基于单片机和CPLD的等精度测频系统

Identical precision frequency measurement system based on MCU and CPLD

基于CPLD芯片与单片机AT89C51、AT89C2051,采用闸门测量技术实现等精度测频。CPLD的结构与功能由VHDL语言描述;单片机的控制与数据计算、处理采用C语言编程实现。利用单片机内部计数器产生闸门脉冲,控制CPLD对标准频率与待测频率的计数,计数值与实际待测频率值的转换和计算的结果用8位静态数码管显示。单片机与CPLD硬件接口采用独立工作方式。经实践验证,系统测频范围在100kHz～4MHz之间,测频精度可达0.1%,系统运行正常,控制效果达到预期目标。

The design which is based on the CPLD chip and single-chip microcomputer AT89C51, AT89C2051, adopts strobe measurement technique to achieve cymometer with equal precision. The structure and functions of CPLD is described by the VHDL language; C language programming is used to actualize the control of single-chip microcomputer and the calculation and processing of data. The gate pulses generated by the internal counter of singlechip control CPLD to count the standard frequency and being measured frequency. The result of conversion and calculation between actual numerical value and the being measured frequency＇s value is displayed with 8-bit static digital tube. The hardware interface of MCU and CPLD uses the independent operation mode. Practice has proved that the system operates normally and can achieve the desired control objectives, with its measurable frequency ranging from 100 kHz to 4 MHz,and at the same time the measurement accuracy meeting 0. 1%.