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Original question:

BQ35100: can't get right current

BQ35100: Can't complete the Board Offset calibration

Florin Nastase
Prodigy 50 points
Part Number: BQ35100
Other Parts Discussed in Thread: BQSTUDIO, EV2400

Hello,

I am trying to calibrate my BQ35100 using an MCU. I have difficulties with the Board Offset calibration, particularly the CCA bit.

After entering calibration mode, I send the BOARD_OFFSET command to the gauge, as detailed in the Board Offset Calibration flowchart from the datasheet. The BCA bit is set to 1, but the CCA bit stays 0, no matter how long I wait.

I have seen other posts with the same problem and the solutions were to use bqstudio. Unfortunately, I can't get an adapter to soon, so bqstudio is not an option for me.

Did anyone succeeded in doing a Board Offset calibration using an MCU?

Thank you,

Florin

  • 0
    TI__Guru** 105760 points

    Hello Florin,

    Could you outline the steps you take to perform the calibration? Make sure you are in ACC mode when you start calibration as well, otherwise calibration may not be successful. Were you able to calibrate the other parameters?

    Unfortunately we always recommend using bqStudio with an EV2400 to sniff the communication lines to make sure you do the same process as the EV2400.

    Sincerely,

    Wyatt Keller

  • 0 in reply to Wyatt Keller
    Prodigy 50 points

    Hello Wyatt,

    1. The steps I took to do the board offset calibration are the following:
      1. Enter calibration mode
      2. Send the Gauge_Start command
      3. Send the Board_Offset command.
      4. Read the Control_Status register. If either CCA or BCA bits are not set, go back to step c.
      5. Wait for CCA and BCA bits to become 0.
      6. Send Gauge_Stop command
      7. Exit calibration mode

    The program continuously cycles between steps c. and d. because the CCA bit is always 0. I introduced delays bigger than the 100 ms specified in the flowchart, so I guess it is not a timing issue.
         
    2. I believe the gauge is in Accumulator mode, since the GE pin is enabled and the Gauge_Start command is sent.
    3. Yes, I was able to complete voltage calibration and CC offset calibration.
         
    Thank you,
    Florin

  • 0 in reply to Florin Nastase
    TI__Guru** 105760 points

    Hello Florin,

    I would make sure you don't pull the CCA status more than twice a second, try increasing the delay to 1 second between polls.

    If you were able to calibrate the other parameters successfully you should be in ACC mode.

    Sincerely,

    Wyatt Keller 

  • 0 in reply to Wyatt Keller
    Prodigy 50 points

    Hello Wyatt,

    Thank you for the provided information. Unfortunately, increasing the delay to 1 second did not help. Is there anything left I can try?

    If not, can I ignore the CCA bit and continue the calibration?

    Is board offset calibration essential? Can I skip doing it?

      

      

    Thank you for your assistance,

    Florin

  • 0 in reply to Florin Nastase
    TI__Guru** 105760 points

    Hello Florin,

    It should be calibrating correctly, I would double check to make sure you are sending the right commands and they're sending successfully. If your board has a good layout with the traces for SRN and SRP are the same length and fairly short it may not be as critical to calibrate board offset.

    Sincerely,

    Wyatt Keller