
RM0453 Rev 2
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RM0453
Power control (PWR)
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REGLPS bit can be used to check that the low-power regulator is ready (see the table
below).
6.5.9 Stop
2
mode
The Stop 2 mode is based on the CPU Deep-Sleep mode combined with peripheral clock
gating and partial power down of the V
CORE
domain. In Stop 2 mode, all clocks in the V
CORE
domain are stopped. PLL, MSI, HSI16 and HSE32 oscillators are disabled. Some of the
logic is powered down except for the CPU1, CPU2 and some peripherals with wakeup
capability (I2C3, LPTIM1 and LPUART1), that can switch on the HSI16 to receive a frame,
and switch off HSI16 after receiving the frame if it is not a wakeup frame. In this case, the
HSI16 clock is propagated only to the peripheral requesting it. The Stop 2 mode uses the
low-power regulator, hence the device only enters Stop 2 mode once the low-power
regulator is ready. The REGLPS bit can be used to check that the low-power regulator is
ready.
Table 52. Stop 1 mode
Stop 1
Description
Mode entry
WFI (wait for interrupt) or WFE (wait for event) while:
– SLEEPDEEP bit is set in Cortex system control register
– No interrupt (for WFI) or event (for WFE) is pending
– LPMS = 0b001 in PWR_CR1 and/or PWR_C2CR1 or higher
On return from ISR while:
– SLEEPDEEP bit is set in Cortex system control register
– SLEEPONEXIT = 1
– No interrupt is pending
– LPMS = 0b001 in PWR_CR1 and/or PWR_C2CR1 or higher
Note: To enter Stop 1 mode, all EXTI line pending bits (in
EXTI pending register (EXTI_PR2)
), and the peripheral
flags generating wakeup interrupts must be cleared. Otherwise, the Stop 1
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). The interrupt source can be external
interrupts or peripherals with wakeup capability. Refer to
, and
If WFE was used for entry and SEVONPEND = 0:
Any EXTI line configured in event mode. Refer to
configurable event input wakeup
.
If WFE was used for entry and SEVONPEND = 1:
Any EXTI line configured in Interrupt mode (even if the corresponding EXTI
interrupt vector is disabled in the NVIC). The interrupt source can be external
interrupts or peripherals with wakeup capability. Refer to
, and
Wakeup event: refer to
Wakeup latency
Longest wakeup time between: MSI or HSI16 wakeup time and regulator wakeup
time from Low-power mode + Flash memory wakeup time from Stop 1 mode.