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BQ76952: bq795202 with CRC enabled comm issues

Kevin Knicker
Expert 1091 points
Part Number: BQ76952
Other Parts Discussed in Thread: BQ34Z100, BQSTUDIO

Tool/software:

Dear TI,

I have a question already posted about communicating with both a bq76952 and a bq34z100.

I explained that I tried all the tricks already posted about the issue and that it didn't work.

It would only allow me to properly talk to the bq3z4100.  The bq76952 never communicated correctly.

The only way I could get it the bq76952 to work was to remove the bq34z100.

Then bqStudio would open the bq76952.  However, it would open with I2C CRC communication.

I realize now that the bq7695202 has CRC enabled.  I have not read up much CRC but I'm wondering if that could be causing the issues I was seeing when trying to communicate with both parts the same bus.

With the bq34z100 being I2C and the bq76952 being I2C with CRC.

I found that using the SWAP_TO_I2C command would get it just I2C.

My only familiarity with the bq76952 is using the Eval Kit which I see comes with the standard bq76952 that does not have CRC Enabled.

Any thoughts on this are appreciated.

Regards,
Kevin

  • 0
    TI__Genius 17795 points

    Hello Kevin,

    Thank you for your patience. 

    Section 5 Device Comparison Table from the datasheet shows that for BQ7695202 version, it comes with CRC Enabled. CRC can help users in detecting transmission errors, however, it can cause issues with communication if the AFE expects a CRC bit when communicating, whereas the MCU does not expect to see/add this extra bit(s). 

    More information on CRC for our device is given in Section 9.2 I2C Communications Subsystem of the technical reference manual. Section 4 I2C with CRC in the Software Development Guide may also be useful to refer too.

    Best Regards,
    Alexis

  • 0 in reply to Alexis_H
    Expert 1091 points

    Hi Alexis,

    Thank you for the reply and for sending links to more info on CRC.

    I will look that information over.

    Just a quick follow up.

    I created a gg file using the bq76952 Eval Kit.  That uses the standard version of the part without CRC.

    I can get the 7695202 version communicating properly now using bqStudio, but when I try to import and then do a Write_All to load the data memory, I end up losing communication and I get a No acknowledge from device.

    Is this because I created a file using the standard part and now I'm trying to write to the 202 version which has CRC?

    Best Regards,

    Kevin

  • +1 in reply to Kevin Knicker
    TI__Genius 17795 points

    Hello Kevin,

    Kevin Knicker said:
    I can get the 7695202 version communicating properly now using bqStudio, but when I try to import and then do a Write_All to load the data memory, I end up losing communication and I get a No acknowledge from device.

    That would make sense why that occurs. bqStudio will automatically detect that the ‘202 uses I2C with CRC and will communicate with the AFE with I2C with CRC.

    When you upload the .gg file from BQ76952 Eval Kit, the default comms is most likely still I2C (unless configured otherwise) and will configure the ‘202 to change to I2C without CRC.

    Restarting bqStudio should help bqStudio recognize it doesn’t need I2C with CRC to communicate with the device. 

    Best Regards,
    Alexis