说明：  DS18B20进行读写操作只要控制好时序就应该没问题的。这个程序在我自己的板子上运行过能正常测温，温度显示到小数点两位。
(DS18B20 to read and write operations as long as the timing control should be no problem. This procedure in my own board to run off to the normal temperature, the temperature display to two decimal places.)