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TCA9548A: Not able to access TCA9548A mux by ipmi

Oliver Lin
Expert 4475 points
Part Number: TCA9548A

Hi expert,

Customer report that they are not able to access TCA9548A with impi command. This is BIOS that will use this command to communicate via SMBUS.

Customer tried as below, show read fail

  • I2cget 1 0x73 0x0F  return : read failed    (BMC can’t access I2C multiplexer)
  • I2cget i2cbus slave address data address

can the team share the email, so I can share some info internally? Or any next step we can try?

  • 0
    TI__Mastermind 26806 points

    Oliver,

    Thanks for reaching out. Are you attempting to read from the device? The TCA9548A has a single control register that is used to control the device. If attempting to read from the device, then there is no register address that needs to be passed to the device. See datasheet section 8.5.3.2 for a thorough explanation of reading from the TCA9548A.

    Assuming this is verified, would you be able to provide oscilloscope shots of the attempted communication? And have you verified that the hardware-selectable addresses are properly assigned as Low-High-High to achieve an address of 0x73?

    You can reach me directly via the email address found by clicking on my name () at the top of this response.

    Best,

    Danny