The BMP085 from Bosch is the best low-cost sensing solution for measuring barometric pressure and temperature as well as altitude. Interfaces to the MCU via I2C interface and is designed to work with 3.3V and 5V systems, equipped with 3.3V regulator, I2C level shifter and the pull-up resistors for the I2C pins.The sensor is based on piezo-resistive technology for EMC robustness, high accuracy and linearity as well as long term stability.