The brain of this project is an AT90S2313 that controls the LED Display thus showing the temperature read from a DS182 temperature sensor. The temperature sensor chip, DS1820 is connected to PD1 with a 4.7k pull-up resistor. The circuit presented here uses only one sensor, but you may tie multiple sensors on the same line and modify the program to read it with the help of internal chip ID.
ATtiny2313 Thermometer: [Link]
This project allows you to log temperature under 2 operating modes: Standalone, the system works standalone and can record a max of 2 temperatures or connected to a PC’s RS232 port thus having the ability to record up to 8 temperatures. The circuit is also interfaced with an LCD that can show 2 temperatures at the same time. It also has a separate DS1302 Real Time Clock (RTC) module with over 3 months backup and supports Wayne’s NTP format for updating the clock from an NTP server. The circuit is controlled by a Atmel AT90S2313, source code and schematics are provided.
LCD Temperature Monitor: [Link]