Datasheet

Instruction Set

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3.4.6.33 NOP

*NOP No operation

Syntax NOP

Operation None

Emulation MOV #0, R3

Description No operation is performed. The instruction may be used for the elimination of instructions

during the software check or for defined waiting times.

Status Bits Status bits are not affected.

The NOP instruction is mainly used for two purposes:

• To fill one, two, or three memory words

• To adjust software timing

NOTE: Emulating No-Operation Instruction

Other instructions can emulate the NOP function while providing different

numbers of instruction cycles and code words. Some examples are:

MOV #0,R3 ; 1 cycle, 1 word

MOV 0(R4),0(R4) ; 6 cycles, 3 words

MOV @R4,0(R4) ; 5 cycles, 2 words

BIC #0,EDE(R4) ; 4 cycles, 2 words

JMP $+2 ; 2 cycles, 1 word

BIC #0,R5 ; 1 cycle, 1 word

However, care should be taken when using these examples to prevent

unintended results. For example, if MOV 0(R4), 0(R4) is used and the

value in R4 is 120h, then a security violation occurs with the watchdog

timer (address 120h), because the security key was not used.

CPU SLAU144J–December 2004–Revised July 2013

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