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MPC5777C FlexCAN Rx/Tx issue

Question asked by Dmitry Belov on Feb 1, 2019
Latest reply on Feb 5, 2019 by Dmitry Belov



I am trying to use FlexCAN on MPC5777C-516DS board without motherboard. So, I use DB9  (connected to GPIO[83] and GPIO[84] pins of MPC5777C)  to connect with other CAN interface device for test communication. Jumpers on MPC5777C-516DS: J506 1-2, 4-5; j507 1-3, 2-4.


I am referring example "Example-MPC5777C-FlexCAN-simpleTXRX-ECCdisabled-GHS616" (but work only with FlexCAN_A which connected to DB9). After upload the program I have next scenario:

- FlexCAN_A_Init() - successful;

- Trying to send 1 byte, ext. frame with CANA_TransmitMsg();

- Can not pass endless loop "while ( CAN_A.IFLAG1.B.BUF31TO8I  == 0)"

- Look at Error and Status 1 register (CAN_ESR1). It have 0x4036 value (Buss off, Bit0 error).


I checked up physical connection and signals on CAN bus:

physical connection is ok;

- when I send 1 byte from MPC5777C-516D I have some signals on CNTXA line (attachment "CANbus_CNTXA.jpg"), but have no signal on CAN bus after MC33908LAE transceiver. 

- when I send 1 byte from my other CAN interface device to MPC5777C-516D, I have signals on CAN bus and the similar signal on CNRXA line (attachment "CANbus_CNRXA.jpg"). But CAN interface device reports an timeout error (like it is only 1 device on CAN bus).


Please suggest what kind of problem it can be.

Thank you.