Take a SNES controller extension cable. Find the end of the cable that would plug into the console (it's the one that looks the same as the connector on the mouse). Using a spudger or other tool, pry the shell off the connector to access the wires (you can be destructive if you like, the shell does not need to be re-used).
Note how each wire is connected, because there's not a standard color code. You'll need to note the color or wire marking for:
- Ground (GND)
- Data
- Latch
- Clock
- VCC (5V)
Non-standard wire colors inside the author's SNES controller extension cable.
Round end of the connector is to the left in this particular view.
Now, clip the wires, strip them, stick them through the pads of the QT Py, and solder in place:
- VCC to 3V
- GND to GND
- Clock to SCK
- Data to MISO
- Latch to RX
After soldering, clip any excess wire that remains.
While the original SNES controllers were designed to operate at 5V, the author's mouse was verified to work properly at 3.3V. This simplifies the circuit, because otherwise level shifting converters would be needed.
