Fingerprint Scanner - TTL (GT-521F32)

Fingerprint scanners are awesome! Why use a key when you have one right at the tip of your finger? Unfortunately, they're often unreliable or difficult to implement. Well not anymore! This great GT-521F32 fingerprint module from ADH-Tech communicates over TTL Serial so you can easily embed it into your next project. The module itself does all of the heavy lifting behind reading and identifying the fingerprints with an onboard optical sensor and 32-bit ARM Cortex M3 processor.

To get started, just register each fingerprint that you want to store by sending the corresponding command and pressing your finger against the reader three times. The fingerprint scanner can store different fingerprints, and the database of prints can even be downloaded from the unit and distributed to other modules. In addition to the fingerprint "template," the analyzed version of the print, you can retrieve the image of a fingerprint and even pull raw images from the optical sensor!

This module is the economical version of the GT-521F52 and can store up to 200 different fingerprints. It is capable of 360° fingerprint recognition and download/upload templates using serial interface. Additionally, the GT-521Fxx series features a resolution of 450dpi, with a false acceptance rate of <0.001% and a false rejection rate of <0.1% while only needing <1.5 seconds to identify a unique fingerprint!

The module is small and easy to mount using four mounting holes surrounding the sensor. The onboard JST-SH connector has four signals: Vcc, GND, Tx and Rx. A compatible JST-SH pigtail can be found in the Hookup Accessories section below.

Note: Please be aware that even though this fingerprint scanner is equipped with the same connector we use on all of our Qwiic boards, it is NOT Qwiic or I2C compatible. That being said, all of our Qwiic cables, like our 100mm version, will work for this board.

  • Simple UART & USB communication protocol
  • Complies with USB 2.0 full-speed specification
  • Ultra-thin optical sensor
  • Resolution 450dpi
  • Capable of 360° recognition
  • Storage for 200 unique fingerprints
  • Wake up on Finger Function
  • Works well with dry, moist or rough fingerprints
  • Anti-scratch with surface high hardness ≧ 5H
  • 1:1 verification, 1:N identification
  • High-accuracy and high-speed fingerprint identification technology
  • 4x mounting holes
  • 2x JST SH connectors

Fingerprint Scanner - TTL (GT-521F32) Product Help and Resources

Fingerprint Scanner (GT-521Fxx) Hookup Guide

March 1, 2018

This tutorial provides information about how to connect to ADH-Tech's fingerprint scanner (GT-521F32) and how to use it with Hawley's FPS_GT511C3 library for Arduino.

Core Skill: Programming

If a board needs code or communicates somehow, you're going to need to know how to program or interface with it. The programming skill is all about communication and code.

2 Programming

Skill Level: Rookie - You will need a better fundamental understand of what code is, and how it works. You will be using beginner-level software and development tools like Arduino. You will be dealing directly with code, but numerous examples and libraries are available. Sensors or shields will communicate with serial or TTL.
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Core Skill: Electrical Prototyping

If it requires power, you need to know how much, what all the pins do, and how to hook it up. You may need to reference datasheets, schematics, and know the ins and outs of electronics.

1 Electrical Prototyping

Skill Level: Noob - You don't need to reference a datasheet, but you will need to know basic power requirements.
See all skill levels


Looking for answers to technical questions?

We welcome your comments and suggestions below. However, if you are looking for solutions to technical questions please see our Technical Assistance page.

  • Member #1504914 / about 5 years ago / 1

    Can I use it with Hardware Serial on the ESP32 and program it on Arduino IDE?

  • LJC41 / about 5 years ago / 1

    is there a way using arduino code to put it in standby? Im using the FPS_GT511C3 library and it doesnt appear to be a function to do this but the data sheet shows there is a stanby. With an arduino pro mini and Fingerprint Scanner - TTL (GT-521F32), im drawing around 100 mA continuously and im worried about battery drain being to fast. The FPS is drawing about 70 mA alone. Any help or pointing me to a website would be greatly appreciated!!

  • Member #1417765 / about 6 years ago * / 1

    I probably missed it or it's assumed and stupid to ask, but ... what memory type stores fingerprints? Do I need to re-enroll all the fingerprints after power shutdown? Thanks UPDATE: It does ... found it on your great youtube video :)

    • Member #57306 / about 5 years ago * / 1

      Clarification, in case the following is an issue for anyone: First- YES, it remembers the "fingerprints" you asked it to, even across the power going off and then on again. BUT: It is NOT storing images of the fingerprint. It does a mathematical thing when you show it a fingerprint, and it remember the result of that. When you later show it a new fingerprint scan, and ask "do you know this?", it does the mathematical thing again, and checks the answer obtained from the new scan to the answers from old scans. It only stores the answer from the "thing".... BUT, BUT.... Yes: It CAN "give you" a copy of a scan, a copy of the raw image, as captured. (Being able to see the raw images is very useful when you are learning how to "do it".) And you can save that. But the device is not storing the fingerprints, in their raw form.

Customer Reviews

4.7 out of 5

Based on 7 ratings:

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1 of 1 found this helpful:

Nice little piece of hardware

Works exactly as described. My only complaint is with the hookup instructions/tutorial. The instructions should mention that when the device is correctly hooked up, it will not give any indication that it is ready to go. You need to run a sketch on it (e.g. FPS_Blink.ino) before it shows any signs of life. I spent an inordinate amount off time fiddling with the wires before realizing I needed to run a sketch. Maybe its just my inexperience talking. But a little LED somewhere would be a nice touch.

1 of 1 found this helpful:

Simple to set up and Easy to use

My son just started 7th grade STEM. In the second week of school, they were asked to redesign a product to make it simpler or better. He chose to make a fingerprint ID padlock. Without much experience in electronics, he was able to follow the tutorial for this fingerprint scanner and connect it to his Redboard that he got last Christmas. He added a servo and within a couple of hours he was able to make a working prototype that would automatically lock the shackle and unlock only with a recognized print - A+ all the way!

Good quality

Receive after 9 days in Rwanda

Works as advertised.

I've run this with the SDK and it is easy to program and seems to detect my finger consistently should be easy to add to a project. I didn't see the need for more than 32 fingers but you could exceed that number quickly if multiple people, hands and fingers are programmed so it might be worth getting the one with larger memory.

Works great!

The fingerprint scanner works great! I am using it with the 5 volt pro micro with a level translator and an extra power supply to convert 5 volt to 3.3 volts. I would recommend getting the 3.3 volt pro micro and you wouldn't have to do any level translation that way.

Pretty darn Reliable

I started building a Nerf gun armory that was fingerprint locked for my boys with the Adafruit scanner and results were very spotty. It worked okay, but sometimes took a frustrating amount of scans before working. Nothing against that product, I probably don't have the coding clout to really dive in and tweak it. I switched over to this and it seems much more reliable (or at least simplified). Only difference between the two is that this one required the logic level converter where as the other did not.

Easy to use

I’m a noob so I loved how simple it was to follow the hookup guide. It is fast and accurate.