摘  要：恒流源的使用是十分广泛的，而且在许多情况下是必不可少的。它可以应用于差动放大电路和脉冲发生电路，向差分放大电路提供偏置电流来稳定它的静态工作点，还可以用做恒流源负载提高放大倍数。57856

本次数控直流恒流源的设计采用51系列单片机为核心，外围配置了键盘模块，液晶显示控制模块，模数转换模块，恒流源模块和数模转换模块，通过软件和硬件的结合，实现了整个系统的设计。数控直流恒流源由数字控制器、检测电路、驱动电路和通信电路组成。数字控制器通过控制晶体管的导通量，来实现电源参数的稳定控制。数控直流恒流源与传统的恒流源相比，具有方便、操作简单、输出电流的稳定性高等特点。

毕业论文关键字：单片机 ，A/D ， D/A ，恒流源

Abstract: The constant current source is widely used, and in many situations is essential. It can be applied to the differential amplifier circuit and pulse generating circuit, provide bias current amplifying circuit to stabilize the quiescent point, and also can be used as the active load in order to improve the magnification.

The design of numerical control dc constant current source with 51 series single chip processor as the core, the external design of the keyboard module, LCD display control module, analog-to-digital conversion module, constant current source module and digital to analog conversion module, through the combination of software and hardware, and realizes the design of the whole system. Numerical control dc constant current source is composed of a digital controller, the detection and driver circuit, communication circuit.The digital controller controls the transistor conduction flux, to realize the stability control of power parameters. Numerical control dc constant current source compared with traditional voltage current source, with easy and convenient operation, high output current stability, etc.

Key words: MCU;A/D Converter; D/A Converter; Constant Current Source

1 绪论 5

1.1 概述 5

1.2 工作原理 5

1.3 种类和发展趋势 5

1.4 本论文的主要任务 6

2 设计方案 6

2.1 总体设计方案分析 6

2.2 各模块设计方案分析 7

3．数控直流恒流源系统设计 9

3.1 微处理器的设计 9

3.2 键盘模块设计 11

3.3 显示模块设计 12

3.4 A/D模块设计 13

3.5 D/A模块设计 14

3.6 恒流源模块设计 17

4.程序设计及流程图 19

4.1 主流程图 19

4.2 部分模块程序和流程图 20

5.系统调试及结果分析 22

5.1 仿真调试 23

5.2 电路软硬件结合调试 23

5.3 结果分析 24

5.4 软件设计中的不足 24

结  语 25

参考文献 26

致  谢 27

附录