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Power control (PWR)
198
for details on how to enter and exit Stop 1 mode.
5.3.8 Stop
2
mode
The Stop 2 mode is based on the Cortex
®
-M4 deepsleep mode combined with peripheral
clock gating. In Stop 2 mode, all clocks in the V
CORE
domain are stopped, the PLL, the MSI,
the HSI16 and the HSE oscillators are disabled. Some peripherals with wakeup capability
(I2C3 and LPUART) can switch on the HSI16 to receive a frame, and switch off the 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.
SRAM1, SRAM2 and register contents are preserved.
The BOR is always available in Stop 2 mode. The consumption is increased when
thresholds higher than V
BOR0
are used.
Note:
The comparators outputs, the LPUART outputs and the LPTIM1 outputs are forced to low
speed (OSPEEDy=00) during the Stop 2 mode.
Table 28. Stop 1 mode
Stop 1 mode
Description
Mode entry
WFI (Wait for Interrupt) or WFE (Wait for Event) while:
– SLEEPDEEP bit is set in Cortex
®
-M4 System Control register
– No interrupt (for WFI) or event (for WFE) is pending
– LPMS = “001” in PWR_CR1
On Return from ISR while:
– SLEEPDEEP bit is set in Cortex
®
-M4 System Control register
– SLEEPONEXIT = 1
– No interrupt is pending
– LPMS = “001” in PWR_CR1
Note: To enter Stop 1 mode, all EXTI Line pending bits (in
), 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
Table 57: STM32L4x5/STM32L4x6 vector table
If WFE was used for entry and SEVONPEND = 0:
Any EXTI Line configured in event mode. Refer to
.
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
Table 57: STM32L4x5/STM32L4x6 vector table
.
Wakeup event: refer to
Section 14.3.2: Wakeup event management
Wakeup latency
Longest wakeup time between: MSI or HSI16 wakeup time and regulator
wakeup time from Low-power mode + Flash wakeup time from Stop 1
mode.