AM2732: A bus off and error frame when there is a short circuit between CAN_H and 12V (or CAN_L and GND)

Shawn Li(Radar)

Part Number: AM2732

Hi team,

My customer tells me there is a bus off and error frame when there is a short circuit between CAN_H and 12V (or CAN_L and GND). They want to make 1732 send CAN message normally under this situation. Can you help look this issue?

Regards,

Shawn

12 days ago

0 Shawn Li(Radar) 9 days ago

TI__Prodigy 315 points

Hi team,

Any update?

0 Mike Pridgen 9 days ago in reply to Shawn Li(Radar)

TI__Mastermind 20965 points

Hi Shawn,

Which CAN transceiver is being used here? The AM2732 only supports CAN_TX and CAN_RX, which are digital IO signals. The CAN transceiver converts the TX/RX signals to BUS IO level signals connected onto the CAN bus.

Thanks,
Mike

0 Shawn Li(Radar) 9 days ago in reply to Mike Pridgen

TI__Prodigy 315 points

Hi Mike,

Customer uses the AM2732 EVM to do test, it will send error frame and trigger bus off. And the EVM is using TCAN1042

0 Mike Pridgen 9 days ago in reply to Shawn Li(Radar)

TI__Mastermind 20965 points

Hi Shawn,

Thanks for the specifics on the transceiver. You may want to take a look at this e2e post on what happens on TCAN10xx devices when the CANH/L lines have different bus failures, including CANH to battery voltage and CANL to ground: https://e2e.ti.com/support/microcontrollers/arm-based-microcontrollers-group/arm-based-microcontrollers/f/arm-based-microcontrollers-forum/901434/please-explain-what-happens-when-canh-is-shorted-to-vbat-canh-shorted-to-gnd-canl-shorted-to-vbat-and-canl-shorted-to-gnd

Looking at the two failures you listed (CANH to 12V and CANL to GND), for those lines in the document attached to the above e2e thread, the transceiver will continue to operate with the other CANH/L signal toggling at increased amplitude with some highlighted concerns regarding degradation and timing. If the transceiver is still operating, I would expect the CAN TX/RX interface to the AM273x to be unaffected by the bus shorts.

For further details, I recommend reaching out to the CAN Transceiver team.

Thanks,
Mike

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AM2732: A bus off and error frame when there is a short circuit between CAN_H and 12V (or CAN_L and GND)