Arduino based Automatic Light Controller

1.  Arduino Uno
2. PIR Sensor.
3. LDR Sensor.
4. 1k & 10k Resistors
5. 12V Relay
6. BC548 Transistor
7. Switches.

Circuit Diagram

Program Code

Day night Switch with Occupancy Sensor (Automatic Light Controller)

const int RELAY =12;   //Lock Relay or motor
//Key connections with arduino
const int on_key =3;
const int off_key =2;
int counter =0, manual =0;
//Sensor Connections
const int LDR = A5 ;
const int PIR =4;
//=================================================================
// SETUP
//=================================================================
void setup (){
pinMode ( RELAY , OUTPUT );
pinMode ( on_key , INPUT );
pinMode ( off_key , INPUT );
pinMode ( PIR , INPUT );
//Pull up for setpoint keys
digitalWrite ( on_key , HIGH );
digitalWrite ( off_key , HIGH );
digitalWrite ( PIR , HIGH );
digitalWrite ( RELAY , LOW );        //Turn off Relay
}   //
=================================================================
// LOOP
//=================================================================
void loop (){
//Turn on Lights if Motion is detected and Light intensity is low
if( digitalRead ( PIR )== HIGH )
{
counter =1000; //Set 10 Seconds time out counter
if( counter >15) //Motion detected for 1.5 Seconds
{
if( analogRead ( LDR )>512) //Light intensity is low
{
digitalWrite ( RELAY , HIGH ); //Turn on Lights
}
}
} counter –;
if( counter ==0)
{
if( manual ==0) //Check that it is not manually turned on
{
digitalWrite ( RELAY , LOW );
}
}
//Get user input for setpointsif( digitalRead ( on_key )== LOW )
{
digitalWrite ( RELAY , HIGH ); //Turn on Lights
manual =1; //Manually it is turned on
}     if(digitalRead ( off_key )== LOW )
{
digitalWrite ( RELAY , LOW ); //Turn off Lights
manual =0;
} delay (10); //Update at every 10mSeconds
}//
=================================================================