How to Use Fingerprint Scanner: Examples, Pinouts, and Specs

A fingerprint scanner is an electronic device that captures a digital image of the fingerprint pattern. This image is processed by the scanner's software to create a biometric template, which can be used to identify or authenticate the individual. Fingerprint scanners are widely used in security systems, access control, time attendance systems, and more recently in mobile devices for unlocking and transactions.

• Security and access control systems
• Time and attendance tracking
• Mobile device unlocking and authentication
• Secure transactions and payment systems

• Supply Voltage: Typically 3.3V to 6V
• Operating Current: 20mA (average)
• Peak Current: 50mA (during fingerprint capture)
• Communication Interface: UART (TTL Serial)
• Resolution: 500 DPI (dots per inch)
• Image Capture Area: 15.5mm x 18.0mm
• Enrollment Time: < 2 seconds per fingerprint
• Matching Time: < 1 second
• Storage Capacity: Varies by model (e.g., 1000 fingerprints)
• False Acceptance Rate (FAR): < 0.001%
• False Rejection Rate (FRR): < 1.0%

1. Power Connection: Connect the VCC pin to a 3.3V or 5V power supply, and the GND pin to the ground.
2. Data Connection: Connect the TX and RX pins to a microcontroller or computer capable of UART communication.
3. Initialization: Upon power-up, the fingerprint scanner will perform a self-check and be ready to receive commands.

• Ensure that the power supply is stable and within the specified voltage range.
• Avoid static discharge by grounding yourself before handling the scanner.
• Keep the fingerprint scanner's surface clean and free from dust or oil.
• When enrolling fingerprints, ensure that the finger is placed squarely on the sensor for best results.
• Use UART libraries or modules that support the scanner's communication protocol.

#include <SoftwareSerial.h>

SoftwareSerial mySerial(10, 11); // RX, TX

void setup() {
  Serial.begin(9600);
  while (!Serial); // Wait for serial port to connect
  mySerial.begin(57600); // Set the baud rate for the fingerprint scanner
  Serial.println("Fingerprint Scanner ready.");
}

void loop() {
  if (mySerial.available()) {
    Serial.write(mySerial.read()); // Forward what the fingerprint scanner sends
  }
  if (Serial.available()) {
    mySerial.write(Serial.read()); // Forward what we receive on the serial monitor
  }
}

• Scanner not recognized: Ensure that the wiring is correct and the power supply is within the specified range.
• Poor fingerprint recognition: Clean the scanner surface and try re-enrolling the fingerprint.
• Communication errors: Verify the baud rate and the UART connections.

• Double-check all connections and ensure that the pins are not shorted.
• If using a breadboard, ensure that all connections are secure and not loose.
• For communication issues, use a logic analyzer or oscilloscope to verify the UART signals.

Q: Can the fingerprint scanner work with a 5V system? A: Yes, most fingerprint scanners are designed to work with both 3.3V and 5V systems.

Q: How many fingerprints can the scanner store? A: It depends on the model, but a common capacity is around 1000 fingerprints.

Q: What is the best way to enroll a fingerprint? A: Place the finger flat and squarely on the sensor, and follow the enrollment process as per the scanner's instructions. It may require multiple touches to capture different angles of the fingerprint.

Q: How secure is the fingerprint scanner? A: Fingerprint scanners are generally secure, with a low false acceptance rate. However, the overall security also depends on the implementation of the system using the scanner.