Auto Wakeup (Awu) From Low-Power Mode; Table 8. Standby Mode - ST STM32F101 Series Reference Manual

RM0008
Exiting Standby mode
The microcontroller exits Standby mode when an external Reset (NRST pin), IWDG Reset,
a rising edge on WKUP pin or an RTC alarm occurs. All registers are reset after wakeup
from Standby except for
After waking up from Standby mode, program execution restarts in the same way as after a
Reset (boot pins sampling, vector reset is fetched, etc.). The SBF status flag in the
control/status register (PWR_CSR)
Refer to
Table 8.
Standby mode
Mode entry
Mode exit
Wakeup latency
I/O states in Standby mode
In Standby mode, all I/O pins are high impedance except:
Reset pad (still available)
TAMPER pin if configured for tamper or calibration out
WKUP pin, if enabled
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 due to the fact that the Cortex™-M3 core is
no 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. For more details, refer to
Section 20.15.1: Debug support for low-power
3.3.6

Auto Wakeup (AWU) from low-power mode

The RTC can be used to wakeup the MCU from low-power mode without depending on an
external interrupt (Auto Wakeup 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
Power control/status register
Table 8 for more details on how to exit Standby mode.
Standby mode
WFI (Wait for Interrupt) or WFE (Wait for Event) while:
– Set SLEEPDEEP in Cortex™-M3 System Control register
– Set PDDS bit in Power Control register (PWR_CR)
– Clear WUF bit in Power Control/Status register (PWR_CSR)
WKUP pin rising edge, RTC alarm, external Reset in
Reset.
Regulator start up. Reset phase
(PWR_CSR).
indicates that the MCU was in Standby mode.
Description
modes.
Power control (PWR)
Power
NRST
pin, IWDG
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