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BQ40Z80: About the use of PEC function of BQ40Z80

zhang jianhang
Prodigy 130 points
Part Number: BQ40Z80

Hi Ti's experts，

When I was testing the CRC check function of the BQ40Z80, I used the logic analyzer to read the data, and found that with the HPE register turned on and the HPE register turned off, the read data was the same, with CRC check. The data of the SOC is read individually (as shown in the figure), and the temperature is also read, and it is found that there is a PEC check code.
Is it because the BQ40Z80 is already turned on by default? Or other reasons? Or am I reading it wrong?
Please help me, thank you.

  • 0
    TI__Guru** 105590 points

    Hello Zhang,

    PEC is always enabled when reading data, the settings you're referring to are for when the gauge is in MASTER mode and it initiates the communication.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 130 points

    Hi Wyatt，

    Thanks for your answer.

    According to what you said, the BQ40Z80 has enabled the PEC function by default, so I don't need to enable any registers?

    If the bq40z80 of the battery is the slave and the customer's device is the master, and the customer's device needs to use the PEC (CRC) function when reading the data of the battery bq40z80, does the battery bq40z80 need to set the HPE to 1? (turns HPE red, see picture above)

    If there is more information about the PEC function of BQ40Z80, please let me know, thanks.

  • +1 in reply to zhang jianhang
    TI__Guru** 105590 points

    Hello Zhang,

    Yes that's correct, the CPE and HPE bits are only for broadcasts from the gauge, you can read the descriptions in the TRM section 5.11 Charge Control SMBus Broadcasts.

    You do not need to modify any of the HPE or CPE bits if you are not broadcasting with the gauge.

    Sincerely,

    Wyatt Keller