Posted on January 26, 2018 at 21:05
Hi, I'm writing an application with a STM32L051 (32 pin, 64kB ROM).
This application uses the RTC and I wanted to use the RTC periodic auto wake-up feature to update the time display every 60 seconds.
THE PROBLEM:
It looks like the interrupt only happens once at the expected time: after 60 seconds (or any other value I tried)
I found an other person having the same problem on a L053 processor using HAL libraries, but no answer or solution was presented. I don't use HAL libraries.
My interrupt code looks like this:
void RTC_IRQHandler(void)
{
// when Intr. pending
if ((EXTI->PR & EXTI_PR_PIF20) == EXTI_PR_PIF20){
RTC->ISR &= ~(RTC_ISR_WUTWF); // CLR Wake Up intr. flag
EXTI->PR |= EXTI_PR_PIF20; // CLR intr. pending flag (Write 1)
secs = 0;
GetTimeDate();
if ( BTF(KlokStat,klok_on) || BTF(KlokStat,sleep) ){
DisplayTime(hrs,mins);
}
// the 4 lines below were all to test for a solution, to no avail...
RTC->CR = RTC_CR_WUTE | RTC_CR_WUTIE;
NVIC_ClearPendingIRQ(RTC_IRQn); // CLR intr pending register
EXTI->IMR |= EXTI_IMR_IM20; // re-enable RTC wake-up intr.
NVIC_EnableIRQ(RTC_IRQn); // Re-eanble NVIC for RTC */
}
}
The RTC wake-up initialisation code:
/* RTC init function */
static void MX_RTC_Init(void)
{
RTC->WPR = 0xCA; // Unlock Write access for RTC registers
RTC->WPR = 0x53;
RTC->CR &= ~RTC_CR_WUTE; // Disable wake up timer to modify it
// Wait until it is allow to modify wake up reload value
while((RTC->ISR & RTC_ISR_WUTWF) != RTC_ISR_WUTWF)
{
/* add time out here for a robust application */
}
RTC->WUTR = 0x3B; // wake-up period = 60 sec. 0x3B=59
// enable WU tmr, WU tmr Intr. and WU clk =1Hz
RTC->CR = RTC_CR_WUTE | RTC_CR_WUTIE | RTC_CR_WUCKSEL_2;
RTC->WPR = 0xFE; // write protect/lock again
RTC->WPR = 0x64;
EXTI->RTSR |= EXTI_RTSR_RT20; // trigger on rising edge
// EXTI->FTSR |= EXTI_FTSR_FT20; // no trigger on falling edge
EXTI->IMR |= EXTI_IMR_IM20; // enable RTC wake-up intr. going through EXTI 20 line to NVIC
//EXTI->EMR |= EXTI_IMR_IM20; // enable RTC wake-up event necessary?????????
NVIC_EnableIRQ(RTC_IRQn); // Configure NVIC for RTC
NVIC_SetPriority(RTC_IRQn,2); // Set priority for RTC (=2, low priority)
}
My application does *not* sleep, so no real 'wake up' things, I just want to use the interrupt routine to update the clock.
I'm also confused by the interrupt/event thing, but enabling the EXTI event does not make any difference.
Any help or tips are highly appreciated.
Thanks, Tom
#once #stm32l0x #wake-up #rtc #interrupt
