DS18B20 is a digital temperature sensor with wide applicable voltage, simple interface with microprocessor, measuring temperature range of -55~+125℃, accuracy of ±0.5℃. It can directly read out the measured temperature, and can implement 9~l2-bit digital value reading mode according to actual requirements through simple programming. It works in the voltage range of 3—5.5 V, and adopts various packaging forms, which makes the system design flexible and convenient. The set resolution and user-set alarm temperature are stored in the EEPROM and remain unchanged after power off.