TPS26750: I2Ct read of Transmit Source Capabilities Register(0x32) registers not as I have programmed the EEPROM.

Erik Kearney

Part Number: TPS26750

Tool/software:

Hi There,

I am working on a project with a TPS26750 with support for 5 SPR PDO and one EPR PD up to 140W (28v @5A).

I have configured the firmware using the USBCPD Application Customization tool and programmed my board using a Aardvark programmer.

The board appears to be working as expected and I can selected the programmed PDOs and EPR and it outputs the correct voltages.

I want to be able to monitor and control the TPS26750 via the I2Ct interface but I am finding that when I read register 0x32 it doesn't have the same setting that I programmed the EEPROM with.

I have attached a logic analyser capture of the read from register 0x32, I am expecting that PDO and EPR (in bits 0-5) should be 5 and 1 respectively but they are coming out as 7 and 7.

I suspect I am missing something, any assistance would be appreciated.

Thanks in advance

Regards

Erik

p.s. I don't appear to be able to upload the .sal file, I have tried on multiple browsers and computers.

3 months ago

+1 Christopher Lim1 3 months ago

TI__Mastermind 37855 points

Hi Erik,

Can you share the json you are using and the raw data you read from register 0x32?

Have you taken into account the "Num bytes" byte when using the I2C interface?

Thanks and Regards,

Chris

0 Erik Kearney 3 months ago in reply to Christopher Lim1

Prodigy 30 points

Hi Chris,

I didn't take the "Num bytes" byte in to account, thank you for pointing that out, I totally missed that.

I also spotted that I had reversed the bit order of the PDO bytes, which also didn't help.

Thank you for that, I can now successfully read the registers.

Regarding changing the number of active PDO & EPRs on the fly can I just change the "number of valid PDO" and "number of valid EPR" bits of register 0x32 or do I also need to zero the TX source PDO bits

Thanks

Erik

+1 Christopher Lim1 3 months ago in reply to Erik Kearney

TI__Mastermind 37855 points

Hi Erik,

Yes, you can just change the number of valid PDOs.

Thanks and Regards,

Chris

0 Erik Kearney 3 months ago in reply to Christopher Lim1

Prodigy 30 points

Thanks Chris, much appreciated.

Regards

Erik

0 Christopher Lim1 3 months ago in reply to Erik Kearney

TI__Mastermind 37855 points

You're welcome.

I'm closing this thread now, but if you have any questions related to it, feel free to re-open it by responding below. For any new questions, please submit a new E2E thread.

Thanks and Regards,

Chris

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TPS26750: I2Ct read of Transmit Source Capabilities Register(0x32) registers not as I have programmed the EEPROM.