A little Arduino sketch that maps a potentiometer value to a row of LEDs

pot_led.pde

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

void setup() {
  // declare the LED pins as OUTPUTs:
  pinMode(2, OUTPUT);  
  pinMode(3, OUTPUT);  
  pinMode(4, OUTPUT);  
  pinMode(5, OUTPUT);
  pinMode(6, OUTPUT);  
  Serial.begin(9600); //for testing
}

void loop() {
  // read the value from the sensor:
  sensorValue = analogRead(sensorPin);   
  // map the sensor range (0-1023) to the number of LEDs (4, plus one for off)
  mappedValue = map(sensorValue, 0, 1023, 0, 5);
  
  // for testing
  Serial.println(sensorValue);  
  Serial.println(mappedValue);
  
  // loop through all of the pins
  for(int i = 0; i <= 4; i++){
    // if a pin is within the mapped sensor value, turn it on
    if(i < mappedValue){
      // +2 because pins 0 and 1 are for serial I/O
      digitalWrite(i+2, HIGH);
    // if a pin is outside sensor value, turn it off
    } else {
      digitalWrite(i+2, LOW);
    }
  }
}