwise.

C Rd7 ∧ Rr7 ∨ Rr7 ∧ R7 ∨ R7 ∧ Rd7

Set if the absolute value of the contents of Rr plus previous carry is larger than the absolute value of the Rd; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

; Subtract r1:r0 from r3:r2
sub r2,r0 ; Subtract low byte
sbc r3,r1 ; Subtract with carry high byte 

Words 1 (2 bytes)

Table 6-93. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.94 SBCI – Subtract Immediate with Carry SBI – Set Bit in I/O Register

6.94.1 Description

Subtracts a constant from a register and subtracts with the C flag, and places the result in the destination register Rd.

Operation:

(i) Rd ← Rd - K - C

Syntax: Operands:

Program Counter:

(i) SBCI Rd, K 16 ≤ d ≤ 31, 0 ≤ K ≤ 255

PC ← PC + 1

16-bit Opcode:

0100 KKKK dddd KKKK

6.94.2 Status Register (SREG) and Boolean Formula

H Rd3 ∧ K3 ∨ K3 ∧ R3 ∨ R3 ∧ Rd3

Set if there was a borrow from bit 3; cleared otherwise.

S N ⊕ V, for signed tests.

V Rd7 ∧ K7 ∧ R7 ∨ Rd7 ∧ K7 ∧ R7

Set if two's complement overflow resulted from the operation; cleared otherwise.

N R7

Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0 ∧ Z

The previous value remains unchanged when the result is zero; cleared otherwise.

C Rd7 ∧ K7 ∨ K7 ∧ R7 ∨ R7 ∧ Rd7

Set if the absolute value of the constant plus previous carry is larger than the absolute value of Rd; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

; Subtract 0x4F23 from r17:r16
subi r16,0x23 ; Subtract low byte
sbci r17,0x4F ; Subtract with carry high byte 

Words 1 (2 bytes)

Table 6-94. Cycles

Name Cycles
AVRe 1
AVRxm	1
AVRxt 1
AVRrc	1

6.95 SBI – Set Bit in I/O Register

6.95.1 Description

Sets a specified bit in an I/O Register. This instruction operates on the lower 32 I/O Registers – addresses 0-31.

Operation:

(i) I/O(A,b) ← 1

Syntax: Operands: Program Counter:

(i) SBI A, b 0 ≤ A ≤ 31, 0 ≤ b ≤ 7 PC ← PC + 1

16-bit Opcode:

1001 1010 AAAA Abb

6.95.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

sbi 0x1C,0 ; Set bit 0 at address 0x1C

Words 1 (2 bytes)

Table 6-95. Cycles

Name Cycles
AVRe 2
AVRxm	1
AVRxt	1
AVRrc	1

6.96 SBIC – Skip if Bit in I/O Register is Cleared

6.96.1 Description

This instruction tests a single bit in an I/O Register and skips the next instruction if the bit is cleared. This instruction operates on the lower 32 I/O Registers – addresses 0-31.

Operation:

(i) If I/O(A,b) == 0 then PC ← PC + 2 (or 3) else PC ← PC + 1

Syntax: Operands: Program Counter:

(i) SBIC A,b

0 ≤ A ≤ 31, 0 ≤ b ≤ 7 PC PC + 1, Condition false - no

skip

PC ← PC + 2, Skip a one word instruction

PC ← PC + 3, Skip a two word instruction

16-bit Opcode:

1001 1001 AAAA Abb

6.96.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

wait:
sbic 0x1C,1 ; Skip next instruction if 0x1C bit 1 is cleared
rjmp wait ; Bit not cleared yet
nop ; Continue (do nothing) 

Words 1 (2 bytes)

Table 6-96. Cycles

Name Cycles
	i ii iii
AVRe 1 2 3
AVRxm 2 3 4
AVRxt 1 2 3
AVRrc 1 2 N/A

i) If the condition is false (no skip).

ii) If the condition is true (skip is executed) and the instruction skipped is one word.

iii) If the condition is true (skip is executed) and the instruction skipped is two words.

6.97 SBIS – Skip if Bit in I/O Register is Set

6.97.1 Description

This instruction tests a single bit in an I/O Register and skips the next instruction if the bit is set. This instruction operates on the lower 32 I/O Registers – addresses 0-31.

Operation:

(i) If I/O(A,b) == 1 then PC ← PC + 2 (or 3) else PC ← PC + 1

Syntax:

Operands:

Program Counter:

(i) SBIS A,b

0 ≤ A ≤ 31, 0 ≤ b ≤ 7

PC ← PC + 1, Condition false - no skip

PC ← PC + 2, Skip a one word instruction

PC ← PC + 3, Skip a two word instruction

16-bit Opcode:

1001

1011

AAAA

Abbb

6.97.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

waitset:
sbis 0x10,0 ; Skip next instruction if bit 0 at 0x10 is set
rjmp waitset ; Bit not set
nop ; Continue (do nothing) 

Words 1 (2 bytes)

Table 6-97. Cycles

Name Cycles
	i ii iii
AVRe 1 2 3
AVRxm 2 3 4
AVRxt 1 2 3
AVRrc 1 2 N/A

i) If the condition is false (no skip).

ii) If the condition is true (skip is executed) and the instruction skipped is one word.

iii) If the condition is true (skip is executed) and the instruction skipped is two words.

6.98 SBIW - Subtract Immediate from Word

6.98.1 Description

Subtracts an immediate value (0-63) from a register pair and places the result in the register pair. This instruction operates on the upper four register pairs and is well suited for operations on the Pointer Registers.

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) R[d+1]:Rd ← R[d+1]:Rd - K

Syntax:

Operands:

Program Counter:

(i) SBIW Rd,K

d 24, 26, 28, 30, 0 ≤ K ≤ 63

PC ← PC + 1

16-bit Opcode:

1001

0111

KKdd

KKKK

6.98.2 Status Register (SREG) and Boolean Formula

S N ⊕ V, for signed tests.

V R15 ∧ Rdh7

Set if two's complement overflow resulted from the operation; cleared otherwise.

N R15

Set if MSB of the result is set; cleared otherwise.

Z R15 ∧ R14 ∧ R13 ∧ R12 ∧ R11 ∧ R10 ∧ R9 ∧ R8 ∧ R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x0000; cleared otherwise.

C R15 ∧ Rdh7

Set if the absolute value of K is larger than the absolute value of Rd; cleared otherwise.

R (Result) equals R[d+1]:Rd after the operation.

Example:

sbiw r24,1 ; Subtract 1 from r25:r24
sbiw YL,63 ; Subtract 63 from the Y-pointer(r29:r28) 

Words 1 (2 bytes)

Table 6-98. Cycles

Name Cycles
AVRe 2
AVRxm 2
AVRxt 2
AVRrc N/A

6.99 SBR - Set Bits in Register

6.99.1 Description

Sets specified bits in register Rd. Performs the logical ORI between the contents of register Rd and a constant mask K, and places the result in the destination register Rd. (Equivalent to ORI Rd,K.)

Operation:

(i) Rd ← Rd v K

Syntax: Operands: Program Counter:

(i) SBR Rd, K 16 ≤ d ≤ 31, 0 ≤ K ≤ 255 PC ← PC + 1

16-bit Opcode:

0110

KKKK

dddd

KKKK

6.99.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-		0			-

S N ⊕ V, for signed tests.

v0

Cleared.

N R7

Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x00; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

sbr r16,3 ; Set bits 0 and 1 in r16
sbr r17,0xF0 ; Set 4 MSB in r17 

Words 1 (2 bytes)

Table 6-99. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.100 SBRC - Skip if Bit in Register is Cleared

6.100.1 Description

This instruction tests a single bit in a register and skips the next instruction if the bit is cleared.

Operation:

Operation:

(i) If Rr(b) == 0 then PC PC + 2 (or 3) else PC PC + 1

Syntax: Operands: Program Counter:

(i) SBRC Rr,b 0 ≤ r ≤ 31, 0 ≤ b ≤ 7 PC ← PC + 1, Condition false - no

skip

PC ← PC + 2, Skip a one word instruction

PC ← PC + 3, Skip a two word instruction

16-bit Opcode:

1111

110r

rrrr

0bbb

6.100.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

sub r0,r1 ; Subtract r1 from r0
sbrc r0,7 ; Skip if bit 7 in r0 cleared
sub r0,r1 ; Only executed if bit 7 in r0 not cleared
nop ; Continue (do nothing) 

Words 1 (2 bytes)

Table 6-100. Cycles

Name Cycles
	i ii iii
AVRe 1 2 3
AVRxm 1 2 3
AVRxt 1 2 3
AVRrc 1 2 N/A

i) If the condition is false (no skip).

ii) If the condition is true (skip is executed) and the instruction skipped is one word.

iii) If the condition is true (skip is executed) and the instruction skipped is two words.

