Instruction mnemonics

The Assembler accepts mnemonic instructions from the instruction set. A summary of the instruction set mnemonics and their parameters is given here. For a detailed description of the Instruction set, refer to the AVR Data Book.

Arithmetic and Logic Instructions

Mnemonic Operands Description Operation Flags Cycles
ADD  Rd,Rr  Add without Carry  Rd = Rd + Rr  Z,C,N,V,H,S  1
ADC Rd,Rr Add with Carry Rd = Rd + Rr + C Z,C,N,V,H,S 1
SUB Rd,Rr Subtract without Carry Rd = Rd - Rr Z,C,N,V,H,S 1
SUBI Rd,K8 Subtract Immediate Rd = Rd - K8 Z,C,N,V,H,S 1
SBC Rd,Rr Subtract with Carry Rd = Rd - Rr - C Z,C,N,V,H,S 1
SBCI Rd,K8 Subtract with Carry Immedtiate Rd = Rd - K8 - C Z,C,N,V,H,S 1
AND Rd,Rr Logical AND Rd = Rd · Rr Z,N,V,S  1
ANDI Rd,K8 Logical AND with Immediate Rd = Rd · K8 Z,N,V,S 1
OR Rd,Rr Logical OR Rd = Rd V Rr Z,N,V,S 1
ORI Rd,K8 Logical OR with Immediate Rd = Rd V K8 Z,N,V,S 1
EOR Rd,Rr Logical Exclusive OR Rd = Rd EOR Rr Z,N,V,S 1
COM Rd One's Complement Rd = $FF - Rd Z,C,N,V,S 1
NEG Rd Two's Complement Rd = $00 - Rd Z,C,N,V,H,S 1
SBR Rd,K8 Set Bit(s) in Register Rd = Rd V K8 Z,C,N,V,S 1
CBR Rd,K8 Clear Bit(s) in Register Rd = Rd · ($FF - K8) Z,C,N,V,S 1
INC Rd Increment Register Rd = Rd + 1 Z,N,V,S 1
DEC Rd Decrement Register Rd = Rd -1 Z,N,V,S 1
TST Rd Test for Zero or Negative Rd = Rd · Rd Z,C,N,V,S 1
CLR Rd Clear Register Rd = 0 Z,C,N,V,S 1
SER Rd Set Register Rd = $FF None 1
ADIW Rdl,K6 Add Immediate to Word Rdh:Rdl = Rdh:Rdl + K6  Z,C,N,V,S 2
SBIW Rdl,K6 Subtract Immediate from Word Rdh:Rdl = Rdh:Rdl - K 6 Z,C,N,V,S 2
MUL Rd,Rr Multiply Unsigned R1:R0 = Rd * Rr Z,C 2
MULS Rd,Rr Multiply Signed R1:R0 = Rd * Rr Z,C 2
MULSU Rd,Rr Multiply Signed with Unsigned R1:R0 = Rd * Rr Z,C 2
FMUL Rd,Rr Fractional Multiply Unsigned R1:R0 = (Rd * Rr) << 1 Z,C 2
FMULS Rd,Rr Fractional Multiply Signed R1:R0 = (Rd *Rr) << 1 Z,C 2
FMULSU Rd,Rr Fractional Multiply Signed with Unsigned R1:R0 = (Rd * Rr) << 1 Z,C 2
 

