基于ARM和ADS1248高精度测温装置的设计

摘要

In order to realize the high precision collection of the temperature parameters of the critical parts in the medical refrigeration cabinet under ultra-low temperature environment,a multi-channel high-precision temperature measuring device is designed.The device is designed based on high precision dedicated temperature measurement A/D chip ADS1248;the STM32 series MCU with high efficiency Harvard structure is selected as the control core;the Pt100 platinum resistance is used as the temperature sensor;the four-wire method is used for temperature measurement.In the measurement method of external reference voltage,a high precision reference resistor is used,so that the accuracy of Pt100 can be improved.The 24-bit ADS1248 integrated chip is selected,which includes PGA amplifier,constant current source,etc.,thus the higher resolution is met,while the device is simplified,and the efficiency is enhanced.The nonlinearity of Pt100 is optimized by the combined method of table look up method for difference,and Newton iteration method.Its accuracy is improved.The temperature parameters are stored in Flash memory.Test results show that in the temperature range of 30~300 ℃,the accuracy of the device is up to±0.01 ℃,and it can meet the accuracy requirement of medical facility under ultra-low temperature environment.%为了实现医疗制冷柜在超低温环境中对关键部位温度参数的高精度采集,设计了一种多路高精度测温装置.装置基于高精度测温专用A/D芯片ADS1248设计,选取具有高效哈佛结构的STM32系列单片机作为控制核心,以Pt100铂电阻作为温度传感器,使用四线制测量方法,在外部参考电压测量法中采用了一个高精度参考电阻,使Pt100的精确度得以提高.选用了24位的ADS1248集成芯片,包括PGA放大器、恒流源等,在满足较高的分辨率同时简化了装置,提高了效率.通过查表差值法和牛顿迭代法相结合的方法优化了Pt100的非线性特性,提高了其精度,并将温度参数存入Flash储存器.测试结果表明,在30~300 ℃温度范围内,本装置精度达到±0.01 ℃,能够满足医疗器械在超低温控制中的精度要求.