6.101 SBRS – Skip if Bit in Register is Set

6.101.1 Description

This instruction tests a single bit in a register and skips the next instruction if the bit is set.

Operation:

(i) If Rr(b) == 1 then PC PC + 2 (or 3) else PC PC + 1

Syntax:

Operands:

Program Counter:

(i) SBRS Rr,b

0 ≤ r ≤ 31, 0 ≤ b ≤ 7

PC ← PC + 1, Condition false - no skip

PC ← PC + 2, Skip a one word instruction

PC ← PC + 3, Skip a two word instruction

16-bit Opcode:

1111

111r

rrrr

0bbb

6.101.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

sub	r0,r1	; Subtract r1 from r0
sbrs	r0,7	; Skip if bit 7 in r0 set
neg	r0	; Only executed if bit 7 in r0 not set
nop		; Continue (do nothing)

Words 1 (2 bytes)

Table 6-101. Cycles

Name Cycles
	i ii iii
AVRe 1 2 3
AVRxm 1 2 3
AVRxt 1 2 3
AVRrc 1 2 N/A

i) If the condition is false (no skip).

ii) If the condition is true (skip is executed) and the instruction skipped is one word.

iii) If the condition is true (skip is executed) and the instruction skipped is two words.

6.102 SEC - Set Carry Flag

6.102.1 Description

Sets the Carry (C) flag in SREG (Status Register). (Equivalent to instruction BSET 0.)

Operation:

(i) C ← 1

Syntax:	Operands:	Program Counter:
(i) SEC	None	PC ← PC + 1

16-bit Opcode:

1001

0100

0000

1000

6.102.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----1

c 1

Carry flag set.

Example:

sec ; Set Carry flag
adc r0,r1 ; r0=r0+r1+1

Words 1 (2 bytes)

Table 6-102. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.103 SEH – Set Half Carry Flag

6.103.1 Description

Sets the Half Carry (H) flag in SREG (Status Register). (Equivalent to instruction BSET 5.)

Operation:

(i) H ← 1

Syntax: Operands: Program Counter:

(i) SEH None PC ← PC + 1

16-bit Opcode:

1001 0100 0101 1000

6.103.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	1	-	-	-	-	-

H 1

Half Carry flag set.

Example:

seh ; Set Half Carry flag 

Words 1 (2 bytes)

Table 6-103. Cycles

Name Cycles
AVRe 1
......continued
Name Cycles
AVRxm 1
AVRxt 1
AVRrc 1

6.104 SEI - Set Global Interrupt Enable Bit

6.104.1 Description

Sets the Global Interrupt Enable (I) bit in SREG (Status Register). The instruction following SEI will be executed before any pending interrupts.

Operation:

(i) 1

Syntax: Operands: Program Counter:

(i) SEI None PC ← PC + 1

16-bit Opcode:

1001 0100 0111 1000

6.104.2 Status Register (SREG) and Boolean Formula

ITHSV		NZC
1	-	-	-	-	-	-	-

1 1

Global Interrupt Enable bit set.

Example:

sei ; set global interrupt enable
sleep ; enter sleep, waiting for interrupt
; note: will enter sleep before any pending interrupt(s) 

Words

1 (2 bytes)

Table 6-104. Cycles

Name Cycles
AVRe	1
AVRxm 1
AVRxt 1
AVRrc 1

6.105 SEN – Set Negative Flag

6.105.1 Description

Sets the Negative (N) flag in SREG (Status Register). (Equivalent to instruction BSET 2.)

Operation:

(i) N ← 1

Syntax: Operands: Program Counter:

(i) SEN None PC ← PC + 1

16-bit Opcode:

1001 0100 0010 1000

6.105.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----1--

N 1

Negative flag set.

Example:

add r2,r19 ; Add r19 to r2
sen ; Set Negative flag 

Words 1 (2 bytes)

Table 6-105. Cycles

Name Cycles
AVRe	1
AVRxm	1
AVRxt	1
AVRrc	1

6.106 SER - Set all Bits in Register

6.106.1 Description

Loads 0xFF directly to register Rd. (Equivalent to instruction LDI Rd, 0xFF).

Operation:

(i) Rd ← 0xFF

Syntax: Operands: Program Counter:

(i) SER Rd 16 ≤ d ≤ 31 PC ← PC + 1

16-bit Opcode:

1110 1111 dddd 1111

6.106.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

clr	r16	; Clear r16
ser	r17	; Set r17
out	0x18,r16	; Write zeros to Port B
nop		; Delay (do nothing)
out	0x18,r17	; Write ones to Port B

Words 1 (2 bytes)

Table 6-106. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt	1
AVRrc	1

6.107 SES - Set Sign Flag

6.107.1 Description

Sets the Sign (S) flag in SREG (Status Register). (Equivalent to instruction BSET 4.)

Operation:

(i) S ← 1

Syntax: Operands: Program Counter:

(i) SES None PC ← PC + 1

16-bit Opcode:

1001 0100 0100 1000

6.107.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
---1----

s 1

Sign flag set.

Example:

add r2,r19 ; Add r19 to r2
ses ; Set Negative flag 

Words 1 (2 bytes)

Table 6-107. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.108 SET - Set T Bit

6.108.1 Description

Sets the T bit in SREG (Status Register). (Equivalent to instruction BSET 6.)

Operation:

(i) T 1

Syntax: Operands: Program Counter:

(i) SET None PC ← PC + 1

16-bit Opcode:

1001 0100 0110 1000

6.108.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	1	-	-	-	-	-	-

T 1 T bit set.

Example:

set ; Set T bit 

Words 1 (2 bytes)

Table 6-108. Cycles

Name Cycles
AVRe 1
......continued
Name Cycles
AVRxm 1
AVRxt 1
AVRrc 1

6.109 SEV - Set Overflow Flag

6.109.1 Description

Sets the Overflow (V) flag in SREG (Status Register). (Equivalent to instruction BSET 3.)

Operation:

(i) V ← 1

Syntax: Operands: Program Counter:

(i) SEV None PC ← PC + 1

16-bit Opcode:

1001 0100 0011 1000

6.109.2 Status Register (SREG) and Boolean Formula

ITHSV		NZC
-	-	-	-	1	-	-	-

V V: 1

Overflow flag set.

Example:

add r2,r19 ; Add r19 to r2
sev ; Set Overflow flag 

Words

1 (2 bytes)

Table 6-109. Cycles

Name Cycles
AVRe	1
AVRxm 1
AVRxt 1
AVRrc 1

6.110 SEZ – Set Zero Flag

6.110.1 Description

Sets the Zero (Z) flag in SREG (Status Register). (Equivalent to instruction BSET 1.)

Operation:

(i) Z 1

Syntax: Operands: Program Counter:

(i) SEZ None PC ← PC + 1

16-bit Opcode:

1001 0100 0001 1000

6.110.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----1-

Z 1

Zero flag set.

Example:

add r2,r19 ; Add r19 to r2
sez ; Set Zero flag 

Words 1 (2 bytes)

Table 6-110. Cycles

Name Cycles
AVRe	1
AVRxm	1
AVRxt	1
AVRrc	1

6.111 SLEEP

6.111.1 Description

This instruction sets the circuit in sleep mode defined by the MCU Control Register.

Operation:

(i) Refer to the device documentation for a detailed description of SLEEP usage.

Syntax: Operands: Program Counter:

(i) SLEEP None PC ← PC + 1

16-bit Opcode:

1001 0101 1000 1000

6.111.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

mov r0,r11 ; Copy r11 to r0
ldi r16,(1<<SE) ; Enable sleep mode
out MCUCR, r16
sleep ; Put MCU in sleep mode 

Words 1 (2 bytes)

Table 6-111. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.112 SPM (AVRe) – Store Program Memory

6.112.1 Description

SPM can be used to erase a page in the program memory, to write a page in the program memory (that is already erased), and to set Boot Loader Lock bits. In some devices, the Program memory can be written one word at a time. In other devices, an entire page can be programmed simultaneously after first filling a temporary page buffer. In all cases, the program memory must be erased one page at a time. When erasing the program memory, the RAMPZ and Z-register are used as page address. When writing the program memory, the RAMPZ and Z-register are used as page or word address, and the R1:R0 register pair is used as data ^(1) . The Flash is word-accessed for code space write operations, so the least significant bit of the RAMPZ register concatenated with the Z register should be set to '0'. When setting the Boot Loader Lock bits, the R1:R0 register pair is used as data. Refer to the device documentation for the detailed description of SPM usage. This instruction can address the entire program memory.

