This digital thermometer is built as additional feature for car without outside temperature indicator. The project is built based on Attiny2313 microcontroller and DS18S20, 1 Wire Parasite-Power Digital Thermometer sensor from Maxim.
The project uses LM2574 for voltage regulator to protect the thermometer from noisy car power source where voltages can spike up to 40V. It is equipped with alphanumeric LED for display. The firmware is written in C and is compiled with WinAVR. Download: schematic & firmware.