/*
  AnalogReadSerial

  Reads an analog input on pin 0, prints the result to the Serial Monitor.
  Graphical representation is available using Serial Plotter (Tools > Serial Plotter menu).
  Attach the center pin of a potentiometer to pin A0, and the outside pins to +5V and ground.

  This example code is in the public domain.

  https://www.arduino.cc/en/Tutorial/BuiltInExamples/AnalogReadSerial
*/

int oldSensVal = 1; //initialize sensor value 
int count = 0; //initialize count of magnet passes 

void setup() {
  Serial.begin(9600); //start serial communication
  pinMode(3, OUTPUT);
  pinMode(4, OUTPUT);
}

void loop() {

  int sensorValue = digitalRead(2);  //read sensor value, save as 'sensorValue'
  if (sensorValue==0){  //if sensor value is 0, i.e. detects magnet
    Serial.print("magnet");  //..print 'magnet'
    if (sensorValue!=oldSensVal){  //if the sensor value has just changed
      count++;  //count that as an additional count for magnet passed
    digitalWrite(3,HIGH);
    digitalWrite(4,HIGH);
    }
  }
  else{  //otherwise..
    Serial.print(sensorValue);  //print the sensor Value (0 or 1)
    digitalWrite(3,LOW);
    digitalWrite(4,LOW);
  }
  Serial.print("-");
  Serial.println(count); //display the total count of magnet passes
  delay(10);  //delay period (ms)
  oldSensVal = sensorValue;  //set currentvalue as the previous value 
}