Short between PF0-OSC_IN and PF1-OSC_OUT pins may cause the MCU stop running.

[ElvisWei]

Hi,

In my experiment based on the STM32F091, a crystal connects between PF0-OSC_IN and PF1-OSC_OUT pins. When the two pins short which may lead the MCU stop working.

Please let me know how to address the issue.

Best regards,

Elvis

[Tesla DeLorean]

How did they short?

Is the code running but stuck in Error Handler as clock didn't start? Part doesn't start external clock itself.​

[ElvisWei]

The examination (short the two pings) may be required during a safety test to check if the hardware failure could cause an unacceptable risk to the system.

The two pings connect to a 16M Hz crystal for CAN bus communication, and when it short will cause the code stop running.

Is that any suggestion on the situation? 

Many thanks,

Elvis

[waclawek.jan · Accepted solution]

In startup, make sure that after HSE enable, the wait for the HSERDY flag does not loop forever, and if it exits with finding out the failure, switch to HSI.

During runtime, use CSS; read the Clock security system (CSS) subchapter of RCC chapter in RM0091.

JW

[ElvisWei]

Hi JW,

Thank you for the advice. I will look into it.

Regards,

Elvis