Circuit Documentation

Summary

The circuit in question is designed to integrate an Arduino Mega 2560 with an HC-SR04 Ultrasonic Sensor, an ESP32-CAM module, and an RFID-RC522 reader. The system is powered by a 12v5ah Battery. The Arduino Mega 2560 serves as the central processing unit, interfacing with the ultrasonic sensor for distance measurement, the RFID reader for identification purposes, and the ESP32-CAM for potential wireless communication and image processing capabilities. The circuit is likely intended for a security or monitoring application, where visitor counting and identification are crucial.

Component List

Arduino Mega 2560

• Microcontroller board based on the ATmega2560
• Provides a large number of IO pins, including digital, analog, PWM, I2C, and SPI
• Operates at 5V and can be powered via USB or an external power source

HC-SR04 Ultrasonic Sensor

• Sensor for measuring distance via ultrasonic waves
• Operates typically at 5V
• Includes a trigger and echo pin to initiate measurement and receive the reflected signal

ESP32 - CAM

• A small-sized camera module with Wi-Fi capabilities
• Operates at 3.3V or 5V
• Includes IO pins for interfacing with other devices and sensors

RFID-RC522

• RFID reader for reading MIFARE cards and tags
• Operates at 3.3V
• Communicates via SPI with the host controller

12v5ah Battery

• Provides a 12V power source
• Used to power the entire circuit through voltage regulation on the Arduino Mega 2560

Wiring Details

Arduino Mega 2560

• 5V connected to HC-SR04 VCC, ESP32-CAM 5V
• 3V3 connected to RFID-RC522 3.3V
• GND connected to HC-SR04 GND, ESP32-CAM GND, RFID-RC522 GND, and 12v5ah Battery 12v -
• VIN connected to 12v5ah Battery 12v +
• D7 PWM connected to HC-SR04 TRIG
• D8 PWM connected to HC-SR04 ECHO
• D21/SCL connected to ESP32-CAM IO4
• D20/SDA connected to ESP32-CAM IO2
• D10 PWM connected to RFID-RC522 RST
• D52 connected to RFID-RC522 SCK
• D50 connected to RFID-RC522 MISO
• D53 connected to RFID-RC522 SDA
• D51 connected to RFID-RC522 MOSI

HC-SR04 Ultrasonic Sensor

• VCC connected to Arduino Mega 2560 5V
• TRIG connected to Arduino Mega 2560 D7 PWM
• ECHO connected to Arduino Mega 2560 D8 PWM
• GND connected to Arduino Mega 2560 GND

ESP32 - CAM

• 5V connected to Arduino Mega 2560 5V
• GND connected to Arduino Mega 2560 GND
• IO4 connected to Arduino Mega 2560 D21/SCL
• IO2 connected to Arduino Mega 2560 D20/SDA

RFID-RC522

• 3.3V connected to Arduino Mega 2560 3V3
• RST connected to Arduino Mega 2560 D10 PWM
• GND connected to Arduino Mega 2560 GND
• SCK connected to Arduino Mega 2560 D52
• MISO connected to Arduino Mega 2560 D50
• SDA connected to Arduino Mega 2560 D53
• MOSI connected to Arduino Mega 2560 D51

12v5ah Battery

• 12v + connected to Arduino Mega 2560 VIN
• 12v - connected to Arduino Mega 2560 GND

Documented Code

Arduino Mega 2560 Code

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

#define SS_PIN 10 // Pin connected to RFID reader's SDA
#define RST_PIN 9 // Pin connected to RFID reader's RST
MFRC522 mfrc522(SS_PIN, RST_PIN); // Create MFRC522 instance

#define TRIGGER_PIN 2
#define ECHO_PIN 3
#define VISITOR_COUNTER_LED 13

int visitorCount = 0;

// List of valid student IDs
String validStudentIDs[] = {"123456789", "987654321", "111213141", "555666777"};
int numStudents = sizeof(validStudentIDs) / sizeof(validStudentIDs[0]);

void setup() {
  Serial.begin(9600);
  Wire.begin(8); // Initialize I2C with address 8
  Wire.onReceive(receiveEvent);

  SPI.begin(); // Initialize SPI bus
  mfrc522.PCD_Init(); // Initialize MFRC522

  pinMode(TRIGGER_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(VISITOR_COUNTER_LED, OUTPUT);

  Serial.println("System Initialized");
}

void loop() {
  // Check for RFID tag
  if (mfrc522.PICC_IsNewCardPresent() && mfrc522.PICC_ReadCardSerial()) {
    Serial.println("RFID Tag Detected");
    // Read and authenticate RFID
    authenticateRFID();
  }

  // Check for visitor count
  long duration, distance;
  digitalWrite(TRIGGER_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIGGER_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIGGER_PIN, LOW);
  duration = pulseIn(ECHO_PIN, HIGH);
  distance = (duration / 2) * 0.0344;

  if (distance < 50) { // Adjust threshold as needed
    visitorCount++;
    Serial.print("Visitor Count: ");
    Serial.println(visitorCount);
    digitalWrite(VISITOR_COUNTER_LED, HIGH);
    delay(1000); // Debounce time
    digitalWrite(VISITOR_COUNTER_LED, LOW);
  }

  delay(500); // Adjust as needed
}

void receiveEvent(int howMany) {
  while (Wire.available()) {
    char c = Wire.read(); // Read face recognition result
    if (c == '1') {
      Serial.println("Face Matched: GREEN");
    } else {
      Serial.println("Face Not Matched: RED");
    }
  }
}

void authenticateRFID() {
  String rfidTag = "";
  for (byte i = 0; i < mfrc522.uid.size; i++) {
    rfidTag += String(mfrc522.uid.uidByte[i] < 0x10 ? "0" : "");
    rfidTag += String(mfrc522.uid.uidByte[i], HEX);
  }
  rfidTag.toUpperCase();
  Serial.print("RFID Tag: ");
  Serial.println(rfidTag);

  bool isValid = false;
  for (int i = 0; i < numStudents; i++) {
    if (rfidTag == validStudentIDs[i]) {
      isValid = true;
      break;
    }
  }

  if (isValid) {
    Serial.println("RFID Authorized: GREEN");
  } else {
    Serial.println("RFID Unauthorized: RED");
  }
}

ESP32 - CAM Code

#include <WiFi.h>
#include <Wire.h>

#define I2C_ADDRESS 8 // Address for I2C communication with Arduino Mega

// Replace with your network credentials
const char* ssid = "YOUR_SSID";
const char* password = "YOUR_PASSWORD";

void setup() {
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("Connected to WiFi");

  Wire.begin(); // Join I2C bus as master
}

void loop() {
  // Placeholder for face recognition
  bool faceMatched = performFaceRecognition();

  // Send face recognition result to Arduino Mega
  Wire.beginTransmission(I2C_ADDRESS);
  Wire.write(faceMatched ? '1' : '0'); // Send '1' if face matches, '0' otherwise
  Wire.endTransmission();
  
  delay(2000); // Adjust delay as needed
}

// Dummy function for face recognition
bool performFaceRecognition() {
  // Replace with actual face recognition logic
  return random(0, 2); // Randomly return true or false
}

This concludes the documentation for the provided circuit design, component list, wiring details, and embedded code.