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TCAN1044AV-Q1: TCAN1044AVDRQ1 supported CANH and CANL shorted Fault Condition?

Shubham Jagtap
Prodigy 110 points

Part Number: TCAN1044AV-Q1

Hello Concern,

We are using the TCAN1044AVDRQ1 in one our product. We are testing fault condition for CAN bus Communication.

When We Shorted CANH - CANL bus line, CAN Communication halted-  CAN bus goes off ( Which is Intended) - Both Line Voltage during Fault Condition is ~2.5V.

But When Fault Removed - CAN Bus Communication is not Recovered. CAN Bus get Freeze and Required the Hard power Reset.

Is this CAN Fault Condition (CANH Shorted to CANL) supported by TCAN1044 device or not?

As Other Fault condition working as expected --> Auto CAN recovery is there. 

CANH Shorted to GND and VBAT

CANL shorted to GND and VBAT.

Issue - Scenario - CAN H Shorted to CAN L: - 

Normal operation                                                                  CAN H Shorted to CAN L- fault Condition                                   After Fault Condition Removed

~ Shubham 

  • 0
    TI__Mastermind 26806 points

    Shubham,

    What is the state of TXD during this process? While in Normal mode, do you have any insight into whether the state of TXD is changing?

    Best,

    Danny

  • 0 in reply to Danny Bacic
    Prodigy 110 points

    Hello Danny,

    During the Fault Condition (CAN H Shorted to CANL) - Both lines having ~2.5V. 

    After Fault Condition Removed --> There is Data on TXD and RXD Line. but Communication is started at CANoe Tool Trace Window.

  • 0 in reply to Shubham Jagtap
    TI__Mastermind 26806 points

    Shubham,

    The CANoe tool will stop communication when the node falls bus-off. Note that when a bus fault is applied, communication is likely not possible. This is not an issue with the transceiver; rather, it is just the byproduct of a bus fault.

    When the CAN controller determines that there have been a sufficient number of failed transmissions, the node will fall bus-off and cease communicating. This is not because of the transceiver but rather a part of the CAN protocol.

    One recommendation I might offer: Instead of having communication run continuously, try sending each frame manually. In doing so, you would be able to see the effect of a bus fault, but you'd also be able to keep the number of failed transmissions low enough that the node will continue attempting to communicate once the fault is removed.

    Note that the TCAN1044AV-Q1 has no protocol awareness. It is a device that translates signals from TXD --> CAN and from CAN --> RXD.

    Best,

    Danny

  • 0 in reply to Danny Bacic
    Prodigy 110 points

    This Means, if our Node is Connected in ecosystem with Different ECU (Other Node) - Then Bus-off fall when there is shorting of CANH and CANL lines at our end and Cease the communication. And After Fault Removed - It will Restart the Communication??

    When We are testing it with CANoe tool, then after Shorting CAN Line, Communication get cease and Unable to Resume the Communication-- is this understanding Right??

    After The Bus-off Condition, CAN Controller need a reset to resume the communication- If this is case then it can be done through the SW.??

  • +1 in reply to Shubham Jagtap
    TI__Mastermind 26806 points

    Shubham,

    Yes, it sounds like you're understanding correctly. The bus-off state is a feature of the controller rather than the transceiver itself. This is why a power cycle was allowing communication to resume.

    Depending on the software you're using, a software reset should be sufficient to resume communication after this kind of event.

    Best,

    Danny