Branch Instructions

Mnemonic Operands Description Operation Flags Cycles
RJMP k Relative Jump PC = PC + k +1 None 2
IJMP None Indirect Jump to (Z) PC = Z None 2
EIJMP None Extended Indirect Jump (Z) STACK = PC+1, PC(15:0) = Z, PC(21:16) = EIND None 2
JMP k Jump  PC = k None 3
RCALL k Relative Call Subroutine STACK = PC+1, PC = PC + k + 1 None 3/4*
ICALL None Indirect Call to (Z) STACK = PC+1, PC = Z  None 3/4*
EICALL None Extended Indirect Call to (Z) STACK = PC+1, PC(15:0) = Z, PC(21:16) =EIND None 4*
CALL k Call Subroutine STACK = PC+2, PC = k None 4/5*
RET None Subroutine Return PC = STACK None 4/5*
RETI None Interrupt Return PC = STACK I 4/5*
CPSE Rd,Rr Compare, Skip if equal  if (Rd ==Rr) PC = PC 2 or 3 None 1/2/3
CP Rd,Rr Compare Rd -Rr Z,C,N,V,H,S 1
CPC Rd,Rr Compare with Carry Rd - Rr - C Z,C,N,V,H,S 1
CPI Rd,K8 Compare with Immediate Rd - K Z,C,N,V,H,S 1
SBRC Rr,b Skip if bit in register cleared if(Rr(b)==0) PC = PC + 2 or 3 None 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
SBIC P,b Skip if bit in I/O register cleared if(I/O(P,b)==0) PC = PC + 2 or 3 None 1/2/3
SBIS P,b Skip if bit in I/O register set if(I/O(P,b)==1) PC = PC + 2 or 3 None 1/2/3
BRBC s,k Branch if Status flag cleared if(SREG(s)==0) PC = PC + k + 1 None 1/2
BRBS s,k Branch if Status flag set if(SREG(s)==1) PC = PC + k + 1 None 1/2
BREQ k Branch if equal if(Z==1) PC = PC + k + 1 None 1/2
BRNE k Branch if not equal if(Z==0) PC = PC + k + 1 None 1/2
BRCS k Branch if carry set if(C==1) PC = PC + k + 1 None 1/2
BRCC k Branch if carry cleared if(C==0) PC = PC + k + 1 None 1/2
BRSH k Branch if same or higher if(C==0) PC = PC + k + 1 None 1/2
BRLO k Branch if lower if(C==1) PC = PC + k + 1 None 1/2
BRMI k Branch if minus if(N==1) PC = PC + k + 1 None 1/2
BRPL k Branch if plus if(N==0) PC = PC + k + 1 None 1/2
BRGE k Branch if greater than or equal (signed) if(S==0) PC = PC + k + 1 None 1/2
BRLT k Branch if less than (signed) if(S==1) PC = PC + k + 1 None 1/2
BRHS k Branch if half carry flag set if(H==1) PC = PC + k + 1 None 1/2
BRHC k Branch if half carry flag cleared if(H==0) PC = PC + k + 1 None 1/2
BRTS k Branch if T flag set if(T==1) PC = PC + k + 1 None 1/2
BRTC k Branch if T flag cleared if(T==0) PC = PC + k + 1 None 1/2
BRVS k Branch if overflow flag set if(V==1) PC = PC + k + 1 None 1/2
BRVC k Branch if overflow flag cleared if(V==0) PC = PC + k + 1 None 1/2
BRIE k Branch if interrupt enabled if(I==1) PC = PC + k + 1 None 1/2
BRID k Branch if interrupt disabled if(I==0) PC = PC + k + 1 None 1/2
* Cycle times for data memory accesses assume internal memory accesses, and are not valid for accesses through the external RAM interface. For the instructions CALL, ICALL, EICALL, RCALL, RET and RETI, add three cycles plus two cycles for each wait state in devices with up to 16 bit PC (128KB program memory). For devices with more than 128KB program memory, add five cycles plus three cycles for each wait state.

Data Transfer Instructions

Mnemonic Operands Description Operation Flags Cycles
MOV Rd,Rr Copy register Rd = Rr None 1
MOVW Rd,Rr Copy register pair Rd+1:Rd = Rr+1:Rr, r,d even None 1
LDI Rd,K8 Load Immediate Rd = K None 1
LDS Rd,k Load Direct Rd = (k) None 2*
LD Rd,X Load Indirect Rd = (X) None 2*
LD Rd,X+ Load Indirect and Post-Increment Rd = (X), X=X+1 None 2*
LD Rd,-X Load Indirect and Pre-Decrement X=X-1, Rd = (X) None 2*
LD Rd,Y Load Indirect Rd = (Y) None 2*
LD Rd,Y+ Load Indirect and Post-Increment Rd = (Y), Y=Y+1 None 2*
LD Rd,-Y Load Indirect and Pre-Decrement Y=Y-1, Rd = (Y) None 2*
LDD Rd,Y+q Load Indirect with displacement Rd = (Y+q) None 2*
LD Rd,Z Load Indirect  Rd = (Z) None 2*
LD Rd,Z+ Load Indirect and Post-Increment Rd = (Z), Z=Z+1 None 2*
LD Rd,-Z Load Indirect and Pre-Decrement Z=Z-1, Rd = (Z) None 2*
LDD Rd,Z+q Load Indirect with displacement Rd = (Z+q) None 2*
STS k,Rr Store Direct (k) = Rr None 2*
ST X,Rr Store Indirect (X) = Rr None 2*
ST X+,Rr Store Indirect and Post-Increment (X) = Rr, X=X+1 None 2*
ST -X,Rr Store Indirect and Pre-Decrement X=X-1, (X)=Rr None 2*
ST Y,Rr Store Indirect (Y) = Rr None 2*
ST Y+,Rr Store Indirect and Post-Increment (Y) = Rr, Y=Y+1 None 2
ST -Y,Rr Store Indirect and Pre-Decrement Y=Y-1, (Y) = Rr None 2
ST Y+q,Rr Store Indirect with displacement (Y+q) = Rr None 2
ST Z,Rr Store Indirect (Z) = Rr None 2
ST Z+,Rr Store Indirect and Post-Increment (Z) = Rr, Z=Z+1 None 2
ST -Z,Rr Store Indirect and Pre-Decrement Z=Z-1, (Z) = Rr None 2
ST Z+q,Rr Store Indirect with displacement (Z+q) = Rr None 2
LPM None Load Program Memory R0 = (Z) None 3
LPM Rd,Z Load Program Memory Rd = (Z) None 3
LPM Rd,Z+ Load Program Memory and Post-Increment Rd = (Z), Z=Z+1 None 3
ELPM None Extended Load Program Memory R0 = (RAMPZ:Z) None 3
ELPM Rd,Z Extended Load Program Memory Rd = (RAMPZ:Z) None 3
ELPM Rd,Z+ Extended Load Program Memory and Post Increment Rd = (RAMPZ:Z), Z = Z+1 None 3
SPM None Store Program Memory (Z) = R1:R0 None -
ESPM None Extended Store Program Memory (RAMPZ:Z) = R1:R0 None -
IN Rd,P In Port Rd = P None 1
OUT P,Rr Out Port P = Rr None 1
PUSH Rr Push register on Stack STACK = Rr None 2
POP Rd Pop register from Stack Rd = STACK None 2
* Cycle times for data memory accesses assume internal memory accesses and are not valid for accesses through the external RAM interface. For the LD, ST, LDD, STD, LDS, STS, PUSH and  POP instructions, add one cycle plus one cycle for each wait state.