The SPM instruction is not available on all devices. Refer to Appendix A.

Note: 1. R1 determines the instruction high byte, and R0 determines the instruction low byte.

Operation:

(i)	PS(RAMPZ:Z) ← 0xffff	Erase program memory page
(ii)	PS(RAMPZ:Z) ← R1:R0	Write program memory word
(iii)	PS(RAMPZ:Z) ← R1:R0	Load page buffer
(iv)	PS(RAMPZ:Z) ← BUFFER	Write page buffer to program memory

(v) BLBITS ← R1:R0 Set Boot Loader Lock bits

Syntax: Operands: Program Counter:

(i)-(v) SPM None PC ← PC + 1

16-bit Opcode:

1001 0101 1110 1000 

6.112.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

; This example shows SPM write of one page for devices with page write
; - the routine writes one page of data from RAM to Flash
; the first data location in RAM is pointed to by the Y-pointer
; the first data location in Flash is pointed to by the Z-pointer
; - error handling is not included
; - the routine must be placed inside the boot space
; (at least the do_spm sub routine)
; - registers used: r0, r1, temp1, temp2, looplo, loophi, spmcrval
; (temp1, temp2, looplo, loophi, spmcrval must be defined by the user)
; storing and restoring of registers is not included in the routine
; register usage can be optimized at the expense of code size

equ PAGESIZEB = PAGESIZE*2 ; PAGESIZEB is page size in BYTES, not words
org SMALLBOOTSTART

write_page:
    ; page erase
ldi spmcrval, (1<<PGERS) + (1<<SPMEN)
call do_spm ; transfer data from RAM to Flash page buffer
ldi looplo, low(PAGESIZEB) ; init loop variable
ldi loophi, high(PAGESIZEB) ; not required for PAGESIZEB<=256

wrloop:
    ld r0, Y+
    ld r1, Y+
    ldi spmcrval, (1<<SPMEN)
call do_spm
adiw ZL, 2
sbiw looplo, 2 ; use subi for PAGESIZEB<=256
brne wrloop ; execute page write
subi ZL, low(PAGESIZEB) ; restore pointer
sbci ZH, high(PAGESIZEB) ; not required for PAGESIZEB<=256
ldi spmcrval, (1<<PGWRT) + (1<<SPMEN)
call do_spm ; read back and check, optional
ldi looplo, low(PAGESIZEB) ; init loop variable
ldi loophi, high(PAGESIZEB) ; not required for PAGESIZEB<=256
subi YL, low(PAGESIZEB) ; restore pointer
sbci YH, high(PAGESIZEB)

rdloop:
    lpm r0, Z+
    ld r1, Y+
    cpse r0, r1
jmp error
sbiw looplo, 2 ; use subi for PAGESIZEB<=256
brne rdloop

ret ; return 

do_spm:
    in temp2, SREG ; input: spmcrval determines SPM action
    cli ; disable interrupts if enabled, store status

wait:
    in temp1, SPMCR ; check for previous SPM complete
    sbrc temp1, SPMEN
    rjmp wait

    out SPMCR, spmcrval ; SPM timed sequence
    spm

    out SREG, temp2 ; restore SREG (to enable interrupts if originally enabled)

    ret 

Words 1 (2 bytes)

Table 6-112. Cycles

Name Cycles
AVRe -	(1)
AVRxm N/A
AVRxt N/A
AVRrc N/A

Note:

1. Varies with the programming time of the device.

6.113 SPM (AVRxm, AVRxt) – Store Program Memory

6.113.1 Description

SPM can be used to erase a page in the program memory and to write a page in the program memory (that is already erased). In some devices, the program memory can be written one word at a time. In other devices, an entire page can be programmed simultaneously after first filling a temporary page buffer. In all cases, the program memory must be erased one page at a time. When erasing the program memory, the RAMPZ and Z-register are used as page address. When writing the program memory, the RAMPZ and Z-register are used as page or word address, and the R1:R0 register pair is used as data ^(1) . The Flash is word-accessed for code space write operations, so the least significant bit of the RAMPZ register concatenated with the Z register should be set to '0'.
Refer to the device documentation for a detailed description of SPM usage. This instruction can address the entire program memory.
The SPM instruction is not available on all devices. Refer to Appendix A.
Note: 1. R1 determines the instruction high byte, and R0 determines the instruction low byte.
Operation:

(i) PS(RAMPZ:Z) ← 0xffff Erase program memory page
(ii) PS(RAMPZ:Z) ← R1:R0 Write to program memory word		(1)
(iii)	PS(RAMPZ:Z) ← R1:R0 Load Page Buffer	(2)
(iv)	PS(RAMPZ:Z) ← BUFFER	Write Page Buffer to program memory(2)
(v)	PS(RAMPZ:Z) ← 0xffff, Z ← Z + 2	Erase program memory page, Z post incremented
(vi)	PS(RAMPZ:Z) ← R1:R0, Z ← Z + 2	Write to program memory word, Z post incremented(1)

(vii) PS(RAMPZ:Z) ← R1:R0, Z ← Z + 2 Load Page Buffer, Z post incremented (2)
(viii) PS(RAMPZ:Z) ← BUFFER, Z ← Z + 2 Write Page Buffer to program memory, Z post incremented ^(2)

Syntax: Operands: Program Counter:

(i)-(iv) SPM None PC ← PC + 1

(v)-(viii) SPM Z+ None PC ← PC + 1

Notes:

1. Not all devices can write directly to program memory, see device data sheet for detailed description of SPM usage.
2. Not all devices have a page buffer, see device data sheet for detailed description of SPM usage.

16-bit Opcode:

(i)-(iv) 1001	0101 1110	1000
(v)-(viii)	1001 0101 1111	1000

6.113.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Words 1 (2 bytes)

Table 6-113. Cycles

Name	Cycles
	i-iii	iv-vi
AVRe	N/A	N/A
AVRxm	-(1)	-(1)
AVRxt	-(1)	-(1)
AVRrc	N/A	N/A

Note:

1. Varies with the programming time of the device.

6.114 ST – Store Indirect From Register to Data Space using Index X

6.114.1 Description

Stores one byte indirect from a register to data space. The data space usually consists of the Register File, I/O memory, and SRAM, refer to the device data sheet for a detailed definition of the data space.

The data location is pointed to by the X (16-bit) Pointer Register in the Register File. Memory access is limited to the current data segment of 64 KB. To access another data segment in devices with more than 64 KB data space, the RAMPX in the register in the I/O area has to be changed.

The X-Pointer Register can either be left unchanged by the operation, or it can be post-incremented or pre-decremented. These features are especially suited for accessing arrays, tables, and Stack Pointer usage of the X-Pointer Register. Note that only the low byte of the X-pointer is updated in devices with no more than 256 bytes of data space. For such devices, the high byte of the pointer is not used by this instruction and can be used for other

purposes. The RAMPX Register in the I/O area is updated in parts with more than 64 KB data space or more than 64 KB program memory, and the increment/ decrement is added to the entire 24-bit address on such devices.

Not all variants of this instruction are available on all devices.

The result of these combinations is undefined:

ST X+, r26

ST X+, r27

ST -X, r26

ST-X, r27

Using the X-pointer:

Operation: Comment:

(i) DS(X) ← Rr X: Unchanged
(ii) DS(X) ← Rr, X ← X+1 X: Post incremented
(iii) X ← X - 1, DS(X) ← Rr X: Pre decremented

Syntax: Operands: Program Counter:

(i) ST X, Rr 0 ≤ r ≤ 31 PC ← PC + 1
(ii) ST X+, Rr 0 ≤ r ≤ 31 PC ← PC + 1
(iii) ST -X, Rr 0 ≤ r ≤ 31 PC ← PC + 1

16-bit Opcode:

(i) 1001 001r		rrrr	1100
(ii)	1001 001r	rrrr	1101
(iii)	1001 001r	rrrr	1110

6.114.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

clr	r27	; Clear X high byte
ldi	r26,0x60	; Set X low byte to 0x60
st	X+,r0	; Store r0 in data space loc. 0x60(X post inc)
st	X,r1	; Store r1 in data space loc. 0x61
ldi	r26,0x63	; Set X low byte to 0x63
st	X,r2	; Store r2 in data space loc. 0x63
st	-X,r3	; Store r3 in data space loc. 0x62(X pre dec)

Words

1 (2 bytes)

Table 6-114. Cycles

Name	Cycles
	(i)	(ii)	(iii)
AVRe	2^(1)	2^(1)	2^(1)
......continued
Name Cycles
	(i) (ii) (iii)
AVRxm 1	(1)	1(1)	2(1)
AVRxt 1	(2)	1(2)	1(2)
AVRrc 1 1 2

Notes:

1. Cycle times for data memory access assume internal RAM access and are not valid for accessing external RAM.
2. Cycle time for data memory access assumes internal RAM access, and are not valid for access to NVM. A minimum of one extra cycle must be added when accessing NVM. The additional time varies dependent on the NVM module implementation. See the NVMCTRL section in the specific devices data sheet for more information.

