Can3 of MPC5606B Rx electrical level is not normal

[iswanghe]

Hi, I am Wang He. Now I am Using MPC5606B to manage 6ch CAN bus. Can3 Rx electrical level is not normal while the other 5ch CAN bus are normal.

Can3 Rx wave form is like this:

Low level is 2V,  not 0V, while the other 5ch CAN bus Rx is 0V.

Schematic is like this:(the 6ch CAN bus are same)

The configuration of CAN3 is different from the other 5ch CAN bus is:

SIU.PCR[36].R = 0x0101;

SIU.PCR[37].R = 0x0A01;

For eaxmple, CAN4's configuration is like this:

SIU.PCR[94].R = 0x0601;

SIU.PCR[95].R = 0x0101;

I am looking forward to your guide. THANK You very much!

[PetrS]

Hi,

Try to swap 2 digital isolators to check if the issue is really due to PC[4] pin or external HW. What is the signal on transceiver's RXD3 output?

Also be sure there is nothing else connected to the PC[4] pin and finally check the PCR[36] is not modified from your setting.

BR, Petr

[iswanghe]

Hi,

Thank you for your reply.

Digital isolator of CAN3 is normal(I have swaped ). The waveform on Transceiver's RXD3 and isolator's RXD are nomal also.

I am very curious. What problems can cause the waveform.(Low level is 2V,  not 0V)

[PetrS]

I did a quick test with CAN_3 module on TRK-MPC5606B and have no issue. RX pin (PC4) has normal levels.

Try to use different pin for CAN3RX, PE[9] or PF[9]) if those are not used.

BR, Petr