BMP180 is a pressure sensor from Bosch. Detailed description is here:

The BMP180 sensor uses I2C protocol to read out barometric pressure values. You need to connect the SDA and SCL pins accordingly (the Arduino's datasheet might refer to this interface as TWI or Wire).


BMP180 pinWhere to connect
GNDAny ground pin (on Arduino)
3.3V3.3V voltage source
VINIf 3.3V not connected, connect to 5.0V
SCLSCL pin on Arduino (for example, A4 on a Pro-Mini)
SDASCL pin on Arduino (for example, A5 on a Pro-Mini)