Circuit Documentation

Summary

This circuit is designed to create an RFID Attendance System using an Arduino Uno R3 as the central microcontroller. The system features an RFID reader for logging attendance, a Real-Time Clock (RTC) for timekeeping, a SIM800L module for sending SMS messages, a piezo buzzer for audible alerts, an LCD display for user feedback, and two LEDs (red and green) to indicate access status. The system is powered by the Arduino's 3.3V and 5V outputs and includes resistors for current limiting to the LEDs.

Component List

RFID-RC522

• Description: An RFID reader/writer module for contactless communication at 13.56MHz.
• Pins: VCC (3.3V), RST, GND, IRQ, MISO, MOSI, SCK, SDA

Piezo Buzzer

• Description: An electronic buzzer for producing sound.
• Pins: pin 1, pin 2

LCD I2C Display

• Description: A liquid crystal display with an I2C interface for showing text and numbers.
• Pins: GND, VCC, SDA, SCL

Resistor (200 Ohms)

• Description: A resistor with a resistance of 200 Ohms, used for current limiting.
• Pins: pin1, pin2

LED: Two Pin (red)

• Description: A red light-emitting diode for indicating status.
• Pins: cathode, anode

LED: Two Pin (green)

• Description: A green light-emitting diode for indicating status.
• Pins: cathode, anode

DS3231 RTC

• Description: A highly accurate I2C real-time clock with a built-in temperature-compensated crystal oscillator.
• Pins: 32K, SQW, SCL, SDA, VCC, GND

SIM800L

• Description: A GSM/GPRS module for cellular communication.
• Pins: NFT, RING, VCC, DTR, RST, MIC +, RXD, MIC-, TXD, SPK+, GND, SPK-

1-Channel Relay (5V 10A)

• Description: A relay module for controlling high power devices.
• Pins: NC, signal, C, power, NO, ground

Arduino Uno R3

• Description: A microcontroller board based on the ATmega328P.
• Pins: USB Port, Power Jack, Not Connected, IOREF, RESET, 3.3V, 5V, GND, VIN, A0-A5, SCL, SDA, AREF, Digital I/O pins 0-13

Wiring Details

RFID-RC522

• VCC (3.3V) to Arduino Uno 3.3V
• RST to Arduino Uno pin 9
• GND to common ground
• IRQ not connected
• MISO to Arduino Uno pin 12
• MOSI to Arduino Uno pin 11
• SCK to Arduino Uno pin 13
• SDA to Arduino Uno pin 10

Piezo Buzzer

• pin 1 to common ground
• pin 2 to Arduino Uno pin 7

LCD I2C Display

• GND to common ground
• VCC to Arduino Uno 5V
• SDA to Arduino Uno A4/SDA
• SCL to Arduino Uno A5/SCL

Resistor (200 Ohms)

• One resistor between RFID-RC522 GND and common ground
• Another resistor between LED cathodes and common ground

LED: Two Pin (red)

• cathode to 200 Ohm resistor
• anode to Arduino Uno pin 5

LED: Two Pin (green)

• cathode to 200 Ohm resistor
• anode to Arduino Uno pin 4

DS3231 RTC

• VCC to Arduino Uno 5V
• GND to common ground
• SCL to Arduino Uno A5/SCL
• SDA to Arduino Uno A4/SDA

SIM800L

• VCC to Arduino Uno 5V
• GND to common ground
• RST to Arduino Uno pin 8
• RXD to Arduino Uno pin 2
• TXD to Arduino Uno pin 3

1-Channel Relay (5V 10A)

• power to Arduino Uno 5V
• ground to common ground
• signal to Arduino Uno pin 6

Arduino Uno R3

• Powered via USB Port or Power Jack
• Ground pins connected to common ground
• Digital and analog pins connected as specified above

Documented Code

/*
 * RFID Attendance System using Arduino Uno R3
 * This system uses an RFID reader to log attendance, an RTC to check the time,
 * a SIM800L module to send messages to parents, a buzzer for alerts, an LCD
 * display for messages, and two LEDs to indicate access status.
 */

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <SPI.h>
#include <MFRC522.h>
#include <DS3231.h>
#include <SoftwareSerial.h>

// Pin definitions
#define RST_PIN 9
#define SS_PIN 10
#define GREEN_LED_PIN 4
#define RED_LED_PIN 5
#define BUZZER_PIN 7
#define RELAY_PIN 6
#define SIM800_TX 3
#define SIM800_RX 2

// Initialize components
LiquidCrystal_I2C lcd(0x27, 16, 2);
MFRC522 rfid(SS_PIN, RST_PIN);
DS3231 rtc(SDA, SCL);
SoftwareSerial sim800(SIM800_TX, SIM800_RX);

void setup() {
  // Initialize serial communication
  Serial.begin(9600);
  sim800.begin(9600);

  // Initialize LCD
  lcd.begin();
  lcd.backlight();

  // Initialize RFID
  SPI.begin();
  rfid.PCD_Init();

  // Initialize RTC
  rtc.begin();

  // Initialize pins
  pinMode(GREEN_LED_PIN, OUTPUT);
  pinMode(RED_LED_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(RELAY_PIN, OUTPUT);

  // Welcome message
  lcd.setCursor(0, 0);
  lcd.print("RFID Attendance");
  lcd.setCursor(0, 1);
  lcd.print("System");
  delay(2000);
  lcd.clear();
}

void loop() {
  // Check for RFID card
  if (!rfid.PICC_IsNewCardPresent() || !rfid.PICC_ReadCardSerial()) {
    return;
  }

  // Get current time
  DateTime now = rtc.now();

  // Check if student is on time
  if (isOnTime(now)) {
    grantAccess();
  } else {
    denyAccess();
  }

  // Halt PICC
  rfid.PICC_HaltA();
}

bool isOnTime(DateTime now) {
  // Define the allowed time range (e.g., 8:00 AM to 9:00 AM)
  DateTime start(2023, 1, 1, 8, 0, 0);
  DateTime end(2023, 1, 1, 9, 0, 0);
  return now >= start && now <= end;
}

void grantAccess() {
  // Turn on green LED
  digitalWrite(GREEN_LED_PIN, HIGH);
  digitalWrite(RED_LED_PIN, LOW);

  // Activate relay
  digitalWrite(RELAY_PIN, HIGH);

  // Display message
  lcd.setCursor(0, 0);
  lcd.print("Access Granted");

  // Send SMS
  sendSMS("Access Granted");

  // Deactivate relay after delay
  delay(5000);
  digitalWrite(RELAY_PIN, LOW);
  lcd.clear();
}

void denyAccess() {
  // Turn on red LED
  digitalWrite(RED_LED_PIN, HIGH);
  digitalWrite(GREEN_LED_PIN, LOW);

  // Activate buzzer
  digitalWrite(BUZZER_PIN, HIGH);
  delay(1000);
  digitalWrite(BUZZER_PIN, LOW);

  // Display message
  lcd.setCursor(0, 0);
  lcd.print("Access Denied");

  // Send SMS
  sendSMS("Access Denied");

  delay(5000);
  lcd.clear();
}

void sendSMS(String message) {
  sim800.print("AT+CMGF=1\r");
  delay(100);
  sim800.print("AT+CMGS=\"+1234567890\"\r");
  delay(100);
  sim800.print(message);
  delay(100);
  sim800.write(26);
  delay(1000);
}

This code is responsible for controlling the RFID Attendance System. It initializes the components, checks for RFID card presence, verifies the time with the RTC, grants or denies access accordingly, and sends SMS messages using the SIM800L module. The LCD displays messages, and the LEDs and buzzer provide visual and audible feedback.