6.115 ST (STD) – Store Indirect From Register to Data Space using Index Y

6.115.1 Description

Stores one byte indirect with or without displacement from a register to data space. The data space usually consists of the Register File, I/O memory, and SRAM, refer to the device data sheet for a detailed definition of the data space.

The data location is pointed to by the Y (16-bit) Pointer Register in the Register File. Memory access is limited to the current data segment of 64 KB. To access another data segment in devices with more than 64 KB data space, the RAMPY in the register in the I/O area has to be changed.

The Y-Pointer Register can either be left unchanged by the operation, or it can be post-incremented or pre-decremented. These features are especially suited for accessing arrays, tables, and Stack Pointer usage of the Y-Pointer Register. Note that only the low byte of the Y-pointer is updated in devices with no more than 256 bytes of data space. For such devices, the high byte of the pointer is not used by this instruction and can be used for other purposes. The RAMPY Register in the I/O area is updated in parts with more than 64 KB data space or more than 64 KB program memory, and the increment/ decrement/displacement is added to the entire 24-bit address on such devices.

Not all variants of this instruction are available on all devices.

The result of these combinations is undefined:

ST Y+, r28

ST Y+, r29

ST -Y, r28

ST -Y, r29

Using the Y-pointer:

Operation: Comment:

(i) DS(Y) ← Rr Y: Unchanged

(ii) DS(Y) ← Rr, Y ← Y+1

(iii) Y ← Y - 1, DS(Y) ← Rr

(iv) DS(Y+q) ← Rr

Syntax:

Operands:

Y: Post incremented

Y: Pre decremented

Y: Unchanged, q: Displacement

Program Counter:

(i) ST Y, Rr 0 ≤ r ≤ 31 PC ← PC + 1
(ii) ST Y+, Rr 0 ≤ r ≤ 31 PC ← PC + 1
(iii) ST -Y, Rr 0 ≤ r ≤ 31 PC ← PC + 1
(iv) STD Y+q, Rr 0 ≤ r ≤ 31, 0 ≤ q ≤ 63 PC ← PC + 1

16-bit Opcode:

(i) 1000 001r rrrr 1000
(ii) 1001 001r rrrr 1001
(iii)	1001 001r rrrr 1010
(iv)	10q0 qq1r rrrr 1qqq

6.115.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

clr	r29	; Clear Y high byte
ldi	r28,0x60	; Set Y low byte to 0x60
st	Y+,r0	; Store r0 in data space loc. 0x60(Y post inc)
st	Y,r1	; Store r1 in data space loc. 0x61
ldi	r28,0x63	; Set Y low byte to 0x63
st	Y,r2	; Store r2 in data space loc. 0x63
st	-Y,r3	; Store r3 in data space loc. 0x62(Y pre dec)
std	Y+2,r4	; Store r4 in data space loc. 0x64

Words

1 (2 bytes)

Table 6-115. Cycles

Name	Cycles
	(i)	(ii)	(iii)	(iv)
AVRe	2^(1)	2^(1)	2^(1)	2^(1)
AVRxm	1^(1)	1^(1)	2^(1)	2^(1)
AVRxt	1^(2)	1^(2)	1^(2)	1^(2)
AVRrc	1	1	2	N/A

Notes:

1. Cycle times for data memory access assume internal RAM access and are not valid for accessing external RAM.
2. Cycle time for data memory access assumes internal RAM access, and are not valid for access to NVM. A minimum of one extra cycle must be added when accessing NVM. The additional time varies dependent on the NVM module implementation. See the NVMCTRL section in the specific devices data sheet for more information.

6.116 ST (STD) – Store Indirect From Register to Data Space using Index Z

6.116.1 Description

Stores one byte indirect with or without displacement from a register to data space. The data space usually consists of the Register File, I/O memory, and SRAM, refer to the device data sheet for a detailed definition of the data space.

The data location is pointed to by the Z (16-bit) Pointer Register in the Register File. Memory access is limited to the current data segment of 64 KB. To access another data segment in devices with more than 64 KB data space, the RAMPZ in the register in the I/O area has to be changed.

The Z-Pointer Register can either be left unchanged by the operation, or it can be post-incremented or pre-decremented. These features are especially suited for Stack Pointer usage of the Z-Pointer Register. However, because the Z-Pointer Register can be used for indirect subroutine calls, indirect jumps, and table look-up, it is often more convenient to use the X- or Y-pointer as a dedicated Stack Pointer. Note that only the low byte of the Z-pointer is updated in devices with no more than 256 bytes of data space. For such devices, the high byte of the pointer is not used by this instruction and can be used for other purposes. The RAMPZ Register in the I/O area is updated in parts with more than 64 KB data space or more than 64 KB program memory, and the increment/decrement/displacement is added to the entire 24-bit address on such devices.

Not all variants of this instruction are available on all devices.

The result of these combinations is undefined:

ST Z+, r30

ST Z+, r31

ST -Z, r30

ST -Z, r31

Using the Z-pointer:

Operation: Comment:

(i) DS(Z) ← Rr Z: Unchanged
(ii) DS(Z) ← Rr, Z ← Z+1 Z: Post incremented
(iii) Z Z - 1 , DS(Z) Rr Z : Pre decremented
(iv) DS(Z+q) ← Rr Z: Unchanged, q:

Displacement

Syntax: Operands: Program Counter:

(i) ST Z, Rr 0 ≤ r ≤ 31

PC ← PC + 1

(ii) ST Z+, Rr

0 ≤ r ≤ 31

PC ← PC + 1

(iii) ST -Z, Rr

0 ≤ r ≤ 31

PC ← PC + 1

(iv) STD Z+q, Rr

0 ≤ r ≤ 31, 0 ≤ q ≤ 63

PC ← PC + 1

16-bit Opcode :

(i)	1000	001r	rrrr	0000
(ii)	1001	001r	rrrr	0001
(iii)	1001	001r	rrrr	0010
(iv)	10q0	qq1r	rrrr	0qqq

6.116.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

clr	r31	; Clear Z high byte
ldi	r30,0x60	; Set Z low byte to 0x60
st	Z+,r0	; Store r0 in data space loc. 0x60(Z post inc)
st	Z,r1	; Store r1 in data space loc. 0x61
ldi	r30,0x63	; Set Z low byte to 0x63
st	Z,r2	; Store r2 in data space loc. 0x63
st	-Z,r3	; Store r3 in data space loc. 0x62(Z pre dec)
std	Z+2,r4	; Store r4 in data space loc. 0x64

Words 1 (2 bytes)

Table 6-116. Cycles

Name Cycles
	(i) (ii) (iii) (iv)
AVRe 2	(1)	2^(1)	2^(1)	2^(1)
AVRxm 1	(1)	1^(1)	2^(1)	2^(1)
AVRxt 1	(2)	1^(2)	1^(2)	1^(2)
AVRrc 1 1 2 N/A

Notes:

1. Cycle times for data memory access assume internal RAM access and are not valid for accessing external RAM.
2. Cycle time for data memory access assumes internal RAM access, and are not valid for access to NVM. A minimum of one extra cycle must be added when accessing NVM. The additional time varies dependent on the NVM module implementation. See the NVMCTRL section in the specific devices data sheet for more information.

6.117 STS – Store Direct to Data Space

6.117.1 Description

Stores one byte from a Register to the data space. The data space usually consists of the Register File, I/O memory, and SRAM, refer to the device data sheet for a detailed definition of the data space.

A 16-bit address must be supplied. Memory access is limited to the current data segment of 64 KB. The STS instruction uses the RAMPD Register to access memory above 64 KB. To access another data segment in devices with more than 64 KB data space, the RAMPD in the register in the I/O area has to be changed.

