Introduction: Arduino Based Fingerprint Machine

Hi Guys,

I have made a fingerprint machine at home using Arduino and Adafruit fingerprint sensor.

This fingerprint sensor will verify the authorized (pre-saved) users, indicate a green LED and display an authorization approval.

For non authorized fingerprints it will give you a red LED indication.

In this tutorial I will explain it step by step.

It will take some attention and dedication to you to complete this task.

Check out my DIY video on how I did it below:

(The sponsors of the video is JLCPCB, Leading PCB manufacturing company from China, where I got my PCB design manufactured. you can find them here: You may make a PCB board, or use a dot board or bread board depending on your preferences.)

Step 1: Things You Need

Here are the things you need:

1. Adafruit fingerprint sensor

2. Arduino development board

3. LCD display + I2C module

4. Red and Green LEDs (1 from each)

5. Enclosure

6. Jumper wires etc.

Step 2: Connection

Please find the connection diagram in the link below:

Note: The fingerprint sensor connections are made here for the Arduino Nano board (we use D0, and D1).

But if you are using some other versions of Arduino board the pins will probably be different. You have to find the software serial pins of the board and connect the RX with the TX of fingerprint sensor and connect the TX with the RX of fingerprint sensor. Then you have to modify it in the coding as well.

I strongly prefer you to watch the below video to understand how to do it.

Step 3: Connection Cont...

If you done with connecting the fingerprint sensor, then follow connecting the LCD display + I2C module as mentioned in the connection diagram that was provided in the previous step.


As given...

VCC - Arduino 5V pin
GND - Arduino ground pin

SDA - Analog Pin A4 of Arduino nano (if you are using some other arduino board, the pin may change. Google it in such a case).

SCL- Analog Pin A5 of Arduino nano (if you are using some other arduino board, the pin may change. Google it in such a case).

Then connect the Red and Green LEDs as mentioned in the provided connection diagram.

Step 4: Coding

There are some important things to understand in this section.

Before you upload the coding of the fingerprint sensor, Let's fix the LCD+I2C coding issues, if there is any.

1. If you are using my coding, then you need to download and save the following I2C library:

Please watch this video and read out the description box of the video also for doing it correctly and error fiixing.

Even some new I2C versions may not support the library. In such case, you have to first find our the related library, and fix your I2C+LCD display to working. Then you have to modify the I2C part of my coding. that would require some skills, But can be done successfully with some more efforts!!!

Step 5: Coding Cont...

Well, If you are successful with the I2C and LCD part, fine. If your I2C version is different and you now made it worked with appropriate libraries and all, then you have to modify and fix it in the final coding I will provide you in next step.

Now Let's jump into the fingerprint module work.

Before uploading my final coding to your device, You have to enroll your authorized fingers right?

That is very essential!

For this purpose I strongly recommend you to watch the below videos:

If you have watched them, you can successfully enroll the authorized fingers now.

So now find the adafruit fingerprint sensor library here:

Please copy this library also and save it inside arduino libraries.

Now, here is the coding for enrolling the fingers as mentioned in the above videos (you can find it in the description box of the videos as well):

Now you are all good to enroll the fingers using your serial monitor!!!

Step 6: Coding Cont... & Demonstration!

If you have successfully come through all the above steps, now the things will be a piece of cake for you.

You have all the related libraries downloaded, and you have fixed the LCD+I2C issue (if there was), and your fingerprint sensor also working fine.

Now this is the Final coding for verifying the fingerprints using the fingerprint machine:


Well, sometimes you may have to edit the LCD+I2C part if you are using another version of the I2C module... If you have made your LCD display + I2C module working in the previous steps, then editing that part in the final coding will be a piece of cake for you.

So, all set. Now you can fix things inside an enclosure, provide power, and you will be able to verify the fingerprints of authorized persons!!!

I strongly recommend you to watch my DIY video on how I did it, so that you can make it crystal clear!!!

Good Luck!!!