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SN65HVD233 Test Equipment

Kathleen Gayo
Intellectual 620 points
Other Parts Discussed in Thread: SN65HVD233

Hi,

I've been working on a project that requires a CAN Bus and our EEs had decided to use SN65HVD233 CAN Bus Transceivers. I had programmed our controller and had the controller codes consulted by two other embedded system engineers. They had verified correct settings however, I was not able to read the data sent by the microcontroller.

My setup is composed of a microcontroller connected to the SN65HVD233 via CAN Bus and the output of the CAN Bus is connected to a CAN Bus Analyzer which will display the data transmitted from the microcontroller over CAN bus or vice versa. 

What equipment can I use to verify that the Transceiver receives and transmits data?

Thanks,

Kat

  • 0
    TI__Mastermind 20820 points

    Hi Kathleen,


    Thank you for your post! A CAN Bus Analyzer should be sufficient to verify the data on the CAN bus as long as your capture tool has the ability to display the incoming packets and there content. You could also use a scope to trigger on an incoming packets with time scale zoomed out so to capture the whole packet this way you can verify the individual bits inside the packet once you have it on the scope.


    Are you sure that your CAN controller is working properly? Have you verified that controller is transmitting and the data it is transmitting is correct?

    The SN65HVD233 has a standby mode that is controlled via pin 8 on the device. For normal operation pin 8 should be pulled low (ground). If pin 8 is high the device will be in standby mode and will not transmit or receive anything to and from the bus.


    I hope this helps please let me know if you continue to have problems and I will be glad to help you through the debug effort.

  • 0
    TI__Guru 62920 points
    Hi Kat,

    The simplest check would probably to just probe various signals using an oscilloscope. You can verify the transmit direction is working by monitoring the TXD input and the CAN bus (CANH and CANL) waveforms to make sure they match what you expect. Similarly, the receive direction can be verified by checking the RXD output signal against the CANH/CANL signals ("dominant" levels should result in a low-level output, and "recessive" levels should result in a high-level output).

    In case anything looks off, a couple common mistakes are (1) not placing termination resistances on the bus (a differential load, typically two parallel 120-Ohm resistors, is required for CAN bus operation) and (2) inadvertently using the "loopback" mode by driving pin 5 high instead of low.

    Please let me know if you have any other questions.

    Regards,
    Max
  • 0 in reply to Miguel Robertson
    TI__Guru 62920 points
    Sorry, I must have been writing my post at the same time as Mike. I definitely agree with all of his comments above as well. Thanks, Mike!

    Max