If you're happy creating your own circuit for the LEDs and button switches, as it's often one of the first things you learn in electronics, then skip over this page. Otherwise read on!
This project uses a lot of wires, so color coding or labelling them can help (tape / pen / colored heat-shrink). It uses all of the ground connections available on the Raspberry Pi Pico, but other configurations are possible.
In fact, only one wire on each switch needs careful management: the positive line of the LED, as the LED has a fixed polarity (direction).
First find the LED direction / polarity.
Starting with just one arcade button for now, connect the larger sized (0.25" / 6.3mm) spade connectors onto the metal tabs at the two larger sides of the switch unit (marked LED in the image).
The other ends of the wires need to be cut and stripped (>2mm), then insert one of the two wires into a ground connection on the board. To make life easier, the back of the Terminal PiCowbell has big white bands labelling the ground connections. Make sure you have undone the screw gate first! Tighten the wire screw gate.
Take the second wire and insert it into the 3.3 volt connection on the Raspberry Pi Pico, and then power the Pico using a USB cable. If the LED is illuminated then you got lucky, otherwise the wires need to be swapped around.
Unplug the board from USB power, and also the LED wire connected to 3.3 volts, then label the two wires you've just identified as positive (3v3) and negative (ground). The button switch connections are not polarised, so the direction doesn't matter, just connect wires to them.
Your arcade buttons switch unit should now have four wires connected, with one of those routed to ground.
Repeat this procedure for four all of the arcade buttons.
Wire up the circuit as described (shown above). You can vary the pins as they don't need special functionality.
Connect the positive wires for the LEDs to pins GPIO 2 onwards (3, 4, 5) ideally keeping them in button order.
Later, during testing of the lights, it'll be easier to identify which is which again and swap wires if needed.
Turn the Pico Terminal board 180 degrees around so you're now looking at pins GPIO 18-21. It's not necessary, but I found it easier to hold and wire up this way.
Connect the first wire from each of the button switches to GPIO 18 onwards (19, 20, 21).
Finally, wire the remaining four switch wires to ground pins.
This layout uses the default I2C pins (GPIO 4+5), so use others if you plan to connect I2C devices!
Page last edited June 18, 2025
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