https://github.com/clockworkpi/GameShellDocs
clockwork_Mainboard_Schematic.pdf
search Debug UART
and here is the order in reality
reference picture
from left to right is
blue green yellow white
1, 2, 3, 4…
in above Mainboard Schematic Layout
so if you want a usb-uart connector, just leave the blue alone and connect the
green(rx) yellow(tx) ,white(GND) and it will be done