SN32F100 Series
32-Bit Cortex-M0 Micro-Controller
SONiX TECHNOLOGY CO., LTD
Page 63
Version 1.9
4.3.3.1
Entering Deep power-down mode
Follow these steps to enter Deep power-down mode from Normal mode:
1.
Pull the DPDWAKEUP pin externally HIGH (Please confirm pull-up time to ensure that the DPDWAKEUP pin
already in the pull-up state).
2.
(Optional) Save data to be retained during Deep power-down to the DATA bits in
3.
Write 1 to DPDEN bit in
register to enable Deep power-down mode.
4.
Time spent between step 1 and step 5 shall longer than 20 us.
5.
Execute ARM Cortex-M0 WFI instruction.
After step 5, the PMU turns off the on-chip voltage regulator and waits for a wake-up signal from the DPDWAKEUP pin.
4.3.3.2
Exiting Deep power-down mode
Follow these steps to wake up the chip from Deep power-down mode:
1. DPDWAKEUP pin transition from HIGH to LOW.
–
The PMU will turn on the on-chip voltage regulator. When the core voltage reaches the power-on-reset (POR)
Trigger point, a system reset will be triggered and the chip reboots.
– All registers except the PMU_BKP0 to PMU_BKP 15 and PMU_CTRL will be reset.
2. Once the chip has rebooted, read DPDEN bit in
register to verify that the reset was caused by a
wake-up event from Deep power-down and was not a cold reset.
3. Clear the DPDEN bit in
4. (Optional) Read the stored data in the backup registers.
5. Setup the PMU for the next Deep power-down cycle.
4.4 WAKEUP INTERRUPT
System will exit Deep-sleep mode when GPIO indicates a GPIO interrupt to the ARM core. The all GPIO port pins are
served as wakeup pins. The user must program the registers for each pin to set the appropriate edge polarity for the
corresponding wakeup event. Only edge sensitive is supported to wakeup MCU. Furthermore, the interrupts
corresponding to each input must be enabled in the NVIC.
4.5 WAKEUP
4.5.1 OVERVIEW
Under low power
mode, program doesn’t execute. The wakeup trigger can wake the system up to normal mode. The
wakeup function builds in interrupt operation and trigger system executing interrupt service routine as system wakeup
occurrence.
The wakeup trigger sources of the Sleep mode are all interrupts and the RESET pin.
The wakeup trigger sources of the Deep-sleep mode are the GPIO interrupt, RTC interrupt, and the RESET pin.
The wakeup trigger source of the Deep Power-down mode is DPDWAKEUP pin which is input pull-up before
entering DPD mode.
4.5.2 WAKEUP TIME
When the system is in Sleep mode, the high clock is enabled or disabled by F/W. If the high clock stops and MCU is
waken up from Sleep mode, MCU waits for 2048 external high-speed oscillator clocks and 32 internal high-speed
oscillator clocks as the wakeup time to stable the oscillator circuit. After the wakeup time, the system goes into the
normal mode.
