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S3C8275X/F8275X/C8278X/F8278X/C8274X/F8274X INSTRUCTION SET
6-43
IDLE — Idle Operation
IDLE
Operation:
The IDLE instruction stops the CPU clock while allowing system clock oscillation to continue. Idle
mode can be released by an interrupt request (IRQ) or an external reset operation.
In application programs, a IDLE instruction must be immediately followed by at least three NOP
instructions. This ensures an adeguate time interval for the clock to stabilize before the next
instruction is executed. If three or more NOP instructons are not used after IDLE instruction,
leakage current could be flown because of the floating state in the internal bus.
Flags: No flags are affected.
Format:
Bytes Cycles Opcode
(Hex)
Addr Mode
dst
src
opc 1 4 6F – –
Example: The instruction
IDLE ; stops the CPU clock but not the system clock
NOP
NOP
NOP