The DS1920 provides direct-to-digital 9-bit temperature readings over a range of -55°C to +100°C in 0.5° increments. The iButton® communicates with a processor using the 1-Wire® protocol through a hardware port interface. The port interface provides both the physical link and handles the communication protocols that enable the processor to access iButton resources with simple commands. Two bytes of EEPROM can be used either to set alarm triggers or for storing user data.