EZ-PD™ CCG3 USB Type-C to DisplayPort Cable Solution

[KRingg]

I've developed a design based on the EZ-PD™ CCG3 USB Type-C to DisplayPort Cable Solution reference circuit (and firmware). One big difference in my design is that I need access to the legacy USB 2.0 datapath (pins A6/A7 on the USB-C connector, pins 21/22 on the CYPD3120). My understanding is that the CCG3 uses these pins for:

1. Programming Firmware
2. Establishing Billboard (for hosts that don't support DisplayPort over USB-C Alt-Mode)

Is that correct? If I don't need billboard functionality, can I disconnect the DP/DM lines from the CYPD3120 (after initial programming) and use them for other purposes (while still running DisplayPort over USB-C Alt Mode)?

My plan is to run DP/DM through a DIP switch, which will be set one-way during initial programming and another during runtime operation. Does that sound like a reasonable approach? Thank you!

[KyTr_1955226 · Accepted solution]

You should be able to do that, I think.  Assuming that a mechanical switch won't electrically mess too much with the D+/D- signals.  At USB 2.0 speeds I'd think you should be OK?

In my Alt-Mode monitor application after the CCG3 takes down the billboard (default 60 seconds iirc?  It's configurable how long to have the billboard up) I have it toggle a GPIO tied to a USB Mux IC that muxes the USB signals to a PSoC5 for system control/monitoring.  So it can definitely be switched over to another device.

[KRingg]

Awesome, thank you! This certainly gives me a high degree of confidence in the design.

I'm going to proceed with PCB fab+asm and will update this thread once I've confirmed the approach.