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Hi!
We were looking at making a DisplayPort-to-USB-C adapter for our docking station solution to support video docking for legacy laptops. Looking at the reference design for the "EZ-PD™ CCG3 USB Type-C to DisplayPort Cable Solution" ref-design, what HW/SW changes would be needed to run this "backwards"?
The adapter will only be used towards the dock which has a similar design as the CCG4 dock ref design, so the reverse-plug support would be done at the dock side using the PS8742.
Kind Regards
Olof
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Hi Olof,
You'll need to enable the marco in the firmware as well as modify the parameter with configuration utility.
You don't need those pull-up/pull-down since you use the AUX channel of CCG3. CCG3 has programmable pull-up and pull-down termination on the AUX_P/AUX_N pins.
Regards,
Eddie
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Hi Olof,
The difference between C-to DP adapter and DP-to-C adapter is that you need to find a MUX that support the correct signal flow. The other hardware part do not need specific change. If you install CCGx Host SDK, you can find CYPD3125-40LQXI_notebook project actually support Alternate Mode when CCG3 is DFP, and that can meet your requirement.
Regards,
Eddie
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Hi Eddie!
Thanks for getting back! Just so I really get this: I understand that when making a DP-source / host-like device (like a laptop), the mux is needed to support the use of a simple C-to-DP dongle without a mux and that the responsibiliy of switching the data-lanes and aux-lanes falls on the host. But in the case I describe, the mux would still be there in the dock, so is it really required that the C-to-DP adapter also has a mux? We can assume that the product would be "specified" to not support other scenarious where it be used in combination with another adapter that doesn't has a mux.
BR
Olof
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Hi Olof,
As long as the Type-C port is a recepatcle, a MUX is needed for data transfer. That is the feature of Type-C port(reversible).
Regards,
Eddie
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Hi Eddie!
So in the case of the DP-to-C adapter having a C-plug instead of a C recepatcle, there would be no need for the mux in the adapter?
So coming back to the reference design of the the Cypress C-to-DP adapter where there is a plug and not a recepatcle, would it be possible to turn this into a DP-to-C adapter without the need for adding the mux?
Cheers
Olof
BR
Olof
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Hi Olof,
Your understand is correct. This reference design you attched could support DP-to-C with correct firmware. And you can refer to CY4531 for designing DP-to-C hardware with a mux:https://www.cypress.com/documentation/development-kitsboards/cy4531-ez-pd-ccg3-evaluation-kit
Regards,
Eddie
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Hi!
Ok, so we based on the firmware for the adapter which is in the 3.0.2 SDK, is the changes only configuration changes (using PD Configuration Utility) or is there any FW changes as well? I think it is mainly the SVID/DP Mode/AMA VDO parameters that it would be good to get some input on. Or we could just use the ones from the CCG3 Host project?
I noticed that there were no pull-up/pull-down on the AUX-lines on the reference paddle-card, but you have them on the CCG3 Host reference design. These are not needed?
BR
Olof
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Hi Olof,
You'll need to enable the marco in the firmware as well as modify the parameter with configuration utility.
You don't need those pull-up/pull-down since you use the AUX channel of CCG3. CCG3 has programmable pull-up and pull-down termination on the AUX_P/AUX_N pins.
Regards,
Eddie