Idle Mode - Samsung S3F84B8 User Manual

S3F84B8_UM_REV 1.00

8.2.1.3 Idle Mode

Idle mode is invoked by the IDLE (opcode 6FH) instruction. In Idle mode, the CPU operations are halted while
select peripherals remain active. During Idle mode, the internal clock signal is gated off to the CPU, but not to the
interrupt logic and timer/counters. Port pins retain the mode (input or output) they had at the time of entering Idle
mode.
There are two ways to release the Idle mode:
1. Execute a Reset: All system and peripheral control registers are reset to their default values and the contents
of all data registers are retained. The Reset automatically selects a slow clock (f
and CLKCON.4 are cleared to "00B". If interrupts are masked, Reset is the only way to release Idle mode.
2. Activate any enabled interrupt, causing Idle mode to be released: When you use an interrupt to release Idle
mode, the CLKCON.3 and CLKCON.4 register values remain unchanged and the selected clock value is
used. The interrupt is then serviced. The interrupt service routine will then return to the instruction immediately
following the STOP instruction.
NOTE: Only external interrupts that are not related to clock can be used to release the Stop mode. To release the Idle mode,
any type of interrupt (that is, internal or external) can be used.
Before entering the STOP or IDLE mode, ADC must be disabled. Otherwise, the STOP or IDLE current will increase
significantly.
8-5
8 RESET AND POWER-DOWN
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