Mickael_Biyotee

Associate II

Solved

RTC is not incremented with a voltage Vbat below 0.6V

3 replies
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Hello,
we use an STM32WB55 with an RTC backup via a super capa.
when the Vbat voltage drops below 0.6V, the RTC registers are no longer incremented.
if the board reboots at this point, we have a datetime offset.
is it possible to detect this problem when the STM32WB55 starts up?

thank you in advance for your help

Power

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mƎALLEmBest answer

ST Technical Moderator

Hello,

You can use ADC in watchdog mode:

To give better visibility on the answered topics, please click "Best answer" on the reply which solved your issue or answered your question.

Measure the VBAT voltage on startup with the ADC and, if it was below the threshold, require that the RTC be reset.

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mƎALLEmBest answer

ST Technical Moderator

Hello,

You can use ADC in watchdog mode:

To give better visibility on the answered topics, please click "Best answer" on the reply which solved your issue or answered your question.

Mickael_BiyoteeAuthor

Associate II

Thanks for your answers.
I added reading VBat at CPU startup and resetting the RTC if necessary and it works very well.