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BQ78350-R1: BQ78350-R1 Reading Unseal and FullAccess Key and changing them

Yusuf KAYA
Intellectual 630 points
Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQ76940, , BQSTUDIO

I have designed battery management system with Bq78350-R1 and Bq76940 and programmed its data memory. Now I would like to read unseal and fulleccess keys and change them for sealing my device. Many times I have read the pages releated to this topic in the bq78350-R1 datasheet. Although ı have experience about sealing the battery management ICs like Bq20Z655, I can not understand the instructions of the datasheet for sealing the IC. (I am using Battery Management Studio)

Can you please explain to change the unseal key step by step? Thank in advance.

  • 0
    TI__Guru 54715 points
    Hi Yusuf,
    The keys should generally work the same, bqStudio is a different interface which does some processing for you. To change the unseal key with bqStudio using the block command shown in the technical reference manual section 17.2, and the corrected example of 17.2.31:

    With the bqStudio Advanced Comm SMB tool:
    1. Set block write 44 and data 35 00 23 01 67 45 AB 89 EF CD
    2. Seal the pack
    3. Sent the unseal command either with
    The unseal command button, enter: 67452301
    Or in the Advanced Comm SMB tab, Write Word to command 00, 2 words within 4 seconds: 2301 then 6745
  • 0 in reply to WM5295
    Intellectual 630 points
    Thank you for quick reply.
    I followed your instructions but I received "Write Block : No acknowledge from device" message when I set block write 44 and data 35 00 23 01 67 45 AB 89 EF CD
    Even so, will i send the "Seal the pack" instruction? Do i have another problem?
    Thanks.
  • 0 in reply to Yusuf KAYA
    TI__Guru 54715 points
    Hi Yusuf,
    If the communication is not reliable I would not send the "seal" instruction since the key may not be known. Of course the gauge will seal on reset if it has previously been sealed, so writing the key successfully before power cycle on a sealed pack is needed, otherwise you may not know the key. In full access mode you can write and read the keys. When sealed you must know the key.
    In a quick test a part showed successful communication even when sealed and it rejected the key.
    You may want to turn off dashboard refresh. I have not seen this cause a problem with block write, but less communication may help. Also be sure the inputs to the monitor part are stable and the I2C communication with the gauge is OK. If the gauge gets busy with an intermittent I2C it may NACK the SMBus.
  • 0 in reply to WM5295
    Intellectual 630 points
    Thank you. I tried the same instructions with another computer and then i could sealed the device with my own key.