• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 63 subscribers
  • Views 767 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Compiler/BQ20Z95: I2C(SMbus) bit sequences

yj w
Prodigy 130 points

Part Number: BQ20Z95

Tool/software: TI C/C++ Compiler

Bq20z95 Sealed to Unsealed，default unsealkey is 0414,3672.

I2C(SMbus) commands bit sequences:Start+0x16+ACK+0x00+ACK+0x14+ACK+0x04+ACK+0x72+ACK+0x36+ACK+Stop. Is this right? now,that the ack after 0x72 not be received. And unseal no success.

thanks.

  • 0
    TI__Expert 6575 points

    Both the unseal and full access keys are two part keys. so the first part word write to 0x00 with 0x0414 has to be done separately from the second part i.e. word write to 0x00 with 0x3672. Same sequence for the full-unseal, both parts have to be sent separately.

    The two parts must be sent within 4 seconds of each other.

    Here is a capture when unsealing from the TI software:

    The circles in blue show the unseal and full access commands being sent.

    The circles in black show the verification by reading the operation status register to see that the seal and full access bits are cleared (this was for a different device, so the bits are different and can be ignored.)

    Regards,

    Swami

  • 0 in reply to Swaminathan Ramanathan75031
    Prodigy 130 points

    Thanks very much for your reply!

    Now, the unsealkey has been wrote into successfully. But the unsealing is failing. Maybe the unsealkey have been changed.

    And I have another question: the sbs command, ManufacturerName(0x20), has 12 bytes returning, but I could only receive 2 bytes, what can I do?

    The bit sequence now: Start + 0x16 + ACK + 0x20 + ACK + Sr + 0x17 + ACK + receive byte + ACK + … + Stop.

    Then, which standard specification is the bit sequences based on? Is SBD, SBS or SMBus specification? Where can I download that?