The DS18B20 is a simple and inexpensive temperature sensor. The sensor operates by an OneWire system, which needs, besides the connections for ground and the supply voltage, only one wire to read the temperature values. By this bus system, it is possible to run multiple sensors which is also described in this tutorial.
In the following article we extend the Tiny RTC module with a DS18B20 temperature sensor, which either already exists on the board or we simply add by soldering. This article is an extension of: Time and calendar functions with a real time clock module based on the DS1307 and an Arduino.