Sometimes we need device to measure temperature and if needed accuracy isn`t great you can make it yourself. This digital thermometer scheme is so simply to repeat, and I think it has enough accuracy (about 0.5C) for many applications. The heart of this circuit is microcontroller ATtiny2313.
Microcontroller is clocked by the external crystal resonator 4MHz (remember, that ATtiny2313 shipped with connected internal RC-circuit, and you need to write appropriate fuse bits). The temperature range of DS1820 is from -55C to +125C (-67F … +257F). Sensor is required about 750mS to convert temperature into 9 bit word. The temperature sensor sends data via 1-wire bus. Voltage supply is about 3-5 Volts. The program for microcontroller AVR has written on assembler and compiled into AVR Studio.
Digital thermometr with DS1820 scheme: