BQ34Z100-G1 I2C communication errors

Wade Baker

Other Parts Discussed in Thread: BQ34Z100-G1, BQSTUDIO, EV2400

My application uses a MK70FN1M0VMJ12 µC to talk to the bq34z100-g1 via the I2C bus. It works most of the time but occasionally the gas gauge chip fails to accurately report the SOC. Sometimes it continuously reports 100% and other times it continuously reports 0%. I have clock stretching and glitch filtering enabled on the µC and I have monitored the bus during the failures and seen the gas gauge reporting 100% or 0% continuously. When this happens the standard data registers also report erroneous data. Has anyone else seen this phenomenon and found a work-around for it?

over 8 years ago

0 ThomasCosby over 8 years ago

TI__Guru 73830 points

Wade,
What clock frequency are you using? You could try reducing the clock frequency, if you are operating above 100 KHz. Have you tried using the EV2300 and bqStudio to communicate with the device? If so, have you seen any communications issues using these tools?
Tom

0 Wade Baker over 8 years ago in reply to ThomasCosby

Prodigy 70 points

Tom,
Thanks for the very quick response! I've been told by the firmware engineer that it is not alway the case that all the registers are reporting incorrect data. Many times it is just the SOC, remaining capacity, and voltage registers that report incorrectly. We started out communicating at 100kHz but we lowered it to 25kHz several weeks ago on the theory that we may have frequency induced communication errors. I tested our application using the EV2300, bqStudio, and the bq34z100-g1 evaluation board and I never saw the errors occur with that setup. What frequency does bqStudio use to communicate?

0 ThomasCosby over 8 years ago in reply to Wade Baker

TI__Guru 73830 points

Wade

The bqStudio program is not tied to a specific frequency, but it is used with the EV2300 or EV2400.

EV2300: about 65 KHz

EV2400: about 93 KHz

Tom

0 Wade Baker over 8 years ago in reply to ThomasCosby

Prodigy 70 points

Thank you Tom.

0 Matt Housey over 8 years ago in reply to Wade Baker

Prodigy 50 points

Hi Tom,
I working with Wade on this issue. We are seeing a couple of scenarios:

1. The SOC and remaining capacity are reporting 0% and 0 mAh respectively, and the voltage register is reporting 36000 mV which is out range. Max voltage should be 13800 mV. This typically occurs when the device that the battery is connected to is powered up.
2. We have seen the SOC remain stuck at 100% for several hours despite there being a significant drain on the battery over that time.

These scenarios don't happen frequently but often enough to cause concern that the SOC is not reading reliably. What would cause the two scenarios above? Is there a register or a bit we can read to verify that the SOC reading is valid?

Thanks,
Matt

0 ThomasCosby over 8 years ago in reply to Matt Housey

TI__Guru 73830 points

You may see voltage and capacity reporting issues as the device is reset and the firmware is initializing, but they should report correctly after a few seconds. Are you using the TI EVM? What type of cells are you using and have you verified that you have a good ChemID match?

0 Matt Housey over 8 years ago in reply to ThomasCosby

Prodigy 50 points

We will wait for the firmware to initialize to help ensure we read valid data (we are using our device not the TI EVM). We do have a good match on the ChemID.

What would cause the SOC to remain at 100% for several hours despite a significant drain on the battery?

Is there a register or bit we can read to verify the SOC is valid?

Thanks,

Matt

0 ThomasCosby over 8 years ago in reply to Matt Housey

TI__Guru 73830 points

That is usually caused by a poor ChemID match. If you can send a log file and srec file from the pack , then I can help to analyze it.

0 Matt Housey over 8 years ago in reply to ThomasCosby

Prodigy 50 points

I have attached a zip-file with 3 files in it. Let me know if this is what you need or if you need more info.

Thanks,

Matt

0100_0_16-bq34z100G1_Production_Programming_File_2.zip

0 ThomasCosby over 8 years ago in reply to Matt Housey

TI__Guru 73830 points

Matt
The Flash Update OK Voltage is set too high and it may be preventing the gauge from updating the flash. It should be set at a cell level, so try setting it to 700mV.
Tom

0 Matt Housey over 8 years ago in reply to ThomasCosby

Prodigy 50 points

Tom,

Thanks, we will set the Flash Update OK Voltage to 700 mV and give that a try. We will let you know how that turns out.

Matt

0 Matt Housey over 8 years ago in reply to ThomasCosby

Prodigy 50 points

Tom,

We changed the Flash Update OK Voltage to 700 mV and now the SOC is reading properly. Thanks for you help!

Matt

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BQ34Z100-G1 I2C communication errors