mid_06_ardu.ino

#include <SoftwareSerial.h>

int rx=2;  int tx=3;
SoftwareSerial BTSerial(rx, tx);

const int ledPin = 13;

void setup() {
  BTSerial.begin(9600);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  if(BTSerial.available()) {
    char ind = BTSerial.read();
    if(ind == 'H')
      digitalWrite(ledPin, HIGH);
    if(ind == 'L')
      digitalWrite(ledPin, LOW);
  }
}