I2C Issues

Hi there, not sure if anyone can help?

I have 2 compass modules, one is the HMC6352 (http://www.coolcomponents.co.uk/catalog/product_info.php?products_id=192) the other one is the CMPS09 (http://proto-pic.co.uk/products/Tilt-Compensated-Magnetic-Compass.html) i've used commonly used code for both compasses and just get a heading of 0 degrees from both.

I did have one of the compass modules (HMC6352) working fine for some time, then suddenly it stopped working, so i bought the second one thinking i had fried the first one somehow, but the CMPS03 compas module doesn't want to work.

Is there a good way to test the I2C interface and prove its working?

Many thanks to everyone/anyone who can help

Got something else you can connect the areduino to? Another arduino perhaps?
Or maybe use a scope and see if the lines toggle correctly as your interface is working.

the only other thing i have is a gps, servo, led's all stuff that doesn't use i2c, don't have access to an oscilloscope either. Any other ideas really appreciated.

I'm glad this came out just now. I had a problem with Duemilanove and I2C devices, just couldn't figure out what was making me nuts. I tried this http://todbot.com/blog/2009/11/29/i2cscanner-pde-arduino-as-i2c-bus-scanner/ , and my Duemilanove couln't find any I2C devices.

As this topic wakes me up again, I take another look to my system, and there it was, too obvious. I was connected my SDA and SCL pins to Duemilanoves digital IO 4 and 5, not Analog IN 4 and 5, as it was in the picture.

Well, thanks for this!!!

Cheers, Kari