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S3C831B/P831B
INSTRUCTION SET
STOP — Stop Operation
STOP
Operation:
The STOP instruction stops the both the CPU clock and system clock and causes the
microcontroller to enter Stop mode. During Stop mode, the contents of on-chip CPU registers,
peripheral registers, and I/O port control and data registers are retained. Stop mode can be
released by an external reset operation or by external interrupts. For the reset operation, the
RESET pin must be held to Low level until the required oscillation stabilization interval has
elapsed.
In application programs, a STOP 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 STOP instruction,
leakage current could be flown because of the floating state in the internal bus.
Flags:
No flags are affected.
Format:
opc
Example:
Bytes
Cycles
Opcode
(Hex)
1
4
7F
Addr Mode
dst
src
–
–
The statement
STOP
NOP
NOP
NOP
; halts all microcontroller operations
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