摘要：在工程实践中，经常会遇到各种需要测量转速的场合，测量转速的方法分为模拟式和数字式两种。模拟式采用测速发电机为检测元件，得到的信号是模拟量。数字式通常采用光电编码器，霍尔元件等为检测元件，得到的信号是脉冲信号。随着微型计算机的广泛应用，特别是高性能价格比的单片机的出现，转速测量普遍采用以单片机为核心的数字式测量方法。

　　　本文便是运用ＭＣＳ－51单片机控制的数字转速计。本系统就是对电机转速进行测量，显示电机的转速。设计主要用ＭCＳ－51作为控制核心，由传感器、LED数码显像管构成。本文重点是测量速度并显示在4位LED数码管上。其优点硬件是电路简单，软件功能完善，测量速度快、精度高、控制系统可靠，性价比较高等特点。

关键词：51单片机，光电传感器，转速计

Abstract: In the project practice, we will meet each kind to need frequently to survey the rotational speed the situation, the survey rotational speed method divides into the simulation type and the digital two kinds. The simulation type uses measured that the fast generator is the detecting element, obtains the signal simulates the quantity. Digital usually uses the electro-optical encoder, the Hall part and so on is the detecting element, obtains the signal is the signal impulse. Along with microcomputer's widespread application, specially high performance price compared to monolithic integrated circuit's appearance, the tachometric survey uses generally take the monolithic integrated circuit as the core digital measuring technique I graduated from the Design of the issue is control of the intelligent use of SCM speed measuring instrument. The system is the motor speed measurement,can communicate that the motor speed, and to observe the motor running the basic situation. 

    The main design　ＭCＳ－51 control as the core, by the Hall sensor, LED digital CRT. Give full play to the performance of the SCM. This paper is to measure the speed and displayed in five LED digital pipe. The advantage of a simple hardware and software capabilities improve, measuring speed, high precision and control system reliable, cost-effective and so on.

Keywords: ＭCＳ－51；Photoelectric sensor；Tachometer