Arduino-Based Fingerprint Attendance System

1. Introduction

An Arduino-Based Fingerprint Attendance System using R307 is a secure and reliable biometric system used to record attendance using fingerprints. Unlike RFID or password systems, fingerprint-based systems are highly secure and cannot be duplicated easily.

The R307 Fingerprint Sensor is widely used because of its high accuracy, built-in storage, and fast recognition speed. This project is ideal for schools, colleges, and offices.

2. Components

Arduino UNO / Nano
R307 H Fingerprint Sensor (1000 finger storage)
DS3231 RTC Module
16x2 LCD Display with I2C
Buzzer
Jumper Wires
Breadboard
Power Supply

3. Circuit and Connections

PINOUT LCD WITH I2C

R307 Fingerprint Sensor

VCC → 5V
GND → GND
TX → Arduino Pin 2
RX → Arduino Pin 3

RTC DS3231

SDA → A4

SCL → A5

VCC → 5V

GND → GND

Buzzer

Positive → Pin 8
Negative → GND

LCD

SDA → A4
SCL → A5
VCC → 5V
GND → GND same as RTC since it is a shared wire system

4. Detailed Step By Step Circuit Working

The fingerprint sensor scans the finger and converts it into a digital template.
This template is stored inside the sensor memory.
When a user places a finger:
- Sensor captures fingerprint
- Compares with stored templates
If match found:
- Arduino receives ID number
Arduino then:
- Activates buzzer (confirmation)
- Displays message on LCD (optional)
If no match:
- Access denied

5. Fingerprint Enrollment Code (IMPORTANT – DO THIS FIRST)

Before running the main project, you must register fingerprints into the sensor memory.

Step 1: Upload Enrollment Code


#include <Adafruit_Fingerprint.h>
#include <SoftwareSerial.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// Fingerprint Sensor
SoftwareSerial mySerial(2, 3);
Adafruit_Fingerprint finger = Adafruit_Fingerprint(&mySerial);

// LCD (I2C)
LiquidCrystal_I2C lcd(0x27, 16, 2);

int id = 1; // Change this for each new user

void setup() {
  Serial.begin(9600);
  finger.begin(57600);

  lcd.init();
  lcd.backlight();

  lcd.setCursor(0, 0);
  lcd.print("Enroll Finger");

  if (finger.verifyPassword()) {
    Serial.println("Sensor ready");
    lcd.setCursor(0, 1);
    lcd.print("Sensor Ready");
  } else {
    Serial.println("Sensor error");
    lcd.setCursor(0, 1);
    lcd.print("Sensor Error");
    while (1);
  }

  delay(2000);
  lcd.clear();
}

void loop() {
  enrollFingerprint();
}

// Enrollment Function
void enrollFingerprint() {

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Place Finger");

  // Wait for finger
  while (finger.getImage() != FINGERPRINT_OK);

  finger.image2Tz(1);

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Remove Finger");
  delay(2000);

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Place Again");

  // Wait again
  while (finger.getImage() != FINGERPRINT_OK);

  finger.image2Tz(2);

  // Create model
  if (finger.createModel() == FINGERPRINT_OK) {

    if (finger.storeModel(id) == FINGERPRINT_OK) {
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Stored ID:");
      lcd.setCursor(0, 1);
      lcd.print(id);

      Serial.println("Stored Successfully!");

    } else {
      lcd.clear();
      lcd.print("Store Failed");
    }

  } else {
    lcd.clear();
    lcd.print("Error Try Again");
  }

  delay(3000);
}

Step 2: Important Instructions

Open Serial Monitor
Follow instructions:
- Place finger
- Remove
- Place again
Fingerprint will be stored with ID

Step 3: Repeat for Multiple Users

Change:


int id = 1;

👉 Use:

ID 1 → Student 1
ID 2 → Student 2

6. Main Code (Attendance System)


#include <Adafruit_Fingerprint.h>
#include <SoftwareSerial.h>
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <RTClib.h>

// Fingerprint
SoftwareSerial mySerial(2, 3);
Adafruit_Fingerprint finger = Adafruit_Fingerprint(&mySerial);

// LCD
LiquidCrystal_I2C lcd(0x27, 16, 2);

// RTC
RTC_DS3231 rtc;

int buzzer = 8;

void setup() {
  Serial.begin(9600);
  finger.begin(57600);

  lcd.init();
  lcd.backlight();

  pinMode(buzzer, OUTPUT);

  if (!rtc.begin()) {
    lcd.print("RTC Error");
    while (1);
  }

  if (!finger.verifyPassword()) {
    lcd.print("Sensor Error");
    while (1);
  }

  lcd.print("System Ready");
  delay(2000);
  lcd.clear();
}

void loop() {
  lcd.setCursor(0, 0);
  lcd.print("Place Finger");

  int id = getFingerprintID();

  if (id != -1) {

    DateTime now = rtc.now();

    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("ID:");
    lcd.print(id);

    lcd.setCursor(0, 1);
    lcd.print(now.hour());
    lcd.print(":");
    lcd.print(now.minute());

    Serial.print("ID:");
    Serial.print(id);
    Serial.print(", Date:");
    Serial.print(now.day());
    Serial.print("/");
    Serial.print(now.month());
    Serial.print("/");
    Serial.print(now.year());
    Serial.print(", Time:");
    Serial.print(now.hour());
    Serial.print(":");
    Serial.println(now.minute());

    digitalWrite(buzzer, HIGH);
    delay(1000);
    digitalWrite(buzzer, LOW);

    delay(3000);
    lcd.clear();
  }
}

int getFingerprintID() {
  if (finger.getImage() != FINGERPRINT_OK) return -1;
  if (finger.image2Tz() != FINGERPRINT_OK) return -1;
  if (finger.fingerSearch() != FINGERPRINT_OK) return -1;

  return finger.fingerID;
}

7. Detailed Step By Step Code Working

Library Used
- Adafruit_Fingerprint.h for sensor communication
Enrollment
- Fingerprint scanned twice
- Stored in sensor memory
Recognition
- Finger scanned
- Compared with stored data
Matching
- If match → returns ID
Action
- Buzzer ON
- Attendance recorded in Serial Monitor

8. Tips

Store up to 1000 fingerprints (sensor dependent)
Clean sensor surface regularly
Use stable power supply
Assign unique IDs properly
Add RTC for date/time logging

9. Uses

School attendance system
Office biometric system
Access control systems
Secure authentication projects

10. Conclusion

The Arduino-Based Fingerprint Attendance System using R307 is a highly secure and efficient solution. It is easy to implement and can be upgraded with database, IoT, and cloud storage.

************************************************************************************************

12. For RTC Load this code first for settings up time

#include <Wire.h>

#include <RTClib.h>

RTC_DS3231 rtc;

void setup() {

Serial.begin(9600);

if (!rtc.begin()) {

Serial.println("RTC not found");

while (1);

}

// Set RTC time from computer

rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));

Serial.println("RTC Time Set!");

}

void loop() {}

How to setup RTC: Details are given in https://simplebasicelectronics.blogspot.com/2026/04/arduino-water-reminder-bell-system.html

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