Macropad Keyboard

Have you ever wanted to build a small keyboard that quickly encodes your most-used phrases or keystrokes (think Control+Alt+Delete) to your computer? A Macropad is an excellent tool for this purpose. By following these instructions you can build up a working 3x4 keypad that can be programmed quickly to keep all of your phrases you don't need to type out anymore.

The instructions below assume you will source or design the Macropad housing (this excellent one was designed by Eric Busby).

Alternatively, you can simply adjust these steps to get a working and functional design.

• Macropad RP2040 Bare Bones (Item 5100 in Adafruit). If sold out, Digi-Key might have it here
• Clear Keycaps for MX Compatible Switches - 12-pack PID: Item 5068
• Kailh Mechanical Key Switches - Linear Red - 12 Pack PID: Item 5122
• USB extension cable with ON/OFF switch, male to female
• 6-inch Male to USB-C cable
• Printed case for comfort (.stl files attached)
• Silicon feet for the case for a sturdy, slip-proof setup
• Helpful tools: X-acto knife and blades, precision screwdriver set (check out the iFixit!)

Total cost: about $100 without case.

(For 3D-printed case only): With an X-acto blade, carefully peel off the OLED screen from the Macropad RP2040 (keeping the ribbon intact and attached to the board and the screen). This will allow the panel to seamlessly slip through the 3D-printed plate slot later and rest on the surface that will face the user.

Start from the top and carefully drag across the bottom to break the adhesive until you can easily pull off the screen, retaining the data ribbon connection.

Insert the screws into the base, making sure they are perpendicular to the top base surface so that the PCB can be threaded in without difficulty.

Using the same screws that were pre-set into the base, finish threading into the PCB, making sure you don't tighten a screw completely without starting the other screws (similar to putting on a car wheel - see star pattern).

The top 3D-printed plate can then be placed on top, in preparation for the keys that will lock the plate in place against the board.

Keeping your eye on the orientation of the two terminals that stick out from the key's underbelly, mount each key carefully until it clicks into place.

Note: Later, when you test the keys with power, proper mounting can be confirmed when there is positive feedback from the OLED screen (it will display the key that was pressed). If you don't get a response, you may then need to remount the key if you accidentally bent the terminals and did not make a proper connection. The copper key terminals can be easily reformed and repaired with a pair of small needlenose pliers.

If you get to this step, this connection should be a breeze.

Be aware that the switch itself should pass through the round opening before locking it with the round key. The second illustration shows how the harnesses should look once the key is in place.

Find the half-moon pattern of the knob and the PCB's rotary encoder and mate them with a little pressure. A good connection should allow the knob to rotate through the 20 detents and allow a direct press (to provide the additional select button or enter bootloader mode along with the reset button).

For a comfortable and slip-proof keyboard, stick on four silicon footpads to the underside of the case. It will make all the difference!

There are several methods for programming your Macropad, but I have had seamless success with CircuitPython. I would recommend going here to commence with the programming and start up your new device! Once your first unit is made, you can later copy the folder contents you use for your first Macropad configuration directly onto the others.