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BQ25895M: Unable to set register values on some devices

Tino Ruland
Prodigy 50 points
Part Number: BQ25895M

Hello,

I'm having a very strange problem with some BQ259895 and BQ259895M. All are fitted on identical PCBs, Microcontroller firmware is also the same on all boards.

Some BQ259895/M cannot be configured correctly, e.g. Registers REG02 and REG03 don't change their default value although other values are written. When I re-read the registers the default values are still there. I already disabled the BQ's watchdog, but no change. I have no idea what else to do..

  • 0
    TI__Guru**** 167236 points
    Tino,

    That is very strange. Just to confirm, you can change the ICHARGE register and it stays that after the default watchdog timer expires, since it is disabled? If so, can you send scope shots of your I2C SCL and SDA when you write to REG02 and REG03?
  • 0 in reply to Jeff F
    Prodigy 50 points

    Hi Jeff,

    thank you very much for the quick reply. It did point me into the right direction. When trying to do the scope screenshots I noticed that on the problematic boards the registers weren't written at all. Strangely enough all read commands were executed correctly. It turned out to be a problem with the I2C-driver for the PIC microcontroller used. After changing this all works fine.

    So I think problem is resolved now.