Ultra Sonic Sensor Hand Written
int trig=3;int echo=2;int led=9;
void setup(){ Serial.begin(9600); pinMode(trig,OUTPUT); pinMode(echo,INPUT); pinMode(led,OUTPUT);}
void loop(){ int duration; int distance; digitalWrite(trig,HIGH); delay(1000); digitalWrite(echo,LOW); duration=pulseIn(echo,HIGH); distance= (duration/2) /29.1; Serial.print(distance); Serial.print("cm\n"); delay(1000);if (distance=13){digitalWrite(led,HIGH);}}