Fingerprint Scanner (GT-521Fxx) Hookup Guide

Contributors: bboyho
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Hardware Overview


The GT-521F32 and GT-521F52 have a lot in common with the previous models. They have the same protocol commands and packet structure. Code that was implemented for previous models should be functionally the same. The fingerprint scanner has the ability to:

  • Enroll a Fingerprint
  • Identify a Fingerprint
  • Capable of 360° Recognition

However, there are a few differences in the boards. These include:

  • Different Board Layout
  • 4x Mounting Holes
  • 2x JST SH Connectors
  • Touch Interface

One significant difference to keep in mind when integrating the fingerprint scanner in a project is the number of fingerprints that the device can hold. The GT-521F32 costs less but it can hold only 200 fingerprints. The GT-521F52 is slightly more expensive but it can hold 3000 fingerprints.

Technical Specs GT-521F32 / GT-521F52
CPU ARM Cortex M3 Cortex
Sensor optical
Window 16.9mm x 12.9mm
Effective Area of the Sensor 14mm x 12.5mm
Image Size 258x202 Pixels
Resolution 450 dpi
Max # of Fingerprints 200 / 3000
Matching Mode 1:1, 1:N
Size of Template 496 Bytes(template) + 2 Bytes (checksum)
Serial Communication UART (Default: 9600 baud) and USB v2.0 (Full Speed)
False Acceptance Rate (FAR) < 0.001%
False Rejection Rate (FRR) < 0.01%
Enrollment Time < 3 sec (3 fingerprints)
Identification Time <1.5
Operating Voltage 3.3V ~ 6Vdc
Operating Current < 130mA
Touch Operating Voltage 3.3Vdc
Touch Operating Current < 3mA
Touch Standby Current < μ5

The image below shows the fingerprint scanner's optical sensing area where the device will be able to scan your fingerprint.

Fingerprint GT-521Fxx Optical Sensing Area

There is a marking next to the JST-SH connector that indicates polarity. The JST-SH connector breaks out the pins for serial UART and power. While the input voltage is between 3.3V and 6V, the UART's logic level is only 3.3V. You will need a logic level converter or voltage divider to safely communicate with a 5V device.

Fingerprint GT-521Fxx Power and Serial UART Connector Pinout

Fingerprint Touch Interface

The GT-521F32 and GT-521F52 have the ability to sense if a finger is placed on the optical sensing area. Upon contact with the metal frame around the optical sensing area, the ICPCK will output 3.3V (HIGH). Otherwise, the ICPCK will be 0V (LOW)

Touch State ICPCK Pin Status
Finger Initially Touching the Frame LOW => HIGH
No Finger Touching LOW => LOW
Finger Touching the Frame HIGH => HIGH
Removing a Finger From the Frame HIGH => LOW