FINGERPRINT Click

How does it work?

FingerPrint Click is based on the GTS-511E2 module, one of the world's thinnest optical touch fingerprint sensors, from ADH Technology. It is one of the simplest ways to integrate biometric security into your design, where the fingerprint takes a digital image of the fingerprint pattern using visible light. The Fingerprint Click features a VGA CMOS image sensor in a plastic housing with image resolutions of 860 DPI for VGA, with an effective sensing area of just 12 x 14mm and very low TV distortion. The image sensor has an 8bit/pixel image grayscale, with a maximum 256 gray level. Considering how dark it is when a finger presses the lens, an LED illuminates it from one side while the other sends the image through the lens to the processor.

This Click board™ carries an STM32F415RG MCU for processing the images and forwarding them to an external MCU or a PC. One of two interfaces can be used with the host MCU over the mikroBUS™ socket, SPI or UART, where an SPI serial interface is predefined. Also, the STM32 has its data-ready pin labeled as RDY and routed to the AN pin of the mikroBUS™ socket used as an interrupt to inform our host MCU when it has data ready for further processing. Alongside a Reset button for the general reset feature of the FingerPrint Click, there are also two LED indicators, DATA and STAT, for status indication, a JTAG header for upgrading an STM32 MCUs firmware, and an unpopulated GPIO header that gives access to I2C, SPI, and UART interfaces of the companion STM32 MCU.

The onboard STM32 MCU comes with the USB HID Bootloader that comes in handy for using this board as a stand-alone device, along with the Mini-B USB connector and our created application available on Libstock. After five seconds, the PC will recognize this Click board™ as Mikroe’s USB HID Bootloader when connected to the PC. The following steps describe how the application works:

• Place your finger on the sensor on the Click
• Press the button at the bottom left corner of the screen
• After you see the image of your fingerprint, press the button at the bottom right corner of the screen to save the image. If you want to add more fingerprint images, repeat the process.

The application offers different CMOS image sensor settings, such as exposure or global gain.

This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. However, the Click board™ comes equipped with a library containing functions and an example code that can be used, as a reference, for further development.

Specifications

Pinout diagram

This table shows how the pinout on FINGERPRINT Click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
STM32 Data Ready	RDY	1	AN	PWM	16	NC
	NC	2	RST	INT	15	NC
SPI Chip Select	CS	3	CS	RX	14	TX	UART TX
SPI Clock	SCK	4	SCK	TX	13	RX	UART RX
SPI Data OUT	SDO	5	MISO	SCL	12	NC
SPI Data IN	SDI	6	MOSI	SDA	11	NC
Power Supply	3.3V	7	3.3V	5V	10	NC
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

FINGERPRINT Click electrical specifications