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) DS(k) ← Rr

Syntax:

Operands:

Program Counter:

(i) STS k,Rr

0 ≤ r ≤ 31, 0 ≤ k ≤ 65535

PC ← PC + 2

32-bit Opcode:

1001 001d dddd 0000
kkkk kkkk kkkk kkkk

6.117.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

lds r2,0xFF00 ; Load r2 with the contents of data space location 0xFF00
add r2,r1 ; add r1 to r2
sts 0xFF00,r2 ; Write back 

Words 2 (4 bytes)

Table 6-117. Cycles

Name Cycles
AVRe 2	(1)
AVRxm 2	(1)
AVRxt 2	(2)
AVRrc N/A

Notes:

1. Cycle times for data memory access assume internal RAM access and are not valid for accessing external RAM.
2. Cycle time for data memory access assumes internal RAM access, and are not valid for access to NVM. A minimum of one extra cycle must be added when accessing NVM. The additional time varies dependent on the NVM module implementation. See the NVMCTRL section in the specific devices data sheet for more information.

6.118 STS (AVRrc) – Store Direct to Data Space

6.118.1 Description

Stores one byte from a Register to the data space. The data space usually consists of the Register File, I/O memory, and SRAM, refer to the device data sheet for a detailed definition of the data space.

A 7-bit address must be supplied. The address given in the instruction is coded to a data space address as follows:

ADDR[7:0] ← (INST[8], INST[8], INST[10], INST[9], INST[3], INST[2], INST[1], INST[0])

Memory access is limited to the address range 0x40...0xbf of the data segment.

This instruction is not available on all devices. Refer to Appendix A.

Operation:

(i) (k) ← Rr

Syntax: Operands:

Program Counter:

(i) STS k,Rr 16 ≤ r ≤ 31, 0 ≤ k ≤ 127

PC ← PC + 1

16-bit Opcode:

1010 1kkk dddd kkkk

6.118.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

Example:

lds	r16,0x00	; Load r16 with the contents of data space location 0x00
add	r16,r17	; add r17 to r16
sts	0x00,r16	; Write result to the same address it was fetched from

Words 1 (2 bytes)

Table 6-118. Cycles

Name Cycles
AVRe N/A
AVRxm N/A
AVRxt N/A
AVRrc 1

Note: Registers r0...r15 are remapped to r16...r31.

6.119 SUB – Subtract Without Carry

6.119.1 Description

Subtracts two registers and places the result in the destination register Rd.

Operation:

(i) Rd ← Rd - Rr

Syntax:

Operands:

Program Counter:

(i) SUB Rd,Rr

$$ 0 \leq d \leq 3 1, 0 \leq r \leq 3 1 $$

$$ \mathrm{PC} \leftarrow \mathrm{PC} + 1 $$

16-bit Opcode:

0001 10rd

dddd rrrr

6.119.2 Status Register and Boolean Formula

Set if there was a borrow from bit 3; cleared otherwise.

S N ⊕ V, for signed tests.

V Rd7 ∧ Rr7 ∧ R7 ∨ Rd7 ∧ Rr7 ∧ R7

Set if two's complement overflow resulted from the operation; cleared otherwise.

N R7

Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x00; cleared otherwise.

C Rd7 ∧ Rr7 ∨ Rr7 ∧ R7 ∨ R7 ∧ Rd7

Set if the absolute value of the contents of Rr is larger than the absolute value of Rd; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

sub r13,r12 ; Subtract r12 from r13
brne noteq ; Branch if r12<>r13
...
noteq:
nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-119. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.120 SUBI – Subtract Immediate

6.120.1 Description

Subtracts a register and a constant, and places the result in the destination register Rd. This instruction is working on Register R16 to R31 and is very well suited for operations on the X, Y, and Z-pointers.

Operation:

(i) Rd ← Rd - K

Syntax: Operands: Program Counter:

(i) SUBI Rd,K

16 ≤ d ≤ 31, 0 ≤ K ≤ 255

PC ← PC + 1

16-bit Opcode:

0101

KKKK

dddd

KKKK

6.120.2 Status Register and Boolean Formula

H Rd3 ∧ K3 ∨ K3 ∧ R3 ∨ R3 ∧ Rd3

Set if there was a borrow from bit 3; cleared otherwise.

S N ⊕ V, for signed tests.

V Rd7 ∧ K7 ∧ R7 ∨ Rd7 ∧ K7 ∧ R7

Set if two's complement overflow resulted from the operation; cleared otherwise.

N R7

Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x00; cleared otherwise.

C Rd7 ∧ K7 ∨ K7 ∧ R7 ∨ R7 ∧ Rd7

Set if the absolute value of K is larger than the absolute value of Rd; cleared otherwise.

R (Result) equals Rd after the operation.

Example:

subi r22,0x11 ; Subtract 0x11 from r22
brne noteq ; Branch if r22<>0x11
...
noteq:
nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-120. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.121 SWAP – Swap Nibbles

6.121.1 Description

Swaps high and low nibbles in a register.

Operation:

(i) SWAP Rd 0 ≤ d ≤ 31 PC ← PC + 1

16-bit Opcode:

1001 010d dddd 0010

6.121.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
----

R (Result) equals Rd after the operation.

Example:

inc	r1	; Increment r1
swap	r1	; Swap high and low nibble of r1
inc	r1	; Increment high nibble of r1
swap	r1	; Swap back

Words 1 (2 bytes)

Table 6-121. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc	1

6.122 TST - Test for Zero or Minus

6.122.1 Description

Tests if a register is zero or negative. Performs a logical AND between a register and itself. The register will remain unchanged. (Equivalent to instruction AND Rd,Rd.)

Operation:

(i) Rd ← Rd ∧ Rd

Syntax:

Operands:

Program Counter:

(i) TST Rd

$$ 0 \leq d \leq 3 1 P C \leftarrow P C + 1 $$

16-bit Opcode: (see AND Rd, Rd)

0010 00dd dddd dddd

6.122.2 Status Register (SREG) and Boolean Formula

ITHSVNZC
-	-	-		0			-

S N ⊕ V, for signed tests.

v0

Cleared.

N R7

Set if MSB of the result is set; cleared otherwise.

Z R7 ∧ R6 ∧ R5 ∧ R4 ∧ R3 ∧ R2 ∧ R1 ∧ R0

Set if the result is 0x00; cleared otherwise.

R (Result) equals Rd.

Example:

tst r0 ; Test r0
breq zero ; Branch if r0=0
...
zero:
nop ; Branch destination (do nothing) 

Words 1 (2 bytes)

Table 6-122. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.123 WDR – Watchdog Reset

6.123.1 Description

This instruction resets the Watchdog Timer. This instruction must be executed within a limited time given by the WD prescaler. See the Watchdog Timer hardware specification.

Operation:

(i) WD timer restart.

Syntax: Operands: Program Counter:

(i) WDR None PC ← PC + 1

16-bit Opcode:

1001 0101 1010 1000

6.123.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Example:

wdr ; Reset watchdog timer 

Words 1 (2 bytes)

Table 6-123. Cycles

Name Cycles
AVRe 1
AVRxm 1
AVRxt 1
AVRrc 1

6.124 XCH - Exchange

6.124.1 Description

Exchanges one byte indirect between the register and data space.

The data location is pointed to by the Z (16-bit) Pointer Register in the Register File. Memory access is limited to the current data segment of 64 KB. To access another data segment in devices with more than 64 KB data space, the RAMPZ in the register in the I/O area has to be changed.

The Z-Pointer Register is left unchanged by the operation. This instruction is especially suited for writing/reading status bits stored in SRAM.

Operation:

(i) DS(Z) ↔ Rd

Syntax: Operands: Program Counter:

(i) XCH Z, Rd 0 ≤ d ≤ 31 PC ← PC + 1

16-bit Opcode:

1001 001r

rrrr 0100

6.124.2 Status Register (SREG) and Boolean Formula

I	T	H	S	V	N	Z	C
-	-	-	-	-	-	-	-

Words 1 (2 bytes)

Table 6-124. Cycles

Name Cycles
AVRe N/A
AVRxm 2
AVRxt N/A
AVRrc N/A

7. Appendix A Device Core Overview

7.1 Core Descriptions

The table list all instructions that vary between the different cores and marks if it is included in the core. If the instruction is not a part of the table, then it is included in all cores.

