This library was tested on ATmega 16 @ 8 MHz.
You have to read sensor's individual calibration data and pass it every time when fetching readings.
Bmp180CalibrationData calibrationData;
uint8_t result = mp180ReadCalibrationData(&calibrationData);
if (result == BMP180_OK) {
Bmp180Data bmp180Data;
result = bmp180ReadData(BMP180_OSS_STANDARD, &bmp180Data, &calibrationData);
if (result == BMP180_OK) {
float temperature = bmp180Data.temperatureC;
long pressure = bmp180Data.pressurePa;
}
}