GT-521F32 - Finger Print Sensor Module

Description of GT-521F32 Sensor

The GT-521F32 fingerprint sensor is an optical sensor with a 258x202 pixel resolution. The sensor module has a 32- bit microcontroller based around the ARM cortex processor core to analyze the data. It can be interfaced with products using the UART communication protocol. The GT module also has a function to be wakened up, when a finger is placed onto the metal frame around the fingerprint sensor.

 

Features and Specifications of GT-521F32 Sensor

Below are some of the mentioned Features and Specifications of the Fingerprint sensor module:

1. Integrated CPU: ARM Cortex M3 core
2. Operating voltage: 3.3V-6V
3. Maximum operating current: 130mA
4. Window Size: 16.9x12.9 (Effective sensor window: 14x12.5)
5. Image Size: 258x202 pixel
6. Resolution: 450dpi
7. Maximum number of fingerprints: 200 fingerprints
8. Communication Interface: UART & USB 2.0
9. Identification Time: <1.5 sec

 

Pin Configuration of GT-521F32 Sensor

The GT-521F32 sensor module has two connection ports, one for communication (Left side from top view) and the other one for the touch IC connector (Right side from top view).

 

UART Connector

Pin Type	Description
TX	Transmitting serial data
RX	Receiving serial data
GND	Ground
VCC	Input Voltage(3.3V-6V)

 

Touch IC Connector

Pin Type	Description
VCC	Input Voltage
GND	Ground
ICPDA	Program Mode: In-circuit programming data/address pin
ICPCK	Program mode：In-circuit programming clock pin Normal mode：It could be the wake-up function from touch IC to VIL

 

Alternatives for GT-521F32 Sensor

AS608, SEN0348, SEN0359, R307, R503, Adafruit AT42QT1012

 

Equivalent of GT-521F32 Sensor

GT-521F52 (Can store up to 3000 fingerprints)

 

Note: More technical information can be found in the GT-521F32 Datasheet linked at the bottom of this page.

 

Working of the GT-521F32 Sensor

A Fingerprint sensor is an optical sensor. It works by flashing a bright light over your finger and capture a digital picture of your fingerprint. The light-sensitive microchip converts the digital image into a series of 0’s and 1’s by checking the ridges(peaks) and valleys(gaps) of the fingerprint. The series of 1’s and 0’s generated is individual to every person which creates a unique ID for every fingerprint.

 

Connecting the GT-521F32 sensor with the MCU/MPU

A 4 pin JST-SH connector is used to connect the sensor module to an MCU/MPU. There is a polarity indicator next to the JST-SH connector for a distinction of the pin terminal. The connector breaks out the pins for power and UART communication. You will need a logic level converter or a voltage divider to safely communicate with the 5V device.

Note: While using the module with a 5V Arduino, make sure to use either a dedicated logic level converter or a voltage divider circuit using resistors.

 

Touch State Monitoring Statuses

The sensor module has the feature of auto wake up whenever a finger is placed over the window or the metal frame.

To use this functionality, you need to connect three pins from the Touch IC connector; VCC(+3.3V), Ground, and the ICPCK pin. The ICPCK pin provides an output (Low or High) based upon the placement of the finger onto the touchpad(metal frame). The VCC pin of the GT module can be connected to the 3.3V pin of the microcontroller, the ground pin of the module to the ground of the MCU, and the ICPCK can be connected to any digital pin on the MCU/MPU.

 

The table below mentions the status of the ICPCK pin after the different positions of the finger placed on the metal case.

Touch State	ICPCK Pin Status
Finger initially touching the metal frame	Low → High
No finger touching the frame	Low → Low
Finger touching the frame	High → High
Removing finger from the frame	High → Low

 

Applications of GT-521F32 Sensor

Here are some of the application where the GT-521F32 sensor can be used:

1. Security systems
2. School Attendance system
3. Home/Office Locks
4. Biometrics
5. Smartphone unlocking

 

2D model of GT-521F32 Sensor

Below is the 2D model of the GT-521F32 Sensor, All the dimensions are in millimeters. The dimensions can be used to create custom footprints to design your own PCB or CAD models.