Day: May 9, 2011

NOTE: Need a button? Now you can buy one! Visit raster.etsy.com.

I was in need of a button, but not just any button. A USB-enabled button that could emulate a single key being pressed on a keyboard. This is that button…

It consists of the following materials:

I used a Teensy as it’s a very simple (and cheap!) way to emulate a USB HID. I do wish the Teensy had mounting holes. I ended up not mounting it at all and letting it just hang loose, which should be fine, as it’s so lightweight. There’s a bit of electrical tape wrapped around the Teensy and the solder joints.

For the box, I wanted something metal, so it would be heavier and more sturdy than the typical plastic project box. Matt Gauger of Milwaukee Makerspace suggested I check out Mammoth Electronics, as they make boxes for guitar pedals. I ended up choosing their “tall” enclosure.

For the button, I really like this button over the one I ended up using, but it was too tall to fit in the project box. Unless you’re a “button snob” you probably won’t notice much difference between the two.

If you’ve got USB cables lying around, use one… otherwise, you can get one from Monoprice for less than a dollar. I pretty much buy all my cables from Monoprice.

As for the rubber feet, I picked some up at the local hardware store… as well as some black spray paint. (Note: If you are ordering the button from Sparkfun, just get the rubber feet from them too!)

There was one more item I needed. The button needs a 27.3 mm hole to fit into, which means I needed a hole that was 1.07480315 inches wide. Well, 1.07480315 inches is pretty close to 1.0 inches, so I ended up getting an Ace Bi-Metal Variable Pitch Hole Saw. (The link is not the exact one that I got. I ended up getting mine at the local Ace Hardware store.)

As for the process, the Teensy part took a small amount of time, (see the AWESOME Button) and the drilling was a little tricky, as the 1.0 inch hole was just slightly too small. A bit of creative drilling with a regular drill bit fixed that though. The spray painting was the real time consuming part of it all. As for the assembly, I originally envisioned mounting the Teensy on the bottom plate of the box, and having a hole where the USB connector would be accessible, but I ended up going with what you see in the photo. (I just used the Dremel to cut a small groove for the cable to fit into.)

And why do I need a yellow button that can emulate a key being pressed? Well, sometimes you just need a yellow button that can emulate a key being pressed…

Note: A number of people have asked for the code I used, and even though it is in the comments, I thought I should post it in here as well.

/*
 * Button.pde
 */

void setup() {
  Serial.begin(9600);
  pinMode(10, INPUT_PULLUP);
  delay(500);
}

void loop() {
  if (digitalRead(10) == HIGH) {
    delay(10);
  } else {
    Keyboard.print(" "); // we print a space
    delay(1000);
  }
  delay(10);
}

Another Processing sketch, fairly simple. This one does introduce a function (or subroutine) named ‘makeBox’ that we pass some values into.

See it in action here!

You can also see where we used height/2 which is the proper way to center something on the screen, rather than taking the 600 we specified and just using 300 as the halfway point.

/*
 * 20110509.pde
 */

void setup() {
  size(800, 600);
  background(0);
  stroke(255);
  noFill();
}

void draw() {
  
  for (int xVal = 5; xVal < (width - 20); xVal = xVal + 20) {
    int myWidth = 10;
    int myHeight = xVal/2;
    int yVal = (height/2) - (myHeight/2);
    int myColor = xVal/4;
    
    makeBox(xVal, yVal, myWidth, myHeight, myColor);
    
    }

}

void makeBox(int x, int y, int w, int h, int c) {
  stroke(c);
  rect(x, y, w, h);
}

(These sketches may not be all that impressive, but it’s giving me a chance to flex my programming muscles in Processing.)

Tags code, graphics, processing