利用CPLD设计高速等精度频率测量仪

Design of high speed and equal precision cymometer through CPLD

介绍了等精度测频原理,该原理具有在整个测试频段内能够保持恒定的高精度优点;利用VHDL语言设计了高速的等精度测频模块,并下载到CPLD中,通过与单片机的独立接口,将测量到的数据传送到单片机中,由单片机完成计算和显示的功能;采用CPLD配合单片机的设计方案,具有造价较低、速度高、精度高的优点,并且可以通过软件下载而达到仪器硬件升级的目的;该测频仪克服了直接测频仪对测量频率需要采用分段测试的局限。

This paper introduced equal precision method of cymometer,that the precision would not be changed in whole measured frequency domain. High speed and high precision module of measuring frequence was desingned by using VHDL, the measured data was sent to SCM by absolute interface, and performance calculation function of calculation and display were conducted by SCM. It had the advantage of high speed and high precision, avoided the localization of subsection measure in direct measuring frequency. The design using CPLD and SCM had the excellence of economy,high speed,high precision, and it is of avail in debugging circuit or improving circuit by sofrware .