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TPS 65381 spi writes only go into effect after reset

Other Parts Discussed in Thread: TMS570LS0332, TPS65381-Q1

Hi,

I am using the TPS65381 with the TMS570LS0332.  I am using the SPI interface to read and write to the device registers.  Reading registers works fine, but I have found that when I write a value to a register, when I read it back it still shows the old value.  If I cycle power and then read the register it shows the value I wrote.  I have tried this with multiple registers.

 

Is this normal behavior? Do I need to do some sort of soft reset of the TPS chip after a write?

  • Hi David,

    I'm moving your thread to the Automotive forums as they support the TPS65381-Q1.   

    Regards,
    Sem Amesawu

  • Which state of the device are you trying to write and which register?  Many of the registers can only be written in diagnostic state and may NOT be written in active state?  By power cycle of the device what do you mean? 

    If you can clarify more exactly when and how you are writing, reading and what a power cycle means to you we can try to dig into it more.

    - Scott

  • I was writing in the diagnostic state.  I tried a few configuration registers, but I can't remember specifically which ones.

     

    By power cycle I mean physically removing 24V power from the board that contains the TPS chip, then plugging it back in.

     

  • Are you 100% sure you were in diagnostic state?  Could you have had the software lock bit set?  Complete power cycling should only bring back the default state in the registers, not write them as they behave like RAM except for the default states. 

    Have you tried a 2nd unit? 

    - Scott