Writing analog value to a digital pin

1) Use the reading from Analog pin to modify the voltage output on Digital pin.

2) Only digital pins marked with tilda are capable of accepting pulse width modulated signals

analogWrite(PMW digital pin, value)

Writes an analog value (PWM wave) to a pin

The value should be in range 0 - 255

Sketch for fading LED

void setup() {
  // put your setup code here, to run once

  // Write value to one of the digital pins marked with ~
  pinMode(6, OUTPUT);

}

void loop() {
  // put your main code here, to run repeatedly:

  // read analog input
  //possible values 0 - 1023
  int potValue = analogRead(A0);

  int mappedValue = map(potValue,0,1023,0,255);

  // popssible values 0 - 255
  analogWrite(6,mappedValue);
  // can also approximate like this
  // analogWrite(6, potValue/4);

}