/**
* @brief Initialize RTC.
*
* @notapi
*/
void rtc_lld_init(void){
/* RSF bit must be cleared by software after an APB1 reset or an APB1 clock
stop. Otherwise its value will not be actual. */
RTC->CRL &= ~RTC_CRL_RSF;
/* Required because access to PRL.*/
rtc_lld_apb1_sync();
/* All interrupts initially disabled.*/
rtc_lld_wait_write();
RTC->CRH = 0;
/* Callback initially disabled.*/
RTCD1.callback = NULL;
/* IRQ vector permanently assigned to this driver.*/
nvicEnableVector(RTC_IRQn, CORTEX_PRIORITY_MASK(STM32_RTC_IRQ_PRIORITY));
}
/**
* @brief Enable access to registers and initialize RTC if BKP domain
* was previously reseted.
* @note: Cold start time of LSE oscillator on STM32 platform
* takes about 3 seconds.
*
* @notapi
*/
void rtc_lld_init(void){
uint32_t preload;
rccEnableBKPInterface(FALSE);
/* Enables access to BKP registers.*/
PWR->CR |= PWR_CR_DBP;
/* If the RTC is not enabled then performs a reset of the backup domain.*/
if (!(RCC->BDCR & RCC_BDCR_RTCEN)) {
RCC->BDCR = RCC_BDCR_BDRST;
RCC->BDCR = 0;
}
#if STM32_RTC == STM32_RTC_LSE
if (!(RCC->BDCR & RCC_BDCR_LSEON)) {
RCC->BDCR |= RCC_BDCR_LSEON;
while (!(RCC->BDCR & RCC_BDCR_LSERDY))
;
}
preload = STM32_LSECLK - 1;
#elif STM32_RTC == STM32_RTC_LSI
/* TODO: Move the LSI clock initialization in the HAL low level driver.*/
RCC->CSR |= RCC_CSR_LSION;
while (!(RCC->CSR & RCC_CSR_LSIRDY))
;
/* According to errata sheet we must wait additional 100 uS for
stabilization.
TODO: Change this code, software loops are not reliable.*/
uint32_t tmo = (STM32_SYSCLK / 1000000) * 100;
while (tmo--)
;
preload = STM32_LSICLK - 1;
#elif STM32_RTC == STM32_RTC_HSE
preload = (STM32_HSICLK / 128) - 1;
#endif
/* Selects clock source (previously enabled and stabilized).*/
RCC->BDCR = (RCC->BDCR & ~RCC_BDCR_RTCSEL) | STM32_RTC;
/* RTC enabled regardless its previous status.*/
RCC->BDCR |= RCC_BDCR_RTCEN;
/* Ensure that RTC_CNT and RTC_DIV contain actual values after enabling
clocking on APB1, because these values only update when APB1
functioning.*/
RTC->CRL = 0;
while (!(RTC->CRL & RTC_CRL_RSF))
;
/* Write preload register only if its value differs.*/
if (preload != ((((uint32_t)(RTC->PRLH)) << 16) + (uint32_t)RTC->PRLL)) {
rtc_lld_wait_write();
/* Enters configuration mode and writes PRLx registers then leaves the
configuration mode.*/
RTC->CRL |= RTC_CRL_CNF;
RTC->PRLH = (uint16_t)(preload >> 16);
RTC->PRLL = (uint16_t)(preload & 0xFFFF);
RTC->CRL &= ~RTC_CRL_CNF;
}
