Hardware design of embedded fingerprint identification system

Zhang Jinhai

Marine college

Shandong jiaotong university

Weihai ,China

e-mail: zhangjinhai76@163.com

Abstract—In the modern age, people enjoy the advantages coming from the information technology. At the same time, all kinds of problems of information security appear. Those methods which are used to identify someone’s status according to his marker or knowledge have been limited. Thereby, some new techniques based on biological characteristics, especially the fingerprint identification, have been developed quickly.

Keywords- embedded auto fingerprint identification system; PDIUSBD12; USB Interface

I. INTRODUCTION Today's society, along with the rapid development of

economy and technology, digital, network, information and constantly enhance the level of authentication accuracy, security, have put forward higher requirements. Tradition, by token, documents, passwords and other measures to verify the identity of means, more and more unable to meet the modern needs of secure and reliable authentication. Token, the file may be stolen, the password may be forgotten or crack, the study was verified according to the person themselves, and can provide safe and reliable method of authentication is necessary.

Biometrics is used for authentication and automatically measured their physical characteristics or personal behavioral traits, and these features or characteristics of the template database to compare the data to complete the certification of a solution. That is, a "possess your own" (biometric) identity verification methods, so far a "you have" (token, file, etc.) and "you know" (such as user name, password, etc.) authenticate more reliable, more secure.

Used for biometric identification, and stability must be unique in nature. Research and experience show that people's fingerprints, palm prints, face, voice, iris, retina and so has the uniqueness and stability of the features that each person these characteristics are different from others, and life change, so you can identity of the person identified accordingly. Based on these characteristics, people developed a fingerprint identification, face recognition, voice recognition and other biometric technology, many current technologies are maturing and can be applied. Commonly used in a variety of biometrics technology, system recognition accuracy and achieve cost comparisons shown in Table 1.

Fingerprint biometric technology is the most thoroughly studied in school, the most widely used to develop the most mature technology. Fingerprint is the end of the front finger uneven skin texture, the lines in the patterns, breakpoints and crossover points are different, and based on the uniqueness of these different characteristics, we can put a man with his finger the corresponding up, by comparing his fingerprint characteristics and pre-stored fingerprint characteristics, to verify his true identity, that is what we call the fingerprint identification technology.

Table 1 Comparison of various biometric technologies

Type Identification reliability

1: N matching

value of equipment

Volume

Fingerprint best Yes Lower smallestIris best Yes High LargerRetinal best Yes High LargerPalm Better No Higher largeFacial General No Low smallerSound General No Lower smallest

The same compared to other biometrics, fingerprint recognition technology has the following characteristics:

1) Fingerprint can provide unique individual characteristics, and characteristics of precision and complexity sufficient to meet the high accuracy of the identification of needs. And each person's fingerprint is very fixed, very difficult to change.

2) To facilitate access to fingerprint samples, easy to develop recognition systems, and practical. At present, the standard fingerprint sample database, to facilitate the identification system software development, In addition, the fingerprint identification system to complete the hardware portion of the sampling functions are also easier to achieve.

3) Neither one's fingers the same fingerprint, so not only can provide multiple fingerprint samples can also facilitate the use of multiple fingerprints constitute multiple passwords, improve system security. At the same time, does not increase the burden on system design.

4) Fingerprint acquisition mode is non-invasive and non-sensitivity of the acquisition, the operator is easy to be accepted. A cquisition equipment and relatively simple, easy miniaturization and cheaper.

5) Fingerprint template is not used in the original fingerprint image, but the key to the fingerprint image

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feature extraction, so less storage capacity. In addition, the input fingerprint image to provide key features, you can greatly reduce the burden of network transmission, easy to implement remote confirmation, to support the computer network functions.

II. OVERALL DESIGN OF EMBEDDED FINGERPRINT IDENTIFICATION SYSTEM

For offline operation currently embedded fingerprint identification system, in most cases, a single microprocessor. In this system, it is necessary because the microprocessor complex image processing, but also responsible for monitoring the peripheral task, which makes the system to process the low efficiency of the fingerprint, the system function is simple and, more importantly, for the system upgrade or extensions are very inconvenient.

