TPS65987D: I2C addressing

David Mckinney

Expert 6850 points

Part Number: TPS65987D

During some initial testing with the TPS65987D we found what appears to be an issue in the datasheet.

According to the datasheet the I2C address for I2C1, and I2C2 are defined as follows:

Based on our testing though, I2C2 is behaving as I2C1 from and address perspective.

If "ADCIN2" is 3.3V I2C2 ACK's at 0x23,

If "ADCIN2" is 0.0V I2C2 ACK's at 0x20.

This is what I would expect if we were interfacing to I2C1.

But since we are connected to I2C2. ADCIN2 should have no effect on I2C2 address, which based on the table should be fixed at 0x38.

Let me know if we are missing something.

over 6 years ago

0 David Mckinney over 6 years ago

TI__Expert 6850 points

Attachment.pdfAttached full question with images.

0 Eric Beljaars over 6 years ago in reply to David Mckinney

TI__Mastermind 36756 points

Hi David,

The I2C1 address will change with the ADCIN2 setting. The I2C2 address will be fixed at 0x38 unless they are changing the "External Processor" configuration in global system configuration. I would suggest leaving that setting to "Default" unless they have an external TBT controller.

If this answers your question, PLEASE select This resolved my issue

Thanks,
Eric

0 David Mckinney over 6 years ago in reply to Eric Beljaars

TI__Expert 6850 points

I fully agree with what was said above, that is exactly how I read it from the datasheet, and matches what I included in the question, and hence the expected result.

This is my original question:

"We are connected to I2C2. ADCIN2 should have no effect on I2C2 address, which based on the table should be fixed at 0x38"

So maybe a way to rephrase it is.

When I talk to the I2C2 I do NOT get an ACK at 0x38 as the datasheet and you agree should be the case.

I instead get ACK's at 0x20 and 0x23 depending on the state of ADCIN2.

Or another way of looking at it is the following:

0 David Mckinney over 6 years ago in reply to David Mckinney

TI__Expert 6850 points

Attachment2.pdf

0 Eric Beljaars over 6 years ago in reply to David Mckinney

TI__Mastermind 36756 points

Hi David,

Please check the customer's configuration for the "External Processor" Field in the Global System Configuration Register. Additionally, please see if this behavior can be reproduced on the EVM.

Thanks,
Eric

0 David Mckinney over 6 years ago in reply to Eric Beljaars

TI__Expert 6850 points

The part would be in default register configuration. So basically power applied and then I2C scan done. No prior code loaded.

0 Eric Beljaars over 6 years ago in reply to David Mckinney

TI__Mastermind 36756 points

Hi David,

Could you please load a basic image into the SPI Flash? Please also include steps on how to reproduce this on our EVM.

Thanks,
Eric

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TPS65987D: I2C addressing