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SN65HVD230: SN65HVD230 output issue.

Vincent Hsieh
Expert 1895 points
Part Number: SN65HVD230


Dear Sir,

We use SN65HVD230 in T-BOX, but it will let car's CAN BUS fail.

Could you help us to check the attached file?

SN65HVD230 issue.docx

  • 0
    TI__Mastermind 20820 points
    Hi Vincent,

    What is your failure mode? The CAN waveforms you show in the attached file look pretty reasonable to me and you have provided no information about what is wrong. "but it will let car's CAN BUS fail" is not enough information to begin the debug process.
  • 0 in reply to Michael Peffers
    Prodigy 10 points

    To insert the failure T-BOX on the car and connect computer to capture the car CAN signal but engineer could'nt receive the normal information of car system.

    To measure the abnormal waveform as appendix.

    To insert the normal T-BOX on the same car and measure the abnormal waveform as same appendix. 

    Car's CAN BUS fail.docx

  • 0 in reply to Michael Peffers
    Expert 1895 points

    To insert the failure T-BOX on the car and connect computer to capture the car CAN BUS signal but engineer could'nt receive the normal car information.

    To measure the abnormal waveform Photo of CAN BUS on car as appendix.

    Then to insert the normal T-BOX on the same car and measure the normal waveform Photo of CAN BUS as same appendix.

    3250.Car's CAN BUS fail.docx

  • 0 in reply to Vincent Hsieh
    TI__Guru 62920 points
    Hi Vincent,

    Is it possible for you to zoom in on the waveforms? With the current time scale, it is hard to see much of a difference between the passing and failing waveforms.

    Can you also confirm that both the passing and failing boxes are configured to operate at the same rate and use the same identifiers (i.e., no other changes besides the CAN transceiver)? Which CAN transceiver allows the boxes to work?

    Max
  • 0 in reply to Miguel Robertson
    Expert 1895 points

    Dear Sir,

    We will use SN65HVD230 in 40 device network, the total distance of about 50 meters.

    Have anything that needs to be considered?

  • 0 in reply to Vincent Hsieh
    TI__Guru 62920 points
    Vincent,

    The cabling topology should be linear (ideal case) with termination resistors at both ends. “Stubs” (unterminated branches to different nodes) should be kept as short as possible in order to minimize signal reflections. The cabling should also have a controlled differential characteristic impedance (nominally 120 Ω)

    The total round-trip propagation delay for the CAN signals should be within one bit period. This is required for the bit-wise arbitration in the CAN protocol to function properly. Typically it needs to be ~70%-80% of a bit period or less to ensure adequate timing margin in the receiving controller. Both the cable delays and transceiver delays (specified as loop times) need to be considered along with the bit period length (inverse of data rate).

    You should also be careful that the total bus capacitance is not too high for the bus to operate at the intended data rate. The total capacitance is a sum of all the node capacitances as well as the capacitance introduced by the cabling. This capacitance can distort the CAN waveforms since it tends to affect the dominant-to-recessive signal transition (which is undriven or weakly driven) more than the recessive-to-dominant edge (which is driven strongly by the active CAN transceiver).

    For a summary of other general CAN networking guidelines, you can refer to this application note: www.ti.com/.../slla270.pdf.

    Best regards,
    Max