TPS65987D: SRDY rejected

Marek Roszko

Intellectual 380 points

Part Number: TPS65987D

I have a system where I have the traditional sink PDOs for 5V/3A, 9V/3A, 15V/3A and 20V/3A requested.

I have the two PP switches setup as:

PP1 - Source only

PP2 - Source or Sink, Wait for SRDY

The system is negotiating the sink contract with the source and the 20V/3A is selected.

I can measure the 20V coming from the source on VBUS. However, everytime I attempt the SRDY command to enable PP2, I simply get Task Rejected status.

This is the status both before and after attempting SRDY using the application tool

Is there anything I'm not aware of for SRDY to work? I have tried SRDY using both my firmware doing I2C and the Application Customization Tool using an Aardvark.

Is there better debug information somewhere on why it was rejected?

over 1 year ago

0 Alex Liu over 1 year ago

TI__Genius 12665 points

Hi Marek

Can you send me your .pjt project file so I can take a look at your configuration?

Additionally, are you using our EVM or your own system?

Best,

Alex

0 Marek Roszko over 1 year ago in reply to Alex Liu

Intellectual 380 points

Sure.

We are using our own system that actually has 4x independent TPS65987D chips for four separate 60W ports.

Here, one thing to note, the project is set to DFP. We are altering it to UFP at runtime by changing the Port Configuration register later on.

TPS65987-adapter-adv.pjt

0 Alex Liu over 1 year ago in reply to Marek Roszko

TI__Genius 12665 points

Hi Marek,

The PD controller is rejecting the SRDY command because of a setting you have configured in the 0x29 Port Control register.

In the port control register of your project file, you have both the "Externally Powered" and "Sink Control Bit" fields checked. When both fields are checked (set to 1), the sink switch is held open. For this reason, the SRDY command was unable to close the PP2 switch when sinking and was returning REJECT_CMD.

Please uncheck the "Sink Control Bit" in the 0x29 Port Control register. You can keep the "Externally Powered" bit set. I have tested and verified this on my side that the SRDY command does close the sink path switch with this fix.