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MPC5777C MCAN Module Problem

Question asked by Luke Zhang on Nov 27, 2018
Latest reply on Nov 28, 2018 by Petr Stancik

Hi all,


I'm currently working on the MCAN module for MPC5777C using MPC57xx motherboard. My problem is under the same code, same configuration, the MCAN module sometimes working, sometimes not. When it not working, the error from MCAN0_PSR LEC field is 0x05, which indicate during the transmission of a message, the device wanted to send a dominant level but the monitored bus value was recessive.


The error only happens at system boot up, after it successfully boot, if MCAN is working, it always working. 


I hooked up oscilloscope with MCAN_0 pins and trigger the edge when it boot up, and


here's the image when it working (Yellow - MCAN0_TX; Green - MCAN0_RX):



here's the image when it not working (Yellow - MCAN0_TX; Green - MCAN0_RX)



Both case are using same code and same configuration, and when it boot up, whether is working or not, seems pretty random.