Biometric technology is the use of the human body's inherent physiological characteristics (such as fingerprints, facial images, red film, etc) and behaviors (such as writing, sound, gait, and so on) for the identification of personal identity.
Biometric technology than traditional authentication methods for more security, privacy and convenience.
Biometric technology has not forgotten, security performance fine, difficult to counterfeit or stolen, along with "portable" and where available, etc.Biometric works is the use of biometric devices on biometric sample, extract the unique characteristics and translating it into digital code and further integrate these characteristics of template code that people interact with identification device for authentication, identification device gets its characteristics and the characteristics of the database template on, to determine whether the match to decide to accept or reject the person.
But many are used for authentication of biometric technology, fingerprint identification technology is by far the most convenient, reliable and non-infringement and inexpensive solutions.Fingerprint as the human body in the most obvious appearance features, have a unique, universal, uniqueness, ease of acquisition, and other advantages.
Fingerprint identification technology utilizing human fingerprint stability and unique physiological characteristics, as it's a kind of "Live ID", and fingerprint irreplaceable nature, the adoption of the fingerprint identification security greatly increased, and as the image processing pattern recognition methods for developing and maturing of the fingerprint sensor technology, fingerprint identification methods in the financial, public security, access control, household management and other areas with good prospects. Fingerprint capture relatively easy; fingerprint recognition algorithm has been more mature. Because the fingerprint with the fingerprint scanning speed, convenience, miniaturization and other advantages of fingerprint recognition technology has gradually entered the civil market, and applied to many embedded devices, but how do you improve fingerprint recognition system of recognition and stability, lower costs, and extending stability and node distribution, there is a range of technology challenges.Therefore, this article examines the contents of the AT91SAM7X256 CPU arm core as the core, external extension MBF200 fingerprint sensor constitute fingerprint recognition server hardware, system software portable real-time multi-tasking operating systems μ C/O S-Ⅱ, file system, application software implementation LwIP, fingerprint recognition.
The method has a low cost, small footprint, scalability is stronger.1 principle of distributed fingerprint recognition system and hardware design
Fingerprint identification technology is primarily concerned with four modules: read fingerprint image, extract features, save data and comparison.
Read through the fingerprint reader device to a human fingerprint image, and then on the preliminary processing of the original image to make it more clear, and then through fingerprint recognition software to establish the characteristics of fingerprint data. Find the software from the fingerprint is called "node" (minutiae) data point, namely the fingerprint ridge bifurcation, terminated or loop the coordinates for the location at which point both the uniqueness of 7 above. Usually finger average has 70 nodes, so this method will produce approximately 500 data. These data, commonly referred to as the template. Fuzzy comparison of a computer. Put two fingerprint templates to calculating their similarity, the resulting two fingerprint matching results.Hardware circuit realization to the microprocessor AT91SAM7X256, peripheral circuits include MBF200 fingerprint identification module, Ethernet physical layer (PHY) transceiver RTL8201BL, large-capacity data FlashAT45DBl61D, hardware calendar clock devices DSl302, power circuits, a reset and clock circuit, as shown in Figure 1.
1.1 AT91SAM7X256 devices and application MBF200 module
ATMEL company launched AT91SAM7X256 is based on a 32-bit ARM7TDMI microprocessors.
It's a chip also integrates 256 kh on-chip Flash and 64 KB of SRAM, no need for external memory expansion. There are also integrated within the device port, USB2.0, as well as a wealth of on-chip peripherals resources, powerful. AT9lSAM7X256 reset controller can manage chip power-on sequence and the entire system. Microcontrollers with embedded 10/100 Mb/s Ethernet MAC (Ethernet), CAN, full-speed (12 Mb/s) USB2.0, extensive network of real-time embedded systems design, its performance is stable, powerful, can be widely used in protocol conversion, telecommunications, industrial control field. Application development AT91SAM7X256 fingerprint recognition system can effectively controlling costs. Industrial network stability needs to be strong, but the experiment proves that more than 60 per cent of bus bandwidth usage will cause conflict.Fujitsu MBF200 is the launch of an advanced solid-state fingerprint sensor, it can automatically detect fingerprints, but also with various interface modes, capacitive sensors, capacitive sensor array consists of two metal electrodes, all metal electrode capacitor plate, acts as a contact fingers as 2nd capacitor plate, the device surface passivation layer as the two plates of insulating layer.
When your finger touches the sensor surface, fingerprint of uneven in sensor arrays produce changes in capacitance on, thus giving rise to a two-dimensional array voltage changes, and fingerprint sensor image. The use of standard C13MS technology with solid state devices, capacitive 500 dpi resolution, the sensor area of 1.28 cmxl.50 cm. Automatic fingerprint detection capability, containing 8-bit ADC, offers 3 types of bus interface. 5 V operating voltage of power consumption less than 70 mW.1.2 Ethernet interface circuit design
AT91SAM7X256 internal integration with MAC controller that can support the MII interface and RMII interfaces.
RTL820lBL is the industrial-grade with MII interface 10/100 Mb/s, low power Ethernet transceiver, 25 MHz clock output, reduced power mode, the intelligent system provides reliable high-quality network solutions, factories and enterprises and other harsh operating environment set up to support real-time transmission of Ethernet, IEEE 802.3u technical standards. Ethernet interface circuit schematic diagram shown in Figure 2.2 distributed fingerprint recognition system software design
2.1 μ C/O S-Ⅱ system transplant
[1] [2]
No comments:
Post a Comment