software part, wrote the assembler language. Because originally design the design method to
adopt module, improve the range of measuring frequency. And the drawing of this
design,including hardware and software programming
Keywords: Measurement; Cymometer; Single-Chip computer; Compilation
目 录
1.1 数字频率计的发展和意义.................................................................................................................1
1.2 数字频率国外的发展形势.................................................................................................................2
2 系统总体设计.................................................................................................................................................3
2.1 系统设计要求......................................................................................................................................3
2.2 测频方法..............................................................................................................................................3
2.3 系统设计思路......................................................................................................................................4
2.4 系统设计框图......................................................................................................................................4
3 系统硬件设计.................................................................................................................................................5
3.1 单片机模块..........................................................................................................................................5
3.1.1 AT89C52 介绍..........................................................................................................................5
3.1.2 单片机引脚分配......................................................................................................................6
3.1.3 复位电路...................................................................................................................................6
3.1.4 定时/计数器.............................................................................................................................7
3.2 放大整形模块......................................................................................................................................8
3.2.1 与非门 74LS00.........................................................................................................................8
3.2.2 放大整形模块原理图..............................................................................................................9
3.3 分频模块..............................................................................................................................................9
3.3.1 分频器 74LS161 芯片............................................................................................................10
3.3.2 多路选择器 74LS151 芯片....................................................................................................11
3.3.3 分频模块原理图....................................................................................................................12
3.4 显示电路............................................................................................................................................12
3.4.1 频率数值显示电路................................................................................................................13
2 / 34
