5 Low Power Management
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CW6632B Bluetooth 3.0 Audio Player SOC
Version 1.0.0
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5
Low Power Management
5.1
Power Saving Mode
CW6632B device has the low power management mode that can help reducing power consumption when the
device does not require intensive CPU resources and speed. There are four low power modes available: SLEEP
mode, Hold mode, IDLE mode and power down mode.
5.1.1
B
Sleep Mode
SLEEP mode is an ultimate power reduction mode that will stop all the clock sources, and all the memory chip select
signals are disabled to further reduce power consumption. However, before entering sleep mode, all peripherals
should be disabled separately, especially those analog peripherals and memory, unless those peripherals will stop
themselves if no clock source is applied to the peripherals.
Note
: Before Entering SLEEP mode, the system clock is recommended to change back to oscillator clock as the
system clock.
To enter SLEEP mode, user need to write a „1‟ to SLEEP register (Bit0 of PCON0).
During SLEEP mode, the device can be wake up by either external port wakeup reset or watchdog reset or RTCC
reset.
After exit SLEEP mode by wakeup, the device will be reset.
SLEEP mode will enable DECRAM and IRAM and system clock automatically.
5.1.2
Hold Mode
HOLD mode will stop the clock from entering to system. The system clock is gated with the HOLD mode control.
Once enter HOLD mode, clock to the system logic halts. Therefore, there will be no clock switching entering the
system logic so that power consumption is minimized due to no AC switching. However, the clock sources are not
disabled and they are still running. This allows the clock to be resumed in real time without waiting for the PLL to lock
again. Watchdog interrupt, RTCC interrupt, Port interrupt and all reset event will cause system to exit HOLD mode.
TO enter HOLD mode, user need to writ
e a „1‟ to HOLD register (Bit1 of PCON0).
When wakeup from HOLD Mode by port or RTCC, if interrupt is enabled, CW6632B enters corresponding interrupt
service subroutine (ISR), else CW6632B will execute the instruction following HOLD.
When wakeup from HOLD Mode by watchdog, if watchdog reset enable, CW6632B will be reset, else if watchdog
interrupt is enabled, CW6632B
will enter watchdog‟s ISR. Else CW6632B will execute the instruction following
HOLD.
5.1.3
Idle Mode
IDLE mode will stop the clock from entering to the CPU. The CPU clock is gated with the IDLE mode control. Once
enter IDLE mode, clock to the CPU logic halts. Therefore, there will be no clock switching entering the CPU logic so
CPU power consumption is minimized.
All interrupt sources will cause system to exit IDLE mode, which include all peripheral interrupt.