多DS18B20测温电路中的单总线延长技术研究  

The Study of 1-wire Bus Extension Technology in Multiple DS18B20 Temperature Measuring Circuit

作　　者：赵卫东 王继红[2] ZHAO Weidong;WANG Jihong(The Modem Education Technology Center,Hengshui University,Hengshui,Hebei 053000,China;College of Electronic&Information Engineering,Hengshui University,Hengshui,Hebei 053000,China)

机构地区：[1]衡水学院现代教育技术管理中心,河北衡水053000 [2]衡水学院电子信息工程学院,河北衡水053000

出　　处：《衡水学院学报》2022年第1期14-17,55,共5页Journal of Hengshui University

基　　金：衡水市科技计划自筹经费项目(2019014023Z)。

摘　　要：DS18B20单总线多点测温电路中,由于总线线缆分布电容导致充放电效应,造成传输信号的波形失真和时序错位,系统总线长度被限制在100m内,约束了测温系统的空间范围。提出一种通过基于软件控制的总线电压"瞬间拉升"技术。在代码程序控制下,P0.1端驱动总线电压"瞬间拉升"电路,从信号波形上升沿到来时刻,极速增大电容充电电流,总线电压在很短时间内拉升到一定高度,减小了信号波形失真和时序错位,可使总线增至430m。经多次实验,测温系统能够持续稳定工作,验证了该技术是可靠的。另外,通过对DS18B20的IDQ参数及相关电路分析推导,得出总线可驱动传感器数量。In a multi-point temperature measurement circuit based on DS18B20, the distributed capacitance of bus leads to charging-discharging, which distorts the waveforms and dislocates the sequence, and the length of the 1-wire bus was limited in 100 meters. The spatial range of temperature measurement system is constrained by 1-wire bus limitation. In this paper the novel method is proposed that the instantaneous pulled-up bus voltage is controlled by code programming. When P0.1 port voltage is pulled up by programming, the voltage instantaneously increases. Since the rising edge of signal appears, the charging current of the capacitance has a significant increase. As it pulled up the bus voltage in a very short time, the signal distortion is diminished and at the same time the sequence dislocation is decreased. This method can extend the 1-wire bus to 430 meters. In experiences the sustained and stable performance of the temperature measurement system illustrates the reliability of this method. In addition, by the calculation of I;in DS18B20 circuits, the number of sensors in the cable can be deduced.

关 键 词：DS18B20 MCU 单总线协议 分布电容 RC充放电特性 

分 类 号：TP212.9[自动化与计算机技术—检测技术与自动化装置]