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PMBus Receiving NACK from UCD9222 after SOFT_RESET - Please HELP!

Pawan Ghotikar
Expert 1140 points
Other Parts Discussed in Thread: UCD9222

Hi,

I am finding trouble in troubleshooting this specific problem. I have I2C bus connected to UCD9222 for communication using I2C protocol. I use Look Up Table method filled using the commands/data generated by I2C Script using FUSION GUI. I receive NACK after SOFT_RESET. For your reference I have shared the sequence of commands/data as follows

The sequence of commands I send over I2C single master SDA (byte transfer) is 
Start I2C
PHASE_INFO ({addr,Wr}, D2h, 04h, 01h, 04h, 00h, 00h) gets ACK after every byte
Stop I2C
Rail1 ({addr,Wr}, 00h, 00h) gets ACK after every byte
Stop I2C
FREQUENCY_SWITCH ({addr,Wr}, 33h, E8h, FBh) gets ACK after every byte
Stop I2C
Rail2 ({addr,Wr}, 00h, 01h) gets ACK after every byte
Stop I2C
FREQUENCY_SWITCH ({addr,Wr}, 33h, E8h, FBh) gets ACK after every byte
Stop I2C
STORE_DEFAULT ({addr,Wr}, 11h) gets ACK after every byte
Stop I2C for 2.2sec
SOFT_RESET ({addr,Wr}, DBh) gets ACK after every byte
Stop I2C for 2.2sec
PAGE ({addr,Wr}, 00h, 00h) gets ACK for addr, ACK for PAGE command but NACK for Rail1

Can someone suggest why's this happening?

Thanks,

Pawan Ghotikar

  • 0
    TI__Genius 9845 points
    Something to check:
    1. does the I2C driver supports 35ms clock stretching?
    2. if connect Fusion GUI to the device, is there any rail configuration after reset?
  • 0 in reply to Zhiyuan Hu
    Expert 1140 points

    Hi Zhiyuan Hu,

    Thank you. I really appreciate your response. I found out the problem, the Verilog wrapper we used to stream the commands was pulling SCL and SDA hiz at the same time during PAUSE violating the I2C stop condition. This was observed on scope and rectified. I completed the streaming of half of the script using I2C Write and verified that every command was properly acknowledged along with the respective data, if any.

    If I come across anything else will be sharing it. I am grateful for your patience and responses to every question I had.

    Thanks,

    Pawan Ghotikar

  • 0 in reply to Pawan Ghotikar
    TI__Genius 9845 points

    Hi Pawan,

    Glad to know the problem is resolved. Thank you for letting me know.

    Best regards,

    Zhiyuan