//超音波酒精噴灑器


//Ultra sonic sensor上的腳位定義

#define trigPin  2

#define echoPin 3

//LED及WaterPump腳位定義

#define led 9

#define pump 8

//感測距離(單位:inches)
int range = 5;


void setup() {

  Serial.begin(9600);

  pinMode(trigPin, OUTPUT);

  pinMode(echoPin, INPUT);

  pinMode(led, OUTPUT);

  pinMode(pump, OUTPUT);

  digitalWrite(led, HIGH);

  digitalWrite(pump, LOW);

}

void loop()

{

  long duration, inches, cm;


  //觸發時機，當High持續2微秒

  digitalWrite(trigPin, LOW);

  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);

  delayMicroseconds(5);

  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);

  //微秒轉吋，吋再轉公分
  inches = microsecondsToInches(duration);

  cm = microsecondsToCentimeters(duration);

  if(inches < 5) {

    digitalWrite(led, LOW);

    digitalWrite(pump, HIGH);

    delay(100);
  }
else {

     digitalWrite(led, HIGH);

     digitalWrite(pump, LOW);

     delay(100);
  }

   delay(200);

}

long microsecondsToInches(long microseconds)

{

  return microseconds / 74 / 2;

}


long microsecondsToCentimeters(long microseconds)

{

  // 聲速為340m/s or 29cm/ms

  // 得出的距離要/2，因為所得之距離為來回的總和。

  return microseconds / 29 / 2;

}