基于STC89C52的智能温度变送器的设计

摘要

介绍了一种以STC89C52为核心的智能温度变送器设计方案,使用AD7715进行输入信号处理和A/D转换;AD421做D/A转换及V/I变换,将反映温度的线性变化信号调制成电压信号后,转换成相应的电流信号(0～16 mA),加上系统的静态电流4mA,实现4～20 mA的模拟输出,适用于多种工业热电阻及热电偶温度传感器.文中分析了系统设计的理论依据和软硬件设计方案.该智能温度变送器能实现自动量程转换、自动零点调整和自动校准等功能,使系统具备智能化测量仪器的功能,同时具有RS-232通讯功能.整个电路设计简洁、精度高、稳定性好、成本低廉.%This paper introduced a kind of STC89C52 as the core design of the intelligent temperature transmitter, it used AD7715 for input signal processing and A/D transformation,AD421 completed D/A transformation and V/A transformation. It will reflect the temperature changes in a linear modulation signal into voltage signal,the current signal is converted into the corresponding (from 0 to 16 mA) .plus the system static current 4 mA and realize from 4 mA to 20 mA the analog output,apply to lots of industrial heat resistance and thermocouple temperature sensor. This paper analyzed the system design theory basis and the hardware and software design. The intelligent temperature transmitter to achieve automatic range conversion, automatic zero adjustment and automatic calibration,and other functions, make system has the function of intelligent measuring instruments, and has R.S -232 communication function. The whole circuit design is simple,with high accuracy,good stability and low cost.