 
  
                  Led On/Off using HC-05 Bluetooth Module
                  & Arduino Uno
Components/Equipment Required:
3.   
Smart
Phone
5.   
Breadboard
Circuit
Diagram:

Arduino Program:
int
ledPin=13;
int
state=0;
int
flag=0;
void
setup()
{
 pinMode(ledPin,OUTPUT);
 digitalWrite(ledPin,LOW);
 Serial.begin(9600); 
 }
 void loop()
 {
  if(Serial.available()>0)
  {
   state= Serial.read();
   flag=0; 
   }
   if (state == '0')
   {
    digitalWrite(ledPin,LOW);
    if(flag==0)
    {
      Serial.println("LED: off ");
      flag=1;
      }
    }
    else if (state == '1')
   {
    digitalWrite(ledPin,HIGH);
    if(flag==0)
    {
      Serial.println("LED: on ");
      flag=1;
      }
    } 
  }
Android Application:
            Android application is named as “Bluetooth Terminal HC-05”
            Pairing code is “1234”

