1、1 期刊出自计算机学报，第 6卷，第 4期，2011年 4月 Design of LED Display Control System Basedon AT89C52 Single ChipMicrocomputer Abstract Thispaper introduces display design process about hardware and software based on AT89C52 single chipmicrocomputer. We use a simple external circuit to controlthe display screen, whic
2、h size is 32 192. The display screenalso can display the size of the six 32 32 dot matrixChinese characters by adynamic scan mode, and can bedivided into two small display screen, which can displaytwenty-four Chinese characters whose size is 1616. We canmodify the code to change the content of the d
3、isplaysubtitles can achieve scrolling function and the scroll speedcan be adjusted according to requirements, subtitles canalso achieve pause function. The Chinese character codestored in external data memory, the capacity of datamemory is expanded according to the requirements ofChinese characters
4、we want to show. This display screen hasadvantages of small volume, few hardware and simplecircuit structure. Index Terms LED, Chinese Character Display, I. INTRODUCTION LED display has become an important symbol of thecity lighting, modernization and information society withcontinuous improvement a
5、nd beautification of peoplesliving environment 6. LED lights can be seen in thelarge shopping malls, railway station, docks, undergroundstation, a variety of management window and so on. LEDbusiness has become a fast-growing new industry, a hugemarket space and bright prospects 9. The text, pictures
6、,animation and video are displayed by LEDs light, andcontent can be changed. Some components are thedisplay devices of the modular structure, and whichusually consists of a display module, control system andpower system. The display module is constituted by thelattice structure which consists of LED
7、, and is responsiblefor light-emitting display； the screen can display 2 text,pictures, video and so on by control system which cancontrol light or dark of LED in the corresponding region；Power system is responsible for transforming inputvoltage an d current into voltage and current which thescreen
8、needs. LED dot matrix display extracted displaycharacter font through PC, and sent to the microcontroller,then displayed in the dot matrix screen, which mainlyused for display of indoor and outdoor characters. LEDdot matrix display can be divided into graphic display,image display and video display
9、by displayed content.Compared with the image display, the characteristics ofgraphic display is no difference in gray color whether it ismonochrome or color display. Therefore, graphic displayalso fails to reflect the richness of color, and videodisplay can not only show exercise, clear and full-colo
10、rimages, but also show television and computer signals.Although there are some differences between the three,but the most basic principles are similar 6.SCM has excellent cost performance, small size, highreliability, strong control, and widely used in smartinstruments, mechanical and electrical int
11、egration, realtimeprocess control, robotics, domestic appliances, fuzzycontrol, communications systems and so on.This article described the design by the LED displayrelevant principle, and the design of hardware andsoftware structure are described in detail, finally, wesimulate for the overall desig
12、n and analyze the results. II. System Overall Structure Design Single Chip Microcomputer (SCM) models wereselected according to the target, function, reliability, cost,accuracy and speed of the control system. According tothe actual situation of the subject, the choice of SCMmodels mainly considered
13、 from the following two aspects:First, SCM has strong anti-interference ability； Second,SCM has a higher cost-effective. Due to MCS-51 iswidely used in China, has more information and cancompatible with the more peripheral chips too, inparticular, ATMEL Corporation, introduced a newgeneration microc
14、ontroller in 2003, that is 89S series,and its typical products with high performance and lowcostmicrocontroller is AT89C52. AT89C52 is a lowvoltage, high-performance CMOS 8-bit microcontroller,the chip includes 8 KB read-only program memory(PEROM) which erase can be repeated, 256byte randomaccess da
15、ta memory (RAM), devices adopt 3 high-densitynonvolatile memory technology to produce, compatiblewith the standard MCS-51 instruction set and the 8052products, while the chip built-in general-purpose 8-bitcentral processing (CPU) , Flash storage unit, can beapplied to the more complex control applic
16、ations10.The system was realized by the circuitry which ismade up of AT89C52 chip, Clock circuit, reset circuit,column scan driver circuit, line drive circuit and the six32 32 LED dot matrix, the overall structure of LEDcharacters display is shown in Fig.1. A display unit iscomposed of dot matrix an
17、d two 74HC154. Line datasignal is divided into two parts, which is given by the two8255A respectively, but the 8255A data are from the P0port the master controller AT89C52. The columnscanning signal of each character was given by the two74HC154, the 74HC154 12 pieces and was divided intosix groups.
18、The input signal of 74HC154 was given bythe P1.0P1.3 of AT89C52. External data memory 6264connected with the AT89C52 the P0 port. Figure 1 The overall structure of LED characters display III. SYSTEM HARDWARE CIRCUIT DESIGN A. Circuit Design of MCU Control System The size of Chinese characters is 32
19、32, butmicrocontroller has 32 I/O port, and cant meet designrequirements, so the I/O port must expand, the data portexpansion was implemented by two 8255A. The data portexpansion is shown in Fig.2, 74HC373 is the addresslatch, and latch low eight address, the low eight addresssignals of 6264 provided by it, but the high eight addresssignals of 6264provided by P2.0P2.4,
