BQ34Z100-G1: Communication stuck

Hello,

Today's a holiday and no one is in the office. We will get back to you tomorrow.

Regards,

Nick Richards

Hello Nick:

How is going? 

The production is on hold because of this issue. So much appreciate if you can help. A meeting may be helpful, and I can ask our FAE to help on the arrangement.

Thank you!

Chen

Hi Chen,

I have talked with the FAE and provided the best advice I could. It is difficult to solve your issue due to not being able to communicate with the gauge or being able to fully drain the battery. It appears that both of these fix the issue but are not possible.

Do you have any new information about what specifically is happening when the i2c lines get stuck?

Regards,

Evan

Hello Evan:

We just got more field failures with the exactly problem, that I2C CLC is short to GND internally. 

During our email exchange, Bilge mentioned if the IC is in ROM mode. I don't believe so, but if it is the case, how can we get it out of this mode? I can send couple failed batteries to you if you need.

Thank you!

Chen

Hello Evan:

Thanks for sharing the information. We just tried but it didn't work, as expected. At this point, do you or your team have any other suggestions? We have some samples and can send to you for further diagnostic. 

Thank you very much.

Chen

Hi Chen,

Does the MCU you are using utilize clock stretching? Are there multiple masters on I2C lines? These could be the issue.

The i2c lines get stuck low but a reset cmd can still be received to reset the gauge. So when the lines get stuck low is after the master request data?

Thanks,

Evan

Hello Evan:

Confirmed the MCU doesn't use clock stretching, and only ONE master on the I2C bus, for both the device and the charger.

I tried to send the reset command through BQStudio and EV2300, but no response from the fuel gauge. So far the only way to reset the fuel gauge is a hard reset with B+ disconnected. Could you share the more details, like step by step instruction of the cmd feeding?

We can't duplicate this issue on our end so far, but based on the failure description from customer, this issue can occur both on the charger and device.

Thanks.

Chen

Hi Chen,

This maybe your issue the BQ34z100 will perform clock stretching occasionally, so the MCU used also has to support clock stretching, or else communication may not work properly.

The BQ34z100 needs to be Unsealed to send a reset cmd. If this is not already being done.

Please let me know if you are able to replicate the issue.

Regards,

Evan

Hello Evan:

The communication can't be connected, and the CLK is stuck at "low". So I don't think we can unseal the pack and send the command. We still can't duplicate the issue on our end, even with the "recovered" packs.

Do you have any other suggestions? Is this the only time you heard of this kind of issue?

Thanks.

Chen