RFID.cpp

/*
 * Main functionality:
 *  Read RFID: read the RFID card and find the unique identifier of the card
 *  Registration: a new student must have to be registered. Through register mode a new RFID card can be register
 *  Verification: verify RFID card by checking in the registered list
 */

#include <MFRC522.h>

#include <SPI.h>

#define number_of_student 50 //assume total 50 student can entrol in a course
#define CS 10
# define RST 9
MFRC522 rfid(CS, RST);

class RFID {

  public:
    String uniqueRFID;
  String enroled_student[number_of_student];
  int registered_id = 0;

  void registerCard(String id);
  String readRFID();
  void verifyCheckIn();
  void modeSelectorDisplay();
  bool isRegisteredStudent(String id);
  void unRegisterCard(String id);

};

//function for mode selection
void RFID::modeSelectorDisplay() {
  Serial.println("Press 1: to register a new student");
  Serial.println("Press 2: to remove an existing student");
  Serial.println("Press 3: to access into the class");

}

//function is used to register for a new RFID card
void RFID::registerCard(String id) {
  if (registered_id != 0) //if there are some existing registered student
  {
    for (int i = 0; i < registered_id; i++) {
      if (enroled_student[i] == id) {
        Serial.println("Already registered");
        return;
      }

    }
  }
  enroled_student[registered_id] = id;
  registered_id++;
  Serial.println("Register a new student");

}

bool RFID::isRegisteredStudent(String id) {
  for (int i = 0; i < registered_id; i++) {
    if (enroled_student[i] == id) {
      return true;
    }

  }

  return false;
}

void RFID::unRegisterCard(String id) {
  int pos = -1;
  if (registered_id != 0) //if there are some existing registered student
  {
    for (int i = 0; i < registered_id; i++) {
      if (enroled_student[i] == id) {
        pos = i;
        registered_id--;
        break;
      }
    }

    if (pos == -1) {

      Serial.println("This student is not a registered student");

    } else {
      for (int i = pos; i < registered_id - 1; i++) {
        enroled_student[i] = enroled_student[i + 1];

      }
      Serial.println("Unregister successfully");
    }

  }

}

void setup() {

  // Init Serial port
  Serial.begin(9600);

  while (!Serial);

  // Init SPI bus
  SPI.begin();
  // Init MFRC522 
  rfid.PCD_Init();

}

RFID obj;
int mode = 0;
void loop() {
  obj.modeSelectorDisplay();
  //Check the register mode: applicable for only new student
  mode = Serial.parseInt();
  while (!Serial.available()) {}
  delay(1000);
  if (mode == 1) {
    Serial.println("Register mode is selected");
    String str = obj.readRFID();
    //str.replace(" ","");
    Serial.println(str);
    obj.registerCard(str);
  }

  //Unregister student
  else if (mode == 2) {
    Serial.println("Unregister mode is selected");
    String str = obj.readRFID();
    Serial.println(str);
    obj.unRegisterCard(str);
  }

  //attendence mode 
  else if (mode == 3) {
    Serial.println("Attendence mode is selected");
    if (rfid.PICC_IsNewCardPresent()) {
      String str = obj.readRFID();
      //str.replace(" ","");
      bool registeredStudent = obj.isRegisteredStudent(str);
      if (registeredStudent == true) {
        Serial.println("ID: "+str+" you are Welcome.");
      } else {
        Serial.println("You are not a registered student");
      }

    }

  }
  mode = 0;
  delay(3000);

}

String RFID::readRFID() {
  rfid.PICC_ReadCardSerial();
  uniqueRFID = String(rfid.uid.uidByte[0]) + " " + String(rfid.uid.uidByte[1]) +
    " " + String(rfid.uid.uidByte[2]) + " " + String(rfid.uid.uidByte[3]);
  return uniqueRFID;
}