The BMP180 is a simple barometric pressure and temperature sensor. It can measure barometric pressure from 300 to 1100 hPa, and temperature from -40°C to 85°C with ±1.0°C accuracy. It uses a piezo-resistive sensor to measure the air pressure around it. It also has an analog to digital converter and a control unit with EEPROM and a serial I2C interface. It uses I2C for communicating with the microcontrollers.
It can be used for monitoring weather changes or for measuring altitude.