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How to unseal th BQ27410-G1?

jakob.schaeffler
Prodigy 10 points

Hello,

currently I try to get a proper communication between my microcontroller and the gas gauge  BQ2741-G1.

Reading the specific adresses for DEVICE_TYPE or DEVICE_NAME gives the expected result. Also a read of the Operation Configuration register results the default value 0x19. But the result of the Control Status register is 0x0008, what i do not expect. According to datasheet information I would expect something like  0x6000 that shows me an active sealed state.

Actually, I have two questions:

What is a normal status register value for the gas gauge configured by default?

And how do I get the gas gauge unsealed to configure it? The datasheet says by a consecutive sending of   two 2-byte unseal keys. The default key is given as a 4-byte. Now I'm not sure about the byte order of the key .

Best wishes,


Jakob

  • 0
    TI__Genius 14985 points

    0576.How to SEAL and UNSEAL.ppt

    Hi Jakob,

    I've attached an example illustrating the sealing and unsealing process using our EVSW.

    Your gauge will be unsealed by default and will stay that way until you send the seal command.  Once sealed, it will always return to the sealed state if you reset it, even if you have unsealed it.  Usually it is sealed at the end of your production line.

    Sealing it prevents modification of the dataflash parameters, and also prevents anyone from viewing your dataflash settings.  Sealing is also recommended because it also protects the RAM registers.  If unsealed, it is possible for an accidental write to the RAM registers (like Voltage(), for example) to cause unexpected behavior.  Of course the Voltage( ) register will update itself quickly, but there is a very tiny window where a write might cause strange things to happen if a crazy voltage is written to it.  It's not likely, but possible, so sealing will protect against that.  On the other hand, some customers use the gauges in the field without sealing.  Nonetheless, TI's recommendation is to always seal the gauge before shipping your product.