功能：实现对DS18B20的读取 原理：单总线协议 注意：单总线协议对延时要求比较严格，此程序中采用的是11.0592M的晶振，如果使用其他的晶振请跟据DS18B20的资料修改延时参数-functions : to achieve DS18B20 read Principle : single-bus protocol attention : single-bus protocol to delay requirements more stringent, this procedure is used in the crystal 11.0592M if the use of other crystal please According to the information DS18B20 delay parameter changes