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SN65HVD251: Can I use SN65HVD251 to communicate with a Single Wire CAN device ?

Daniel Flor
Intellectual 430 points
Part Number: SN65HVD251

Can I use one of the lines of CAN HS (CANH for example) to communicate on a Single Wire CAN bus in a compatible way ? By "compatible" I mean that the whole system should support valid SAEJ2411 baud rates, If so, what is the recommended way of doing it ? Specifically, should CANL be left floating, connected to ground, or something else?

  • 0
    TI__Guru 74252 points

    EuMesmo,

    It is possible to use a 5V CAN transceiver to communicate on single wire CAN bus, and the SN65HVD251 can work with the low data rates of SAE J2411 specification. The way this can be achieved is shorting CANL to GND, then using the transceiver as a standard CAN transciever. If you click my username you will find my email, and if you email me I can send over a presentation illustrating this method.

    This device is not compatible with other portions of the SAE J2411 specification, but it can work at 33.3 kbps and 83.3 kbps as specified by SAE J2411.

    Please let me know if you have any other questions.

    Regards,

  • 0 in reply to Eric Hackett
    Intellectual 430 points

    Hello, Eric,

    I sent to you the email, thank you. But, I have another doubt, you said that this device is not compatible with other portions of the SAE J2411 specification, can you give me some examples of portions of the SAE J2411 that this device is not compatible ? I'm designing a automotive scan module, so, would be helpfull to be aware of the limitations of this method.

    Thank you.

  • 0 in reply to Daniel Flor
    TI__Guru 74252 points

    EuMesmo,

    I'm not sure I received your email, can you try re-sending it?

    And I'm looking into the specific parameters right now, but in general single-wire CAN requires a different type of physical layer transceiver design. There are other single-wire CAN transceivers on the market with different fault handling pins and features that an ISO11898-2 CAN transceiver does not have.

    I'll get back to this thread when I have more details. Thanks for you patience on this.

    Regards,

  • 0 in reply to Eric Hackett
    Intellectual 430 points

    Yes, eric, I re-sent to you right now. I can send you my e-mail address too if you want.

    Regards,

    Daniel.

  • 0 in reply to Daniel Flor
    TI__Guru 74252 points

    EuMesmo,

    I was able to read through the J2411 specification for Single Wire CAN. In the specification there is a requirement for the pinout of the transceiver, which the SN65HVD251 does not meet. Single Wire CAN dedicated transceivers have a specific pinout and function of each pin that is different from a ISO 11898-2 specified CAN transceiver. Along with this, there is also a separate voltage signal scheme for normal messaging and wake-up signaling that is based on the voltage level of the bus. This cannot be done on the SN65HVD251. Wake signals in the J2411 have a higher voltage level relative to the communication signals.

    Please let me know if you have any other questions.

    Regards,