In the embedded fingerprint recognition system, we will be divided into fingerprint recognition algorithm module control module plus two parts. Among them, the algorithm is part of the microprocessor DSP processor selection, mainly to complete the fingerprint collection, preprocessing, and the matching algorithm software; and control module microcontroller as the processor used, mainly to complete customer service system, the system interface and other tasks. Thus, as the algorithm model of the DSP processor to perform its superior data processing capability, concentrate on the completion of the fingerprint processing algorithms; the microcontroller can use it to control the ability to achieve and convenient features to facilitate the completion of the external monitoring. Based on dual-core DSP and microcontroller, the embedded fingerprint identification system hardware block diagram shown in Figure 1:

Figure 1 System hardware block diagram Around the dual-processor DSP and microcontroller, the

system consists of a fingerprint module, fingerprint processing module, the user interaction module and communication module with the computer a few parts.

The complete independence of embedded fingerprint identification system fingerprint entry, image processing, feature extraction and matching, fingerprint feature template access, and through communication interface with the computer, the fingerprint template database backup and restore. System uses a modular design, the composition and flexibility of applications. The system either as an independent use of embedded devices, the other functions of the system expansion and optimization, will be applied to the fingerprint identification system on different occasions.

New user registration, through keyboard input up ID, then the system collected by the DSP control fingerprint

sensor user fingerprint data, if collected valid fingerprint, fingerprint processing through the DSP received fingerprint template data, and then the system into the system, the fingerprint template database . User logs in, if we adopt the 1:1 ratio of strategies, the user enters their registration with the ID, the system prompt, DSP user fingerprint image acquisition, and then the fingerprint template and database comparison, the success back to the login information. If necessary, you can also user information through the USB interface and the corresponding templates are uploaded to the PC machine backup. When the embedded system data is lost, USB interface can also be stored in the backup PC, downloaded to the system.

A. Design of Control Module In this system, the control module includes

microcontroller core is based on user interaction part of the communication interface with the PC-part and part of the communication interface with the DSP. As the system control module core processor P89C52, its interface with limited resources, while more difficult to complete the above work. By the system cost, development time cycle and inheritance considerations, switching to other processors is not very convenient, so must be considered on the basis of this processor to complete multiple tasks.

Because the system works in case the registration and login, you need the keyboard and LCD as well as communication with the DSP, USB interface idle time; and when using the USB interface, keyboard, LCD is not working. So when the MCU to complete these tasks, can be implemented on the TDM interface. The most important is the completion of the MCU data bus P0 reuse. The specific implementation shown in Figure 2:

Figure 2 the data bus connecting of single chip machine

B. Design of Algorithm Module Algorithm module and the DSP core to complete the

fingerprint collection, processing, matching and preservation work is the embedded core of Automatic Fingerprint Identification System. Fingerprint processing and matching in the process of the algorithm contains a large number of complex work, you need an efficient and stable digital signal processing platform, ie a strong "core" basis. Generated by

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TI, 5000 series digital processor chips for its outstanding performance and low price as our first choice when designing the module.

In addition, fingerprint matching, you need to fingerprint the fingerprint database generated by treatment with the current fingerprint module fingerprint template matching, we can not have come at every match in real-time processing fingerprint database, fingerprint database are generally those in the pre-generated fingerprint template stored in the non-volatile memory in power-down. And when the system is running offline, the handler code must also be stored to the non-volatile memory power-down, the view of this, the system must also be extended outside the FLASH memory.

External storage system in the DSP circuit design, to ensure two things, namely DSP external memory interface with a variety of memory signals between the hardware is connected properly, and DSP external memory interface and timing between the various types of memory match.

III. USB HARDWARE INTERFACE AND FIRMWARE IMPLEMENTATION

A. Introduction of USB bus USB (Universal Serial Bus) is a universal serial bus.

With the improvement of technology and the rapid development of information technology, people have a higher serial communication requirements. Compatible with low and high speed development of a communication technology, so as to provide a majority of computer users can be shared, scalable and easy to use the serial bus to become the common goal of many manufacturers. In order to achieve the consistency of a computer system bus, from COMPAQ, INTEL, MICROSOFT and NEC and other companies to develop a new, fast, bidirectional, synchronous transmission and data transmission can be hot swap bus, referred to as the USB bus.

With the various types of USB products launched, USB communication becomes more widely the advantages of well-known. As a universal serial data bus, for the embedded fingerprint identification system and for communication between PC, USB has many advantages.

