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BQ40Z50-R1: Interface with BQStudio over third party device

Part Number: BQ40Z50-R1
Other Parts Discussed in Thread: BQSTUDIO, , BQ40Z50, EV2400, GPCCHEM

Dear all,

please confirm if I can use MCP2221 USB To UART/I2C/SMBUS as a interface (bridge) for the BQStudio.

I have searched a lot on this topic and wasn't able to find proper interface device between PC host and the BQ40Z50-R1 device. Some other BQ... products use Texas Instruments evaluation boards for the interface. It is hard to find the source code for the MCU that could be use to operate with the BQ40Z50.

If possible, please refer me to the BQStudio interface user manual or application note.

Thank You in advance!

  • Hi!

    BQStudio is PC program and get access to bq40z50 across EV2300 bridge (inside ev2300 have mcu with usb interface and i2c/smbus to target).

    Your can't use "MCP2221" instead ev2300 for BQStudio..

    Your can use "MCP2221" instead BQStudio for custom read/write operation over USB-i2c. But your need to write the own equivalent the BQStudio - i/o to open "MCP2221-device", send i2c command, recieve answer from bq40z50, decode and show.. etc

    >It is hard to find the source code for the MCU that could be use to operate with the BQ40Z50.

    Your can use any library for your MCU for read/write access for i2c bus - BQ40z50 is ordinary slave for i2c access..

    If MCU have not i2c cores, may be use any two gpio for emulate i2c protocol.. If electric level of signal (sda, scl) the same, of course..

  • OK! I understand. Thank You.

    Meanwhile, I've read a lot of documentation on the BQ40Z50-R1 and I do have more of this doc's to go trough.

    Is there some kind of quick start guide to initialize 2S battery without the EV2300/2400? I managed to bridge the SMBus and the PC terminal so I can send/receive HEX data from the BMS.

    I would like to make a BMS initialization and start the battery learning process.
  • I think - No.. It is very difficult, almost impossible.. Arguments:
    - by default ChemId=0x100, and not fact what your chemistry of cells will coincide to default (how to change ChemId w/o ev2300 it unknown, not public data)
    - procedures of calibrations - current, voltage, temperature (ADC) w/o ev2300 very hardly - your need manually recalculate value to correction and write to flash inside bq40z50

    But, theoretically, if you are satisfied with the default accuracy, then you can make correction only for basic parameters and have work prototype of pack..
    You need simple functions to/from i2c(smbus) bus - read/write word, r/w block of data and map of flash and registers by bq40z50

    >Is there some kind of quick start guide to initialize 2S battery without the EV2300/2400?
    I think - no..
  • Thx again!

    I did dig around the BQStudio files and I've managed to find that the chemistry for the NCR18650B is 2012 or 2017:

    [520_Chem]
    ChemID=2012
    Description=NiCoMn/carbon
    NumKnownCells=1
    HF_Data=1
    2OCV_Data=1
    1=Panasonic: NCR18650B (3350mAh)

    *Description NiCoMn/carbon
    Chemical ID 2012
    Vqdis_min 3313
    Vqdis_max 3314
    SOC_min, % 6
    SOC_max, % 7
    Rhf,mOhm -1
    Rhf_lo -84
    Rhf_hi -52
    Qmax 3366
    Ra0_charge NaN


    or:


    [525_Chem]
    ChemID=2017
    Description=NiCoMn/carbon, -20C
    NumKnownCells=1
    HF_Data=1
    2OCV_Data=1
    1=Panasonic: NCR18650B (3350mAh)

    *Description NiCoMn/carbon, -20C
    Chemical ID 2017
    Vqdis_min 3313
    Vqdis_max 3314
    SOC_min, % 6
    SOC_max, % 7
    Rhf,mOhm 61
    Rhf_lo -350
    Rhf_hi -57
    Qmax 3367
    Ra0_charge NaN



    If I understand correctly, this data can't be written to the bq40z50 without the BQStudio?!

    I am totally new to this and I'm trying to learn as much a I can.
  • If you have bqStudio, then look into %path-to-bqstudio%\chemistry\chemdat.txt

    and make compare you data with default:

    % Rhf,mOhm Rhf_lo Rhf_hi Qmax Ra0_charge

    LiCoO2/graphitized carbon (default) 100 3737 3800 26 54 NaN NaN NaN 0 NaN

    I think, this file consist only text for human, but really data encrypted to files with names chemdat4/chemdat8 etc

    >If I understand correctly, this data can't be written to the bq40z50 without the BQStudio?!

    yep, at the top of this page in search window enter for example "chemid" for more information..

    PS I saw a couple of threads with attempts to sniff the protocol

  • Hi Mario,

    I would recommend you get an EV2300 or EV2400 and download bqStudio. It will make your life much easier starting off.  You need to configure you device and create a golden image, which you will need to use bqStudio to do. The route you are taking we can't support you and there's no guarantee of success.

    We recommend running a charge, relax, discharge, relax, charge cycles on the cells with logging time, voltage, current  and temp. The submitting it to our online GPC tool to find the best chemID match for your cells. Then you can use bqStudio chemistry tab to select and program the best matched chemID. Once you've gotten the chem ID, you then perform an optimization cycle (charge, relax, discharge, relax, charge cycles) for the bq40z50-R1 to learn the cells and update resistance table and QMax. Once this is complete you can create and golden image file. If you want to use a Micro for production there's an app note you can follow to program the data flash settings created in the golden image to other packs with bq40z50-R1.

    Here are some resources:

    http://www.ti.com/tool/GPCCHEM

    www.ti.com/.../slua743.pdf

    www.ti.com/.../slua734a.pdf

  • Why is this happening? :/

    Something is wrong with the charge current in the CHARGE mode. What could be wrong.

  • What's your Charge current settings for Rec and standard temp? It looks like your CHG FET is turning off and on.
  • Your can see actual alert/alarm in Registers Window (Main Screen, bottom, Red/Green/Gray). Press "Scan" to automatic refresh..
    Try reduce the charge current or use more powered PSU
  • Please check the data memory dump.

    Battery is 2S (3P x 3350mAh), Vbatmax = 8.4V, Ichg,max = 1.5A

    drive.google.com/.../view
  • Can you provide a log file when this is occurring or screen capture of the dashboard when the current drops to 0mA. Of course you have to enable scan to continuously refresh the screen when the gauge updates status.
  • Dear Damian,

    I managed to resolve all issues with the data logging and testing but I am currently trying to figure out what to do with the Report file that GPCCHEM generated.

    There are variables in the Report files that do not correlate with any of the BQ40Z50-R1 registers. I will c/p the data below.
    What to do next and how to be sure that learning process is finished correctly?


    GPC_CEDV.txt

    EMF 3481
    EDVC0 119
    EDVC1 0
    EDVR1 1390
    EDVR0 14066
    EDVT0 5490
    EDVTC 9
    VOC75 7890
    VOC50 7626
    VOC25 7508


    OCV11.txt

    SOC, % OCV, mV
    0 3002
    10 3289
    20 3417
    30 3494
    40 3549
    50 3612
    60 3701
    70 3798
    80 3884
    90 3995
    100 4109