This is a android apps to control Three switch or relay with arduino board. This is a simple example apps to control anything. We give with code to operate and make a tutorial to use and learn about Android and Arduino Bluetooth communication. arduino code :- char blueToothVal; //value sent over via bluetooth char lastValue; //stores last state of device (on/off) int led = 9; int ledone = 2; int ledtwo = 3; void setup() { Serial.begin(9600); pinMode(led,OUTPUT); pinMode(ledone, OUTPUT); pinMode(ledtwo, OUTPUT); } void loop() { if(Serial.available()) {//if there is data being recieved blueToothVal=Serial.read(); //read it } if (blueToothVal=='n') {//if value from bluetooth serial is n digitalWrite(led,HIGH); //switch on LED if (lastValue!='n') Serial.println(F("LED 1 is on")); //print LED is on lastValue=blueToothVal; } else if (blueToothVal=='f') {//if value from bluetooth serial is n digitalWrite(led,LOW); //turn off LED if (lastValue!='f') Serial.println(F("LED 1 is off")); //print LED is on lastValue=blueToothVal; } if (blueToothVal=='a') {//if value from bluetooth serial is n digitalWrite(ledone,HIGH); //switch on LED if (lastValue!='a') Serial.println(F("led 2 is on")); //print LED is on lastValue=blueToothVal; } else if (blueToothVal=='b') {//if value from bluetooth serial is n digitalWrite(ledone,LOW); //turn off LED if (lastValue!='b') Serial.println(F("led 2 is off")); //print LED is on lastValue=blueToothVal; } if (blueToothVal=='c') {//if value from bluetooth serial is n digitalWrite(ledtwo,HIGH); //switch on LED if (lastValue!='c') Serial.println(F("led 3 is on")); //print LED is on lastValue=blueToothVal; } else if (blueToothVal=='d') {//if value from bluetooth serial is n digitalWrite(ledtwo,LOW); //turn off LED if (lastValue!='d') Serial.println(F("led 3 is off")); //print LED is on lastValue=blueToothVal; } delay(1000); } Want to know more and with Bangla tutorial... Visit.... http://workitbd.com/bshaniuno/ or http://workitbd.com/page.php?86