Circuit Documentation

Summary

This circuit is designed to utilize an Arduino UNO as the central microcontroller to interface with an RFID-RC522 module for RFID card reading, control an LED and a buzzer for visual and audible feedback, and use a pushbutton to manually reset the system. The RFID reader checks for authorized tags and activates the LED and buzzer when a match is found. The pushbutton allows for manual deactivation of the LED and buzzer.

Component List

Arduino UNO

• Microcontroller board based on the ATmega328P
• It has 14 digital input/output pins, 6 analog inputs, a 16 MHz quartz crystal, a USB connection, a power jack, an ICSP header, and a reset button.

RFID-RC522

• An RFID reader/writer module
• Operates at 13.56 MHz frequency
• Interfaces with the Arduino via SPI

Buzzer

• An electromechanical component that produces sound
• Typically used for audible alerts or alarms

LED: Two Pin (orange)

• A basic light-emitting diode
• Emits orange light when powered

Resistor (220 Ohms)

• A passive two-terminal electrical component
• Implements electrical resistance as a circuit element

Resistor (10k Ohms)

• Another resistor with a higher resistance value
• Often used for pull-up or pull-down applications

Pushbutton

• A simple switch mechanism for controlling some aspect of a machine or a process
• Usually provides a way to manually open or close an electrical circuit

Wiring Details

Arduino UNO

• 3.3V connected to RFID-RC522 VCC (3.3V)
• 5V connected to Pushbutton Pin 4
• GND connected to LED cathode, Resistor (10k Ohms) pin1, Buzzer GND, and RFID-RC522 GND
• D13 connected to RFID-RC522 SCK
• D12 connected to RFID-RC522 MISO
• D11 connected to RFID-RC522 MOSI
• D10 connected to RFID-RC522 SDA
• D9 connected to RFID-RC522 RST
• D8 connected to Buzzer PIN
• D4 connected to Pushbutton Pin 3
• D3 connected to Resistor (220 Ohms) pin1

RFID-RC522

• VCC (3.3V) connected to Arduino UNO 3.3V
• RST connected to Arduino UNO D9
• GND connected to Arduino UNO GND
• IRQ not connected
• MISO connected to Arduino UNO D12
• MOSI connected to Arduino UNO D11
• SCK connected to Arduino UNO D13
• SDA connected to Arduino UNO D10

Buzzer

• PIN connected to Arduino UNO D8
• GND connected to Arduino UNO GND

LED: Two Pin (orange)

• cathode connected to Arduino UNO GND
• anode connected to Resistor (220 Ohms) pin2

Resistor (220 Ohms)

• pin1 connected to Arduino UNO D3
• pin2 connected to LED anode

Resistor (10k Ohms)

• pin1 connected to Arduino UNO GND
• pin2 connected to Pushbutton Pin 2 and Pin 1

Pushbutton

• Pin 4 connected to Arduino UNO 5V
• Pin 3 connected to Arduino UNO D4
• Pin 2 connected to Resistor (10k Ohms) pin2
• Pin 1 connected to Resistor (10k Ohms) pin2

Documented Code

#include <SPI.h>
#include <MFRC522.h>

#define RST_PIN 9     // Reset pin for RFID
#define SS_PIN 10     // SDA/SS pin for RFID
#define LED_PIN 3     // LED connected to pin 3
#define BUZZER_PIN 8  // Buzzer connected to pin 8
#define BUTTON_PIN 4  // Button to turn off LED and buzzer

MFRC522 rfid(SS_PIN, RST_PIN);

boolean isSystemActive = false; // Keeps track if LED and Buzzer are on

// Replace with the UID of your RFID tag (4 bytes)
byte authorizedUID[4] = {0xAB, 0xCD, 0x12, 0x34};

void setup() {
  // Initialize serial communication
  Serial.begin(9600);
  
  // Initialize RFID module
  SPI.begin();
  rfid.PCD_Init();
  
  // Set pin modes
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(BUTTON_PIN, INPUT_PULLUP);  // Use internal pull-up resistor for the button
  
  // Start with LED and buzzer off
  digitalWrite(LED_PIN, LOW);
  digitalWrite(BUZZER_PIN, LOW);
}

void loop() {
  // Check if the button is pressed (LOW because of pull-up resistor)
  if (digitalRead(BUTTON_PIN) == LOW && isSystemActive) {
    // Turn off the LED and buzzer manually
    digitalWrite(LED_PIN, LOW);
    digitalWrite(BUZZER_PIN, LOW);
    isSystemActive = false;  // Reset system state
    delay(500);  // Debouncing
  }

  // Look for RFID cards
  if (!rfid.PICC_IsNewCardPresent() || !rfid.PICC_ReadCardSerial()) {
    return;
  }
  
  // Check if the UID matches the authorized one
  if (checkUID(rfid.uid.uidByte)) {
    // Turn on LED and buzzer
    digitalWrite(LED_PIN, HIGH);
    digitalWrite(BUZZER_PIN, HIGH);
    isSystemActive = true;  // Set system to active state
  }

  // Halt the PICC and stop reading
  rfid.PICC_HaltA();
  rfid.PCD_StopCrypto1();
}

// Function to compare the scanned UID with the authorized one
boolean checkUID(byte *uid) {
  for (byte i = 0; i < 4; i++) {
    if (uid[i] != authorizedUID[i]) {
      return false;
    }
  }
  return true;
}

This code is designed to run on the Arduino UNO and interfaces with the RFID-RC522 module to read RFID tags. When an authorized tag is detected, the LED and buzzer are activated. The pushbutton allows the user to reset the system, turning off the LED and buzzer. The code includes setup and loop functions, as well as a helper function checkUID to compare the scanned UID with the authorized one.