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BQ76952: I2C Communication Issue with BQ76952 - SDA Line Stuck Low

Vinod b
Prodigy 30 points
Part Number: BQ76952

Tool/software:

Hello TI Community,

I'm experiencing an issue with the BQ76952 IC in my project where the SDA line is stuck low while the SCL line remains high. This happens during field operations, and I'm unable to get back to normal communication state even after trying bus recovery methods effectively. Here are the details of my setup and steps I've tried:

1. MCU: Renesas RA2L1
2. I2C Speed: 400 kHz
3. Pull-Up Resistors: Currently using 4.7kΩ

-  Steps Tried:
1. Bus Recovery: Generated clock pulses on SCL and ensured a STOP condition, but SDA remains low.

Note: The I2C line comes to a normal state only if I reset the BMS IC (resetting the master MCU has no effect). The problem is that resetting the BMS IC erases any manually updated configurations apart from OTP.

Any insights or recommendations to resolve the SDA line being stuck low would be greatly appreciated.

Thank you!

  • 0
    TI__Mastermind 42060 points

    Hello Vinob,

    I assume you already tried generating the 8+1 clock signals to attempt to release the bus. Correct?

    Have you tried performing a partial reset by pulling RST_SHUT high for less than one second? The following FAQ explains partial resets.

    Besides that, does the MCU that you are using support clock stretching? The BQ76952 will perform clock stretching occasionally, so the MCU used also has to support clock stretching, else communication may not work properly.

    Best Regards,

    Luis Hernandez Salomon

  • 0
    Prodigy 30 points

    Hello Luis,

    Thank you so much for the reply; it helps. I was worried that resetting the BMS MCU using the RST_SHUT pin would cause a full reset. However, after reading the given article, I understand that performing a partial reset will only reset the communication logic. This approach ensures that only the digital logic is reset without affecting the register settings, maintaining our custom configurations.