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BQ76940 does not respond to I2C

Ushan Karunathilaka
Intellectual 695 points
Other Parts Discussed in Thread: BQ76940

Hi TI experts,

BQ76940 does not respond to any of the I2C commands. According to the oscilloscope traces, it does not generate ACK signal. (bus is not pulled down in the 9th clock cycle)

I have double verified the I2C connection and 'BOOT' signal is given prior to  the I2C communication. Further , voltage at REGOUT is also verified to be at 3.3V. 

I tried all the possible address, (0x08, 0x18, 0x00,0x3f) and the result is the same. Finally I2C commands are given using EV2300 module. Again the oscilloscope traces showed the issued signal is correct and no 'ACK' is received.

What could be the reason for not giving the ACK for the address byte?

Thanks,

Ushan Karunathilaka

  • 0
    TI__Guru 54715 points

    This post seems to have been overlooked.

    It seems you have checked the obvious things.  Some additional items:

    • Be sure the REGSRC is supplied according to the datasheet range.
    • Be sure BAT, VC10X and VC5X are supplied according to the datasheet range.
    • Check that the TS pin voltage at boot is between 1 and 3.6 V
    • Check that CAP1 rises from 0 to 3.3V after boot
    • Check the REGOUT voltage is from the bq76940 and not forced from some other source
    • Check the I2C address on the bus, the 08 address should be 10 on the bus (7 bit vs. 8 bit).
    • Check that the SDA & SCL device pins make contact with the board signals

    Otherwise it seems it must be a damaged device.

  • 0 in reply to WM5295
    Prodigy 10 points

    Wm5295,

       Hi,I found the document in the TI website,
    "I2C Communication and Sample Code for bq76940 with CRC -based on the MSP430"
    Where can I download to this sample code? Thank you very much!

        

  • 0 in reply to jun Chow
    TI__Guru 54715 points

    The code was not released with the document.  It would seem it could be very useful, I will see if it can be found and released.

  • 0 in reply to WM5295
    Intellectual 325 points

    Hi all,

    I have a new project to develop the battery for eBikes.

    And find the bq76940 is suit to ours.

    So where to download the I2C example code?

    I will use it for start-up my firmware.

    Many thanks!!

    Peter.

  • 0 in reply to peter liu2
    TI__Guru 54715 points

    For those searching the forum looking for the I2C CRC example code and finding this post, the code related to the apnote http://www.ti.com/lit/pdf/slva626 can now be found in the product folder under the "Tools and Software" tab or directly at http://www.ti.com/lit/zip/sluc583