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TPS25750: TPS25750 errors during I2C read

Jan Zastera
Intellectual 260 points
Part Number: TPS25750

Hello,

when we read from TPS25750 through I2C we encounter following error:

First byte read over I2C is always 0x04.

E.g. we read register 0x03 MODE and if we read 4 bytes from this address we get '0x04' 'P' 'T' 'C'.

if we read 5 bytes from 0x03 MODE we get '0x04' 'P' 'T' 'C' 'H'

Anybody knows what is going on, please?

Thank you

  • 0
    Intellectual 260 points

    OK, I think I figured it out,

    first received byte gives information on how many bytes will follow, so first bytes received for different registers are

    0x03 MODE    first byte response 4
    0x0F VERSION    first byte response 4
    0x14 INT_EVENT1    first byte response 11
    0x2F DEVICE INFO    first byte response 40

    I had to overlook this behavior in the manuals

  • +1 in reply to Jan Zastera
    TI__Genius 12835 points

    Hi Jan,

    Yes, the first byte response is always the number of bytes, regardless of the register.

    Similarly, when you write to the register, you must first write the register number, then number of bytes, then the data to write.

    Best,

    Alex