/* Use a photoresistor to write characters via Serial Port
   More info and circuit schematic: http://www.ardumotive.com/how-to-use-a-photoresistor-en.html
   Dev: Michalis Vasilakis // Date: 8/6/2015 // www.ardumotive.com
   Changed by: Gleb, Marjo, Perttu, Lukasz*/
   
#include <SoftwareSerial.h>

//Constants
const int pResistor = A3; // Photoresistor at Arduino analog pin A0
const int ledPin =  LED_BUILTIN;// the number of the LED pin

SoftwareSerial mySerial(A0, A1); // RX, TX

//Variables
int value;          // Store value from photoresistor (0-1023)
int ledState = LOW;             // ledState used to set the LED

void setup(){
 pinMode(ledPin, OUTPUT);  // Set lepPin - 9 pin as an output
 pinMode(pResistor, INPUT);// Set pResistor - A0 pin as an input (optional)
}

void loop(){
  value = analogRead(pResistor);

  if (value > 25){ //You can change value "25"
    digitalWrite(ledPin, LOW);  //Turn led off
    Serial.write(43);
  }
  else{
    digitalWrite(ledPin, HIGH); //Turn led on
    Serial.write(44);
  }

  delay(500); //Small delay
}