The DS18B20 digital thermometer provides 9-bit to 12-bitCelsius temperature measurements and has an alarmfunction with nonvolatile user-programmable upper andlower trigger points. The DS18B20 communicates over a1-Wire bus that by definition requires only one data line(and ground) for communication with a central microprocessor.In addition, the DS18B20 can derive powerdirectly from the data line (“parasite power”), eliminatingthe need for an external power supply.Each DS18B20 has a unique 64-bit serial code, whichallows multiple DS18B20s to function on the same 1-Wirebus. Thus, it is simple to use one microprocessor tocontrol many DS18B20s distributed over a large area.Applications that can benefit from this feature includeHVAC environmental controls, temperature monitoringsystems inside buildings, equipment, or machinery, andprocess monitoring and control systems.