MPC5744P CAN bus transmission fault

[timur_redgepov]

Good day everyone!

I work with DEVKIT MPC5744P using Embedded Toolbox in Simulink. I faced a problem listed below.

When there is no message receiver or when CANH and CANL are locked the Tx stops, but Rx still operates. This state stays until the board is being hard reseted. I suppose this is caused by Tx error counter. On the other hand, when I read by FreeMaster software, ECR register is 0 and ESR1 register is 0x40080 in operable mode and in a fault mode ESR1 register is 0x40086.

Could you please give me some reccomendations how to solve this problem?

I attach Simulink model which is used to test CAN messages transmission (2019b version).

[timur_redgepov]

Hi paulvlase,

Let me explain by another way.

If you cause an error of CAN bus, i.e. make a shortcut between CANH and CANL for a while, NXP board disables transmission whereas receive continues to work.

It seems like NXP board has some kind of "safe mode" initially activated when board reacts to CAN bus errors.

Is it possible to switch this mode to constantly operating mode?

Thank you!

Regards,

Timur

[paulvlase]

Hi timur.redgepov@gmail.com‌,

I ran your CAN_DIAG model and it seems that Tx works, I can see the sent messages using a CAN sniffer.

I have some questions to understand your problem:

1. Should the CAN messages be sent or no?

2. "When there is no message receiver" means that there is no CAN receiver block in the model?

3. What do you mean by "or when CANH and CANL are locked"

Regards,

Paul

[constantinrazva]

Hello timur.redgepov@gmail.com,

Sorry for the late response - paulvlase‌ can you take a look at this model?

Kind regards,

Razvan.