Strange I2C Behavior BMP085

Hi-

So I am working on building an altimeter for my quadcopter based around the BMP085. I was having a heck of a time getting it to work so I ran the I2C scanner. The BMP085 did NOT show up. To make sure the error was not in the arduino, I hooked up an extra GY-521 board (MPU-6050) I had laying around and it showed up on the scanner, and even weirder was the BMP085 showed up. I ran the altimeter code and it worked, but only when I had the GY-521 also hooked up, even though Im not reading any data from it it makes the other sensor work. Soooo how do i get the 085 to work with out adding an extraneous I2C device? What is going on here?

-Nick

Hi N314

When using just the BMP085, do you have pullup resistors from SDA and SCL to +5V? If not, maybe the GY-521 breakout board does have these resistors.

Regards

Ray

Yup.

Added 4.7k pullups and all is well.

Thanks, -Nick