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BQ76952: the last ACK frame does not respond

Hui Cao22
Expert 1075 points
Part Number: BQ76952

Tool/software:

We are using BQ76952PFBR on our module, and the IIC communication fails periodically. After software checking, it is found that the last ACK frame does not respond. Have you encountered a similar situation? Please help to have a look.

Fig1.Dense 14 frames + 9 frames, the clock line is pulled low once every 23 frames due to no response from ACK.

Fig2

Fig3 Penultimate frame     Address plus register address    write    Data low byte    Data high byte

  • 0
    TI__Genius 17755 points

    Hello Hui,

    Thank you for sharing those waveforms. Can you share a logic analyzer file/images, as well as what commands/subcommands you were sending when this occurs?

    Our IC also has clock stretching capabilities, so the MCU needs to be able to support that as well. 

    Best Regards,
    Alexis

  • 0 in reply to Alexis_H
    Expert 1075 points

    We did not monitor the IIC data through the logic analyzer. The penultimate frame, as in Figure 3, reads from 76952. In the last frame, as shown in Figure 2, the MCU requests address 0X10 and does not receive an ACK of 76952, so the CLOCK is pulled down by the MCU. In addition, regarding clock stretching capabilities, ACK delayed reply should be caused only when processing a large number of data frames. Will ACK delayed reply be caused when processing simple bus data such as address 0X10?

  • 0 in reply to Hui Cao22
    TI__Genius 17755 points

    Hello Hui,

    Thank you for explaining what you were trying to do. This What is the I2C Device Address of the BQ769x2 Family FAQ may answer your question.

    Best Regards,
    Alexis