说明：  DS18B20数字温度计是DALLAS公司生产的1－Wire，即单总线器件，具有线路简单，体积小的特点。因此用它来组成一个测温系统，具有线路简单，在一根通信线，可以挂很多这样的数字温度计，十分方便。DS18B20产品的特点
(DS18B20 digital thermometer is a DALLAS produced 1-Wire, that is a single bus device, with a simple circuit, small size and characteristics. Therefore, use it to form a temperature measurement system with a simple circuit in a communication line, you can hang many of these digital thermometer is very convenient. DS18B20 characteristics of the product)