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Original question:

Is there a solution to the phenomenon that 'BQStudio and EV 2400 do not detect IC'?

BQ76920EVM: BQ76920EVM

Shubham Mungekar
Prodigy 175 points
Part Number: BQ76920EVM
Other Parts Discussed in Thread: BQ78350, BQ76920, BQSTUDIO, EV2400, , BQ78350-R1

Hi, 

I have recently started using BQ76920 EVM. I have also installed BQ software. I have followed all the instructions mentioned in the evaluation  board manual. But when I open the software, the first thing it shows is  no auto detected device. When I scan the addresses, it shows no address found. But I still select 1E9B_1_03_bq78350_R1.bqz and when the software opens I find only the USB symbol is highlighted and not the other ones (refer pic). I have double checked all the connections, especially the SMB connection from EV2400 to my PC. What could be the issue. Kindly help. Also kindly guide if the software versions are proper in EV2400 and my PC for Bqstudio. as seen in the pic below 

  • 0
    TI__Guru 54715 points
    Hi Shubham,
    See the bq76920EVM user guide figure 2. See also the quick start sequence and other reference material as needed.
    Be sure the cell simulator switches are closed.
    Be sure power is reaching the board
    Be sure the I2C shunts are attached
    Be sure the gauge shunts are installed
    Be sure the 4 wire cable is connected from the EV2xxx SMB connector to the board's SMB connector, be sure wires are not damaged.
    Push the boot button
    Check for 2.5V on the REGOUT test point and GG_PWR.
    If there is no voltage check for missing connections, contamination, shorts or other damage on the board. Be sure the banana jacks have not come loose. Correct any problems.
    If you have voltage on GG_PWR with proper connection and the EV2400 installed as shown in your pictures, perhaps you have an old stock board which did not have firmware. Download and program the bq78350-R1 firmware, then program the device as shown in the user guide.
  • 0 in reply to WM5295
    Prodigy 175 points

    Hi,

    So I began debugging the issue from the start and realized that EV2400 is not being recognized by my PC. Hence I downloaded EV2400 updater and installed on my PC and followed the steps. After this the bq studio software window did show connection and appropriate register values but it disconnected after a few seconds and again the control panel showed EV2400 in unspecified. Kindly assist. why does the connection not remain constant and it shows the error in red font as device not responding in the bottom left of the bq studio software

  • 0 in reply to Shubham Mungekar
    TI__Guru 54715 points
    Hi Shubham,
    The EV2400 shows in unspecified for me also, that is normal. The gauge and registers blanking is common if the gauge shuts down. See the bq76920EVM user guide section 6.3 for reducing cells. From the voltage shown in the registers 4 cells are used but the AFE cell map is set to 5 cells so cell 4 reports near 0V. The gauge will see this low voltage and shut down. Default configuration for the gauge is for 3 cells as shown in figure 12 of the user guide.
    If you can simulate charge current the gauge will stay awake and allow correction of the AFE Cell Map. If current won't flow through the FETs, apply a few mV to the SRP test point with respect to GND to simulate charge current.
  • 0 in reply to WM5295
    Prodigy 175 points

    Hi, 

    As you said and as I have understood - AFE considers 5 cell as default and gauge considers 3 cells as default. How do we clear this discrepancy as I am using 4 cells and I have shorted cell 3 and cell 4 as per the user guide. 

    Can we change the default values to 4 cells in bq studio.

    Also there is a mention in user guide of removing r5 and connecting VC3 and VC4 when using 4 cells, is that step a necessity (I have shorted C3 and C4)  ( page 25 in user guide )

    In bqstudio under data memory >>settings >> Configuration >> AFE Cell Map do we have to change something here? 

    Kindly assist 

  • 0 in reply to Shubham Mungekar
    TI__Guru 54715 points

    Hi Shubham,

    When you set the AFE Cell map, select the same cells for the gauge to monitor as you connected. The gauge will present the selected cells in logical order.  If you short a cell, do not include it in the cell map.

    Default AFE cell map, 3 cells, the minimum supported and with the recommended connection:

    AFE cell map set for 5 cells:

    AFE cell map set for 4 cells according to the bq76920 data sheet connection

    As noted in the bq76920EVM user guide, if you short the unused cell at the input terminal the part will normally work for simple evaluation and display the voltage as you expect, but if you look at the schematic the pins are not really shorted together, there is a resistor back to the cell and circuit performance may be different than a proper connection.  If you short the VCn and VCn+1 pins together also, the input resistors for the unused cell are in parallel.  To get the correct circuit the extra resistor must be removed.

  • 0 in reply to WM5295
    Prodigy 175 points

    Thankyou sir for your reply, it did resolve my issue and the connection is complete. 

    Now when I connect it shows the FET temperature to be 310 deg C, even Cell temperature (showing -273) and TS2 and TS3 temperatures are incorrect. (showing around 300 deg C). During temperature calibration it shows an error (PFA the screenshot). How can I resolve this temperature issue. The error shows the external sensor temperature sensor correction out of range, hence I made Temperature enable-  TS1, TS2, TS3 to be zero and Source bits  to be 0. Still no change. Kindly assist 

    One more doubt I had regarding the chemistry of the battery. I did not find my LiPo battery manufacturer in the list. How can I then define the charging Algorithm if I have to. My battery details on the link below. 

    Thankyou

  • 0 in reply to Shubham Mungekar
    Prodigy 175 points
    Also when I send a command CHEM ID it shows value of result as 0x1210. But I did not find the above in the chemistry table of all the batteries.
  • 0 in reply to Shubham Mungekar
    TI__Guru 54715 points
    Hi Shubham,
    You are using a bq76920, it has only 1 temperature sensor, there are registers for the other sensors but they will read 0. You will not be able to calibrate them. You can leave them at the default display, do not select them for temperature measurement.
    See the technical reference manual for details on selection bits.
    For the cells you will need more information on your cells to properly set up the gauge. The information on the site shown is minimal.
    See the application report Using the bq78350-R1, www.ti.com/.../slua924.pdf for general set up information. You may be able to match a chemistry from data collected from the battery.
    0x1210 is the default chemistry for the bq78350. You can click on the Chemistry ID heading in the bqStudio chemistry tab to sort the table by ID number, this makes it easier to browse for a specific ID.