B. Overview of USB bus USB system consists of three parts: the hosts, devices

and connections. A USB system, there can be only one host, host to the USB host controller interface is called (Host Controller); equipment can be divided into functional devices (Function, also known as peripherals) and Hub (Hub) are two former expansion device as a function of the system, which extended as USB device connection point; connection defines the host and peripheral connection and communication, including bus topology, the internal hierarchical relationships, data transfer and bus access control model parts . The system as a USB peripheral part, we mainly done with the USB interface and USB peripherals between the host PC USB connection.

For USB devices, each USB device can generally have one or more configuration. Each configuration contains one or more interfaces, the interface that the software should be

how to access the hardware. Interface, the lower is the endpoint, an interface is also generally contain one or more endpoints, the endpoint as a communication pipe of an end point, there are four endpoint types: bulk, control, interrupt and synchronous.

In USB communications process, the endpoint and pipe, respectively, play different roles. At the lowest level, USB cable to the main controller and bus interface device connected; the second stage, a control system software pipeline to link up with the logical device in the third stage, a group of the client software and the data pipeline a set of interfaces connected to form the USB communications model.

C. System hardware design USB Interface USB interface hardware interface chip PDIUSBD12

mainly centered design and the physical interface it with the USB connection between the microcontroller. Interface module power supply via jumper selection, which can support USB bus-powered mode and peripheral power supply for the full-speed USB device interface. The design process fully into account the reliability, scalability, and electromagnetic compatibility. The interface circuit shown in Figure 3.

Figure 3 Circuit diagram of USB interface After the completion of the basic circuit design, a

considerable portion of the USB communication protocol implemented by the hardware, so the accuracy of the hardware circuit design and accuracy requirements are very strict, wiring should be reasonable, as far as possible to reduce stray capacitance and electromagnetic interference, hardware will directly affect the quality of the data whether the normal transmission.

VI. DESIGN OF FINGERPRINT ACQUISITION MODULE At present the application of domestic and foreign

markets fingerprint identification equipment, optical identification device has an absolute advantage. One is the optical fingerprint identification device has many years of accumulated technology, equipment, long service life; second optical fingerprint identification device relative to the other two parameters identify the device in the same request identifying the best value for money; The third is the optical fingerprint identification device Fingerprint image has a

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larger area. The manufacture of large fingerprint identification device semiconductor fingerprint image capture area is very expensive, so often taken as a fingerprint sensor crystal is less than 1 square inch area, while optical scanning fingerprint image capture area is larger than 1 square inch, which makes Optical identification device easier to capture the image feature extraction value, improve recognition rate and lower false recognition rate.

According to a fingerprint capture device a few years experience, this system uses U.are.U4000, as shown in Figure 4

Figure 4 U.are.U400 Fingerprint device It is a very compact fingerprint scanner, its internal

precision optical systems, LED light source and the CMOS camera work, the voltage control when the image exposure, automatic correction, and use the Plug and Play USB interface.

In the program implementation, using PowerBuilder written instrument operations will fingerprint and fingerprint recognition algorithm into a dynamic link library package, in PowerBuilder in the necessary function declarations, and then follow the following process to achieve fingerprint collection and registration.

Figure 5 Fingerprint flowchart

V. CONCLUSION This thesis automatic fingerprint identification system

embedded hardware design and implementation, including algorithms and control master module, USB interface and fingerprint collection module, is divided into the following sections: The first part, complete embedded automatic fingerprint identification system architecture:

The first part, complete embedded automatic fingerprint identification system architecture: the processor core, DSP algorithm module to P89C52 microcontroller control module for the controller. Including the algorithm module and external expansion memory, power supply part of the circuit design, and control part of the MCU data bus of the TDM.

The second part, the use of service-chip microcontroller with USB PDIUSBD12 complete USB interface for embedded system design. Some USB devices, including hardware design, firmware design, USB host part of the driver and application design.

The third part, controlled by DSP to complete the fingerprint acquisition, including acquisition module hardware design, acquisition program design, and the reorganization of the fingerprint after collection.

After the integrated fingerprint processing algorithms, the entire system independently fingerprint entry, image processing, feature extraction and matching, fingerprint feature template access, and through communication interface with the computer, the fingerprint template database backup and restore. Due to the modular design, simple changes can be directly or to be used for different security applications, has great marketing potential.

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