I’ve frequently been using USB Type C connectors in my designs, but just for USB 2.0 or even just charging. For debug purposes, I’ve always wondered if I could leverage the extra pins (CC, SBU) for other protocols like a UART or SWD, without exposing any other headers. The question is, what would be the most reasonable way to be compatible with whatever is connected on the UFP?
I think the obvious answer is to implement some buffers/switches for those debug signals, and come up with some handshaking scheme to enable them (when connected to your custom test hardware).
One way could be to purposefully over-voltage the VBUS terminal (while being tolerable to it), enabling the debug signal buffers when connected to custom test hardware).
Has anyone done this, or run across a method to implement this?