voltage-functions.ino

int pwmPin = 9; // output pin supporting PWM
int inPin = 3; // voltage connected to analog pin 3, e.g. a potentiometer
int val = 0; // variable to store the read value
float volt = 0; // variable to hold the voltage read

float analogToVolt(int val) {
  return (5.0 * val) / 1023;
}

int voltToPWM(float volt) {
   return 255 * (volt / 5); 
}

void setup() {
  pinMode(pwmPin, OUTPUT); // sets the pin as output
  Serial.begin(9600);
}

void loop() {
  volt = analogToVolt(analogRead(inPin));
  val = voltToPWM(volt);
  analogWrite(pwmPin, val);
  Serial.print(val);
  Serial.print(", ");
  Serial.println(volt);
}