Design of RMB recognition control system based on STC12C2052

The design of the RMB anti-counterfeiting propaganda station is to popularize the knowledge of anti-counterfeiting currency, demonstrate the anti-counterfeiting features of RMB by playing the video of RMB detailed explanation, and let people have a deep understanding of the knowledge of counterfeit currency through the RMB identification system. It liberates the staff of the Anti-Counterfeiting Volunteer Association from the heavy and repetitive work of promoting banknote identification, and improves the efficiency of anti-counterfeiting currency propaganda. The banknote sorting machine developed here has two functions: counterfeiting detection and playing video promotional films. Counterfeiting detection is achieved through analog and digital circuits and some simple controls. The function of playing video promotional films includes the face value of various banknotes and detailed explanations of banknote anti-counterfeiting features to achieve the purpose of promoting RMB identification.

1 Principle of machine recognition
Currently, the fifth set of RMB is widely used. This set of RMB is specifically aimed at the anti-counterfeiting weaknesses of the fourth set of RMB and uses 10 anti-counterfeiting high-tech technologies, namely: a. Paper; b. Watermark; c. Counter-printing anti-counterfeiting; d. Fluorescent ink; e. Security line anti-counterfeiting; f. Gravure printing; g. Magnetic ink; h. Rainbow printing; i. Invisible numbers and horizontal and vertical double numbers; j. Denomination numbers in optically variable ink.
Among the 10 major anti-counterfeiting features, the features that can be used for machine recognition include: infrared transmittance of watermark; fluorescent effect of paper; magnetic signal of magnetic ink; width of banknote; magnetic encoding of security thread. In this system, the infrared transmittance of watermark and the fluorescent effect of paper are used.
1.1 Identification of infrared transmittance of watermark
A beam of incident light with an intensity of I0 has an intensity of I after passing through a certain medium. Let α be the absorption coefficient of the medium; η be the reflectivity of the medium; and d be the thickness of the medium. Then:
I=I0(1-η)exp(-ad) (1)
Formula (1) shows that the transmitted light intensity of banknotes can reflect the characteristics of the paper, face color and thickness of the banknotes. Through experiments, it was found that the light projection rate of the watermark part of genuine and fake banknotes is significantly different.
1.2 Identification of the fluorescent effect of paper
The working principle of fluorescence detection is to detect the paper quality of RMB. The RMB is made of special paper (containing more than 85% high-quality cotton), while counterfeit banknotes are usually made of ordinary paper that has been bleached. The bleached paper will have a fluorescent reaction under the irradiation of ultraviolet light (blue light with a wavelength of 365 nm) (diffracting blue light with a wavelength of 420-460 nm under the excitation of ultraviolet light), while the RMB has no fluorescent reaction. Therefore, the authenticity of banknotes can be determined by irradiating the moving banknotes with an ultraviolet light source and detecting the fluorescence reflection of the banknotes with a silicon photocell at the same time. Summary: Through these two characteristics, the system automatically picks up the image of the tested currency through a high-definition camera under the action of an auxiliary light source, and then obtains the anti-counterfeiting features through corresponding image processing, and achieves the purpose of identifying the RMB by comparing it with the features of the genuine RMB in the database.

2 Hardware Circuit Design
2.1 Basic Functions
The upper computer uses the MAX232 chip through the serial port to communicate with the lower computer, and realizes the 16-channel output control of serial-to-parallel conversion through a virtual serial port, and then uses the image acquisition module to acquire images, and uses the image acquisition card to send the acquired image information to the image processing unit through USB.
2.2 Control system block diagram
The control system block diagram consists of control module, image acquisition module, RS232 serial communication module, TP168595 module, EASYCAP module, etc.

2.3 System control module
The control module uses STC12C2052. This small single-chip microcomputer with a working voltage of 3.5~5 V and a PDIP-20 package has low power consumption, fast data processing speed of 1 clock/machine cycle, strong stability, strong anti-static, strong anti-interference, low price, automatic encryption and cannot be cracked, and can download programs through the serial port, convenient upgrade and other advantages. It is suitable for precise control instruction system.
The single-chip microcomputer communicates with the host computer through the MAX232 chip, collects 17 channels of data, receives and decodes them, and then realizes 16-channel serial-to-parallel output control through the cascade of 68595.
2.4 Logic circuit module for four-channel image acquisition
The three-channel channel realizes the control of the four-channel image switching acquisition through the logic circuit built by the control relay, which can save one port for the expansion of other functions. The acquisition device uses Microview's MVC1000M, and the driver is written by VC. Each camera has a corresponding ID number, which is easy to write the program of the host computer. EASYCAP is a video capture card with a USB interface. It transmits the collected information to the image processing system via USB, and achieves the purpose of RMB recognition through image processing.

2.5 TPI68595 serial-to-parallel module
TPI68595 realizes 16 output channels through cascading, which is very resource-saving and has OC output, 100mA per segment, fast output speed, signal end, shift pulse end, signal clearing end, and signal storage end, which is suitable for precise control systems.
2.6 Design of auxiliary light source
(1) Top light; (2) Side light; (3) Bottom light.

3 Software design
3.1 Its communication protocol
(1) Baud rate: 4800B/S; (2) Terminal: NJFU; (3) Stop bit: #; (4) There are two modes of communication: interruption and query. This system uses the query method for communication; (5) The communication method is that the upper computer actively contacts the lower computer; (6) Data frame format: NJFU, D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 D13 D14 D15 D16 D17#. [page]

3.2 Data Analysis

Among them, D13, D14, and D15 control 4 cameras through the logical relationship composed of relays:

Allocation of memory units of the lower computer:

3.3 Communication between the host computer and the slave computer (see Figure 3)
The communication program of the host computer is written in C language, which can be used as a working system design language to write system applications, and can also be used as an application design language to write applications that do not rely on computer hardware, and has good portability.

The communication program of the lower computer is written in assembly language, which has the advantages of efficient writing and direct and precise control of the hardware. The output subroutine of the lower computer adopts the weighted addition algorithm.

4 Conclusion
Experimental debugging has proved that the system has reliable stability and occupies less hardware interfaces (only one serial port of the lower computer), and has been well applied in the design of the RMB anti-counterfeiting propaganda workstation.