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TPS929240-Q1: The TPS doesn't answer any of the read commands that worked with the 16 channel version

Simon Rioufol
Prodigy 10 points
Part Number: TPS929240-Q1

Hello, 

We are currently trying to communicate with a TPS929240 but it doesn't answer any of our READ requests

We are using the same code we used for the 16 channels TPS, and it worked perfectly on this one.

But since we changed for a 24 channels nothing... The TPS is supplied with 10V and we can see that the VLDO output is active, meaning the TPS is correctly working. The ERR pin is not pulled down.

Thank you for your help

  • 0
    TI__Expert 3510 points

    Hi Simon,

    There are a number of factors that could be causing this. First, I'd like you to confirm that the DEV_ADDR byte in your UART frame matches the device address set according to ADDR2, ADDR1, and ADDR0 pins. The 24 channel device has three address pins while the 16 channel device has four so I suspect that if you are trying to use the same code you may be addressing a device that is no longer present on the bus. 

    Thanks,

    Jaron

  • 0 in reply to Jaron Wilson
    Prodigy 10 points

    Hello, 

    Thank you for your answer. We are using the external adressing method so we connected ADDR2, ADDR1 and ADDR0 to the GND. We are using 00h in the DEVICE_ADDR used in the byte. Could it be something else ?

  • 0 in reply to Simon Rioufol
    TI__Expert 3510 points

    Hi Simon, 

    And to confirm is there only 1 device on the bus? Or if there is more than 1, they are all uniquely addressed? Can you probe the RX and TX nodes and confirm that you are seeing the waveforms you expect on RX?

    Thanks,

    Jaron

  • 0 in reply to Jaron Wilson
    Prodigy 10 points

    Yes only one device on the bus. While probing, the RX waves were as expected. It's worth mentionning we tried switching with another TPS in case of a problem with the component but we have the same problem.

    Simon

  • 0 in reply to Simon Rioufol
    TI__Expert 3510 points

    Okay thanks for checking that. What about details of the board? Are you using the same board you used with the 24 channel device but with a 16 channel device populated in place of it? Although they are the same package they do not have identical pinout. 

    Jaron

  • 0 in reply to Jaron Wilson
    Prodigy 10 points

    The board is a different one, adapted for a 24 channel TPS (or it should be). Supply and VBAT are provided with a 10V Buck regulator as well as FS0. We are only using 15 channels (the goal is to prove the solution can work with any number of channel) so 9 channels are left unconnected. RX and TX have a 47k pullup resistor connected to VLDO.

    If I can provide any other information please tell me.

    Simon

  • 0 in reply to Simon Rioufol
    TI__Expert 3510 points

    Can you send the board schematic and code to jaron@ti.com and I can further assist in your debug over email. 

    Thanks,

    Jaron