Situatie

Required Components

Component	Quantity	Description
Arduino Uno / Nano / Mega	1	Main controller
Fingerprint Sensor (R307 / ZFM-20 / Adafruit)	1	Biometric identification
16×2 LCD with I2C Module	1	Display user messages
12V Solenoid Lock	1	Door/box locking mechanism
5V Relay Module	1	Controls solenoid lock
12V Power Supply	1	Powers solenoid
Jumper Wires	–	Connections

The fingerprint sensor scans the user’s finger. Arduino checks if the fingerprint matches a stored ID. If it matches, the relay is activated and unlocks the solenoid lock. The LCD shows:

• Scanning
• Access Granted
• Access Denied

Fingerprint Sensor → Arduino

VCC → 5V
GND → GND
TX  → D2
RX  → D3

I2C LCD → Arduino

VCC → 5V
GND → GND
SDA → A4
SCL → A5

Relay Module → Arduino

IN  → D8
VCC → 5V
GND → GND

Solenoid Lock Power Wiring

12V+ → COM on Relay
NO   → Solenoid +
Solenoid - → 12V -

IMPORTANT: Use a diode (1N4007) across solenoid terminals to prevent voltage spikes.

Arduino Code (Copy & Paste)

This code controls the fingerprint module, LCD display, and solenoid lock.


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

SoftwareSerial fingerSerial(2, 3); // RX, TX
Adafruit_Fingerprint finger = Adafruit_Fingerprint(&fingerSerial);
LiquidCrystal_I2C lcd(0x27, 16, 2);

int relayPin = 8;

void setup() {
lcd.init();
lcd.backlight();

pinMode(relayPin, OUTPUT);
digitalWrite(relayPin, LOW); // lock OFF at start

lcd.setCursor(0, 0);
lcd.print("Fingerprint");
lcd.setCursor(0, 1);
lcd.print("Access System");

delay(2000);
lcd.clear();

finger.begin(57600);
if (finger.verifyPassword()) {
lcd.print("Sensor Ready");
} else {
lcd.print("Sensor Error");
while (1);
}
delay(2000);
lcd.clear();
}

void loop() {
lcd.setCursor(0, 0);
lcd.print("Place Finger...");
lcd.setCursor(0, 1);
lcd.print(" ");

int result = getFingerprintID();

if (result >= 0) {
lcd.clear();
lcd.print("Access Granted");
unlockDoor();
} else if (result == -1) {
lcd.clear();
lcd.print("Access Denied");
delay(1500);
}

lcd.clear();
}

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

return finger.fingerID; // valid ID returned
}

void unlockDoor() {
digitalWrite(relayPin, HIGH); // open lock
delay(3000); // unlock duration
digitalWrite(relayPin, LOW); // lock again
}


You must add fingerprints before using the system.

1. In Arduino IDE, go to File → Examples → Adafruit Fingerprint Sensor Library → Enroll
2. Upload the sketch
3. Open Serial Monitor
4. Type the fingerprint ID number (1–127)
5. Place finger twice when instructed

Fingerprint is now stored.

LCD Display Messages

Event	Message
Startup	Fingerprint Access System
Ready	Sensor Ready
Waiting	Place Finger…
Match	Access Granted
No Match	Access Denied

Troubleshooting

• Fingerprint not detected: TX/RX wiring reversed
• LCD not showing text: Wrong I2C address (try 0x3F)
• Solenoid not activating: Check relay NO/COM wiring
• Machine resets: Solenoid drawing current — use separate 12V supply.

Solutie

Tip solutie

Permanent