本单片机系统采用AT89S52控制，整个硬件系统由A/D、D/A转换、LED显示、键盘、串行通信等模块组成。本设计只完成了单片机部分的开发设计，没有设计外部的采集和控制电路。因为没有外部采集电路，所以不能完成具体的测量功能，要完成具体的测量功能（如测量压力、温度、湿度）还要配上外部的各种传感器采集电路和相应的软件。若配上采集电路和相应的软件就能将测量结果用LED数码管十进制显示出来，其中包括了A/D、D/A转换，还可以用按键来控制，进行人机对话；系统中设置了5个按键，其中1个是复位键，其余的4个键，用程序来控制实现不同的功能。之所以没有设计外部采集电路是因为设计了外部采集电路系统的功能就比较单一，不方便系统功能的外部扩展。该系统还能实现单片机与PC机的串行通信和编程的下载、软件设计的时钟显示。

关键词：单片机AT89S52；串行通信；A/D转换；D/A转换；LED数码管显示  

It adopts AT89S52 to control the Single Chip microcomputer system, the whole hardware system is composed of A/D and D/A transformation, LED display, keyboard, serial communication. The design has only completed part of the exploitation design and has not designed the circuit of external collection and control. Because of having not finished the external collection circuit, the material function of measuring has not been finished, in order to finlsh the material function of measuring such as measuring the pressure, temperature or the moisture, and it should be equiped with external sensor collection circuit and the relevant software. If collection circuit and the relevant software are equiped, it can realize that the metrical results are displayed by numeral tube LED in term of decimal system, including A/D and D/A transformation, it also can be controlled by keystroke, makes the man-machine conversation. The system is mounted by five keystroke, one restoring key, another four keys which can be used to realize different functions under the control of program. The reason why the external collection circuit has not been designed is because that the function of it will be single if it is designed and it will not be convenient to spread the function of the system. Here the whole system can realize serial communication of Single Chip Micyoco and machine PC, the download of programming, the display of the clock which is designed by software.

Key words: Microcomputer AT89S52; serial communicaiton; A/D transformation; D/A tranformaiton; LED numeral tube display