BQ76905: Missing Driver Code

Jeffrey Peng

Part Number: BQ76905

Hello,

I'm working with this BQ76905 device to read the voltage, external temperature, and coulomb counter for a 2-cell lifepo4 battery pack and I've been writing my own driver code to do that. I took a look at the sample driver code provided for this device just today and I do have one question about that: why is there no sample code on how to read the coulomb counter (PASSQ) that I can use as reference? All I see are several variables defined to be used for reading the coulomb counter (PASSQLSB, PASSQMSB, PASSQTIME), but I don't see the PASSQ register being read in the sample driver anywhere (BQ7690x_functions.c). So if your team actually wrote any sample code how to read the PASSQ register, where can I find it?

5 months ago

0 Michael Bradbourne 5 months ago

TI__Genius 16695 points

Hello Jeffrey,

If the code is not in the driver, then it likely does not exist. I cannot answer the question about why the function you are looking for does not exist because I was not on the team when the driver was written.

You should be able to call the subcommand function with PASSQ (which is defined in the header file) to read the data, however.

Regards,
Michael

0 Jeffrey Peng 5 months ago in reply to Michael Bradbourne

Prodigy 10 points

Well if I were to send you my driver code for the BQ76905 device, would you be able to verify that I'm reading the coulomb counter correctly? Because I'm currently having an issue where the coulomb counter reads I'm getting are total nonsense and it'd be great if I check with your team first to make sure that my driver code is correct.

0 Michael Bradbourne 5 months ago in reply to Jeffrey Peng

TI__Genius 16695 points

Hi Jeffrey,

I could take a look at the driver code. I am not a firmware expert, however, but I can make sure that the logical flow of the code makes sense for how the device operates.

Regards,
Michael

0 Jeffrey Peng 5 months ago in reply to Michael Bradbourne

Prodigy 10 points

Okay, since you're not a firmware expert and you weren't on the team when the BQ76905 driver was written, then can you consult someone on the team who is a firmware expert and was already working at TI when the driver was written? Otherwise your technical support isn't going to be very helpful.

0 Michael Bradbourne 5 months ago in reply to Jeffrey Peng

TI__Genius 16695 points

Hello Jeffrey,

It seems that the code follows the general flow to read the subcommand properly. I don't see how each of the functions operate, however.

If you use the TI provided driver and the Subcommands function, are you able to get data that is not nonsense?

Regards,
Michael

0 Jeffrey Peng 5 months ago in reply to Michael Bradbourne

Prodigy 10 points

Well like I said before, the TI driver has no sample code for the PASSQ subcommand that I can use. Otherwise I would've tried that by now.

0 Michael Bradbourne 5 months ago in reply to Jeffrey Peng

TI__Genius 16695 points

Hello Jeffrey,

There is a subcommand function that will call a subcommand in the driver:

From my understanding of the driver, you can call this function within another function to read the coulomb counter and return the value RX_32Byte.

Regards,
Michael

0 Jeffrey Peng 5 months ago in reply to Michael Bradbourne

Prodigy 10 points

Okay, let me try using that subcommand function then to read the coulomb counter. I'll let you know if it works once I get the chance.

0 Michael Bradbourne 5 months ago in reply to Jeffrey Peng

TI__Genius 16695 points

Hi Jeffrey,

Sounds good. Thanks, I want to see if this is indeed a firmware issue rather than a device issue. You are able to call other subcommands, correct?

Regards,
Michael

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BQ76905: Missing Driver Code