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Original question:

TPS25750: 4CC commands always rejected

TPS25750: USB-PDF-CHG-EVM-01 - I2Cr task rejected with reason '0x04'

Cosmin Briceag
Prodigy 160 points
Part Number: TPS25750
Other Parts Discussed in Thread: BQ25798

Tool/software:

Hello,

I'm facing an issue while trying to read a remote register from BQ25 via TPS25750. The 4CC 'I2Cr' is always rejected with reason '0x04'. Please find below a trace snippet.

Do you have any idea why would that happen ?

I power the EVM-01 only from USB-C, no battery connected on VBAT, would be this the reason the TPS device does not function correctly ?

UPDATE:

I connected 3S Li-Ion 11.1V battery to VBAT (J2) and the device gets stuck in 'PTCH' mode. No 4CC command is accepted. Moreover, according to the reference manual, the MODE register is a 4bytes length but if i read only 4bytes then the content is truncated, please find below the picture.

Thank you,
Best Regards,
Cosmin

  • +1
    TI__Mastermind 34126 points

    Hi Cosmin, 

    Can you provide additional details on which BQ25798 register you're trying to read via "I2Cr" and the input data from the trace snippet you included? 

    Is your system using an EEPROM or EC to load the PD configuration upon boot-up?

    Thanks and Regards,

    Raymond Lin

  • 0 in reply to Raymond Lin
    Prodigy 160 points

    Hi Raymond,

    Thanks a lot for your reply. It turned out that i misinterpreted the registers from the TPS device (it confused me that 'register length' prepended to every reading). Now it works like expected. Though, i can answer to your questions as well.

    1. The BQ25 register i was trying to read was 'REG3B_VBAT_ADC - 0x3B'.
    2. I use the evaluation board so i guess there's an EEPROM, but i do not use it, i write the configuration from the host uC upon boot-up.

    Best Regards,
    Cosmin