In this article we are Interfacing a highly precise pressure sensor with Arduino. It is a package of Pressure, Altitude and Temperature sensor in a single chip. The pressure ranges from 300mbar to 1200mbar. The operating temperature varies from -40-degree Celsius to +85 degree Celsius. The data rate for pressure, altitude and temperature are 20 bits. Application – Sports watches – Data Logger – Project prototyping – Weather station – Navigation and map assistance Advantages The reading of pressure sensor is fast and precise. Using HP203B gives a combination of 2 sensors in a single chip with an I2C interface.