#include <PID_v1.h>

#define PIN_INPUT A2
#define PIN_OUTPUT 6
#define Signal 0

double Setpoint, Input, Output;
double Kp=2, Ki=5, Kd=1;
PID myPID(&Input, &Output, &Setpoint, Kp, Ki, Kd, DIRECT);
int WindowSize = 5000;
unsigned int delayTime = 1000;
unsigned long windowStartTime;
unsigned long previousMillis = 0;

void setup() {
  windowStartTime = millis();
  Setpoint = 100;
  // Input = analogRead(PIN_INPUT);
  // pinMode(PIN_INPUT, INPUT);
  myPID.SetOutputLimits(0, WindowSize);
  myPID.SetMode(AUTOMATIC);
  Serial.begin(9600);
}

void loop() 
{
  Input = analogRead(PIN_INPUT);
  myPID.Compute();

  // turn output pin on/off based on PID output
  if(millis() - windowStartTime > WindowSize)
    windowStartTime += WindowSize; // shift relay window
  
  if(Output < millis() - windowStartTime)
    digitalWrite(PIN_OUTPUT, HIGH);
  else
    digitalWrite(PIN_OUTPUT, LOW);
  // analogWrite(PIN_OUTPUT, Output);

  if(millis() - previousMillis > delayTime)
  {
      previousMillis = millis();
      Serial.println(Input, 2);
      // the following if statment does not work!!!!!
      if(digitalRead(Signal))
        digitalWrite(Signal, LOW);
      else
        digitalWrite(Signal, HIGH);
  }
}