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BQ76PL455A: some questioin of BQ76PL455

user5775351
Prodigy 80 points
Part Number: BQ76PL455A
Other Parts Discussed in Thread: BQ76PL455EVM,

Hello dear

I am using the BQ76PL455EVM board, I have some questions to confirm, thank you.

First, when six batteries are connected and the unused battery monitoring channel has been shorted to the top battery connection, the other channels can still collected voltage,just five or six millivolts.

Second,when balancing  the selected channels,the battery voltage of the adjacent channel will rise.Is this normal?

The next question is the voltage always change. For example, the voltage will change from 3.9997 to 4.0001, and soon changed back.

The last question is How to do software to identify the temperature or voltage from data translated by uart .For example,0B 99B7 998C 99B2 99B3 99B0 99BF 2CB1 ,how can software Identify the data is from which channel. 

Thanks.

  • 0
    TI__Intellectual 2520 points

    Hello Sheng Xu,

    Thank you for evaluating bq76pl455.

    1)The other channels definitely can read out voltage data.

    You can use the setting of NCHAN to mask faults of all unused channels.

    2)It was normal due to IR drop, balancing current times the resistance of cable.

    The channel above channel balanced will report higher cell voltage, and reversely

    for the channel below the channel balanced.

    3) 0.4mV meets the specs of datasheet.

    4)Firstly, you should set CHANNELS to enable the measurement of all kinds of inputs.

    then the sequence of  return data will comply with the setting bits of CHANNELS register.

    Thanks!

    Andy

  • 0 in reply to Andy Li55
    Prodigy 80 points
    Hello Andy，
    thanks you for your answer. I have a problem with the software.
    I used a MCU communicate with BQ76PL455. When i parsing the data from BQ76PL455 ,it always has 0x0 0x6f and 0x0 0x70 ，no matter how many channels I set.
    HERE is the data obtained from the GUI and MCU.
    GUI' DATA : 0B CC 13 CB F8 CB DA CB 5A CE 30 C7 08 56 0A
    MCU' DATA: 0B 00 6F 00 70 CB CE CB 52 CE 35 C7 36 86 04

    The data after Header Byte is always 00 6F 00 70.And other data couldn't updata, always keep the same value as the first time.
    What causes this problem?

    here is my init code:

    //wake up
    GPIO_Pin_Set(GPIOB,PIN5,1);

    WriteReg(0,0x10,0x10e0,2,FRMWRT_ALL_NR);

    WriteReg(0,0x0e,0x10,1,FRMWRT_ALL_NR);
    WriteReg(0,0x0c,0x08,1,FRMWRT_ALL_NR);

    for(ID = 0; ID < 1; ID++)
    WriteReg(0,0x0a,ID,1,FRMWRT_ALL_NR);

    WriteReg(0, 0x10, 0x1080, 2, FRMWRT_SGL_NR);

    WriteReg(0, 0x52, 0xffc0, 2, FRMWRT_SGL_NR);

    //config afe
    WriteReg(0, 0x3d, 0, 1, FRMWRT_SGL_NR);

    //delay
    WriteReg(0, 0x3e, 0xbc, 1, FRMWRT_SGL_NR);

    //oversample
    WriteReg(0, 0x07, 0, 1, FRMWRT_SGL_NR);

    //clear fault
    WriteReg(0, 0x51, 0x38, 1, FRMWRT_SGL_NR);
    WriteReg(0, 0x52, 0xffc0, 2, FRMWRT_SGL_NR);

    //config 6 channels
    WriteReg(0, 0x0d, 0x10, 1, FRMWRT_SGL_NR);
    WriteReg(0, 0x3, 0xcf0000, 4, FRMWRT_SGL_NR);

    //set threshold
    WriteReg(0, 0x90, 0xd1ec, 2, FRMWRT_SGL_NR);
    WriteReg(0, 0x8e, 0x6148, 2, FRMWRT_SGL_NR);

    //cmd to get voltage
    WriteReg(0, 0x2, 0x1, 1, 0);

    Regards.
  • 0 in reply to user5775351
    TI__Intellectual 2520 points

    Hi Sheng,

    Please find datasheet section-8.3 Initialization Set Up for more details.

    And you also can download slva617a_bq76PL455A Software Design Reference for more details.

    Thanks!

    Andy