Interfacing of Bluetooth with Arduino:

Interfacing of Bluetooth with Arduino:

#include <SoftwareSerial.h>//
int led=13;
long previousMillis = 0;      

long interval = 1000;        
int ledState = LOW;          
long Counter=0;
void setup() {

  Serial.begin(9600);
  Serial.println("Bluetooth Connected....");
  pinMode(led,OUTPUT);
}

void loop() {

  unsigned long currentMillis = millis();

  if(currentMillis - previousMillis > interval) {
 
    previousMillis = currentMillis;
     Counter+=1;

    Serial.println(Counter);

    if (ledState == LOW)
      ledState = HIGH;
    else
      ledState = LOW;

   
    digitalWrite(ledpin, ledState);
  }
}

Circuit Diagram: