1、摘 要 佳木斯大学教务处 - i - 摘 要 本系统以直流数控电压源为 设计对象 ， AT89C51 单片机为主控制器，用 DAC0832 实现数字信号向模拟信号的转换。在控制上采用 44 的矩阵式的键盘作为人机沟通器件，通过键盘可以设定输出的电压值，也可以实现输出电压的步进（增加或减小）， 设置步进等级可达 0.1V。在显示端用用两个数码管显示输出，数码管既可以显示输出电压的数值和也可以显示电压值的步进调整过程。在数码管和单片机之间采用两个 74LS164 实现单片机和数码管之间的数据传输， 74LS164 在这里完成了串 /并转换和显示驱动的双重任务 。此设计经键盘向 单片机的 P1 口写
2、入数据，经过 D/A 转换器（ DAC0832）把数字信号变成模拟量输出，再经过运算放大器隔离放大，控制输出功率管的基极，随着功率管基极电压的变化而输出不同的电压。同时在电压输出端接有限流保护电路，防止末端负载电阻过小或短路而造成器件的损坏。单片机系统还兼顾对电压源进行实时监控，如果输出电压超过允许值，则比较器发生翻转，向单片机输送一个中断信号，会实现中断，实现电压的自动复位。 关键字 ： 单片机 ； 数模转换器 ； 电压源 Abstract 佳木斯大学教务处 - ii - Abstract This system take the direct current numerical contr
3、ol Current Voltage Source as the design object, the AT89C51 monolithic integrated circuit primarily controller, by d/a converter AC0832 realization digital signal to simulated signal transformation. Uses 44 the matrix -like keyboard in the control to take the man-machine communication component, may
4、 establish the output through the keyboard the voltage value, also may realize the output voltage step to enter (increase or to reduce), the establishment step enters the rank to be possible to reach 0.1V. In the demonstration end with two digital tubes demonstration output, the digital tube already
5、 may demonstrate the output voltage the value and also may demonstrate the voltage value step enters the alignment procedure. Used between two 74LS164 realization monolithic grated circuit and the digital tube serial communication between the digital tube and the monolithic integrated circuit, 74LS1
6、64 has completed the string in here/and the transformation and the demonstration actuation twofold task. This design reads in the data after the keyboard to the monolithic integrated circuit P1 mouth,(DAC0832) turns after the D/A switch the digital signal the simulation quantity output, again enlarg
7、es after the operational amplifier isolation, the control outputs the power tube the base extremely, outputs the different voltage along with the power tube base voltage change. Meanwhile in the voltage output termination limited class protection circuit, prevented the end load excessively is small
8、or short-circuits creates the component the damage. The monolithic integrated circuit system also gives dual attention to the constant pressure source carries on the real-time monitoring, if the output voltage surpasses the permissible value, then the comparator has the turn over, transports a look-
9、at-me to the monolithic integrated circuit, can realize the severance, the realization voltage automatic reset. Keywords： Monolithic integrated circuit,； D/A converter； Voltage source 目 录 - 1 - 目 录 摘 要 . i Abstract . ii 第一章 绪 论 . 1 1.1 直流稳压电源的发展方向 . 1 1.2 国内发展现状 . 3 1.3 设计的目的 和意义 . 5 第二章 方案设计与论证 . 6 第 三 章 系统硬件设计 . 9 3.1 主控模块 . 9 3.2 稳压电源模块 . 12 3.3 显示模块 . 13 3.4 数 /模转换模块 . 17 3.5 键盘模块 . 18 3.6 放大电路和限流保护模块 . 22 3.7 过压保护电路模块 . 22 第四章 软件设计 . 24 4.1 中断系统设计 . 24 4.2 过压保护程序设计 . 24 4.3 键盘服务程序的设计 . 25 结束语 . 27 致 谢 . 27 参考文献 . 28 附录 A . 30 附录 B . 31 附录 C . 46