Table 7-1. Core Description

Instructions AVR AVRe AVRe+ AVRxm AVRxt AVRrc
ADIW x x x x x
BREAK x x x x x
CALL x x x x
DES x
EICALL x x x
EIJMP x x x
ELPM			x x x
FMUL			x x x
FMULS			x x x
FMULSU			x x x
JMP		x x x x
LAC				x
LAS				x
LAT				x
LDD	x x x x x
LPM x x x x x
LPM Rd, Z		x x x x
LPM Rd, Z+		x x x x
MOVW		x x x x
MUL			x x x
MULS			x x x
MULSU			x x x
SBIW	x x x x x
SPM		x x x x
SPM Z+				x x
STD	x x x x x
XCH				x

7.2 Device Tables

7.2.1 megaAVR ^® Devices

Table 7-2. megaAVR® Devices

Device Core Missing Instructions
AT90CAN128 AVRe+ EIJMP, EICALL
AT90CAN32 AVRe+ ELPM, EIJMP, EICALL
AT90CAN64 AVRe+ ELPM, EIJMP, EICALL
ATmega1280 AVRe+ EIJMP, EICALL
ATmega1281 AVRe+ EIJMP, EICALL
ATmega1284P AVRe+ EIJMP, EICALL
ATmega1284RFR2 AVRe+ EIJMP, EICALL
ATmega1284 AVRe+ EIJMP, EICALL
ATmega128A AVRe+ EIJMP, EICALL
ATmega128RFA1 AVRe+ EIJMP, EICALL
ATmega128RFR2 AVRe+ EIJMP, EICALL
ATmega128	AVRe+ EIJMP, EICALL
ATmega1608 AVRxt	ELPM, SPM, SPM Z+, EIJMP, EICALL
ATmega1609 AVRxt	ELPM, SPM, SPM Z+, EIJMP, EICALL
ATmega162	AVRe+ ELPM, EIJMP, EICALL
ATmega164A AVRe+ ELPM, EIJMP, EICALL
ATmega164PA	AVRe+ ELPM, EIJMP, EICALL
ATmega164P AVRe+ ELPM, EIJMP, EICALL
ATmega165A AVRe+ ELPM, EIJMP, EICALL
ATmega165PA	AVRe+ ELPM, EIJMP, EICALL
ATmega165P AVRe+ ELPM, EIJMP, EICALL
ATmega168A AVRe+ ELPM, EIJMP, EICALL
ATmega168PA	AVRe+ ELPM, EIJMP, EICALL
ATmega168PB	AVRe+ ELPM, EIJMP, EICALL
ATmega168P AVRe+ ELPM, EIJMP, EICALL
ATmega168	AVRe+ ELPM, EIJMP, EICALL
ATmega169A AVRe+ ELPM, EIJMP, EICALL
ATmega169PA	AVRe+ ELPM, EIJMP, EICALL
ATmega169P AVRe+ ELPM, EIJMP, EICALL
ATmega16A AVRe+ ELPM, EIJMP, EICALL
ATmega16HVA AVRe+ ELPM, EIJMP, EICALL
ATmega16HVB AVRe+ ELPM, EIJMP, EICALL
ATmega16HVBrevB AVRe+ ELPM, EIJMP, EICALL
ATmega16M1 AVRe+ ELPM, EIJMP, EICALL
ATmega16U2 AVRe+ ELPM, EIJMP, EICALL
ATmega16U4 AVRe+ ELPM, EIJMP, EICALL
ATmega16 AVRe+ ELPM, EIJMP, EICALL
ATmega2560 AVRe+
ATmega2561 AVRe+
ATmega2564RFR2 AVRe+
ATmega256RFR2 AVRe+
ATmega3208 AVRxt	ELPM, SPM, SPM Z+, EIJMP, EICALL
ATmega3209 AVRxt	ELPM, SPM, SPM Z+, EIJMP, EICALL
ATmega324A AVRe+ ELPM, EIJMP, EICALL
ATmega324PA	AVRe+ ELPM, EIJMP, EICALL
ATmega324PB	AVRe+ ELPM, EIJMP, EICALL
ATmega324P AVRe+ ELPM, EIJMP, EICALL
ATmega3250A	AVRe+ ELPM, EIJMP, EICALL
ATmega3250PA	AVRe+ ELPM, EIJMP, EICALL
ATmega3250P	AVRe+ ELPM, EIJMP, EICALL
ATmega3250 AVRe+ ELPM, EIJMP, EICALL
ATmega325A AVRe+ ELPM, EIJMP, EICALL
ATmega325PA	AVRe+ ELPM, EIJMP, EICALL
ATmega325P AVRe+ ELPM, EIJMP, EICALL
ATmega325	AVRe+ ELPM, EIJMP, EICALL
ATmega328PB	AVRe+ ELPM, EIJMP, EICALL
ATmega328P AVRe+ ELPM, EIJMP, EICALL
ATmega328	AVRe+ ELPM, EIJMP, EICALL
ATmega3290A	AVRe+ ELPM, EIJMP, EICALL
ATmega3290PA AVRe+ ELPM, EIJMP, EICALL
ATmega3290P AVRe+ ELPM, EIJMP, EICALL
ATmega3290 AVRe+ ELPM, EIJMP, EICALL
ATmega329A AVRe+ ELPM, EIJMP, EICALL
ATmega329PA AVRe+ ELPM, EIJMP, EICALL
ATmega329P AVRe+ ELPM, EIJMP, EICALL
ATmega329 AVRe+ ELPM, EIJMP, EICALL
ATmega32A AVRe+ ELPM, EIJMP, EICALL
ATmega32C1 AVRe+ ELPM, EIJMP, EICALL
ATmega32HVB AVRe+ ELPM, EIJMP, EICALL
ATmega32HVBrevB AVRe+ ELPM, EIJMP, EICALL
ATmega32M1 AVRe+ ELPM, EIJMP, EICALL
ATmega32U2 AVRe+ ELPM, EIJMP, EICALL
ATmega32U4 AVRe+ ELPM, EIJMP, EICALL
ATmega32 AVRe+ ELPM, EIJMP, EICALL
ATmega406 AVRe+ ELPM, EIJMP, EICALL
ATmega4808 AVRxt	ELPM, SPM, SPM Z+, EIJMP, EICALL
ATmega4809 AVRxt	ELPM, SPM, SPM Z+, EIJMP, EICALL
ATmega48A AVRe+	CALL, JMP, ELPM, EIJMP, EICALL
ATmega48PA AVRe+	CALL, JMP, ELPM, EIJMP, EICALL
ATmega48PB AVRe+	CALL, JMP, ELPM, EIJMP, EICALL
ATmega48P AVRe+	CALL, JMP, ELPM, EIJMP, EICALL
ATmega48 AVRe+	CALL, JMP, ELPM, EIJMP, EICALL
ATmega640 AVRe+ ELPM, EIJMP, EICALL
ATmega644A AVRe+ ELPM, EIJMP, EICALL
ATmega644PA AVRe+ ELPM, EIJMP, EICALL
ATmega644P AVRe+ ELPM, EIJMP, EICALL
ATmega644RFR2	AVRe+ ELPM, EIJMP, EICALL
ATmega644 AVRe+ ELPM, EIJMP, EICALL
ATmega6450A AVRe+ ELPM, EIJMP, EICALL
ATmega6450P AVRe+ ELPM, EIJMP, EICALL
ATmega6450 AVRe+ ELPM, EIJMP, EICALL
ATmega645A AVRe+ ELPM, EIJMP, EICALL
ATmega645P AVRe+ ELPM, EIJMP, EICALL
ATmega645 AVRe+ ELPM, EIJMP, EICALL
ATmega6490A AVRe+ ELPM, EIJMP, EICALL
ATmega6490P AVRe+ ELPM, EIJMP, EICALL
ATmega6490 AVRe+ ELPM, EIJMP, EICALL
ATmega649A AVRe+ ELPM, EIJMP, EICALL
ATmega649P AVRe+ ELPM, EIJMP, EICALL
ATmega649 AVRe+ ELPM, EIJMP, EICALL
ATmega64AVRe+ ELPM, EIJMP, EICALL
ATmega64C1 AVRe+ ELPM, EIJMP, EICALL
ATmega64HVE2 AVRe+ ELPM, EIJMP, EICALL
ATmega64M1 AVRe+ ELPM, EIJMP, EICALL
ATmega64RFR2 AVRe+ ELPM, EIJMP, EICALL
ATmega64 AVRe+ ELPM, EIJMP, EICALL
ATmega808 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATmega809 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATmega8515 AVRe+ BREAK, CALL, JMP, ELPM, EIJMP, EICALL
ATmega8535 AVRe+ BREAK, CALL, JMP, ELPM, EIJMP, EICALL
ATmega88A AVRe+ CALL, JMP, ELPM, EIJMP, EICALL
ATmega88PA AVRe+ CALL, JMP, ELPM, EIJMP, EICALL
ATmega88PB AVRe+ CALL, JMP, ELPM, EIJMP, EICALL
ATmega88P AVRe+ CALL, JMP, ELPM, EIJMP, EICALL
ATmega88 AVRe+ CALL, JMP, ELPM, EIJMP, EICALL
ATmega8A	AVRe+ BREAK, CALL, JMP, ELPM, EIJMP, EICALL
ATmega8HVA AVRe+ CALL, JMP, ELPM, EIJMP, EICALL
ATmega8U2 AVRe+ CALL, JMP, ELPM, EIJMP, EICALL
ATmega8	AVRe+ BREAK, CALL, JMP, ELPM, EIJMP, EICALL
AT90PWM161	AVRe+ CALL, JMP, ELPM, EIJMP, EICALL
AT90PWM1	AVRe+ CALL, JMP, ELPM, EIJMP, EICALL
AT90PWM216 AVRe+ ELPM, EIJMP, EICALL
AT90PWM2B AVRe+ CALL, JMP, ELPM, EIJMP, EICALL
AT90PWM316 AVRe+ ELPM, EIJMP, EICALL
AT90PWM3B AVRe+ CALL, JMP, ELPM, EIJMP, EICALL
AT90PWM81 AVRe+ CALL, JMP, ELPM, EIJMP, EICALL
AT90USB1286 AVRe+ EIJMP, EICALL
AT90USB1287 AVRe+ EIJMP, EICALL
AT90USB162 AVRe+ ELPM, EIJMP, EICALL
AT90USB646 AVRe+ ELPM, EIJMP, EICALL
AT90USB647 AVRe+ ELPM, EIJMP, EICALL
AT90USB82 AVRe+ CALL, JMP, ELPM, EIJMP, EICALL

