Problem BOOT

fabricepeden · ‎2016-11-03

Posted on November 03, 2016 at 14:25

Hi all!

I have a problem with STM32 BOOT (I used a STM32F207). If the microcontroller restarts (after power-off), the firmware is blocked during the CLK initialization (and RTC initialization).

I changed capacitor of the RTC (20pF instead of 22pF), and the initialization has been right. But i don't understand why. If you any idea or suggestion ?

Best Regards

#boot-rtc

Tesla DeLorean · ‎2016-11-03

Posted on November 03, 2016 at 15:17

You should avoid long/infinite loops in the reset paths of the firmware.

The LSE can take 10's of seconds to start if the circuit/layout is wrong.

The F2 is very sensitive to component choices and layout.

You must be using a 6-7pF crystal, not the more common 9-12pF ones.

There is an App Note for computing capacitor values, don't just copy other circuits unless your BOM is identical.

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slimen · ‎2016-11-03

Posted on November 03, 2016 at 15:46

Hello,

You can refer to the application note

http://www.st.com/content/ccc/resource/technical/document/application_note/c6/eb/5e/11/e3/69/43/eb/CD00221665.pdf/files/CD00221665.pdf/jcr:content/translations/en.CD00221665.pdf

: Oscillatordesign guide for ST microcontrollers.

Regards