mc9s12xdt256 mscan module hardware error! thanks for help!

[jeffzxg]

hi everyone!

      when i use mscan module of 9s12xdt256 to send out message, i found that my program is run ok on one PCB(PCB1), message can send out correctly, but on the other PCB(PCB2), the program failed, but the program is the same with two PCB.

     i measured the voltage across the txd and rxd pin of XDT256 ON PCB2, I found out that no voltage changed, so i think there is something wrong with the hardware of xdt256 on PBC2.

     my question is what can lead to the damage of the mscan module ? the attachments is my CAN interface circuits.

     thanks for help!

[Lundin]

I've done lots of trouble-shooting on very similar CAN hardware, and in my experience, 9 out of 10 problems are related to poor soldering of the EMI filter. I'd start with a careful check on that.

It seems very unlikely that you would have damaged the MSCAN module itself, unless you had a major ESD shock applied directly to the MCU pins. Otherwise the CAN transceiver would be the one taking the blow, and those always come with transient protection, ESD protection, brown-out protection etc etc. Very robust chips, I have yet to see one damaged.