TPS65982: Configuring DFP/Sink not working

Alex Fields1

Part Number: TPS65982

Hello,

We have an application using the TPS65982 where we want to force it to be a power sink, and a USB2.0 host. We are using the STUSB4710A Power Delivery source IC, (which doesn't have USB2.0 pins) and then routing the USB2.0 pins to a USB/ethernet converter. Because we are using a USB/ethernet converter, but want to be a power sink, we need the TPS65982 to be a USB2.0 host (DFP) and a USBC PD sink. This is similar to the use case of a computer plugging into a docking station, where the computer would like power from the docking station, but needs to transfer data to it as the host.

Whenever we try to have this configuration, the TPS65982 automatically switches to become a UFP. Is there a binary we can access to force it to be a DFP for USB2.0 always, regardless of the power role?

Thanks,

Alex

over 4 years ago

0 Chuck Branch over 4 years ago

TI__Mastermind 32891 points

Alex,

You will need to use the advanced configuration option and generate your project as a DRP that prefers power source.

You will need to change the Transmit Identity Data Object to match this screen capture so that you advertise as a USB2 Peripheral:

Regards,

Chuck

0 Alex Fields1 over 4 years ago in reply to Chuck Branch

Prodigy 125 points

Does "prefers power source" mean the TPS65982 prefers to be a power source or prefers to connect to a power source?

We want the TPS65982 to advertise as a USB2.0 host, not a peripheral.

We want to configure the TPS65982 to be a USB2.0 sinking host. From your response, it sounds like this will make the TPS65982 a sourcing device. Do we want to do the opposite from your suggestion? or am I missing something?

0 Chuck Branch over 4 years ago in reply to Alex Fields1

TI__Mastermind 32891 points

Alex,

I review your question again and I think that the only thing that you will need to do is take your original project file and change the Transmit Identiy Data Object to report the device as a Host only and chagne the product type to either power birck or Hub.

0 Alex Fields1 over 4 years ago in reply to Chuck Branch

Prodigy 125 points

Chuck,

Changing that one parameter does not work. As soon as we plug in power delivery, the TPS65982 automatically negotiates to be a sink UFP.

What are the necesary registers to force the TPS65982 to always be a sink DFP?

0 Chuck Branch over 4 years ago in reply to Alex Fields1

TI__Mastermind 32891 points

Alex,

I will have to review this with someone else internally and get back to you.

Regards,

Chuck

0 Kushal Jaligama over 4 years ago in reply to Chuck Branch

Prodigy 10 points

Hi Chuck,

I'm also working with Alex on the same project - we have tried the option suggested here: https://e2e.ti.com/support/interface-group/interface/f/interface-forum/910322/tps65982-what-steps-should-i-execute-to-perform-swsk-or-swsr-properly?tisearch=e2e-sitesearch&keymatch=TPS65982# which is to enable the "Initiate Swap to Sink, Process Swap to Sink" register, flash the TPS65982, plug in our USB-PD + USB2.0 system, manually set the "Initiate Swap to Sink" register to go to 0, and then issue a SWSk command - however, we are seeing the Power Role stay at "SOURCE" rather than "SINK", despite the I2C command being issued - any pointers here would be greatly appreciated, thanks!

0 Chuck Branch over 4 years ago in reply to Kushal Jaligama

TI__Mastermind 32891 points

Kushal,

I will try to address this idea at the same time.

Regards,

Chuck

0 Chuck Branch over 4 years ago in reply to Chuck Branch

TI__Mastermind 32891 points

Alex,

Are you using the endpoint on the 982 in your system?

The 982 endpoint will always be a UFP, so if you want to support a DFP endpoint, then you will need a USB mux and some other supporting circuitry.

Can you provide me with a block diagram of your system to help me understand how it is configured?

Thanks,

Chuck

0 Alex Fields1 over 4 years ago in reply to Chuck Branch

Prodigy 125 points

Chuck, hopefully this is a descriptive enough block diagram of the relevant features we are utilizing for USB2.0 and USB power delivery We are using the TPS65982ABZBHR which says it has a built in USB2.0 endpoint. We are connecting the USB2.0 lines from the USBC connector to the TPS65982 directly and using your internal mux. We typically have no problem being a DFP endpoint, its only when we simultaneously try to be a sink.

0 Chuck Branch over 4 years ago in reply to Alex Fields1

TI__Mastermind 32891 points

Alex,

On the USB2 OUT, do you have a HUB that will act as a DFP data device on the type C lines?

If this is the case, then you can use the host interface to initiate a Data roll swap from UFP to DFP and this should allow your system to connect. You will need to ensure that you have the USB mux inside of the 65982 setup to present the USB pins instead of the internal endpoint.

Regards,

Chuck

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TPS65982: Configuring DFP/Sink not working