Arduino includes this example, find it under: File > Examples > 3.Analog > Analog Input
Then compile and upload it to your metro. Tweak the potentiometer to change the LEDs brightness.
If you are having trouble finding or loading the example, the code is below:
/*
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://www.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 <sensorValue> milliseconds:
delay(sensorValue);
// turn the ledPin off:
digitalWrite(ledPin, LOW);
// stop the program for for <sensorValue> milliseconds:
delay(sensorValue);
}
Sporadically Working
This is most likely due to a slightly dodgy connection with the potentiometer's pins. This can usually be fixed by taping the potentiometer down.
Not Working?
Make sure you haven't accidentally connected the potentiometer's wiper to digital pin 0 rather than analog pin 0. (the row of pins beneath the power pins)
