一种新型低成本高精度热电阻测温模块的研制

Research and development of a new low cost and high precise thermal resistance temperature measurement module

模块采用STM8S单片机,用恒压中间分压方式进行信号采集,采用低截止频率的RC滤波器,用AD620仪表放大器进行前置放大,用双积分型TLC7135进行数模转换,利用其BUSY管脚和单片机高级定时器的PWM测量功能获取数据。模块具有连接导线的温度补偿,含有零点和满量程校验电路。温度采用实际电路参数进行浮点运算,用线性方程求得近似温度值,再用牛顿迭代法进行精确运算。模块实现8路差分输入,可用Cu50/Cu100/Pt100/Pt1000型号的电阻进行测温,具有断路判断、地址检测功能。测温范围:-200～+550℃,实验证明:可达±0.1%FSR的精度,稳定性极好。

This module uses STM8S MCU,collects signal by the way of constant pressure intermediate partial pressure,adopts low cut-off frequency RC filter,adopts AD620 instrumentation amplifier as preamplifier,and D/A conversion is carried out with double integration TLC7135.And the data is obtained by using its BUSY pin and the PWM measurement function of the MCU advanced timer.The module has temperature compensation for connecting wire,and contains calibration circuit for zero and full scale.Using floating point operation for the actual circuit parameter,approximate temperature value with linear equation is obtained.Finally,the accurate operation is carried out by using Newton＇s method.The module realizes 8 channel differential inputs,can use Cu50/Cu100/Pt100/Pt1000 resistance type to measure the temperature,and has break judgment,address detection function.The measurement range is-200-＋550℃.The experiment shows that the precision can reach ±0.1%FSR,and the stability is excellent.