THE DRIVER CIRCUIT OF CHARACTER DISPLAY BY LED(PART OF SOFTWARE)
Abstract
Main topics on the system is the choice of programme, the frame of hardware system, the main problem-solving in part of software and process of systems, and so on. The choice of programme in this system is three parts: the choice to shift register and then according the shift register to decide whether to expand current and to decide 4-16 Decoder's choice; Finally, there is the choice of external memory, according to the implementation and the speed to take several decisions by the memory. Hardware system is mainly on some principles and functions of a few major chip. These include: performance and its internal functions of core processors AT89S52 ; the shift output-control and the principle of the role of 74 HC595; the connections of 74 HC4514 and uln2803 and its principle of enlarge the current; the control method of I2C in E2PROM memory--24C04 and the timing of its strict control format; the role of RAM and finally is the knowledge of catching up with computer. Software in the system is to solve the main problem in five modules: First, the modules of sending message to 595, and the other is to calculation the addresses of the message, which is essential to normal control of a module, and the third is E2PROM module , in four RAM modules, is the guarantee for the speed to get message, and in the top-five communications module, mainly to know the format of SCON and the baud rate, beside these,there is a process for display. Finally, I will sum up for the system, and subject the problem in this system.
Key words:LED,the display of Large-screen, the system of display