Sleep Mode - Samsung S5PC110 Manual

S5PC110_UM

4.3.7 SLEEP MODE

In SLEEP mode, all power domains are powered down (except ALIVE and RTC), all PLLs are disabled, and the
oscillators (except RTC) are selectively disabled.
To enter the SLEEP mode,
1. Set SLEEP_CFG based on the users' requirements.
2. Set CFG_STANDBYWFI field of PWR_CFG to 2'b11.
3. Set SYSCON_INT_DISABLE field of OTHERS to 1'b1
4. Execute Wait-For-Interrupt instruction (WFI). If SYSCON_INT_DISABLE field of OTHERS is still 1'b1 after
calling wfi instruction, this indicates wfi instruction is ignored by the processor
and user should call wfi instruction again.
Then the SYSCON performs the following sequence to enter SLEEP mode.
1. Complete all active bus transactions.
2. Complete all active memory controller transactions.
3. Allow the external DRAM enter self-refresh mode (to preserve DRAM contents).
4. Disable all PLLs.
5. Selectively disable OSCs except 32.768 KHz.
6. XPWRRGTON becomes low to power off external voltage regulator.
To exit the SLEEP mode, wake up sources referred in section <TODO> Wakeup Sources.
Then the SYSCON performs the following sequence to exit from SLEEP mode.
1. Assert wake-up reset to low.
2. XPWRRGTON becomes high to power on external voltage regulator.
3. Wait for voltage regulator to be stable (around 6ms).
4. Enable the OSC pads if disabled and wait for the OSC stabilization (around 1ms.)
5. Power up all power domains except power domains, which was power-down state before entering the SLEEP
Mode.
6. Release wake-up reset.
Since all modules are powered "OFF" and their states are not preserved in SLEEP mode, you must save and
restore necessary state information before and after SLEEP mode. An example procedure of state saving and
recovery is described in
Section 4.5.3 "State Save and Restore"
on
page 4-24.
4 POWER MANAGEMENT
4-15