Building a USB 2.0 speed cable is almost trivial. Simply connecting D+ and D- through any sort of wiring seems to allow full 480 MBps speeds.
Now I want to jumper a USB-C connector to a USB3.0 Type-A connector as shown. The distances involved are short as you can tell.
I can achieve USB 2.0 speeds no problem by connecting D+ and D- using jumper wire. Easy.
However, using twisted pair wires to jumper SSTX+/SSTX- to TX2+/TX2-, and SSRX+/SSRX- to RX2+/RX2- fail to allow the device to negotiate up to USB3 Superspeed. Note: The device still connects as a USB 2.0 device and operates properly at USB2 speeds.
If I connect the device directly to the computer, it properly negotiates USB3 superspeed and operates at USB3 speeds.
Yes, the same problem occurs if I use TX1 and RX1 - the orientation of the USB-C doesn't matter.
Note: The USB-C cable is actually a USB-A to usb-C superspeed cable. Yes, I have verified continuity on the breakout PCBs shown by connecting them to both ends of the same cable. Circuit continuity between the differential pair pins is verified.