Power control (PWR) RM0367
162/1043 RM0367 Rev 7
Table 37. Stop mode
Stop mode Description
Mode entry
WFI (Wait for Interrupt) or WFE (Wait for Event) while:
– No interrupt (for WFI) or event (for WFE) is pending.
– SLEEPDEEP bit is set in Cortex
®
-M0+ System Control register
– PDDS bit = 0 in Power Control register (PWR_CR)
– WUF bit = 0 in Power Control/Status register (PWR_CSR)
– MSI or HSI16 RC oscillator are selected as system clock for Stop mode
exit by configuring the STOPWUCK bit in the RCC_CFGR register.
Note: To enter the Stop mode, all EXTI Line pending bits (in
Section 13.5.6: EXTI pending register (EXTI_PR)), all peripherals
interrupt pending bits, the RTC Alarm (Alarm A and Alarm B), RTC
wakeup, RTC tamper, and RTC time-stamp flags, must be reset.
Otherwise, the Stop mode entry procedure is ignored and program
execution continues.
On return from ISR while:
– No interrupt is pending.
– SLEEPDEEP bit is set in Cortex
®
-M0+ System Control register
– SLEEPONEXIT = 1
– PDDS bit = 0 in Power Control register (PWR_CR)
– WUF bit = 0 in Power Control/Status register (PWR_CSR)
– MSI or HSI16 RC oscillator are selected as system clock for Stop mode
exit by configuring the STOPWUCK bit in the RCC_CFGR register.
Note: To enter the Stop mode, all EXTI Line pending bits (in
Section 13.5.6: EXTI pending register (EXTI_PR)), all peripherals
interrupt pending bits, the RTC Alarm (Alarm A and Alarm B), RTC
wakeup, RTC tamper, and RTC time-stamp flags, must be reset.
Otherwise, the Stop mode entry procedure is ignored and program
execution continues.
Mode exit
If WFI or return from ISR was used for entry:
Any EXTI Line configured in Interrupt mode (the corresponding EXTI
Interrupt vector must be enabled in the NVIC). Refer to Table 55: List of
vectors.
If WFE was used for entry and SEVONPEND = 0
Any EXTI Line configured in event mode. Refer to Section 13.3.2:
Wakeup event management on page 293
If WFE was used for entry and SEVONPEND = 1
– Any EXTI Line configured in event mode (even if the corresponding EXTI
interrupt is disabled in the NVIC). The interrupt source can be an external
interrupt or a peripheral with wakeup capability (refer to Table 55: List of
vectors).
– A wakeup event (refer to Section 13.3.2: Wakeup event management on
page 293)
Wakeup latency
MSI or HSI16 RC wakeup time + regulator wakeup time from Low-power
mode + FLASH wakeup time
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