ST STM32F301 6 Series Reference Manual page 86

Power control (PWR)
Debug mode
By default, the debug connection is lost if the application puts the MCU in Stop or Standby
mode while the debug features are used. This is because the Arm
longer clocked.
However, by setting some configuration bits in the DBGMCU_CR register, the software can
be debugged even when using the low-power modes extensively.
6.3.6 Auto-wakeup from low-power mode
The RTC can be used to wake-up the MCU from low-power mode without depending on an
external interrupt (Auto wake-up mode). The RTC provides a programmable time base for
waking up from Stop or Standby mode at regular intervals. For this purpose, two of the three
alternative RTC clock sources can be selected by programming the RTCSEL[1:0] bits in the
RTC domain control register
•
Low-power 32.768 kHz external crystal oscillator (LSE OSC).
This clock source provides a precise time base with very low-power consumption (less
than 1µA added consumption in typical conditions)
•
Low-power internal RC Oscillator (LSI RC)
This clock source has the advantage of saving the cost of the 32.768 kHz crystal. This
internal RC Oscillator is designed to add minimum power consumption.
To wake-up from Stop mode with an RTC alarm event, it is necessary to:
•
Configure the EXTI Line 17 to be sensitive to rising edge
•
Configure the RTC to generate the RTC alarm
To wake-up from Standby mode, there is no need to configure the EXTI Line 17.
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