关键词：CMI码，CPLD，VHDL语言
ABSTRACT
With the rapid development of digital communications technology and digital devices are widely used in digital communication, selecting the appropriate transmission pattern in the channel is very important.CMI code is applied to four groups of PCM transmission systems and fiber optic lines commonly used in pattern it has a code conversion device the advantages of a simple easy to clock extraction.CMI code is applied to four groups of PCM transmission systems and fiber optic lines commonly used in pattern it has a code conversion device the advantages of a simple easy to clock extraction. Based on the analysis of CMI coding and decoding theory, a programmable logic device based on CMI decoding method, gives the design schematics, software design process and the simulation waveform CMI codecs.This method provides the hardware design is simple, fast and low cost.At the same time as there is reprogrammable CPLD features, you can modify it online and easy to debug and run the equipment.
