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application: use LSI clock for RTC

This commit is contained in:
King Kévin 2021-03-24 00:23:47 +01:00
parent c67c9a73ef
commit da626f7780
1 changed files with 2 additions and 13 deletions
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15
application.c
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@ -414,20 +414,13 @@ void main(void)
// setup RTC
puts("setup RTC: ");
rcc_periph_clock_enable(RCC_RTC); // enable clock for RTC peripheral
rcc_osc_on(RCC_LSI); // enable LSI clock
while (!rcc_is_osc_ready(RCC_LSI)); // wait until clock is ready
if (!(RCC_BDCR && RCC_BDCR_RTCEN)) { // the RTC has not been configured yet
pwr_disable_backup_domain_write_protect(); // disable backup protection so we can set the RTC clock source
rtc_unlock(); // enable writing RTC registers
#if defined(MINIF401)
rcc_osc_on(RCC_LSE); // enable LSE clock
while (!rcc_is_osc_ready(RCC_LSE)); // wait until clock is ready
rtc_set_prescaler(256, 128); // set clock prescaler to 32768
RCC_BDCR = (RCC_BDCR & ~(RCC_BDCR_RTCSEL_MASK << RCC_BDCR_RTCSEL_SHIFT)) | (RCC_BDCR_RTCSEL_LSE << RCC_BDCR_RTCSEL_SHIFT); // select LSE as RTC clock source
#else
rcc_osc_on(RCC_LSI); // enable LSI clock
while (!rcc_is_osc_ready(RCC_LSI)); // wait until clock is ready
rtc_set_prescaler(250, 128); // set clock prescaler to 32000
RCC_BDCR = (RCC_BDCR & ~(RCC_BDCR_RTCSEL_MASK << RCC_BDCR_RTCSEL_SHIFT)) | (RCC_BDCR_RTCSEL_LSI << RCC_BDCR_RTCSEL_SHIFT); // select LSI as RTC clock source
#endif
RCC_BDCR |= RCC_BDCR_RTCEN; // enable RTC
rtc_lock(); // protect RTC register against writing
pwr_enable_backup_domain_write_protect(); // re-enable protection now that we configured the RTC clock
@ -441,11 +434,7 @@ void main(void)
pwr_disable_backup_domain_write_protect(); // disable backup protection so we can write to the RTC registers
rtc_unlock(); // enable writing RTC registers
rtc_clear_wakeup_flag(); // clear flag for fresh start
#if defined(MINIF401)
rtc_set_wakeup_time((32768 / 2) / WAKEUP_FREQ - 1, RTC_CR_WUCLKSEL_RTC_DIV2); // set wakeup time based on LSE (keep highest precision, also enables the wakeup timer)
#else
rtc_set_wakeup_time((32000 / 2) / WAKEUP_FREQ - 1, RTC_CR_WUCLKSEL_RTC_DIV2); // set wakeup time based on LSI (keep highest precision, also enables the wakeup timer)
#endif
rtc_enable_wakeup_timer_interrupt(); // enable interrupt
rtc_lock(); // disable writing RTC registers
// important: do not re-enable backup_domain_write_protect, since this will prevent clearing flags (but RTC registers do not need to be unlocked)