Posted on March 19, 2017 at 18:08Hi,
I have a strange behaviour with the stm32F746 RTC.
I use a 32768-Hz crystal (I have verified with the scope that it is running).
I initialise as indicated in the following code, but the time register is incremented approximatively every 1500s instead of every 1s. The same code works perfectly with a stm32F429 (same board and same crystal).
Can someone give me an advice ?
Thank you
Edo
static void aProcess_0(void) {
uint32_t time, date, cpt =0;
RCC->APB1ENR |= RCC_APB1ENR_PWREN; // Turn on the PWREN
// Make possible the access to the RTC & RTC backup register.
// Add 1ms delay (for tests).
// After the restart, the RTC is in the protected mode
// Select the 32768-Hz clock & enable the RTC
PWR->CR1 |= PWR_CR_DBP;
kern_suspendProcess(1);
RCC->BDCR = 0;
RCC->BDCR = (RCC_BDCR_RTCSEL_0
| RCC_BDCR_RTCEN
| RCC_BDCR_LSEON);
while (!(RCC->BDCR & RCC_BDCR_LSERDY));
// Remove the write protection
// Enter in the initialization mode
RTC->WPR = 0xCA;
RTC->WPR = 0x53;
// Waiting for ready to write
// Set the new counter values
RTC->ISR |= RTC_ISR_INIT;
while (!(RTC->ISR & RTC_ISR_INITF));
RTC->TR = (K24H<<22)
| ((KHOURS/16)<<20)
| ((KHOURS&0xF)<<16)
| ((KMINUTES/16)<<12)
| ((KMINUTES&0xF)<<8)
| ((KSECONDS/16)<<4)
| ((KSECONDS&0xF)<<0);
RTC->DR = ((KYEARS/16)<<20)
| ((KYEARS&0xF)<<16)
| (KasciiWeek<<13)
| ((KMONTHS/16)<<12)
| ((KMONTHS&0xF)<<8)
| ((KDAYS/16)<<4)
| ((KDAYS&0xF)<<0);
// Exit from the initialization mode
// Set the write protection
RTC->ISR &= ~RTC_ISR_INIT;
RTC->WPR = 0xFF;
while (TRUE) {
kern_suspendProcess(1000);
time = RTC->TR;
date = RTC->DR;
printf('RTC_DR %X RTC_TR = %X %d\n', date, time, cpt++);
}
}
