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BQ79656-Q1: BQ79656: Random Junk Values in Cell Voltage and Temperature Readings

Vaishali Balakrishna Shetty
Prodigy 125 points
Part Number: BQ79656-Q1

Tool/software:

Hello,

I am using the BQ79656 with an STM32 MCU to read cell voltages and temperatures. My setup consists of 8 boards connected with a BQ79600 as the bridge IC.

Most of the time, I can successfully read all cell voltages and temperatures., At random times, a cell voltage or temperature value becomes a junk reading, while all other values remain correct.

Thanks!

  • 0
    TI__Expert 4610 points

    Hello,

    Can you please define what is meant by junk readings? Does this happen consistently or at completely random times? What communication protocol is being used? Have you used our GUI to see if the same results can be seen? A possibility could be your conversion algorithm used to convert the register values to decimal.

    Thank you,

    Zachary

  • 0 in reply to Zachary Balov
    Prodigy 125 points

    Hello,

    Thank you for your response.

    1. The values are much higher or lower than expected.

    2.  The issue happens at completely random times. 

    3.  I am using UART to communicate between the MCU and the BQ79600.

    4.  No, I have not used the GUI to check the results.

    5. I am using the formula (VLSB_ADC * Result in decimal) to convert the register values to voltage.

    Thank you,

  • 0 in reply to Vaishali Balakrishna Shetty
    TI__Expert 4610 points

    Hello,

    Would it be possible to validate your boards using the GUI? The reason I ask is because this might be a system level issue, and this way I am hoping to separate our devices from your MCU.

    Furthermore, to aid in debug, is it possible to send uart logic waveforms between your MCU and base device when the issue happens so we can review?

    Is it possible to send a schematic of your communication to validate BOM?

    Thank you,

    Zachary

  • 0 in reply to Zachary Balov
    Prodigy 125 points

    Hello,

    I have captured the UART communication between the MCU and the BQ79600 during one of the occurrences of a junk reading. Please find the attached screenshots:

    1.UART Data 

    2.Logic Analyzer views:

    Thanks