I am building a wearable prototype where I need two custom PCBs to interface between, and power, a system-on-a-chip on one end, and two sensors on the other. The PCBs will be situated about 0.5—1 m (1.5—3 ft) apart, in different housings. To make the prototype boards as simple as possible (I have very limited PCB design experience) I would need to connect:
- 24 V @ 3 A,
- 3.3 V,
- four data signals, and
- three differential pairs of data (@960 Mbps/lane)
between the boards.
So at the very least 12-13 lines are needed, likely more to accommodate for the current of the 24 V and ground.
Initially, I had DE-15 (HD-15) D-sub connectors in mind for this, but it seems like that would require 4-layer boards to make the routing work (not a deal-breaker, but would be nice to avoid), I am a bit worried about the integrity of the differential pairs — and most importantly — such a connector (and cable mounting) would take considerable space on the sensor side, which needs to be as small, nimble, and light-weight as possible.
The cable does not have to be removable by users, and I would imagine that PCB-mounted connectors would make for a smaller and/or nimbler prototype than panel-mounted connectors.
So I am now considering using (full-featured) USB-C connectors and cable, since they have enough lines, are built for differential pairs, and crucially are considerably smaller than DE-15's. However, it seems needlessly complicated to conform to the USB-C standard for a prototype.
Beside the issue of using a standard port which would likely fry anything else that would be connected to it (I am thinking of modifying the cable and plug housings in some way to mitigate this), is there any other reason why this is a bad idea? I know for instance that (some?) full-featured USB-C cables have integrated electronics, does that prevent non-standard uses of the cable itself?