7.2.2 tinyAVR ^® Devices

Table 7-3. tinyAVR ^® Devices

Device Core Missing Instructions
ATtiny102 AVRrc
ATtiny104 AVRrc
ATtiny10	AVRrc	BREAK
ATtiny11	AVR	BREAK, LPM, LPM Z+ ADIW, SBIW, IJMP, ICALL, LD X, LD Y, LD -Z, LD Z+, LD
ATtiny12	AVR	BREAK, LPM, LPM Z+ ADIW, SBIW, IJMP, ICALL, LD X, LD Y, LD -Z, LD Z+, LD
ATtiny13A	AVRe	CALL, JMP, ELPM
ATtiny13	AVRe	CALL, JMP, ELPM
ATtiny15	AVR	BREAK, LPM, LPM Z+ ADIW, SBIW, IJMP, ICALL, LD X, LD Y, LD -Z, LD Z+, LD
ATtiny1604	AVRxt	ELPM, EIJMP, EICALL, SPM, SPM Z+
ATtiny1606	AVRxt	ELPM, EIJMP, EICALL, SPM, SPM Z+
ATtiny1607	AVRxt	ELPM, EIJMP, EICALL, SPM, SPM Z+
ATtiny1614	AVRxt	ELPM, EIJMP, EICALL, SPM, SPM Z+
ATtiny1616	AVRxt	ELPM, EIJMP, EICALL, SPM, SPM Z+
ATtiny1617	AVRxt	ELPM, EIJMP, EICALL, SPM, SPM Z+
ATtiny1624	AVRxt	ELPM, EIJMP, EICALL, SPM, SPM Z+
ATtiny1626	AVRxt	ELPM, EIJMP, EICALL, SPM, SPM Z+
......continued
Device Core Missing Instructions
ATtiny1627 AVRxt ELPM, EIJMP, EICALL, SPM, SPM Z+
ATtiny1634 AVRe
ATtiny167 AVRe
ATtiny202 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny204 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny20 AVRrc BREAK
ATtiny212 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny214 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny2313A AVRe CALL, JMP, ELPM
ATtiny2313 AVRe CALL, JMP, ELPM
ATtiny24A AVRe CALL, JMP, ELPM
ATtiny24 AVRe CALL, JMP, ELPM
ATtiny25 AVRe CALL, JMP, ELPM
ATtiny261A	AVRe CALL, JMP, ELPM
ATtiny261 AVRe CALL, JMP, ELPM
ATtiny26	AVR	BREAK
ATtiny3216 AVRxt ELPM, EIJMP, EICALL, SPM, SPM Z+
ATtiny3217 AVRxt ELPM, EIJMP, EICALL, SPM, SPM Z+
ATtiny3224 AVRxt ELPM, EIJMP, EICALL, SPM, SPM Z+
ATtiny3226 AVRxt ELPM, EIJMP, EICALL, SPM, SPM Z+
ATtiny3227 AVRxt ELPM, EIJMP, EICALL, SPM, SPM Z+
ATtiny402 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny404 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny406 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny40 AVRrc
ATtiny412 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny414 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny416 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny417 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny424 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny426 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny427 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny4313 AVRe CALL, JMP, ELPM
ATtiny43U AVRe CALL, JMP, ELPM
ATtiny441 AVRe CALL, JMP, ELPM
ATtiny44A AVRe CALL, JMP, ELPM
ATtiny44 AVRe CALL, JMP, ELPM
ATtiny45 AVRe CALL, JMP, ELPM
ATtiny461A AVRe CALL, JMP, ELPM
ATtiny461 AVRe CALL, JMP, ELPM
ATtiny48 AVRe CALL, JMP, ELPM
ATtiny4 AVRc BREAK
ATtiny5 AVRc BREAK
ATtiny804 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny806 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny807 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny814 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny816 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny817 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny824 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny826 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny827 AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL
ATtiny828 AVRe CALL, JMP, ELPM
ATtiny841 AVRe CALL, JMP, ELPM
ATtiny84A AVRe CALL, JMP, ELPM
ATtiny84 AVRe CALL, JMP, ELPM
ATtiny85 AVRe CALL, JMP, ELPM
ATtiny861A AVRe CALL, JMP, ELPM
ATtiny861 AVRe CALL, JMP, ELPM
ATtiny87 AVRe CALL, JMP, ELPM
ATtiny88 AVRe CALL, JMP, ELPM
ATtiny9 AVRc BREAK

7.2.3 AVR ^® Dx Devices

Table 7-4. AVR® Dx Devices

Device Core Missing Instructions
AVR128DA28 AVRxt EIJMP, EICALL
AVR128DA32 AVRxt EIJMP, EICALL
AVR128DA48 AVRxt EIJMP, EICALL
AVR128DA64 AVRxt EIJMP, EICALL
AVR32DA28 AVRxt ELPM, EIJMP, EICALL
AVR32DA32 AVRxt ELPM, EIJMP, EICALL
AVR32DA48 AVRxt ELPM, EIJMP, EICALL
AVR64DA28 AVRxt ELPM, EIJMP, EICALL
AVR64DA32 AVRxt ELPM, EIJMP, EICALL
AVR64DA48 AVRxt ELPM, EIJMP, EICALL
AVR64DA64 AVRxt ELPM, EIJMP, EICALL
AVR128DB28 AVRxt EIJMP, EICALL
AVR128DB32 AVRxt EIJMP, EICALL
AVR128DB48 AVRxt EIJMP, EICALL
AVR128DB64 AVRxt EIJMP, EICALL
AVR32DB28 AVRxt ELPM, EIJMP, EICALL
AVR32DB32 AVRxt ELPM, EIJMP, EICALL
AVR32DB48 AVRxt ELPM, EIJMP, EICALL
AVR64DB28 AVRxt ELPM, EIJMP, EICALL
AVR64DB32 AVRxt ELPM, EIJMP, EICALL
AVR64DB48 AVRxt ELPM, EIJMP, EICALL
AVR64DB64 AVRxt ELPM, EIJMP, EICALL
AVR128DD28 AVRxt EIJMP, EICALL
AVR128DD32 AVRxt EIJMP, EICALL
AVR128DD48 AVRxt EIJMP, EICALL
AVR128DD64 AVRxt EIJMP, EICALL
AVR32DD28 AVRxt ELPM, EIJMP, EICALL
AVR32DD32 AVRxt ELPM, EIJMP, EICALL
AVR32DD48 AVRxt ELPM, EIJMP, EICALL
AVR64DD28 AVRxt ELPM, EIJMP, EICALL
AVR64DD32 AVRxt ELPM, EIJMP, EICALL
AVR64DD48 AVRxt ELPM, EIJMP, EICALL
AVR64DD64 AVRxt ELPM, EIJMP, EICALL

