#include <SoftwareSerial.h>
SoftwareSerial mySerial(0, 1); // RX, TX

const int ledPin =  8; // the number of the LED pin
const int pResistor = 2; // Photoresistor at Arduino analog pin 10

int pResistor_value;          // Store value from photoresistor (0-1023)
int value;

void setup()
{
  mySerial.begin(9600);
  pinMode(pResistor, INPUT);// Set pResistor - A0 pin as an input (optional)
  pinMode(ledPin, OUTPUT);
}

void loop()
{
  pResistor_value = analogRead(pResistor);
  if (mySerial.available() > 0)
  {
    value = mySerial.read();

    if (value == 1)
    {
      digitalWrite(ledPin, HIGH);
    }
    if (value == 2)
    {
      digitalWrite(ledPin, LOW);
    }
    if (value == 3)
    {
      pinMode(1, OUTPUT); // open line to write
      mySerial.println(pResistor_value);
      delay(100);
      pinMode(1, INPUT);
    }
  }
}