STM32F427VITX RTC Init Fails with Timeout

[lbrendel]

During RTC init when RTC_EnterInitMode is called a unit sets the INIT bit of the RTC_ISR register in the HAL but when it waits for the bit set to respond it times out with the bit never being set. I have run this same firmware on hundreds of other units with no issue. If the INITF does not set is it likely due to an internal issue of the microcontroller?

[waclawek.jan]

RTC clock must be set and running. Check RCC_BDCR content and if you've selected LSE as RTC clock, make sure it's running.

Also, make sure the backup domain access is enabled in PWR_CR.DBP (again read it out and check - a quite common error is forgetting to enable PWR clock in RCC) and the proper write-disable sequence has been performed with RTC_WPR.

JW

[lbrendel]

Sure i can check those registers. I assumed that if the RCC LSE init succeeded that it was running but i can go back and double check. With the backup domain access is there anything unique about that that one unit out of 300 is exhibiting this? I can definitely put it in but would have expected this to be a more recurring issue. I could believe that the LSE not being correct could be the issue in this case though.

Thanks for the feedback

[waclawek.jan]

> I assumed that if the RCC LSE init succeeded that it was running

How do you check that that init succeeded?

> With the backup domain access is there anything unique about that that one unit out of 300 is exhibiting this?

I have written wilder bugs than just that... ;)

JW