CAN FD multiple MCUs

[Arjun_Bansal]

I am trying to connect 2 NUCLEO-G0B1RET6 boards,using CAN FD. I previously did it using CAN, But now i am trying to connect these boards using CAN FD. So far no success,I want to know if it is possible to do it using CANFD.Kindly help me in this regard.

[mƎALLEm]

Hello,

Sure you can do it but you should add a FDCAN transceiver to each board.

[Arjun_Bansal]

i am using ROHM41041 transceiver on both boards.please let me know if there is any tutorial for this.I am trying since 3days with no success.

[mƎALLEm]

Sorry I didn't find that transceiver on internet. Do you have its datasheet?

[mƎALLEm]

Another important point to consider:

From your tranceiver datasheet: it's a 5V one (VCC Min: 4.75V, Max: 5.25V)

If I consider you supply it with around 5V, you have an issue with TxD pin minimum 'High level input voltage': 

VIHmin = 0.7 x VCC = 3.5V > IO voltage level provided by the STM32G0 pin (@3.3V).

Even with VCCmin: VIHmin = 0.7 x 4.75 = 3,325V really at the limit!

 

 

[Arjun_Bansal]

What would be your suggestion to overcome this problem?

[mƎALLEm]

Simply use 3.3V transceiver or use voltage level shifter for the final project.

But for testing I think there is an internal pull-up resistor connected to the transceiver TxD pin:

Try to configure CAN_Tx pin in Open Drain. But I cannot guarantee this workaround.

 

[Karl Yamashita]

You can look into the NCV7344 from ON Semiconductor. It's CAN FD compliant and it can interface a 3V-5V Microcontroller.

[mƎALLEm]

Hello,

VIHmin  = 5.05V x 0.7 = 3,535V > 3.316V (VDD) -> out of the transceiver spec. As I said, you have to use a 3.3V transceiver. Or test TxD pin in OD config

[mƎALLEm]

Hi @Arjun_Bansal ,

You're welcome. Please click on Accept as Solution on the reply which solved your first issue (described in your first comment) as its gives a better visibility on the answered topics.

Thank you