The DS18B20 digital thermometer offers 9-bit to 12-bit Celsius temperature measurements and features an alarm function with user-programmable non-volatile upper and lower trigger points. The DS18B20 communicates via a 1-Wire bus, which by definition requires only one data line (and ground) for communication with a central microprocessor. Additionally, the DS18B20 can be powered directly through the data line, eliminating the need for an external power supply. Each DS18B20 has a unique 64-bit serial code, allowing multiple DS18B20s to operate on the same 1-Wire bus. This makes it easy to use a microprocessor to control many DS18B20s distributed over a large area. Applications that can benefit from this feature include HVAC environmental controls, temperature monitoring systems in buildings, devices, or machines, as well as process monitoring and control systems.