However, I wonder if I might be damaging it with the wrong voltage on the SDA and SDC lines. The Vcc input I have hooked to the Arduino 3V3 power. The SDA and SDL lines go to the Arduino A04 and A05 lines. However, I believe that those lines default to 5V, differing from the VCC to the sensor of 3V3. The pressure calculated is correct, but the noise (20 Pa) is higher than expected. Is the voltage mis-match a possible cause of the noise?
Is the voltage on the SDA and SDL likely to damage the BMP085?
I have thought of a possible fix: Hook the Arduino Aref to the 3V3 supply, and use the analogReference (EXTERNAL). Will this change the operating voltage of the I2C outputs on the pins?