Flashing LEDs on a baseball cap

With the ABQ Maker Faire around the corner, I thought it would be neat to dress up for the occasion. Since I had an Arduino Lilypad sitting around, making a flashing LED hat sounded like a good idea. Starting with one of my new Avocado Electronics baseball caps and a bunch of LEDs and resistors, I went to work.

Raw materials: LEDs, resistors, and wire.

At the top of the hat are six tiny holes. Each one is the perfect size to fit a single 3mm LED through it. My first step was to solder six individual circuits each consisting of one LED, one resistor, and ample wire. After soldering these together and keeping close track of polarity, I installed the lights into the hat and ran the wiring to the back.

Lights installed and wire routed to the back of the hat

In the back, all the wires are routed to a Lilypad Arduino. I know that I could have used conductive thread, but I wanted this hat to look like a real hack job.

Back of hat

At the back of the hat is an Arduino Lilypad. Each light is attached to a separate pin. The setup is powered by Sparkfun’s Lilypad power source. It steps up a 1.5V AA battery to 5V for the Lilypad.

Arduino Lilypad Lilypad power source

Here is the code I used in the Arduino to make it work. This code randomly turns the lights on and off.

char light[] = {5, 6, 7, 9, 10, 11}; char crazy[] = {0, 0, 0, 0, 0, 0, 0, 0, 0};
void setup() { 
 for (int x=0; x< 6;x++) { 
  pinMode(light[x], OUTPUT); 
  digitalWrite(light[x], 0); 
} 
 }

void loop() { 
 crazy[0] = random(0,2); 
 crazy[1] = random(0,2); 
 crazy[2] = random(0,2); 
 crazy[3] = random(0,2); 
 crazy[4] = random(0,2); 
 crazy[5] = random(0,2); 
 for (int x=0; x<6; x++) { 
  digitalWrite(light[x], crazy[x]); 
  } 
 delay(200); 
 }

Finally, here is what it looks like now.