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stmhal: Correctly clear wake-up flag before entering standby mode.

This commit is contained in:
Damien George 2015-03-22 21:52:20 +00:00
parent e38b892144
commit 8657342973
1 changed files with 28 additions and 0 deletions
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28
stmhal/modpyb.c
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@ -453,7 +453,35 @@ MP_DEFINE_CONST_FUN_OBJ_0(pyb_stop_obj, pyb_stop);
/// \function standby()
STATIC mp_obj_t pyb_standby(void) {
// We need to clear the PWR wake-up-flag before entering standby, since
// the flag may have been set by a previous wake-up event. Furthermore,
// we need to disable the wake-up sources while clearing this flag, so
// that if a source is active it does actually wake the device.
// See section 5.3.7 of RM0090.
// Note: we only support RTC ALRA, ALRB, WUT and TS.
// TODO support TAMP and WKUP (PA0 external pin).
uint32_t irq_bits = RTC_CR_ALRAIE | RTC_CR_ALRBIE | RTC_CR_WUTIE | RTC_CR_TSIE;
// save RTC interrupts
uint32_t save_irq_bits = RTC->CR & irq_bits;
// disable RTC interrupts
RTC->CR &= ~irq_bits;
// clear RTC wake-up flags
RTC->ISR &= ~(RTC_ISR_ALRAF | RTC_ISR_ALRBF | RTC_ISR_WUTF | RTC_ISR_TSF);
// clear global wake-up flag
PWR->CR |= PWR_CR_CWUF;
// enable previously-enabled RTC interrupts
RTC->CR |= save_irq_bits;
// enter standby mode
HAL_PWR_EnterSTANDBYMode();
// we never return; MCU is reset on exit from standby
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_0(pyb_standby_obj, pyb_standby);