download circuit ,arduino code and app.

1. circuit connection.

2. video link....

3. code for arduino....

int led=13;

void setup() {

pinMode(led,OUTPUT);

Serial.begin(9600);

// put your setup code here, to run once:

}

void loop() {

/// char ab ;

if (Serial.available ())

{

// put your main code here, to run repeatedly:

char ab=Serial.read();

Serial.print(ab);

if ( ab =='a')

{

digitalWrite( led, HIGH);

}

if ( ab=='b' )

{

digitalWrite( led, LOW);

}