1、 I 摘 要 在现代生产过程中，为保证生产安全顺利进行，达到优质生产，提高经济效益和劳 动生产率，节约能源，必须对生产过程的各种参数，例如温度、压力、流量、物位等进 行自动控制。由于传统控制仪表控制精度低、显示也不够直观，因此逐渐被现代仪表所 取代。由单片机构成的液位调节器能够进行自动检测、数据采集与处理、科学计算等。 单片机具有体积小、重量轻、功耗小、价格低、可靠性高和通用灵活等优点。因此现代 仪表已经渗透到我们生活的各个领域。 设计的液位调节器采用单片机 AT89C51 作为核心部件， 辅以模/数转换、 数/模转换、 键盘/显示、输出电路及外部数据存储器扩展部分电路组成。其中模/数转换采用
2、 10 位、 并行输出的A/D转换器TLC1551； 数/模转换采用8位、 串行输出的D/A转换器MAX517； 键盘/显示部分采用 74LS164、74LS165 扩展的串行口组成的独立式键盘及动态显示；输 出电路采用放大器和晶体管组成，把电压信号转换电流信号；外部数据存储器采用 I2C 总线的 PCF8583。为提高液位调节器的控制品质，采用增量式的 PID 算法。 设计的液位调节器具有控制功能灵活，人机对话方便、参数整定、手/自动无扰动切 换等优点。因此，具有很大的应用价值。 关键词：液位控制；模关键词：液位控制；模/数转换；数数转换；数/模转换；单片机；模转换；单片机；PID 运算运算
3、 II Abstract In the modern production process, in order to ensure the smooth progress of production to achieve high-quality production, enhance economic efficiency and labor productivity, energy conservation, the need for the various parameters of the production process, such as temperature, pressur
4、e, flow, level of automatic control and so on. Control instruments in the traditional low-control accuracy, is not enough to show that intuitive, it is gradually replaced by modern instrument. Posed by the single-chip level controller can automatically detect, data acquisition and processing, such a
5、s scientific computing. Single-chip with small size, light weight, small power consumption, low cost, high reliability and the advantages of flexible and versatile. Thus the modern instrument has penetrated into all areas of our lives. Level design AT89C51 single-chip modulator used as a core compon
6、ent, with A / D converter, D / A converter, a keyboard / display, the output circuit and the external data memory extension of the circuit. In which A / D conversion using 10-bit, parallel output of the A / D converter TLC1551; D / A converter using an 8-bit, serial output of the D / A converter MAX517; keyboard / display using 74LS164, 74LS165 series expansion I visit an independent and dynamic keyboard display; output amplifier and transistor circuit composed of voltage signal to current si
