Dallas Semiconductor (Maxim) produces a family of devices that are controlled through a proprietary 1-wire interface. On a 1-wire network, a single "master" device communicates with one or more 1-wire "slave" devices over a single data line, which can also be used to provide power to the slave devices. How to connect such devices to Arduino?

This device, based on an Atmel ATMega168 microcontroller can monitor up to 16 DS18x20 thermometers, with a variable logging rate of 5 to 9999 seconds. The data is displayed on a multi-page LCD display for immediate viewing as well as being sent via RS232 at 19200 baud for recording. Data is time-stamped with an optional on-board 1-Wire real time clock.

This is my very first construction with the cheap Atmel's ATtiny15 and the DS1820 thermometer. The main goal was the BIG display from the 7-segment LED modules. (And cheap + simple construction, of course...)