Bit and Bit-test Instructions

Mnemonic Operands Description Operation Flags Cycles
LSL Rd Logical shift left Rd(n+1)=Rd(n), Rd(0)=0, C=Rd(7) Z,C,N,V,H,S 1
LSR Rd Logical shift right Rd(n)=Rd(n+1), Rd(7)=0, C=Rd(0) Z,C,N,V,S 1
ROL Rd Rotate left through carry Rd(0)=C, Rd(n+1)=Rd(n), C=Rd(7) Z,C,N,V,H,S 1
ROR Rd Rotate right through carry Rd(7)=C, Rd(n)=Rd(n+1), C=Rd(0) Z,C,N,V,S 1
ASR Rd Arithmetic shift right Rd(n)=Rd(n+1), n=0,...,6 Z,C,N,V,S 1
SWAP Rd Swap nibbles Rd(3..0) = Rd(7..4), Rd(7..4) = Rd(3..0) None 1
BSET  s Set flag SREG(s) = 1 SREG(s) 1
BCLR s Clear flag SREG(s) = 0 SREG(s) 1
SBI P,b Set bit in I/O register I/O(P,b) = 1 None 2
CBI P,b Clear bit in I/O register I/O(P,b) = 0 None 2
BST Rr,b Bit store from register to T T = Rr(b) T 1
BLD Rd,b Bit load from register to T Rd(b) = T None 1
SEC None Set carry flag C =1 C 1
CLC None Clear carry flag C = 0 C 1
SEN None Set negative flag N = 1 N 1
CLN None Clear negative flag N = 0 N 1
SEZ None Set zero flag Z = 1 Z 1
CLZ None Clear zero flag Z = 0 Z 1
SEI None Set interrupt flag I = 1 I 1
CLI None Clear interrupt flag I = 0 I 1
SES None Set signed flag S = 1 S 1
CLN None Clear signed flag S = 0 S 1
SEV None Set overflow flag V = 1 V 1
CLV None Clear overflow flag V = 0 V 1
SET None Set T-flag T = 1 T 1
CLT None Clear T-flag T = 0 T 1
SEH None Set half carry flag H = 1 H 1
CLH None Clear half carry flag H = 0 H 1
NOP None No operation None None 1
SLEEP None Sleep See instruction manual None 1
WDR None Watchdog Reset See instruction manual None 1

The Assembler is not case sensitive.

The operands have the following forms:

Rd: Destination (and source) register in the register file
Rr: Source register in the register file
b: Constant (0-7), can be a constant expression
s: Constant (0-7), can be a constant expression
P: Constant (0-31/63), can be a constant expression
K6; Constant (0-63), can be a constant expression
K8: Constant (0-255), can be a constant expression
k: Constant, value range depending on instruction. Can be a constant expression
q: Constant (0-63), can be a constant expression
Rdl:  R24, R26, R28, R30. For ADIW and SBIW instructions
X,Y,Z: Indirect address registers (X=R27:R26, Y=R29:R28, Z=R31:R30)