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BQ76952: Calibrating the device using bqStudio

Kyungjae Lee
Intellectual 650 points
Part Number: BQ76952
Other Parts Discussed in Thread: BQSTUDIO,

Tool/software:

Hi,

Background:

Digging into the E2E forum I found that the python script provided in the "BQ769x2 Calibration and OTP Programming Guide" is not usable as-is due to TI's  proprietary/internal library "bqcomm". Therefore, we've decided to use the bqStudio software to perform the Pack Voltage, Stack Voltage, and the Pack Current calibrations.

Question:

1. Is there a separate guide that describes how to perform calibration using bqStudio?

2. For voltage calibration, if I only want to calibrate the Pack and Stack Voltages, should I enter the applied voltage in the corresponding fields and then click the "Calibrate Voltage" button, leaving all other fields empty?

3. For bqStudio to detect the device, does the device need to retain its default I2C address? Our BMS features two BQ76952 chips, and one of them will be assigned a new address during the OTP process. With that in mind, should I perform the calibration before changing the I2C address through OTP, while both devices are still detectable by bqStudio?

Best regards,

Kyungjae Lee

  • +1
    TI__Genius 17755 points

    Hello Kyungjae,

    1. Section 3.7 Calibration of the BQ76952 Evaluation Module gives a brief guide to using bqStudio to calibrate. We also have this previous forum post that may assist you: BQ76952: Voltage Gain Calibration.

    2. That should be fine.

    3. For bqStudio to autodetect the device, it would need to retain the default I2C address, however, the device address can be manually set. We would recommend changing one of them before connecting bqStudio though so bqStudio will not be confused. 

    Section 2.1 Data Communications in the Design Considerations of Stacked BQ769x2 with High-Side N-MOSFET application note briefly talks about this and may be useful. 

    Best Regards,
    Alexis

  • 0 in reply to Alexis_H
    Intellectual 650 points

    Hi Alexis,

    Thank you for the response. After going through the links you've provided, I came up with a follow up question about the cell voltage gain calibration:

    According to one of the responses in the post BQ76952: Sample calibration code example, it seems that the 'Command Sequence' tab of the BQSTUDIO need to be used instead of the 'Calibration' tab to perform the cell voltage gain calibration . Is this correct?

    Is the best way to perform the cell voltage gain calibration saving the sequence of the commands based on what's described in the 'BQ769x2 Calibration and OTP Programming Guide' as a file and reusing the sequence all throughout the cells in use?

    Best regards,

    Kyungjae Lee

  • +1 in reply to Kyungjae Lee
    TI__Mastermind 42060 points

    Hello Kyungjae,

    The calibration tab of bqStudio is good if you want to perform 1-point calibration. Which for some customers, it is acceptable. 

    For best accuracy, you would want to perform 2-point calibration, which would mean that you'd have to manually find the gain/offset using two voltage points (Using the Calibration application note as reference). This can be done with bqStudio or the MCU, whichever you prefer. 

    Command sequence is not really necessary, unless you want to automate some of the steps shown in Section 2.2 Cell Voltage Gain Calibration to gather the data. 

    Best Regards,

    Luis Hernandez Salomon

  • 0 in reply to Luis H. S.
    Intellectual 650 points

    Thank you Luis for the detailed response! I'll look into the process.

    Best regards,

    Kyungjae Lee