ST STM32F207 series User Manual

RM0033 Rev 9 79/1381
RM0033 Power control (PWR)
83
RTC alternate functions to wake up the device from the Standby mode
• To wake up the device from the Standby mode with an RTC alarm event, it is necessary
to:
a) Enable the RTC alarm interrupt in the RTC_CR register
b) Configure the RTC to generate the RTC alarm
• To wake up the device from the Standby mode with an RTC tamper or time stamp
event, it is necessary to:
a) Enable the RTC time stamp interrupt in the RTC_CR register or the RTC tamper
interrupt in the RTC_TAFCR register
b) Configure the RTC to detect the tamper or time stamp event
• To wake up the device from the Standby mode with an RTC wakeup event, it is
necessary to:
a) Enable the RTC wakeup interrupt in the RTC_CR register
b) Configure the RTC to generate the RTC wakeup event
Safe RTC alternate function wakeup flag clearing sequence
If the selected RTC alternate function is set before the PWR wakeup flag (WUTF) is cleared,
it will not be detected on the next event as detection is made once on the rising edge.
To avoid bouncing on the pins onto which the RTC alternate functions are mapped, and exit
correctly from the Stop and Standby modes, it is recommended to follow the sequence
below before entering the Standby mode:
• When using RTC alarm to wake up the device from the low-power modes:
a) Disable the RTC alarm interrupt (ALRAIE or ALRBIE bits in the RTC_CR register)
b) Clear the RTC alarm (ALRAF/ALRBF) flag
c) Clear the PWR Wakeup (WUF) flag
d) Enable the RTC alarm interrupt
e) Re-enter the low-power mode
• When using RTC wakeup to wake up the device from the low-power modes:
a) Disable the RTC Wakeup interrupt (WUTIE bit in the RTC_CR register)
b) Clear the RTC Wakeup (WUTF) flag
c) Clear the PWR Wakeup (WUF) flag
d) Enable the RTC Wakeup interrupt
e) Re-enter the low-power mode
• When using RTC tamper to wake up the device from the low-power modes:
a) Disable the RTC tamper interrupt (TAMPIE bit in the RTC_TAFCR register)
b) Clear the Tamper (TAMP1F/TSF) flag
c) Clear the PWR Wakeup (WUF) flag
d) Enable the RTC tamper interrupt
e) Re-enter the low-power mode
• When using RTC time stamp to wake up the device from the low-power modes:
a) Disable the RTC time stamp interrupt (TSIE bit in RTC_CR)
b) Clear the RTC time stamp (TSF) flag
c) Clear the PWR Wakeup (WUF) flag

ST STM32F207 series Specifications

General

Brand	ST
Model	STM32F207 series
Category	Microcontrollers
Language	English