The rotating machines measuring speed system based on microcomputer

A new method to measure the speed of rotating machines based on microcomputer and quadrature encoder is presented in this paper. The hardware and software of the measuring speed system are described. This circuit contains active crystal, quadrature decoder chips HCTL-2020 and LCD module. It can meet the requirement of the general speed measuring system. It can also display the speed situation on the LCD module. We can appropriately modify the program to make different displaying model on the LCD module. The speed measuring circuit also provides two interfaces of 9 pins and 15 pins, which is compatible with any other quadrature encoders.