MC33907 with MPC5744P CAN issue

[sanwalsaleem]

Hi folks,

I am working on a project which is based on MC33907 and MPC5744P. I have 3 CAN on board two are using external CAN transceivers and one is using built in CAN transceiver in SBC(MC33907). I am having problems with CAN in SBC. 

CAN TX signal is arriving at SBC PIN but RX is always high  and there is not output on CANH & CANL. SBC is working fine i have double checked all the voltages. CAN0 of MPC5744P is connected with SBC CAN. 

Following things i have tried so far but no luck:

1. Connected CAN0 Signals to CAN1 external transceiver and it works fine. So problem is in SBC

2. Resistance between CANH and CANL is almost 120R which is good and i also checked or short with either ground or supply and there is no short.

3. I checked for the short on CAN TX and RX of SBC and there is no short.

I can see data on CANTX from MCU but CANRX is always high.

I really need help here, i am trying to solve this issue from last 3 days and no success.

[PetrS]

Hi,

By default the SBC's CAN transceiver is disabled, unless the SBC chip is initialized and CAN transceiver enabled via SPI.

Or the SBC can be put into DEBUG mode. When the Debug mode is activated, the CAN transceiver is set to Normal operation mode. To activate the Debug mode, voltage applied to the DEBUG pin must be within the VDEBUG_IL and VDEBUG_IH range at startup.

BR, Petr

[sanwalsaleem]

Yes SBC is in debug mode and i double checked it registers via SPI. 

[mayingge]

Hi 

Have you find the solution?I have met the same problem with you,I will appreciate if you could help me.