Hi,
I work with STM32F412/STM32F413 processor. I have also external LSE.
I have the next problem related to STOP mode and RTC.
There are some scenarios we want the processor to go to sleep for x hours.
The processor goes to sleep for 5 seconds, doing some job and return to sleep for 5 seconds and so on in infinite loop till it is broke by interrupt or if time elapsed( the x hours ).
The problem is that sometimes during the sleep phase - The RTC read after HAL_PWR_EnterSTOPMode is the same as before(sleepTime =0) even if in fact the processor sleeps for 5 seconds(We checked it by led and by debug code). This causes the total sleep time to increase and awakening delayed after several hours!!!!
I thought that maybe because the RTC is not ready between HAL_PWR_EnterSTOPMode and the RTC read, so I added a delay after HAL_PWR_EnterSTOPMode line and also add after the delay a piece of code that if sleepTime is 0 -> reading again the RTC. It seems that it solved the problem, but this is not solution I like and it looks bad. I prefer to a solution to read a register or a variable and by that to know that the RTC is ready to be read.
The next is a sample of the relevant code(without my "solution"):
HAL_RTCEx_SetWakeUpTimer_IT(&hrtc, 5 , RTC_WAKEUPCLOCK_CK_SPRE_16BITS) ;
RTC_TimeTypeDef sTimeBefore , sTimeAfter ;
RTC_DateTypeDef sDateBefore , sDateAfter ;
int sleepTime = 0 ;
int totalSleepTime = 0 ;
.
.
.
.
while( sleep )
{
ReadRTC( &sTimeBefore , &sDateBefore ) ; // This function call to HAL_RTC_GetTime function and
// after that to HAL_RTC_GetDate function
HAL_PWR_EnterSTOPMode( PWR_LOWPOWERREGULATOR_ON , PWR_STOPENTRY_WFE ) ;
ReadRTC( &sTimeAfter , &sDateAfter ) ;
sleepTime = CalculateSleepTime( sTimeBefore , sDateBefore , sTimeAfter , sDateAfter ) ;
totalSleepTime += sleepTime ;
if ( totalSleepTime > x )
sleep = 0 ;
}
.
.
.
.
Please any assistance.
Shai
