#define echoPin PB1
#define trigPin PB2
#define buzzerPin PB4

long duration;
int distance;

/*
  Obstruction Detector using ATtiny85
*/

void setup() {

  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(buzzerPin, OUTPUT);
  digitalWrite(PB0, LOW);

}

void loop() {

  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);

  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);
  distance = duration * 0.0344 / 2;

  if (distance > 200) {
    digitalWrite(buzzerPin, LOW);
  }

  if (distance > 100 && distance < 200) {
    digitalWrite(buzzerPin, HIGH);
    delay(4000);
    digitalWrite(buzzerPin, LOW);
    delay(2000);
  }

  if (distance < 100 && distance > 30) {
    digitalWrite(buzzerPin, HIGH);
    delay(3000);
    digitalWrite(buzzerPin, LOW);
    delay(1000);
  }

  if (distance < 20 && distance > 10) {
    digitalWrite(buzzerPin, HIGH);
    delay(2000);
    digitalWrite(buzzerPin, LOW);
    delay(1000);
  }

  if (distance < 10 && distance > 1) {
    digitalWrite(buzzerPin, HIGH);
    delay(1000);
    digitalWrite(buzzerPin, LOW);
    delay(1000);
  }

  if (distance < 1) {
    digitalWrite(buzzerPin, HIGH);
    delay(500);
    digitalWrite(buzzerPin, LOW);
    delay(500);
  }

  delay(100);

}