Posted on May 17, 2011 at 13:23Hi @all,
I have a problem with the RTC Alarm Interrupt in combination with the Stop mode and do not come to a solution. Can please somebody help me here.
My application has to wake up in 60s intervals and check if it has to do something. The IWDG is active and set to the longest time which is about 17s. As a solution for that I set up an RTC Alarm IRQ which fires every 8s to reset the watchdog and increase a second counter by 8s (this all has not to be exact. For the exact time I use the RTC counter).
That all worked but suddenly very seldom the alarm irq does not fire anymore. So I started to test. Whats wrong with this example:
void RTCAlarm_IRQHandler(void)
{
u32 counter;
if(RTC_GetITStatus(RTC_IT_ALR) != RESET)
{
IWDG_ReloadCounter();
//PWR_BackupAccessCmd(ENABLE);
//RTC_WaitForSynchro();
RTC_WaitForLastTask();
RTC_ClearITPendingBit(RTC_IT_ALR);
/* Clear EXTI line17 pending bit */
EXTI_ClearITPendingBit(EXTI_Line17);
RTC_WaitForLastTask();
counter = RTC_GetCounter();
RTC_WaitForLastTask();
RTC_SetAlarm(counter + 8);
secCounter += 8;
if (secCounter >= 60)
{
...
...
secCounter = 0;
}
...
}
}
in main loop I tried - just for testing purposes this:
while(1)PWR_EnterSTOPMode(PWR_Regulator_LowPower, PWR_STOPEntry_WFI);
As long as the stop mode is not executed the alarm irq works but as soon as the loop is reached the irq hangs in RTC_WaitForLastTask();
Is this method not allowed? Before I used this test the irq didn´t fire anymore at some time ago and not hang in RTC_WaitForLastTask() but with this test the irq hangs.
Can somebody please help getting to understand how to manage this?
Thanks,
Joachim
