BQ20Z70-V160: The meaning of the data being 0x17 when reading data

Masashi Mineda

Part Number: BQ20Z70-V160

Tool/software:

Dear Sirs and Madams,

We are considering the bp20z75-V180.

It has been confirmed that when reading data from the bp20z75-V180 used inside the battery during SMBus communication immediately after clock stretching occurs, the fixed value 0x17 is read.

Is there a reason why 0x17 is sent as a fixed value?

For example, could you please let us know if there is any information on whether 0x17 is always read as an undefined value?

I cannot get the datasheet or TRM for the bp20z75-V180 from your website, so I would like to know about this phenomenon.

Regards,

over 1 year ago

0 Dominik Hartl11 over 1 year ago

TI__Guru 61076 points

Are you able to read anything other than 0x17 from the device?

0 Masashi Mineda over 1 year ago in reply to Dominik Hartl11

Expert 1155 points

Hi Dominik,

Yes, it is possible to read data other than 0x17.

We have attached the waveform from which data other than 0x17 can be read (if communication is successful) to the document I previously attached.

Comparing the beginnings of these two CLK waveforms, we can see that if the next communication is started when a clock stretch occurs, this phenomenon of reading 0x17 will occur.

Regards,

0 Dominik Hartl11 over 1 year ago in reply to Masashi Mineda

TI__Guru 61076 points

Is this always related to clock stretching? What's your I2C host?

0 Masashi Mineda over 1 year ago in reply to Dominik Hartl11

Expert 1155 points

Hi Dominik,

The data to be read after clock stretching will be 0x17.

The BQ20Z70-V160 is built into the battery pack, and the I2C Host is the MCU.

Regards,

0 Dominik Hartl11 over 1 year ago in reply to Masashi Mineda

TI__Guru 61076 points

If this coincides with clock stretching, I recommend adding a delay and retrying if you get 0x17.

0 Masashi Mineda over 1 year ago in reply to Dominik Hartl11

Expert 1155 points

Hi Dominik,

Could you please tell us what the data value 0x17 that was read out means?

Regards,

+1 Dominik Hartl11 over 1 year ago in reply to Masashi Mineda

TI__Guru 61076 points

I don't have detailed error info for the bq20z70-V160 when the gauge isn't ready. This gauge was released almost 20 years ago, which means I can't ask the people who designed it anymore. From your description, it's related to clock stretching, which is related to the gauge not being ready, hence the recommendation is to add a delay.

0 Masashi Mineda over 1 year ago in reply to Dominik Hartl11

Expert 1155 points

Dominik-san,

We will add an additional delay time and confirm.

I understood that you do not know the contents of the read data 0x17.

Regards,

0 Dominik Hartl11 over 1 year ago in reply to Masashi Mineda

TI__Guru 61076 points

Yes, I do not know why you read 0x17.

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BQ20Z70-V160: The meaning of the data being 0x17 when reading data