November 24, 2007
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October 2, 2007
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May 24, 2008
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A Simple but Useful Key

Project Members: 
Jess Kline


I wanted to title my homework "A Useful Cuttingboard" This is because I originally wanted to implement a cutting board that blinks red when someone is cutting something on it and shines green when the board is not in use. This would be helpful for people in the kitchen to know when to not come near or distract someone near a cutting board. However, this implementation required two leds with long soldered wires. Therefore, because I didn't have this material I implemented what I call "A Simple but Useful Key."

This implementation may be even more useful than the cutting board. It is a key that lights up when someone is holding its main surface. It is especially useful when someone is opening a door in the dark.


  • Typical materials: breadboard, arduino board, 2 resistors, 2 mini wires, 5 longer wires, 2 rubber bands
  • Assignment specific materials: A key, an LED with 2 wires twisted around its ends and secured by electric tape, a FSR with two long soldered wires, more electric tape to secure the LED and FSR to the key


* Resistive Sensor Input
* Takes the input from a resistive sensor, e.g., FSR or photocell
* Dims the LED accordingly, and sends the value (0-255) to the serial port
int sensorPin = 0; // select the input pin for the sensor
int ledPin = 11; // select the output pin for the LED
int val = 0; // variable to store the value coming from the sensor
void setup() {
void loop() {
val = analogRead(sensorPin); // read the value from the sensor, 0-1023
analogWrite(ledPin, val/4); // analogWrite (dimming the LED) can be between 0-255
Serial.println(val/4); // writing the value to the PC via serial connection
delay(50); // rest a little...


Useful Key: General setup of useful keyUseful Key

Useful Key in UseUseful Key in Use


yes, very useful! I've

yes, very useful! I've actually seen this on some car keys.. You know what they say about great minds! Nice job implementing it!

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