HCSR04_distance_with_LEDS_demo

/*
 * Loop Logic
 * When an object is closer tha 10cm led 1 is on, 7cm led 2 and 5 cm led 3
 * When the object goes outside these ranges they will turn off after a 1 second delay
 */

#include <HCSR04.h>
const int led1 = 2;
const int led2 = 3;
const int led3 = 4;
HCSR04 hc(5,6); //(trig pin , echo pin)
unsigned long ctus  = 0;
unsigned long readDelay = 10;
unsigned long ctLed1  = 0;
unsigned long ctLed2  = 0;
unsigned long ctLed3  = 0;
unsigned long ledDelay = 2000;
unsigned long ctPrint = 0;
unsigned long spDelay = 1000;
int Close = 100;
int Mid = 150;
int Far = 200;
int distance = 0;

void setup(){
  Serial.begin(9600);
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
  digitalWrite(led1, LOW);
  digitalWrite(led2, LOW);
  digitalWrite(led3, LOW);
}

void readDistance(){
    distance = hc.dist();
    distance = distance*10;
}

void loop(){
  int led1State = digitalRead(led1);
  int led2State = digitalRead(led2);
  int led3State = digitalRead(led3);

  if((millis() - ctus) > readDelay){
    readDistance();
    ctus = millis();
  }

  if((millis() - ctPrint) > spDelay){
    Serial.print(distance);Serial.println(" mm");
    ctPrint = millis();
  }

  if(distance < Far){
    led1State = HIGH;
  }else if(distance >= Far){
    if((millis() - ctLed1) > ledDelay){
      led1State = LOW;
      ctLed1 = millis();
    }
  }

  if(distance < Mid){
    led2State = HIGH;
  }else if(distance >= Mid){
    if((millis() - ctLed2) > ledDelay){
      led2State = LOW;
      ctLed2 = millis();
    }
  }
  if(distance < Close){
    led3State = HIGH;
  }else if(distance >= Close){
    if((millis() - ctLed3) > ledDelay){
      led3State = LOW;
      ctLed3 = millis();
    }
  }
  digitalWrite(led1, led1State);
  digitalWrite(led2, led2State);
  digitalWrite(led3, led3State);
}