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BQ79656EVM-021: Steps for the Temperature measurement and storing the Temperature data

Abhaya Raj Mishra
Intellectual 275 points
Part Number: BQ79656EVM-021
Other Parts Discussed in Thread: MSPM0G3507

Hi, 

I'm using 4 Bq79656 EVM for BMS application. I need to enable the Temperature measurement and need to store data as well. I'm using MSPM0G3507 for interfacing these devices.

I already enabled the Voltage measurement and also storing the voltage data.

Please provide me the steps for enabling the temperature measurement, for board and for coding side as well.

Thanks, and Regards

Abhaya Raj Mishra

  • 0
    TI__Expert 5500 points

    Hi Abhaya,

    To set the GPIOs into OTUT & ADC mode:

    Enable TSREF: write 0x01 to 0x030A

    Set OTUT& ADC mode in GPIO_conf1-4: write 0x09 to registers 0x0E to 0x11

    Start Main ADC in continuous run mode: write 0x06 to 0x030D

    Regards,

    David

  • 0 in reply to David Ray
    Intellectual 275 points

    Sorry for the late reply, I was on leave for some days.

    Ok, I'll try it.
    One more thing, what about the multiplier for the raw data of temp ADC ?

    what should I multiply to get actual temp.

    Thanks and Regards

    Abhaya Raj Mishra

  • 0 in reply to Abhaya Raj Mishra
    TI__Expert 5500 points

    Hi Abhaya,

    For the die temperature, this is register 0x05AE and 0x05AF. Putting the high and low hex readings together and multiplying the decimal value by 0.025 will give you the temperature in Celcius.

    For the GPIOs, the NTC used should have temperature values that correlate to the resistance of the NTC. Since the GPIO pin is pulled up to TSREF and pulled down to ground through a thermistor, the voltage divider equation will define the resistance of the thermistor. Rntc = Rtsref/(Vtsref/Vgpio + 1) where Rntc = the ntc resistance, Vtsref = tsref voltage, Vgpio = gpio voltage, and Rtsref = the resistance of the Tsref pullup resistor. The customer then qualifies the resistance of the NTC over the temperatures wanted. This will then tell you which resistance relates to which temperature.

    Regards,

    David

  • 0 in reply to David Ray
    Intellectual 275 points

    Hi, I have enabled TSREF.

    David Ray said:
    Enable TSREF: write 0x01 to 0x030A

    but i'm getting 0 value for TSREF.

    What is wrong can you please help?

    and one more thing, I have enabled these as well.

    David Ray said:
    Set OTUT& ADC mode in GPIO_conf1-4: write 0x09 to registers 0x0E to 0x11

    I'm getting 0.273899 value for the GPIO.

    is it right?

  • 0 in reply to Abhaya Raj Mishra
    TI__Expert 5500 points

    Hi Abhaya, 

    When you write 0x01 to 0x030A, is TSREF reading 0V with a multimeter? If you read the register what does 0x030A read?

    Abhaya Raj Mishra said:

    I'm getting 0.273899 value for the GPIO.

    is it right?

    Can you post what resistors/ntc is connected to the GPIOs/TSREF so that I can give a better answer on this?

    Regards,

    David

  • 0 in reply to David Ray
    Intellectual 275 points
    David Ray said:
    When you write 0x01 to 0x030A, is TSREF reading 0V with a multimeter? If you read the register what does 0x030A read?

    I write 0x01 to 0x30A and after that I'm reading the TSREF_HI(0x58C) and TSREF_LO(0x58D). This is showing 0 value.

  • 0 in reply to Abhaya Raj Mishra
    TI__Expert 5500 points

    Hi Abhaya,

    TSREF is connected to the main ADC. If the main ADC is not running then TSREF will  not be updating.

    Start Main ADC in continuous run mode: write 0x06 to 0x030D

    Regards,

    David

  • 0 in reply to David Ray
    Intellectual 275 points 

    //set up the main ADC
    WriteReg(0, ACTIVE_CELL, 0x0A, 1, FRMWRT_ALL_W);    //set all cells to active
    WriteReg(0, ADC_CONF1, 0x02, 1, FRMWRT_ALL_W);      //26Hz LPF_Vcell (38ms average)
    WriteReg(0, ADC_CTRL1, 0x0E, 1, FRMWRT_ALL_W);      //continuous run, LPF enabled and MAIN_GO
    delayus(38000+5*TOTALBOARDS);                       //initial delay to allow LPF to average for 38ms (26Hz LPF setting used)


    //set up tmepareture


    WriteReg(0, CONTROL2, 0x01, 1, FRMWRT_STK_W); //to enable the TSREF
    delayms(2);

    ReadReg(0, TSREF_HI, Tref, 2, 0, FRMWRT_ALL_R);
    uint16 Tref_T = (Tref[0] << 8) | Tref[1];
    printf("\n");
    printf("%d\t",Tref_T);


    // here abhaya changed 0x41 to 0x09 and enable 2,3,4 GPIO as well//

    WriteReg(0, GPIO_CONF1, 0x09, 1, FRMWRT_STK_W); //-   Configure GPIO1 for temperature measurement
    WriteReg(0, GPIO_CONF2, 0x09, 1, FRMWRT_STK_W); //-   Configure GPIO2 for temperature measurement
    WriteReg(0, GPIO_CONF3, 0x09, 1, FRMWRT_STK_W); //-   Configure GPIO3 for temperature measurement
    WriteReg(0, GPIO_CONF4, 0x09, 1, FRMWRT_STK_W); //-   Configure GPIO4 for temperature measurement





    WriteReg(0, OTUT_THRESH, 0xFF, 1, FRMWRT_STK_W);  //
    WriteReg(0, OTUT_CTRL, 0b01, 1, FRMWRT_STK_W); //

    Please confirm this sequence is fine?

    Thanks and Regards

    Abhaya Raj Mishra

  • 0 in reply to Abhaya Raj Mishra
    TI__Expert 5500 points

    Hi Abhaya,

    Please move lines 1-5 to after line 25 as the GPIOs and TSREF should be configured before adc_go is enabled.

    Regards,

    David

  • 0 in reply to David Ray
    Intellectual 275 points

    Ya I changed accordingly, but still i'm getting TSREF value as 0.

  • 0 in reply to Abhaya Raj Mishra
    TI__Expert 5500 points

    Hi Abhaya,

    Can you confirm on your board that TSREF is 5V with a multimeter? If TSREF is reading 5V with a multimeter, try adding a delay of 2ms after enabling TSREF.

    Regards,

    David

  • 0 in reply to David Ray
    Intellectual 275 points

    Ok, sure I'll try it.

  • 0 in reply to Abhaya Raj Mishra
    Intellectual 275 points

    In multimeter also it is showing 0 V.

    what should be done?

  • 0 in reply to Abhaya Raj Mishra
    TI__Expert 5500 points

    Hi Abhaya,

    it seems that your device is not communicating with the BQ79656. Here are two items I need that can help:

    1. Setup: Can you send a picture of how the microcontroller is connected to the BQ79656?

    2. Waveforms: Can you send an oscilloscope screenshot of RX and TX on the BQ79656 board? This screenshot should record you sending a read frame of 0x301 on the RX line and the BQ79656's response on the TX line.

    Regards,

    David

  • 0 in reply to David Ray
    Intellectual 275 points

    Ok i'll do it. Please give me some time.

    Thank you.