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BQ78350-R1: Issues setting up and calibrating the BQ78350-R1 using bqStudio

Avak Archanian
Prodigy 120 points
Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQ76940, , BQSTUDIO, EV2400, BQ78350

I'm having trouble setting up and calibrating the BQ78350-R1. Whenever I try calibrating I get the error, "Failed to enter calibration mode with commands 0x2D." Whenever I try to select the SEAL or UNSEAL command I only get back "N/A" as a result and read. I tried writing to the AFE Cell Map to configure the number of cells in my system, however I am now getting the error, "Operation failed because initial read of all data flash failed." Has anyone had these errors and/or know of a way to fix these issues? My system uses the BQ78350-R1 and the BQ76940.  

  • 0
    TI__Guru* 81034 points

    Hi Avak,

    It sounds like you are not able to write to the data flash for some reason. Are you using the EVM and have you previously been able to write to the device data memory?

    A few things to check:

    • In bqStudio, does the Dashboard show that the EV2400 and the bq78350-R1 are both detected?
    • Is the SMBUS port of the EV2400 connected to the SMBUS port on your EVM?
    • What voltage are you applying to the BAT+ and BAT- pins of the EVM?
    • There is a flash parameter Valid Update Voltage that is 3500mV by default. The voltage between VC0 and VC5 must be greater than this value to validate flash writing.
    • If the AFE cell map is pointing to cells that have no voltage applied, the device may have gone through a Voltage based shutdown (see section 8.4.1 of the Technical Reference Manual). Make sure voltage is applied to each of the cells in the cell map.

    Let me know if any of these help to locate the problem.

    Best regards,

    Matt

  • 0 in reply to Matt Sunna
    Prodigy 120 points

    Hello Matt, 

    I'm not using an EVM this is a custom board. There seems to be voltage going into the cells but I can double check to make sure that's the case. It is by default setting Cells 1, 2, and 5 high which seems like an odd combination. I have very recently checked the voltage of the cells for the battery and I'm positive that the voltage drop between VC5 and VC0 is larger 3500mV. I was at one point able to write to flash memory, I'm not sure what caused this to change. It seems as though the chip is either shutting down or resetting because when I launch bqStudio and select the correct gauge .bqz file, it detects the gauge at first and the completely drops communication. Then it keeps going back and forth between losing connection and reestablishing connection. Do you have an idea as to what can cause this? Thanks for you help. 

  • 0 in reply to Avak Archanian
    Prodigy 120 points
    Also, if I try to program the firmware on the gauge, bqStudio tells me I can't because the chip is not in ROM mode. Do you know what this means?
  • 0 in reply to Avak Archanian
    TI__Guru* 81034 points
    Hi Avak,

    I suspect the device is going into shutdown for some reason. Can you show me how the cells are connected and the AFE cell map? If you force a current across the sense resistor, it will prevent the device from going into shutdown. Can you try this and see if it changes the behavior?

    Regards,
    Matt
  • 0 in reply to Matt Sunna
    Prodigy 120 points
    Ah the other end of the BMS is currently not connected to anything. This could possibly be why it is behaving this way. At the moment the battery is plugged in but the BMS itself isn't connected to anything else. This was to be part of a system, but I'm still waiting on those boards to arrive so I currently just have the battery connected to the BMS and I'm trying to configure it that way. Does that sound possible?
  • 0 in reply to Avak Archanian
    Prodigy 120 points
    I'm forcing current through the sense resistor but it is still behaving the same way. I'm also unable to enter FULL ACCESS in order to get the device into ROM mode. Is the current I'm running through the sense resistor too small? Also, the key to get into FULL ACCESS is FFFFFFFF correct? I have not changed the keys as far as I'm aware.
  • 0 in reply to Avak Archanian
    TI__Guru* 81034 points

    Hi Avak,

    Can you send me the following information to help you debug the issue?

    • A screen capture of the bqStudio window showing the Dashboard
    • The results when you run DEVICE_NUMBER from the Command window
    • The results when you click on 'Read All' from the Data Memory screen
    • The AFE cell map and a schematic of how the cells are connected in your system
    • How much current did you apply to the sense resistor?
    • You mentioned that part of your system is not installed - can you send me a schematic highlighting what is missing?

