#include <SoftwareSerial.h>

// define all the pins used
#define LED 5
#define PROX 9
#define ADJ 8
#define PWRMODE 10
#define TX 1
#define RX 2
#define CONTROL 6

// define global variables
volatile int brightness = 0;
volatile boolean dir = true;
volatile boolean detect = false;
volatile int counter = 0;

// for debugging purposes
SoftwareSerial mySerial(RX, TX);

// function to reset the proximity detector
void resetProx() {
  digitalWrite(PWRMODE, LOW);
  delay(5);
  digitalWrite(PWRMODE, HIGH);
}

void setup() {
  pinMode(LED, OUTPUT);
  pinMode(PROX, INPUT);
  pinMode(ADJ, OUTPUT);
  pinMode(PWRMODE, OUTPUT);

// Proximity sensor parameters
// LOW ADJ means higher sensitivity, HIGH means lowest sensitivity
// HIGH PWRMODE means normal mode, LOW means sleep mode
  digitalWrite(PWRMODE, HIGH);
  digitalWrite(ADJ, HIGH);
//  analogWrite(ADJ, 130);

  mySerial.begin(9600);

// allow 1 second before sensing
  delay(1000);
}

void loop() {

  if (digitalRead(PROX) == LOW) {
    if (detect == false && counter < 500) {
      if (brightness > 10) { brightness = 0; dir = true; }
      else { brightness = 254; dir = false; }
    }
    
    detect = true;
    counter++;
  } else {  
    detect = false;
    counter = 0;
  }

  if (counter > 500 && detect == true) {
    if (dir == true)  { brightness++; }
    if (dir == false) { brightness--; }

// define the direction of the brightness change
    if (brightness > 254) { dir = false; delay(500); }
    if (brightness < 1)   { dir = true;  delay(500); }

    delay(10);
  }
  
  analogWrite(LED, brightness);
  analogWrite(CONTROL, brightness);
  delay(1);
}