Table 17. Standby Mode - STMicroelectronics STM32F05 series Reference Manual

RM0091
Entering Standby mode
Refer to
In Standby mode, the following features can be selected by programming individual control
bits:
●
Independent watchdog (IWDG): the IWDG is started by writing to its Key register or by
hardware option. Once started it cannot be stopped except by a reset. See
Section 21.3: IWDG functional description
(IWDG).
●
real-time clock (RTC): this is configured by the RTCEN bit in the Backup domain control
register (RCC_BDCR)
●
Internal RC oscillator (LSI): this is configured by the LSION bit in the Control/status
register (RCC_CSR).
● External 32.768 kHz oscillator (LSE): this is configured by the LSEON bit in the Backup
domain control register (RCC_BDCR)
Exiting Standby mode
The microcontroller exits the Standby mode when an external reset (NRST pin), an IWDG
reset, a rising edge on one of the enabled WKUPx pins or the rising edge of an RTC alarm
occurs (see
Standby except for
After waking up from Standby mode, program execution restarts in the same way as after a
Reset (boot pin sampling, option bytes loading, reset vector is fetched, etc.). The SBF status
flag in the
mode.
Refer to
Table 17.
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)
●
PC13, PC14 and PC15 if configured by RTC or LSE
●
WKUPx pins
Table 17 for more details on how to enter Standby mode.
Figure 227: RTC block
Power control/status register
Power control/status register (PWR_CSR)
Table 17 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-M0 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 event's rising edge, external Reset in
NRST
Reset phase
Doc ID 018940 Rev 1
in Section 21: Independent watchdog
diagram). All registers are reset after wakeup from
(PWR_CSR).
Description
pin, IWDG Reset.
Power control (PWR)
indicates that the MCU was in Standby
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