#define trigPin 3 //Define the HC-SE04 triger on pin 6 on the arduino
#define echoPin 2 //Define the HC-SE04 echo on pin 5 on the arduino
#define bulb 9 //Define the relay signal on pin 9 on the arduino
void setup()
{
Serial.begin (9600); //Start the serial monitor
pinMode(trigPin, OUTPUT); //set the trigpin to output
pinMode(echoPin, INPUT); //set the echopin to input
pinMode (bulb, OUTPUT); //set the bulb on pin 9 to output
}
void loop()
{
int duration, distance; //Define two intregers duration and distance to be used to save data
digitalWrite(trigPin, HIGH); //write a digital high to the trigpin to send out the pulse
delayMicroseconds(500); //wait half a millisecond
digitalWrite(trigPin, LOW); //turn off the trigpin
duration = pulseIn(echoPin, HIGH); //measure the time using pulsein when the echo receives a signal set it to high
distance = (duration / 2) / 29.1; //distance is the duration devided by 2 becasue the signal traveled from the trigpin then back to the echo pin, then divide by 29.1 to convert to centimeters
if (distance < 10) //if the distance is less than 13 CM
{
Light(); //execute the Light subroutine below
}
Serial.print(distance); //Dispaly the distance on the serial monitor
Serial.println(" CM"); //in centimeters
delay(500); //delay half a second
}
void Light() //Start the Light subroutine
{ digitalWrite(bulb, HIGH); //turn on the light
delay (15000); //wait 15 seconds
digitalWrite(bulb, LOW); //turn off the light
}