7.2.4 XMEGA ^® Devices

Table 7-5. XMEGA ^® Devices

Device Core Missing Instructions
ATxmega128A1 AVRxm	LAC, LAT, LAS, XCH
ATxmega128A1U AVRxm
ATxmega128A3 AVRxm	LAC, LAT, LAS, XCH
ATxmega128A3U AVRxm
ATxmega128A4U AVRxm
ATxmega128B1 AVRxm
ATxmega128B3 AVRxm
ATxmega128C3 AVRxm
ATxmega128D3 AVRxm	LAC, LAT, LAS, XCH
ATxmega128D4 AVRxm	LAC, LAT, LAS, XCH
ATxmega16A4 AVRxm	LAC, LAT, LAS, XCH, ELPM, EIJMP, EICALL
ATxmega16A4U AVRxm		ELPM, EIJMP, EICALL
ATxmega16C4	AVRxm	ELPM, EIJMP, EICALL
ATxmega16D4	AVRxm LAC, LAT, LAS, XCH, ELPM, EIJMP, EICALL
ATxmega16E5 AVRxm		ELPM, EIJMP, EICALL
ATxmega192A3 AVRxm	LAC, LAT, LAS, XCH
ATxmega192A3U AVRxm
ATxmega192C3 AVRxm
ATxmega192D3 AVRxm	LAC, LAT, LAS, XCH
ATxmega256A3B AVRxm	LAC, LAT, LAS, XCH
ATxmega256A3BU	AVRxm
ATxmega256A3 AVRxm	LAC, LAT, LAS, XCH
ATxmega256A3U AVRxm

Device Core Missing Instructions
ATxmega256C3 AVRxm
ATxmega256D3 AVRxm LAC, LAT, LAS, XCH
ATxmega32C3 AVRxm LAC, LAT, LAS, XCH, ELPM, EIJMP, EICALL
ATxmega32D3 AVRxm LAC, LAT, LAS, XCH, ELPM, EIJMP, EICALL
ATxmega32A4 AVRxm LAC, LAT, LAS, XCH, ELPM, EIJMP, EICALL
ATxmega32A4U AVRxm ELPM, EIJMP, EICALL
ATxmega32C4 AVRxm ELPM, EIJMP, EICALL
ATxmega32D4 AVRxm LAC, LAT, LAS, XCH, ELPM, EIJMP, EICALL
ATxmega32E5 AVRxm ELPM, EIJMP, EICALL
ATxmega384C3 AVRxm
ATxmega384D3 AVRxm LAC, LAT, LAS, XCH
ATxmega64A1 AVRxm LAC, LAT, LAS, XCH, EIJMP, EICALL
ATxmega64A1U AVRxm EIJMP, EICALL
ATxmega64A3 AVRxm LAC, LAT, LAS, XCH, EIJMP, EICALL
ATxmega64A3U AVRxm EIJMP, EICALL
ATxmega64A4U AVRxm EIJMP, EICALL
ATxmega64B1 AVRxm EIJMP, EICALL
ATxmega64B3 AVRxm EIJMP, EICALL
ATxmega64C3 AVRxm EIJMP, EICALL
ATxmega64D3 AVRxm LAC, LAT, LAS, XCH, EIJMP, EICALL
ATxmega64D4 AVRxm LAC, LAT, LAS, XCH, EIJMP, EICALL
ATxmega8E5 AVRxm ELPM, EIJMP, EICALL

7.2.5 Automotive Devices

Table 7-6. Automotive Devices

Device Core		Missing Instructions
ATA5272	AVRe	CALL, JMP, ELPM
ATA5505	AVRe
ATA5700M322	AVRe+	ELPM, EIJMP, EICALL
ATA5702M322	AVRe+	ELPM, EIJMP, EICALL
ATA5781	AVRe+	ELPM, EIJMP, EICALL

Device Core Missing Instructions
ATA5782 AVRe+	ELPM, EIJMP, EICALL
ATA5783 AVRe+	ELPM, EIJMP, EICALL
ATA5787 AVRe+	ELPM, EIJMP, EICALL
ATA5790N AVRe+	ELPM, EIJMP, EICALL
ATA5790 AVRe+	ELPM, EIJMP, EICALL
ATA5791 AVRe+	ELPM, EIJMP, EICALL
ATA5795 AVRe+	CALL, JMP, ELPM, EIJMP, EICALL
ATA5831 AVRe+	ELPM, EIJMP, EICALL
ATA5832 AVRe+	ELPM, EIJMP, EICALL
ATA5833 AVRe+	ELPM, EIJMP, EICALL
ATA5835 AVRe+	ELPM, EIJMP, EICALL
ATA6285 AVRe+	CALL, JMP, ELPM, EIJMP, EICALL
ATA6286 AVRe+	CALL, JMP, ELPM, EIJMP, EICALL
ATA6612C AVRe+	CALL, JMP, ELPM, EIJMP, EICALL
ATA6613C AVRe+	ELPM, EIJMP, EICALL
ATA6614Q AVRe+	ELPM, EIJMP, EICALL
ATA6616C AVRe	CALL, JMP, ELPM
ATA6617C AVRe
ATA664251 AVRe
ATA8210 AVRe+	ELPM, EIJMP, EICALL
ATA8215 AVRe+	ELPM, EIJMP, EICALL
ATA8510 AVRe+	ELPM, EIJMP, EICALL
ATA8515 AVRe+	ELPM, EIJMP, EICALL
ATtiny416auto AVRxt CALL, JMP, ELPM, SPM, SPM Z+, EIJMP, EICALL

8. Revision History

The revisions in this section are only correlated with the document revision.

8.1 Rev. DS40002198B - 02/2021

1. Editorial change, code examples needed beautification.
2. Corrected instructions affecting two registers had a syntax that did not compile as inline in avr-gcc or xc8.
3. Defined overline symbol as negation.
4. Corrected core overview for AVR ^® DA Family AVRxm to AVRxt.
5. Added to core overview AVR ^® DB and AVR ^® DD Families.
6. Reintroduced the Conditional Branch Summary table with some simplification.

8.2 Rev. DS40002198A - 05/2020

1. Converted to Microchip format and replaced the Atmel document number 0856.
2. Complete review of entire document.
3. Update to all figures in section 2.
4. The section Conditional Branch Summary is removed.
5. Cycle times and operation is updated for all instructions.
6. Every instruction now has a table listing all cycle times for all variations of the AVR core.
7. Addition of Appendix A listing which instructions are valid for the devices.

8.3 Rev.0856L - 11/2016

A complete review of the document.

New document template.

8.4 Rev.0856K - 04/2016

A note has been added to section "RETI – Return from Interrupt".

8.5 Rev.0856J - 07/2014

1. Section Conditional Branch Summary has been corrected.
2. The first table in section "Description" has been corrected.
3. "TBD" in "Example" in section "Description"" has been removed.
4. The LAC operation in section "LAC – Load and Clear" has been corrected.
5. New template has been added.

8.6 Rev.0856I - 07/2010

1. Updated section "Instruction Set Summary" with new instructions: LAC, LAS, LAT, and XCH.
   Section "LAC - Load and Clear"
   Section "LAS – Load and Set"
   Section "LAT – Load and Toggle"

Section "XCH - Exchange"

1. Updated number of clock cycles column to include Reduced Core tinyAVR. (ATtiny replaced by Reduced Core tinyAVR).

8.7 Rev.0856H - 04/2009

1. Updated section "Instruction Set Summary":
   Updated number of clock cycles column to include Reduced Core tinyAVR.
2. Updated sections for Reduced Core tinyAVR compatibility:
   Section "CBI – Clear Bit in I/O Register"
   Section "LD – Load Indirect from Data Space to Register using Index X"
   Section "LD (LDD) – Load Indirect from Data Space to Register using Index Y"
   Section "LD (LDD) – Load Indirect From Data Space to Register using Index Z"
   Section "RCALL – Relative Call to Subroutine"
   Section "SBI – Set Bit in I/O Register"
   Section "ST – Store Indirect From Register to Data Space using Index X"
   Section "ST (STD) – Store Indirect From Register to Data Space using Index Y"
   Section "ST (STD) – Store Indirect From Register to Data Space using Index Z"
3. Added sections for Reduced Core tinyAVR compatibility:
   Section "LDS (16-bit) – Load Direct from Data Space"
   Section "STS (16-bit) – Store Direct to Data Space"

8.8 Rev.0856G - 07/2008

1. Inserted "Datasheet Revision History".
2. Updated "Cycles XMEGA" for ST, by removing (iv).
3. Updated "SPM #2" opcodes.

8.9 Rev.0856F - 05/2008

1. This revision is based on the AVR Instruction Set 0856E-AVR-11/05.
   Changes done compared to AVR Instruction Set 0856E-AVR-11/05:
2. Updated "Complete Instruction Set Summary" with DES and SPM #2.
3. Updated AVR Instruction Set with XMEGA Clock cycles and Instruction Description.

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ISBN: 978-1-5224-7650-4

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