Why my bxCAN peripheral damaged?
CAN tranceivers are very robust. You can verify the truth table of the tranceiver using GPIO mode of the STM32.

Increasing TEC often means it did not receive an acknowledge bit.
You can find the error code in CAN_ESR-&gt;LEC.

If you do not enable to loopback mode you will receive Acknowledgment Error with only one active node on the bus.