This article describes the use of IC cards for the registration management of employees in various industries. Here, the health status card for the catering industry is taken as an example. It is called a terminal because the system can be used both online and stand-alone.
First, the system hardware structure
The system structure is shown in Figure 1-118.
Brief introduction to the work process: First, the PC communicates with the terminal through the serial port, and the relevant information of the personnel engaged in the catering industry is written into the terminal, such as: name, age, unit, various medical history, and whether there is any infection.
The medical and medical testing institutions will approve the opinions, etc.; then the terminal will write the information into the IC card, and the management personnel can hold the IC card terminal to check the health status of the employees at any time.
The MCU uses the 80C31. Because the amount of Chinese character information in this system is large, the dot matrix LCD screen is used to display related Chinese character information; and the determinant keyboard for operating the system is directly composed of the 80C31 I/O port. The buttons include card reading, scrolling, and necessary information writing.
1. IC card selection
At present, there are many manufacturers of IC cards in the world, and there are mainly products of ATMEL, SIEMENS, GEM-PLUS and other companies that are used in China.
Among ATMEL's products, the AT24CXX series is relatively easy to program because its read/write is compatible with the widely used I2C bus (with mature read/write program modules). However, there is no encryption model in the large-capacity IC card, and the IC card used in this section requires more than 8K capacity and requires encryption function, so SIEMENS SLE4428 type IC card is selected. The card has an 8K bit Ez PROM and a 2-byte programmable security code. For detailed usage, please refer to the technical data of the corresponding IC card of SIE-MENS.
2. Hanization
Since the registration card for practitioners is displayed in full Chinese characters and the amount of Chinese characters is large, the GB5199A Chinese character library chip is selected, which contains the national standard one or two Chinese character library. The circuit of the Chinese character library part is shown in Figure 1-119.
Each Chinese character occupies 32 consecutive byte units, and the addressing access Chinese character library is directly addressed by the national standard code as an address. However, since the Chinese character code is discontinuous and cannot correspond to the address of GB5199A, the gate array B202 is used for address conversion (if the newer Chinese character library chip GB5199B is used, the device can be omitted), and the Chinese character library can be found. site.
GB5199A has a total of 18 address lines, but 80C31 has only 16 address lines, which requires addressing extension. Commonly used are I/O line extensions and the extension methods used in this section. Since each Chinese character occupies 32 consecutive bytes, it can be regarded as a large addressing unit, which is subdivided by 5 address lines.
Figure 1 - 119 uses two chip selection lines: one selects 74HC573 and the other selects GB5199A. The 74HC573 is used because the chip is easier to route on a printed circuit board than the commonly used 74LS273 or 74LS373. The operation first sends the 32-byte low byte address as data and latches it to the 74HC573 (note: the data representing the address is latched, not the address, the correct timing of the operation should be ensured); then, press The national standard code is addressed to GB5199A, and the Chinese character font is read; the Chinese character byte address is incremented by 1, and the above operation is repeated 32 times, which is the font dot matrix of the Chinese character.
The LCD screen is 128 & TImes; 64 dot matrix, can display 4 lines & TImes; 8 columns of Chinese characters. There are many ways to get the negative pressure required by LCDs. MAXIM has a range of chips for various voltage conversions, such as the MAX749. The method used in this system is quite clever.
The MAX232E chip is used here because of the need for serial data communication. The chip has an additional function that is not commonly used to provide a +5 to ± 10 V dual charge pump voltage converter. The associated circuit is shown in Figure 1-120, and the negative voltage is derived from the V- pin.
In normal operation, the type of capacitor used as Cl~C4 is not very high, and the typical capacitance value is 1μF. When taking power from the V+ or V- terminal, increasing the capacitance of the charge pump (up to 10 μF) helps maintain performance.
Display Port And Mini Display Port
Display Port And Mini Display Port
Display Port ,Mini Display Port
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