TMS320F28377D: Direct CANbus Node-to-Node Communication without Line Driver

Cody Chen

Tool/software:

Dear All,

I want to test CANbus communication between two nodes, but I don't want to use the CAN line driver between them. Can I directly connect Node1's RX to Node2's TX, and Node1's TX to Node2's RX to establish communication?

Cody

over 2 years ago

0 Hareesh Janakiraman over 2 years ago

TI__Guru* 95315 points

No, you cannot do this. Please refer to 3.2 Why a Transceiver is Needed in www.ti.com/lit/SPRACE5.

0 Hareesh Janakiraman over 2 years ago in reply to Hareesh Janakiraman

TI__Guru* 95315 points

If both MCUs (nodes) are on the same PCB, you can achieve successful communication without a transceiver provided you take care of the requirement that every node should be able to monitor its own transmission. Please search Google images for “CAN communication without transceiver” for circuit ideas.

0 Cody Chen over 2 years ago in reply to Hareesh Janakiraman

Prodigy 240 points

Before the RX input, if I place an OR gate with two inputs—one connected to its own TX and the other connected to the other side's TX—will this configuration work? On my board, I have an FPGA that can create many CAN ports, but I want to connect each pair of nodes one by one to save on transceivers.

+1 Hareesh Janakiraman over 2 years ago in reply to Cody Chen

TI__Guru* 95315 points

No, that will not work. During ACK phase transmitter will put out a 1 but expect to read back a zero. Something like the below will work. Google for more ideas.

C2000™︎ microcontrollers

C2000 microcontrollers forum

TMS320F28377D: Direct CANbus Node-to-Node Communication without Line Driver