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BQ78350: No response to message SBS 0x66 - Lifetime Data Block 7 , & datasheet lengths of payloads do not match the CRC values

Part Number: BQ78350
Other Parts Discussed in Thread: BQ76940EVM, , , BQSTUDIO

Hi

I have a BQ76940EVM. I'm using C++ to communicate with the BQ78350, and I'm looking for the lifetime data blocks. 

I can obtain data for messages 0x60 to 0x65 - i.e. lifetimedata blocks 1, 2 , 3, 4, 5 and 6. 

However, when I ask for response to message 0x66 - i.e. lifetime data block 7, I get no response. 

How can I resolve this- is the layout for requesting messages from lifetime data block 7 not identical to how I would request 1 through 6? 

Also

The datasheet states the payload sizes of the lifetime data blocks, but the CRC value I obtain from the card is, in some cases, different. 

The datasheet shows: 

block 1 - payload 32+1

block 2- payload 32+1

block 3- payload 14+1

block 4- payload 20+1

block 5- payload 14+1

block 6- payload 32+1

block 7- payload 32+1

but I'm currently seeing

block 1 - payload 32

block 2- payload 12

block 3- payload 20 

block 4- payload 14

block 5- payload 32 

block 6- payload 32

The CRC is being calculated as correct when I use payloads of these sizes (mine excludes the PEC). Why is this? What are the lengths supposed to be? 

 

  • Hi Tasha,

    When you say no response, do you mean it is reading all zeros from 0x66? This may be correct since most of the values in this register will initially be zero. 

    Also, can you verify which version of the device firmware is loaded on the BQ78350 IC?

    Regards,

    Matt

  • Hi Matt, 

    I mean no response at all- no data being received for block 7.

    I believe this is the BQ78350-R1 firmware, apologies but I'm unsure of the version number

  • Hi Tasha,

    You can read the firmware version with the 0x0002 MAC command. Another thing you might want to try is using BQStudio to read the firmware version and the Lifetime Data Blocks to verify the result is the same you are seeing.

    Regards,

    Matt