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USB-C-PD-DUO-EVM: TPS65987D registers I2C read back

Boris Risenzon
Prodigy 170 points

Part Number: USB-C-PD-DUO-EVM

Dear Sir/Mam,

I'm trying to read back  I2C registers from TPS65987D sink part of the USB-C-PD-DUO-EVM.

I get very strange values. Generally I read from addresses 0x38, 0x20, 0x21.

As far as I understand:

-slave address 0x38 represents I2C1, which is common for both sink and source ICs.

-slave address 0x20 represents I2C2, which is source IC.

-slave address 0x21 represents I2C2, which is sink IC.

I'm trying to read for example, register 3, and get "APP " from all 3 addresses, which is OK.

I'm trying to read register 4, and get "I2C " only from 0x38, the remaining 2 addresses return zeros.

When I'm trying to read Status, Power Path Status and Power Status registers, I get very unreasonable values.

What can be a reason for that?

Thanks a lot and Best Regards,

Boris.

  • 0
    TI__Mastermind 36756 points
    Hi Boris,

    When you run an I2C Sweep in the Utilities GUI, are you seeing the correct addresses respond?
    There is a known bug with the FTDI chip where it will lock up and return all 0xFF for all fields. If this is what you are seeing, I would suggest power cycling the board to resolve it.

    Thank you,
    Eric
  • 0 in reply to Eric Beljaars
    Prodigy 170 points
    Dear Erik,
    I was not reading the registers though onboard FTDI chip, but rather though my own external SiLabs MCU-based board, connected with wires to J203 of the EVB. USB of FTDI was disconnected. I've got both 0x38, 0x20 and 0x21 answering. Read from reg.#3 gives "APP " for all addresses, read from reg.#4 gives "I2C " from 0x38 only, 0x20 and 0x21 return zeros.
    I tried later to connect FTDI and make reads with the TPS6598x Host Interface Tools, got the same exact result.
    Now I understood that rest of the data (apart from "I2C ") was OK, with help of TPS6598x Host Interface Tools I understood how to interpret them, so this problem is solved for me.
    Now I have another question: I did voltage change between 2 TPS65987D ICs, connected with USB type-C cable by pressing buttons, it worked perfectly, now I want to configure voltage by software.
    Can You please suggest which software configuration sequence should I apply to sink chip so he will initiate voltage swap. Assuming that on source part of the EVB I already pressed, lets say "9V" button.
    Thank You and Best Regards,
    Boris.
  • 0 in reply to Boris Risenzon
    TI__Mastermind 36756 points
    Hi Boris,

    You can download the latest TPS6598x Application Customization Tool. After selecting New Project --> TPS65987D, you will see the option to select either TIDA-050012 or TIDA-050014. You can then modify these configurations to best meet your needs.

    Thank you,
    Eric