    Thanks,

    Matt

  • 0 in reply to Matt Sunna
    Prodigy 120 points

    1. This is a picture of the Dashboard

    2. This is the result when I run DEVICE_NUMBER.

    3. This is the result when I hit Read All.  *Note: I did hit the UNSEAL command and entered 36720414 for the Key which has worked in the past. 

    4. This is how the cells are connected in my schematic. The cell map isn't updating for the reason above so I don't think it would be helpful to you as there is no data. 

    5. I applied about 100mA through the sense resistor. 

    6. This is the part of the system that is missing. Essentially there is no load. *Note: That is not the battery input into the system that is the output of the board. 

    Thank you. 

  • 0 in reply to Avak Archanian
    TI__Guru* 81034 points
    Thanks Avak. This confirms that you are able to communicate with the device. The DEVICE_NUMBER command is giving the correct result. So the device is not in Shutdown.

    It looks like the device is sealed. Can you try reversing the code you entered?: 0414 3672

    Matt
  • 0 in reply to Matt Sunna
    Prodigy 120 points

    It didn't seem to work. Also all of the bit registers are showing low or are grayed out I'm not sure why. I still can't get a stable connection between the bqStudio and the IC, it keeps disconnecting and because of that whenever I send a command it either doesn't get an ACK back, or it timesout. Occasionally it give me an error involving MAC. Could the problem be the EV2400?

  • 0 in reply to Avak Archanian
    TI__Guru* 81034 points
    That is a possibility. Another thing to look at is the I2C connections. If I2C communication is interrupted between the BQ78350 and the BQ76940, the BQ78350 will continuously try to read from the I2C in order to get the data it needs and to clear the interrupts. This will disrupt communication with the SMBUS.

    Can you send the parts of the schematic for the I2C and SMBUS?

    Matt
  • 0 in reply to Matt Sunna
    Prodigy 120 points

    1. This is the I2C connection

    2. This is the SMBUS connection. *Note: One the board itself only the series resistors and the pull up resistors are installed. 

  • 0 in reply to Avak Archanian
    TI__Guru* 81034 points
    Are SCL and SDA connected together at the BQ76940 device? It is hard to tell from the schematic, but it looks this way.
  • 0 in reply to Matt Sunna
    Prodigy 120 points

    They aren't that just happened while I was taking the snip, I double checked the board file and they aren't connected by a trace.

  • 0 in reply to Matt Sunna
    Prodigy 120 points
    The IC may be in some sort of bootloop because it is constantly connecting and disconnecting, and for me to send a command like DEVICE_NUMBER I need to click it continuously until it eventually doesn't fail and goes through.
  • 0 in reply to Avak Archanian
    Prodigy 120 points
    I may have found the issue. It seems I was u sing the BQ7694006DB with the BQ 78350-R1. This AFE supplies 3.3V instead of 2.5V and that might be what is causing me problems. I might have to wait until our next iteration of the board arrives to test this hypothesis. Does this sound like it could be the source of my problems?
  • 0 in reply to Avak Archanian
    TI__Guru* 81034 points

    Hi Avak,

    This might be related. This will change the voltages on the I2C communication. If I2C communication has issues, it will cause the SMBUS communication to become intermittent. Do you have a replacement device so you can test it with the 2.5V regulator? The 3.3V regulator can damage the BQ78350-R1 because it exceeds the abs. max. voltage for the supply.

    Regards,

    Matt

  • 0 in reply to Matt Sunna
    Prodigy 120 points

    I don't have the replacement device yet I'm expecting to get the new boards with the correct IC next week. I cut the trace powering the gauge and supplied my own 2.5V using a power supply but to no avail. I have been powering this chip off of 3.3V for about a month now so I'm fairly certain that at this point the damage is already done. 

  • 0 in reply to Avak Archanian
    TI__Guru* 81034 points
    I'm sorry to hear that. Let's see whether the issue is resolved with the new boards. Let me know next week if the issue still persists.

    Thanks,
    Matt