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BQ78350: Data flash corruption detection

Yoav Gross
Intellectual 365 points
Part Number: BQ78350

Hi,

I have experienced some values changing in the DF of the bq78350 during work.

I would like to validate the DF does not change its static values, I can see there is a ManufacturerAccess() Command 0x0005 - StaticDFSignature.

According to the technical spec it should return the "signature of all static DF" and "The MSB is set to 1 if the calculated signature does not match the signature stored in DF".

1. I am reading with manufacturerData() 2 bytes: first byte 0x25 second byte 0xFD for example - in this case is the first byte the MSB?

2. what kind of checksum is this? if the first byte is reserved? 

3. when will the MSB be set to 1? when will it be reset to 0?

Thanks,

Yoav

  • 0
    Intellectual 365 points
    Hi again,

    I did not get any answers yet, and the ManufacturerAccess() Command 0x0005 - StaticDFSignature is not well documented.
    I want to validate the integrity of the configuration in the data flash, but need to understand the response of this command.

    1. I am reading 2 bytes: first byte 0x25 second byte 0xFD - is the first byte the MSB or are they reverse ordered like 2 byte integers?

    2. what kind of checksum is this? the highest bit is signalling if there was a change, so it cant be a 16 bit checksum...

    3. when will the MSB be set to 1? when will it be reset to 0? from testing I can see that changing a value in the DF causes the signature to change but does not set the MSB to 1.
  • 0
    TI__Intellectual 1735 points

    • Hi,
    • The first byte you read is ox25, so the MSB is 0, it means that  the calculated signature match the signature stored in DF
    • The checksum is used to show that if static DF is changed.
    • If the static DF is changed, MSB will be 1.

  • 0 in reply to answer
    Intellectual 365 points
    Hi Terry,
    I want to test the signature does work, if I change some of the DF values the signature changes, but the MSB is still 0.
    1. How can I simulate a static DF signature mismatch?
    2. Can I have a list of the values in static DF signature?

    Thx,

    Yoav