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HDQ Mode for bq27742

Other Parts Discussed in Thread: BQ27541, BQSTUDIO, EV2400, BQ27742-G1, BQ27742EVM, BQ27541-G1

Hello,

We are using the bq27742 in HDQ mode. We are using a custom programming tool to program and calibrate our PCBAs (no TI tools). What is the sequence of commands to put the gauge into HDQ mode. 

Is this command sequence the same for bq27741 and bq27541?

I've also heard there is a plan to release FW that will enable transition back to I2C mode. Is this true?

Thanks,

Jason

  • hello Jason,
    The command sequence is the same as the bq27741. Their platforms are the same.
    Usually putting our devices into hdq mode is a 1way trip. I do not believe there are any plans to release a tool that will transition back to I2C from hdq.

    thanks

    Onyx

  • Hi Onyx,

    What is the command sequence to get these gauges into HDQ mode?

    Thanks,
    Jason
  • Hi Jason,

    The bq27742 bqstudio  doesn't have the hdq plug in at the moment, however here is a workaround.

    1)      using EV2400 with FW version 0.18

    2)      bqStudio v1.3.37 (latest TI build, but only v1.3.35 is on ti.com; however, v1.3.35 should also autodect the device in HDQ mode; there have been no changes to bqStudio in the HDQ area since v1.3.35)

    3)      bq27742EVM running bq27742-G1 v1.03 FW, communicating fine in I2C mode with bqStudio

    4)      close bqStudio, start EVSW and manually select bq27541-G1

    5)      use the Send to HDQ plugin, click the button to send to HDQ

    a.       gauge will lose communication in I2C at this point

    b.      power cycle the EVM

    6)      close EVSW

    7)      move communication cable from I2C to HDQ ports on EV2400

    8)      move communication cable from I2C to HDQ header on bq27742EVM

    9)      start bqStudio and it autodetects bq27742-G1 and can read registers OK.

     

    thanks

    Onyx

  • Hi Onyx,

    I'm developing a custom programmer and I need the low-level, I2C command sequence to get these fuel gauges into HDQ mode in a production environment. I cannot have our production line performing this work-around.

    I was able to analyze the I2C bus during this transaction (addresses are 7-bit left justified and data is MSB). Please confirm this is accurate.

    1. Verify there is no ACK on address 0x16
    2. Verify fuel gauge is unsealed (fuel gauge is still address 0xAA)
    3. Put the fuel gauge into ROM mode (fuel gauge address is now 0x16)
    4. Write address 0x16, command 0x00, data 0x0D00
    5. Write address 0x16, command 0x64, data 0x0D00
    6. Read from address 0x16, command 0x04. Data should be 0x0113. Is this the only acceptable response?
    7. Write address 0x16, command 0x00, data 0x16 (1 byte)
    8. Write address 0x16, command 0x04, data 0x05 (1 byte)
    9. Write address 0x16, command 0x64, data 0x1B00
    10. Power cycle fuel gauge

    Thanks,

    Jason

  • Hi Jason

    That was some brilliant reverse engineering! You should test on a device to see if it works. On the other had I will check with our tools team for the command sequence and get back to you if it is any different from what you listed..

    thanks

    Onyx

  • Hi Onyx,

    Unfortunately, I have only one design that needs to go to HDQ mode and it uses custom firmware so I'm not sure if this is a good test case. The procedure I outlined fails in this case. At step 6, the fuel gauge returns 0x1013 instead of 0x0113 (returned by a bq27741 eval board).

    Does your tools team have anything to say about this? We need this answered soon as we are starting production next week.

    Thanks,

    Jason

  • Onyx,

    I'm still waiting for an answer.

    ~Jason
  • Texas Instruments,

    Does anyone at TI know how to get these gauges into HDQ mode using generic I2C tools?

    Why is it taking so long to answer this? Are we waiting for an App Note? Is the "go-to" person not around?

  • Hello,
    Your steps 4. 5. 6. are not necessary
    Only do step 3 then steps 7, 8, 9.
    [ note: Step 9 is a CRC check on the command… assuming it’s correct, but did not calculate it.]
    Change step 10 to “Execute firmware command” (now we’ll be in gauge mode)
    Add Step 11. Issue POR command or remove and replace power to PCB.