STM32L431 CAN communication error , testing at -12°environment temperture , use internal crystal, please help to advise it .

[Ljust.1]

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[Tesla DeLorean]

It doesn't have an internal crystal, only an RC based oscillator/pulse generator. Voltage and Temperature will effect, temperature might also effect power supply and other external circuitry.

Design also lacks any way to pull the frequency based on temperature.

Consider a TCXO, that should at least be able to compensate itself.