Snap in Keys

First, use a small screwdriver to remove the base plate.

Then, snap in four keyswitches. It helps to use a consistent orientation as shown here.

Wiring Switches

Each switch needs to have one leg wired to common ground, and the other to a GPIO pin on the Pico.

Start by soldering black wire to connect the ground legs of each switch together (either can be the ground, so just pick one side and be consistent for neatness sake). Solder a few inches of wire to the end of one ground leg to run to the Pico.

Solder a wire about 4-5" (10cm) in length to the free leg on each switch. These will run to their own GPIO pins respectively on the Pico.

Pico Wiring

Now, run the wiring to the Pico.

• Black wire to GND
• Blue to GP0
• Green to GP1
• Yellow to GP2
• White to GP3

Be sure to skip the ground pin on the Pico that site between the GP1 and GP2 pins -- you can tell it's a ground because of the flat end on the copper pad.

Insulate

Add some Kapton tape to the exposed pads and side of the enclosure to avoid any shorts.

Close It Up

Use one screw to fasten the acrylic base to the enclosure. (The other screw hole is obscured by the Pico board.)

Add two rubber feet to the bottom.

Add Keycaps

Place your keycaps on the key switch stems and press down. You're ready to use the Pico Four Keypad!