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BQ34Z100-G1: BQ34Z100-G1: I2C communication issue

C.A.
Intellectual 375 points
Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: BQSTUDIO

Dear all,


I am using a BQ34Z100-G1 and I couldn't finish the optimization cycle. Since I have issues with the I2C communication and I need to create a log file to get the correct ChemID... I am stuck. I tried to solve the problem in my last post but since no one could help me about this, I will try to make a more specific post about this issue...


I am working with the EV2300, bqStudio and my PCB with a BQ34Z100-G1 Gas Gauge. My problem is that I have a communication problem between the  EV2300 and my PCB. It happens periodically, for example after 16 seconds, then after 28 seconds, then 16 seconds again and so on... this is not always this timing. When I record a log file, it's say there is no acknowlegde from the device (err 772 : NACK).

Here is a picture of the issue (current goes to 14A or 0A instead of 250mA... which is nonsense due to the NACK) :

I have 2 pull up resistors of 10K (one for SDA, one for SCL), I measured the timing, the only problem was the rise time which was 2400ns and the datasheet says that it should be max 300ns. I tried to put 1K instead of 10K, the rise times are OK but I still get the same problem.

As long as I have this problem, I cannot get a correct log file, so I cannot get a correct ChemID and record a good Golden Image file...

Anyone has an idea? Thanks in advance.

Best,

Christian

  • 0
    TI__Guru 73830 points
    Christian,
    The 2300ns rise time may not cause a communications problem as long as there is adequate setup and hold time. The voltage levels are more important with respect to detecting high and low bits in the transmission. I did notice from the screenshot that you are using version 3.1C firmware in your EV2300. This is an older version of firmware and some users have encountered I2C communications problems with it. We recommend upgrading the EV2300 to v3.1m or 3.1r to improve I2C performance. The upgrade procedure does require two EV2300 modules and here is an e2e link to the procedure.

    e2e.ti.com/.../2056499

    It is important to keep from discharging the cell to the point where the cell voltage can not longer provide full functionality in the device and this includes flash updates. That is why I recommend not discharging below 3V. It is also important to reach the Cell Term Voltage when running the optimization cycle to provide enough change in DOD to update Qmax and to update all of the Ra grid points in the Ra table. Setting the Cell Term Voltage to 3000 mV and discharging to the level should work. Collect the log data during the process and we can use a Mathcad program to help with the updates should they fail. Of course, the communications problems will have to be remedied first to collect a clean log file.

    Tom
  • 0 in reply to ThomasCosby
    Intellectual 375 points
    Dear Tom,

    Thank you. I will order a new EV2300 module and update the firmware on Monday.

    Could you please tell me why the bit [VOK] is always cleared? If I understand correctly, it is not normal. I guess it is one of the reasons why I cannot manage to finish the optimization cycle and the Learned Status is still at 4. I noticed this during the last discharge. I already have 8 cycles but I made a Reset before the last discharges for information.

    Otherwise, I guess it is not too bad, I have 16 grids, DIS_RUP stayed at 0...

    Best,

    Christian
  • 0 in reply to C.A.
    TI__Guru 73830 points
    The VOK flag will clear after a reset, because there is no valid DOD point set. It should set if you issue an IT Enable command.
  • 0 in reply to C.A.
    Intellectual 375 points
    Dear Tom,

    I received the second EV2300 module. After a few tries I could update the firmware of one module, the communication seems better.

    But... I tried to update the second module... the update crashed at the begining and now I cannot update this module (error 772) and cannot uses it with bqStudio...

    How can I update the 2nd module now? Thanks in advance.

    Best,

    Christian
  • 0 in reply to C.A.
    TI__Guru 73830 points
    I will contact you off-line.