说明：  学习掌握单总线数字式温度传感器 DS18B20的64位激光ROM码的读出方法。读DS18B20 64位ROM码命令（33h）允许主机直接读出从机的64位ROM代码，而无须执行搜索ROM 过程。如果该命令用于多节点系统，则必然发生数据冲突，因为每个从机设备都会响应该命令。64 位激光ROM 从高位到低位依次由8 位CRC、48 位列号和8 位家族代码(28H)组成。
(learning and mastering digital single bus DS18B20 64 laser ROM code to read out the side France. Reading DS18B20 64 orders ROM code (33h) allows mainframe directly read out from the plane of the 64 generation ROM code, and are not required to implement ROM search process. If the order for the multi-node system, the data was inevitable conflict, because each from the plane's equipment will respond to the order. 64 ROM laser from high to low followed by eight CRC, 48 ranks and eight family code (28H).)