【摘要】本设计是基于AT89C2051单片机的软硬件系统设计，硬件电路包括信号预处理电路、波形转换电路、波形整形及分频电路、显示电路，它们在本文中都有详细介绍。在单片机设计中应用单片机的数字运算和控制功能实现了测频量程的自动切换，满足了时间要求和精度要求。

【关键词】频率计；分频；AT89C2051 -【Abstract】This paper presents a design for frequency meter based on AT89C2051 Single-Chip Microcomputer. Several circuits such as signal pretreatment circuit, wave form changing circuit, wave shaping and frequency dividing circuit and display circuit are detailly discussed . Software and hardware system design are needed too. It not only realizes the measuring range automatic switching,but also satisfys the time request and the accuracy requirement by using figure arithmetic and control function of Single-Chip Microcomputer.

【Keywords】Frequency Meter　 Frequency Division　 AT89C2051