SNES output board
Maybe a bit niche, but if you want to use your joystick on a Super Nintendo/Famicom, you can build a board to let you do this quite cheaply.
I thought my GP2040-CE did SNES output, but it turns out I was mistaken and it's SNES input, i.e. connect your SNES controller to the GP2040-CE and use its USB output. I only realized this after having a quick look through the GP2040-CE code and seeing only input functionality.
So I had to make another board to get SNES output. It turns out it's quite simple - just 2 (cheap) parallel-shift chips and some pull-up resistors.
I just connected my controller buttons/stick (signals and common ground) to both boards to use the 2 control boards in parallel. I chained these off my GP2040-CE screw terminals (you can see this in the first photo - white wires go to the SNES board). So there's no need to run dual wires from the buttons themselves.
Only the GP2040-CE is powered if I connect via USB cable, and only the SNES board is powered if I connect via the SNES cable.
I followed this circuit diagram:
https://gamesx.com/controldata/nessnes.htm
It's basically just 2 CD4021 chips, which are widely available and cheap.
The only change I made was adding a 1.2k pull-up resistor on Clock and a 3k pull-up resistor on Latch. This is to make it work on my PAL SNES (with them it will work on all SNESes, but without them it won't work on (some) PAL SNESes).
This page has useful information on the connector pin-out and controller protocol.
http://www.repairfaq.org/REPAIR/F_SNES.html
I used a 5-pin XLR connector to make the cable removable. You can get cheaper ones, but I decided to not skimp on this and got Rean branded ones (Rean is/was a sub-brand of Neutrik).
These XLR connectors are pretty nice - quick to connect/disconnect with a clicky locking tab, and sturdy. Maybe a good alternative to GX aviation style connectors with their screw lock?
| Parts | ||
|---|---|---|
| SNES cable | 1 | £1.68 |
| Board | 1 | £2.17 |
| CD4021BE chips | 2 | £1.44 (for 10) |
| 8-pin chip mount strip | 4 | £0.90 (for 10) |
| 10k resistors | 16 | £0.80 (for 100) |
| 1.2k resistors | 1 | £0.72 (for 100) |
| 3k resistors | 1 | £0.72 (for 100) |
| 16-pin screw terminals | 2 | £3.79 (for 5) |
| Standoffs | 4 | £0.79 (for 25) |
| 5-pin XLR passthough connectors | £7.78 |
I hope this is useful to someone ^_^