It's very small PCB for CN5 on IchigoJam.
This is a simple sample program with Wii Nunchuck. (just show X/Y/BTN)
(for latest 1.2beta firmware on IchigoJam-FAN / library version is here)
100 POKE#700,#F0,#55:IF I2CW(#52,#700,2,#700,0) ERR 110 POKE#700,#40,0:IF I2CW(#52,#700,2,#701,0) ERR 120 @A 130 IF I2CW(#52,#701,1,#701,0) OR I2CR(#52,#701,0,#702,6) ERR 140 ?PEEK(#702),PEEK(#703),PEEK(#707)&3 150 GOTO @A
But I mistook. It's better if this PCB flipped. You need long pin socket to connect this adapter.
I updated it. Try it!
"Connector for Wii Nunchuck to IchigoJam (flipped) by taisukef - Upverter"