ds18b20的Verilog程序，经测试验证可以使用。注意此版本为DALLS DS18B20而不是DS1820,注意加5K上拉电阻。,ds18b20 the Verilog process can be used to verify by testing. Note that this version rather than DALLS DS18B20 for DS1820, the attention of Canadian 5K pull-up resistor.