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UCD3138: Two UCD3138 on one PMBus

Rutskoy Andrey
Intellectual 465 points
Part Number: UCD3138

Hello! 

Need help with PMBus connection. I want to read/write from/to two UCD3138 from one PMBus adapter. How can I do it as GUI only one device detected when I connect both. 

  • 0
    TI__Genius 17090 points

    You need to give them different addresses. If you look in init_pmbus you will see the address being set. The boot ROM always sets the same address for itself.  So in ROM mode you may have a problem. Some people report they can write programs to multiple devices. If that works, you can use a jumper on a pin, or a resistor on an ADC pin to select different addresses on different boards. ADC00 and 01 have current sinks you can turn on to measure an external resistance.

  • 0
    TI__Mastermind 18370 points

    Hi Andrey,

    After you set your devices to two different addresses as Ian suggested, you can use GUI to talk to each one separately.

    Depending on which GUI, you are referring to; if you are working with Fusion studio (Application level GUI), then the address selection is at the upper right side of the window.

    If you are referring to Device GUI, then you need to manually enter the address, under the SMBus/I2C -> SMBus Debug and this time the address field is in the upper left side of the window.

    Regards,

  • 0 in reply to Ian Bower
    Intellectual 465 points

    Dear Ian,

    Do I right understand that in ROM mode all UCD 3138 devicess have the same adress (11d)?

    For the custom address we use current from AD00 and AD01 and read the voltage drop. Then put value to init_PMBus. Another variant directly write the address

     

    Correct?

  • 0 in reply to Rutskoy Andrey
    TI__Genius 17090 points

    Yes, the ROM always has the same address, 11d as you mention.