Power control (PWR) RM0440
252/2126 RM0440 Rev 4
Table 47. Standby mode
Standby mode Description
Mode entry
WFI (Wait for Interrupt) or WFE (Wait for Event) while:
– SLEEPDEEP bit is set in Cortex
®
-M4 with FPU System Control register
– No interrupt (for WFI) or event (for WFE) is pending
– LPMS = “011” in PWR_CR1
– WUFx bits are cleared in power status register 1 (PWR_SR1)
On return from ISR while:
– SLEEPDEEP bit is set in Cortex
®
-M4 with FPU System Control register
– SLEEPONEXIT = 1
– No interrupt is pending
– LPMS = “011” in PWR_CR1 and
– WUFx bits are cleared in power status register 1 (PWR_SR1)
– The RTC flag corresponding to the chosen wakeup source (RTC Alarm
A, RTC Alarm B, RTC wakeup, tamper or timestamp flags) is cleared
Mode exit
WKUPx pin edge, RTC event, external Reset in
NRST pin, IWDG Reset,
BOR reset
Wakeup latency Reset phase
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