The system uses optical fingerprint sensor and arm cortex m3 core stm32f205re, a 32-bit high-performance single chip microcomputer of Yifa semiconductor company, to form the functional main body. It uses Sobel edge detection operator, Gabor filter, image binarization and other image acquisition and processing algorithms to identify the fingerprint image, and constructs a small embedded fingerprint identification module with building block embedding, micro power consumption The program interface is simple and easy to use, convenient for secondary development, high recognition accuracy and high cost performance.

  System hardware circuit design

The whole system design constitutes an integrated optical fingerprint identification module. The module design adopts the principle of optical dark background imaging and adds a unique in vivo detection chip to solve the problems of residual fingerprint false identification and rubber false fingerprint while solving the dry finger effect.

The figure shows the application circuit schematic diagram of optical gc0307 CMOS image acquisition chip. The CMOS image acquisition chip is a built-in component of a high-performance camera with high precision, low power consumption and micro volume. It combines the CMOS image sensor for high-quality VGA image with a highly integrated image processor, embedded power supply and high-quality lens group to output JPEG image or image video stream, and supports 8 / 10 bit digital transmission of JPEG image and YCbCr interface, Provides a complete imaging solution.

  Circuit design of optical fingerprint identification system based on ARM

The function output serial data pin, clock signal pin, reset pin and serial bus pin of CMOS image acquisition core are connected to the GPIO port of stm32f205re, and the image information collected by CMOS chip is read through the analog timing of GPIO port. Since the working frequency of the GPIO port of stm32f205re can reach 120 MHz, it can simulate the timing very accurately and efficiently, and measure 640 × The original image of 480 can be collected into the main processor stm32f205re at the speed of 10 frames / s for image processing.

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