Arduino Projects

R557 Capacitive Fingerprint Sensor or Scanner with Arduino, Biometric Sensor

Biometric Door Lock using Arduino and R557 Fingerprint

R557 Capacitive Fingerprint Sensor:

R557 Capacitive Fingerprint Sensor

R557 Capacitive Fingerprint Sensor or Scanner with Arduino, Biometric Sensor- In today’s article, I am going to use R557 3.3V Capacitive Fingerprint Module with Arduino to control an Electronic Door Lock.So, for this project, you will need an Arduino Uno or Arduino Nano, the R557 Capacitive Fingerprint Module, a 12V Electronic Door Lock, and a relay module.

Since this is a getting-started tutorial, so I am going to cover

  1. The R557 Fingerprint Module Technical specifications
  2. Its wiring details
  3. It’s circuit diagram
  4. How to enroll and manage new fingerprints?
  5. Arduino Programming and
  6. Practical testing.

So, without any further delay, let’s get started!!!

Amazon Links:

Arduino Uno or

Arduino Nano

R557 Capacitive Fingerprint Module

12V Electronic Door Lock

One-channel Relay module

Other Tools and Components:

Top Arduino Sensors:

Super Starter kit for Beginners

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Digital Multimeter

Soldering iron kits

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R557 Capacitive Fingerprint Sensor:

R557 Capacitive Fingerprint Sensor

The R557 Fingerprint Sensor module is a compact and reliable biometric Sensor that can be used to secure doors or other access points. It can also be used in students and employees attendance systems. It’s a low-cost and low-power Fingerprint sensor.  It operates on a low voltage of 3.3V, making it ideal for battery-powered systems. It can be used with 5v and 3.3V compatible controller boards like Arduino, ESP32, STM32, ESP8266, Raspberry Pi Pico, and so on. With this Capacitive Fingerprint sensor, you can easily integrate biometric authentication into your projects.

Technical specifications:

Technical parameter:

Supply voltage: DC 3.3V
Supply current:
Working current: 30mA (typ.)
Peak current: 40mA
Fingerprint image entry time: <0.3 seconds
Collection window area: 12.8mm in diameter
Image pixel: 160*160 pixel
Image Resolution: 508dpi
Match method:
Comparison method (1:1)
Search method (1:N)
Storage capacity: 120 pieces
Security level: five (from low to high: 1, 2, 3, 4, 5)
False Recognition Rate (FAR): <0.0001%
Authentic rejection rate (FRR): <1.0%
Search time: <0.3 seconds (1:1000, average)
Host computer interface: RS232 (TTL logic level, 3.3V)
Communication baud rate: (9600?N)bps where N=1~12 (default value N=6, ie 57600bps)

Working environment:
Temperature: -20 to +45?
Relative humidity: 10%RH-85%RH (non-condensing)

There is an RGB Led inside this module. So, when the fingerprint sensor is ON it shows Blue light. When the Fingerprint scanning operation is successful it shows Green Light, and when the operation is failed, it shows Red light.

It includes a storage capacity of up to 120 fingerprints, a fast recognition speed of under 1 second, and a high-resolution image sensor that captures clear and accurate fingerprints. For more technical specifications read my article available on

R557 Capacitive Fingerprint Sensor Pinout:


1 VT Finger detection

2 Out IRQ

3 VCC 3.3

4 TX 3.3 Logic level

5 RX 3.3 Logic level


R557 Capacitive Fingerprint Sensor wiring details

1st wire is the VT. This is the Finger Detection power and this wire is connected with the 3.3V.

2nd wire is the IRQ. This is the Finger detection signal wire. When there is a finger, it outputs a high signal.

3rd wire is the VCC and it should be connected with 3.3V.

4th and 5th wires are TXD and RXD, both are 3.3V TTL logical level. And

6th wire is the GND and it should be connected with the ground.

Now, let’s go ahead and take a look at the circuit diagram.

R557 Capacitive Fingerprint Sensor with Arduino:

R557 Capacitive Fingerprint Sensor interfacing with arduino

The VT and VCC wires of the R557 Capacitive Fingerprint sensor are connected with the Arduino 3.3V. The IRQ wire is left unconnected. The TXD and RXD wires are connected with the Arduino pins D2 and D3. And the ground wire is connected with the Arduino ground.

The one-channel Relay module is connected with the Arduino pin 13. And on the Left side is the 5V regulated power supply based on the Linear voltage regulator 7805.

Fingerprint Library Installation:

Now, the next step is to install the Arduino Library for the R557 Capacitive Fingerprint Sensor.

For this, open the Arduino IDE. Click on the sketch Menu, go to Include Library, and then click on manage libraries.

adafruit sensor library installation for R557 Capacitive Fingerprint Sensor

Search for the Adafruit Fingerprint.

adafruit sensor library installation for R557 Capacitive Fingerprint Sensor

Click on the install button.

adafruit sensor library installation for R557 Capacitive Fingerprint Sensor

You can see my Adafruit Fingerprint Sensor Library is now installed.

Next, for the Fingerprint enrollment connect your Arduino board with the Laptop/PC and Upload the following sketch into the Arduino Uno or Arduino Nano.

Fingerprint Enrollment Code:

After uploading this code; next open the serial monitor and follow the instructions. If you find it difficult to enroll your fingers then you can follow my video tutorial given at the end of this article. Anyway, I enrolled two fingers “the forefinger and the middle finger” I assigned 3 as an ID to the forefinger and 4 as an to my Middle finger.

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After, enrolling all your fingers. Next, download the following code, and replace my finger ids with yours.

Capacitive Fingerprint Sensor Final Code:

This is the Final Code that I use to lock and unclock the Electronic Door Lock. Let me show you how I used the IDs.

If finger.fingerID == 3 then open the lock. And if you remember 3 is the ID of my forefinger. And similarly, if finger.fingerID == 4 then close the electronic lock. And you know 4 is the ID of my middle finger.

I have already uploaded this program and now let’s watch this Capacitive Fingerprint sensor and Electronic Lock in action.

electronic door lock control with R557 Capacitive Fingerprint Sensor and arduino

Blue light means the sensor is ON and you can place your finger. Right now, you can see the Lock is closed.

R557 Capacitive Fingerprint Sensor

The green color means the finger is successfully scanned and you can see the Electronic Door lock is unlocked. If you see the Red color then it means you are scanning the wrong finger. For the practical demonstration watch the video tutorial given below.

With its low power consumption, fast recognition speed, and easy-to-use software, it is a great choice for both hobbyists and professionals. So, that’s all for now.

Watch Video Tutorial:

Engr Fahad

My name is Shahzada Fahad and I am an Electrical Engineer. I have been doing Job in UAE as a site engineer in an Electrical Construction Company. Currently, I am running my own YouTube channel "Electronic Clinic", and managing this Website. My Hobbies are * Watching Movies * Music * Martial Arts * Photography * Travelling * Make Sketches and so on...

One Comment

  1. Thank you for the amazing tutorial. I want to connect two fingerprint sensors to the same hardware serial. And when I use one sensor, the other would be inactive anyway, so it won’t interfere with the setup and should behave like your demonstration. I can not get it to work. Could you help me modify the code to get that to work? Thank you very much

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