• State
  • Locked Locked
  • Replies 6 replies
  • Subscribers 65 subscribers
  • Views 805 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ27621-G1: Bad Communication with MCU

Lauren Balut
Prodigy 20 points
Part Number: BQ27621-G1
Other Parts Discussed in Thread: MSP430G2553

I attempted to read fuel gauge data with CLI commands but fuel gauge only gives an I2C error and all zeroes.  All the other sensors on this I2C bus work normally.

I connected to logic analyzer and read the I2C3 clock and data: The MCU is constantly trying to write to fuel gauge with no response

All the power signals in this case are good.  Continuity around the fuel gauge is good and the part does not seem to be damaged upon visual inspection; also, no shorts through any connected components.  I have seen this failure on multiple boards tested the same way, and on different firmware versions.

Do you have any ideas on how I might solve/look further into this problem?

  • 0
    TI__Mastermind 27135 points
    Hi Lauren,

    Have you tried writing to 0xAA? 1010101 are only the 7 most significant bits. The first 8 bits of the I2C protocol would be 0xAA or 0xAB.

    Best Regards,
    Ben Lough
  • 0
    Prodigy 160 points
    Hello Lauren Balut,

    i have also faced this type of issue with my battery fuel gauge.
    then i have take one approach to scan i2c device make i2c scanner using msp430g2553 .
    i have successfully read the its i2c address. oxaa
  • 0 in reply to Benjamin Lough
    Prodigy 20 points

    Hi Benjamin,

    Thanks for your response!

    The address is correct, but the device is NAKing its address on this board, suggesting that the part is bad.  On other copies of this board, the fuel gauge responds correctly to this address (0x55) with an ACK and valid data.

    -Lauren

  • 0 in reply to Lauren Balut
    TI__Mastermind 27135 points
    Hi Lauren,

    I would do the following:
    1. Confirm 1.8 V is seen on the VDD pin
    2. Using an oscilloscope, confirm the I2C waveforms are compliant with the bq27621 datasheet. Sometimes tweaking the pullup resistors is necessary due to capacitance on the bus.
    3. Try slowing slowing down the communication frequency and see if the NAKing persists.


    Best Regards,
    Ben Lough
  • 0 in reply to Benjamin Lough
    Prodigy 80 points

    Hi Ben,

    My name is Martha and I am taking over for Lauren on this issue. The issue comes from a larger population of board that all work fine. We have verified that 1.8V is seen on the VDD pin and that the I2C waveforms are compliant with the bq27621 datasheet. At this point only 4 devices out of 2000 have been unable to communicate and continue to NAK. We would really like to get to the bottom of why this is happening and whether we can prevent this issue on future builds. What are the possibilities to start an FA process on your side?

    Thanks,

    Martha Calderon

    EE - Synapse Product Development

  • 0 in reply to Martha Calderon
    TI__Guru 61766 points
    Hello Martha,

    I'll contact you directly via e-mail for FA info.

    Regards,
    Dominik.