TM4C1231H6PGE: loop back for CAN comms

patrick murphy

Part Number: TM4C1231H6PGE

This device has 2 CAN controllers. To use CAN0 and CAN1 as receiver and transmitter could I directly connect them tx to rx OR should they be connected through bus transcievers?

over 8 years ago

0 Bob Crosby over 8 years ago

TI__Guru 72500 points

They must be connected through a transceiver (or logic that mimics the transceiver). The CAN module requires that it see the CAN RX line go low when it drives CAN TX low and it sees CAN RX go low when a different node acknowledges the transmission.

0 patrick murphy over 8 years ago in reply to Bob Crosby

Intellectual 640 points

thanks

0 Charles Tsai over 8 years ago in reply to patrick murphy

TI__Guru**** 191906 points

For very short distance between two nodes such as the two nodes on the same MCU, you can try the below scheme using diodes without the transceiver.

0 cb1_mobile over 8 years ago in reply to Charles Tsai

Guru 117855 points

Clever - I'd not seen that. Should not that pull-up "pull" to 3V3 - not 5V? (i.e. safer for the MCU)

0 Charles Tsai over 8 years ago in reply to cb1_mobile

TI__Guru**** 191906 points

Hi Cb1,
You are correct. The poster needs 3.3V pullup. I was trying to illustrate the diodes in place of the transceiver. Personally, I tried it before in another MCU validation.

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TM4C1231H6PGE: loop back for CAN comms