#define TRIG 3
#define ECHO 2
#define LED 9
#define BUZ 8
void setup() {
Serial.begin(9600);
pinMode(TRIG, OUTPUT);
pinMode(ECHO, INPUT);
pinMode(LED, OUTPUT);
pinMode(BUZ, OUTPUT);
}
long readDistance() {
digitalWrite(TRIG, LOW); delayMicroseconds(2);
digitalWrite(TRIG, HIGH); delayMicroseconds(10);
digitalWrite(TRIG, LOW);
return pulseIn(ECHO, HIGH, 30000) * 0.034 / 2;
}
void loop() {
long d = readDistance();
if (d > 0 && d < 50) {
digitalWrite(LED, HIGH);
digitalWrite(BUZ, HIGH);
Serial.print("ALERT: "); Serial.print(d); Serial.println(" cm");
} else {
digitalWrite(LED, LOW);
digitalWrite(BUZ, LOW);
Serial.print("Clear: "); Serial.print(d); Serial.println(" cm");
}
delay(200);
}