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TCA9548A: Facing issue in accessing the device

Rudra Prakash
Intellectual 370 points
Part Number: TCA9548A
Hi,
 
I am using TCA9548AMRGER in one of my design. Facing some issue in accessing this device. We are not receiving ACK. In place of ACK, NACK is receiving. Can you please help in this regard?
 
 
Thanks & Regards,
Rudra Prakash
  • 0
    Guru 243820 points

    The master might be using the wrong address, or there might be an electrical problem.

    Please show the schematic, and an oscilloscope trace of the failing transaction.

  • 0
    TI__Mastermind 48195 points

    Hi Rudra,

    Sorry to hear you're having trouble interfacing with TCA9548A. As Clemens suggests, this is likely due to the device not recognizing its address when communication begins or some other invalid command is issued after it has been addressed. 

    Can you please double check the configuration of the A0 - A2 pins and confirm the device address matches in software?

    Are you able to determine if you are getting an ACK after the initial address phase and a NACK after following commands - or is the NACK in response to the device address? If this cannot be seen in software, I would recommend using a logic analyser (or oscilloscope) to see where the NACK occurs in relation to the initial communication. If the NACK is in response to a secondary field, be sure that the command is valid device based on possible register configurations.

    Lastly, to check for an electrical problem, you may use an oscilloscope to check that the voltage levels and transitions of the I2C signal are within specified ranges and can be correctly read by TCA9548A. 

    Let us know what you are able to find out and if you have any questions in the meantime. 

    Regards,
    Eric Schott