Variable Resistors (Circuits 08 & 13)

/*
  Analog Input
 Demonstrates analog input by reading an analog sensor on analog pin 0 and
 turning on and off a light emitting diode(LED)  connected to digital pin 13. 
 The amount of time the LED will be on and off depends on
 the value obtained by analogRead(). 
 
 The circuit:
 * Potentiometer attached to analog input 0
 * center pin of the potentiometer to the analog pin
 * one side pin (either one) to ground
 * the other side pin to +5V
 * LED anode (long leg) attached to digital output 13
 * LED cathode (short leg) attached to ground
 
 * Note: because most Arduinos have a built-in LED attached 
 to pin 13 on the board, the LED is optional.
 
 
 Created by David Cuartielles
 modified 30 Aug 2011
 By Tom Igoe
 
 This example code is in the public domain.
 
 http://arduino.cc/en/Tutorial/AnalogInput
 
 */

int sensorPin = A0;    // select the input pin for the potentiometer
int ledPin = 13;      // select the pin for the LED
int sensorValue = 0;  // variable to store the value coming from the sensor

void setup() {
  // declare the ledPin as an OUTPUT:
  pinMode(ledPin, OUTPUT);  
}

void loop() {
  // read the value from the sensor:
  sensorValue = analogRead(sensorPin);    
  // turn the ledPin on
  digitalWrite(ledPin, HIGH);  
  // stop the program for  milliseconds:
  delay(sensorValue);          
  // turn the ledPin off:        
  digitalWrite(ledPin, LOW);   
  // stop the program for for  milliseconds:
  delay(sensorValue);                  
}

/*
 * Force Sensitive Resistor Test Code
 *
 * The intensity of the LED will vary with the amount of pressure on the sensor
 */

int sensePin = 2;    // the pin the FSR is attached to
int ledPin = 9;      // the pin the LED is attached to (use one capable of PWM)

void setup() {
  Serial.begin(9600);
  pinMode(ledPin, OUTPUT);  // declare the ledPin as an OUTPUT
}

void loop() {
  int value = analogRead(sensePin) / 4; //the voltage on the pin divded by 4 (to scale from 10 bits (0-1024) to 8 (0-255)
  analogWrite(ledPin, value);        //sets the LEDs intensity proportional to the pressure on the sensor
  Serial.println(value);              //print the value to the debug window
}