Journal 2017/03/02 #3

Project Plan


– Teensy 3.1, 3.2, LC, etc… or Arduino-based stuff like the Micro, Trinket, Due, Leonardo, etc…
– 4 x Cherry MX switch of choice (salvaged or new) (Get plate-mount if mounting via the plate; use PCB mount if your case is thick)
– 4 x Cherry MX key caps of choice (salvaged or new)
– 24-30 AWG wire
– Solder
– Soldering Iron
– Arduino IDE w/ Teensy Bootloader
– LEDs (Optional)

Creating the case

  1. Download and install a modeling program compatiable with 3d printing. (In this case I have choose blender. This gives me the chance to learn a new software program)
  2. Designing the case, The design I will be taking inspiration from will be located as a picture below. The design can be created using a variety of programs and made of different materials. The square for the cherry switches will be 14mm x 14mm and the keycaps will be 18mm x687474703a2f2f7075752e73682f6d476538562f626166643764613539352e6a7067  18mm. Its important to space your project apart accordingly.
  3. Note that the method of design for case I have chosen is 3d printing but there a variety of different methods you can choose from for example using a old case or a cnc machine. The end result could end up looking something like this.687474703a2f2f7075752e73682f6c334d794f2e6a7067

Wiring in the buttons.

Until I get more clarification or practice wiring in the buttons on the teensy board, Its difficult for me to say exactly what is required. In any case I found a wiring diagram that could be followed. As I update the project I will make sure to include pictures for every step along the way.


Programming the arduino.

This will be a task that I will have to learn about throughout the project, coding arduino is a new experience that I have no done before. In any case I have found example code for the arduino teensy that you can base your project off.

#include <Bounce.h> // this is needed to use the bounce library

#define KEYP_1 KEY_Z // here we are making it easier to change the key bindings later

// button pins
const int key_1 = 0; // input pin for your keyswitch; not necessary but helpful for doing other things like LED effects

Bounce button1 = Bounce(0, 8); // first number is pin number and second number is debounce time

void setup() {
pinMode(key_1, INPUT_PULLUP); // here we are telling the teensy what pin 0 is being used for

void loop() {

button1.update(); // this is reqired for your code to  actually send the keypress to the computer

if (button1.fallingEdge()) { // fallingEdge is when the key is pressed;
if (button1.risingEdge()) { // risingEdge is when the key is not pressed

Key switch flowchart



Throughout this project I expect to encounter several problems that I will have to deal with. In the meantime it comes down to me choosing parts and finding something to do while the parts come in. Luckily I have the chance to learn the code for arduino and to practice using the blender software.

References (This website explaisn the project in an easy DIY format). (This features a list of switches and the differences between each one.)

The point of the project

Now you might be asking yourself, why would I ever want a keypad with only four keys?

This keypad could be used for a limited application of things, therefore would not be ideal for consumers, but can be very useful to those in need of a compact keypad. It can be used for a variety of games, programming macros or as a media control keypad (play, pause volume up, volume down.) In the end the project is also customizable to your own needs allowing you to design more buttons if required.


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