ard.cpp

#define TRIG_PIN 9
#define ECHO_PIN 10
#define ALERT_PIN 13

int distance;
int blinkDelay;

void setup() {
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(ALERT_PIN, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // Measure distance
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  
  long duration = pulseIn(ECHO_PIN, HIGH);
  distance = duration * 0.034 / 2;
  
  Serial.print("Distance: ");
  Serial.println(distance);
  
  // Decide blink speed based on distance
  if (distance > 30) {
    blinkDelay = 0;  // No blink - OFF
  }
  else if (distance > 20) {
    blinkDelay = 400;  // Slow
  }
  else if (distance > 10) {
    blinkDelay = 200;  // Medium
  }
  else if (distance > 5) {
    blinkDelay = 100;  // Fast
  }
  else {
    blinkDelay = -1;  // Constant ON (under 5cm)
  }
  
  // Blink LED or keep constant
  if (blinkDelay == -1) {
    // Constant ON for very close objects
    digitalWrite(ALERT_PIN, HIGH);
    delay(50);
  }
  else if (blinkDelay > 0) {
    // Blink
    digitalWrite(ALERT_PIN, HIGH);
    delay(blinkDelay);
    digitalWrite(ALERT_PIN, LOW);
    delay(blinkDelay);
  }
  else {
    // OFF
    digitalWrite(ALERT_PIN, LOW);
    delay(50);
  }
}

#define TRIG_PIN 9
#define ECHO_PIN 10
#define ALERT_PIN 6

long duration;
int distance;

void setup() {
pinMode(TRIG_PIN, OUTPUT);
pinMode(ECHO_PIN, INPUT);
pinMode(ALERT_PIN, OUTPUT);
Serial.begin(9600);
}

void loop() {

// Ultrasonic trigger
digitalWrite(TRIG_PIN, LOW);
delayMicroseconds(2);
digitalWrite(TRIG_PIN, HIGH);
delayMicroseconds(10);
digitalWrite(TRIG_PIN, LOW);

duration = pulseIn(ECHO_PIN, HIGH, 30000);
if (duration == 0) return;

distance = duration * 0.034 / 2;

// -------- ALERT LOGIC --------

if (distance > 50) {
digitalWrite(ALERT_PIN, LOW); // OFF
}

else if (distance > 30) {
// Slow beep
digitalWrite(ALERT_PIN, HIGH);
delay(500);
digitalWrite(ALERT_PIN, LOW);
delay(500);
}

else if (distance > 15) {
// Fast beep
digitalWrite(ALERT_PIN, HIGH);
delay(200);
digitalWrite(ALERT_PIN, LOW);
delay(200);
}

else {
// Very close → continuous
digitalWrite(ALERT_PIN, HIGH);
}
}