目 录
一 方案设计与论证---------------------------------------------------------3
总体设计方案与比较--------------------------------------------------3
二 模块电路设计及比较-----------------------------------------------------3
2.1电源模块-----------------------------------------------------------4
2.2数码管显示模块-----------------------------------------------------5
2.3 D/A转换模块-------------------------------------------------------7
2.4 恒流源模块---------------------------------------------------------7
三 软件设计---------------------------------------------------------------9
3.1 4*4键盘工作原理---------------------------------------------------9
3.2 数值处理原理------------------------------------------------------10
3.3 程序流程方框图----------------------------------------------------11
3.4 程序清单----------------------------------------------------------12
四 系统测试---------------------------------------------------------------12
4.1 功能测试----------------------------------------------------------12
4.2纹波系数测试-------------------------------------------------------13
五 数据处理---------------------------------------------------------------14
5.1 康铜丝阻值测试---------------------------------------------------14
5.2 误差测试---------------------------------------------------------14
六 发挥与创新-------------------------------------------------------------16
参考文献------------------------------------------------------------------17
仪器仪表------------------------------------------------------------------17
附录----------------------------------------------------------------------18
数控直流电流源(F题)
摘 要: 本设计分四个模块:单片机控制及显示模块,数模(D/A)转换模块,恒流源模块,输出显示模块.单片机控制模块以单片机为核心,对输入电流信号进行转换成数字量输出;恒流源模块将D/A转换来的电压模拟量通过恒流源电路变成恒流;显示模块有两个:一个是由74LS164移位寄存器和数码管构成,显示预值;另一个是在输出端以CC7107为核心的A/D转换芯片,显示实际测量值.此外,本设计可实现电流0—2A且有±1mA和±10mA的两种步进,同时有数码显示输入的电流值.
关键字:键盘控制 D/A转换 恒流源 A/D转换
Constant current resource digital controlled
Abstract: The system is designed basing on a single-chip microcomputer of model AT89C51.The constant current resource of digital controlled includes main four modules--- a DA converter,a constant current resource ,a output display circuit and a single-chip microcomputer controlled circuit. LED provides with beforehand setting and display .It can change and measure the current with a step of 1mA and 10mA by the key of "+"and "-". Because of using model AD7521, It is characteristic of its high precision performance and fine stability. Both the hardware and the software of the system are designed with modules, the system is proved to be well functioning by test.

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