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BQ25600D: Why do SCL and SDA keep same state?

Koyo Asaishi
Intellectual 1960 points
Part Number: BQ25600D
Other Parts Discussed in Thread: BQ25600

Hi team,

MCU send reset signal to BQ25600D through I2C, then reset is turned on.
However SCL and SDA don't start to operate.

Can you estimate why the signal don't operate?
If this situation can be unlocked, please let me know as well.

Best regards,
Koyo

  • 0
    TI__Guru 57621 points

    Koyo,

    1. What do you mean "MCU send reset signal through I2C"? Are you saying MCU pulls SDA and SCL signals low for a while?

    2. What is that "Reset" signal? The charger does not have a "Reset" pin.

    3. What do you mean "However SCL and SDA don't start to operate."? What charger actions do you expect?

    Thanks,

    Ning.

  • 0 in reply to Ning T
    TI__Intellectual 1960 points

    Hi Ning,

    Sorry for my wrong descriptions.

    First of all, the waveform of SDA and SCL were contrary waveform.
    Then, reset signal was not input BQ25600 but just for MCU.

    When Low of reset is input MCU, the MCU is initialized.
    Therefore SDA and SCL should be High because both line is pulled up through 10kohm resister and both inputs of BQ25600 is Hi-Z.

    My question is why is SDA Low when MCU is reset and SDA keep low after Reset become High?

    According to this waveform and MCU operation, BQ25600 is restarted after Reset become High and spending long time.
    We suspect the reason SDA keep Low is caused by a gap of clock between master and slave.

    Could you share your thoughts?

    Best regards,
    Koyo

  • 0 in reply to Koyo Asaishi
    TI__Guru 57621 points

    Koyo,

    When the host stops sending SCL clocks for some reason, the device holds SDA low to wait for SCL signals.

    Thanks,

    Ning.