I've been using a Honeywell HMC6352 digital compass module with an Arduino Uno to get heading data for a project, and it's been working well. I have recently started to try to move the project off of breadboards though, and have run into something unexpected; the module has started to only report between roughly 110 and 240 degrees.
I'm pretty sure that the issue is not loose connections; I've encountered those, and usually a loose VCC or Ground results in consistent readings of 0.0, while a loose SDL or SDA results in no output at all.
I've come up with a couple of things that may be the culprit, but am not sure which is the most likely or if this is a common issue that is caused by something else. Any ideas?
Short between the SDL and SDA wires; they're plugged into the A4/A5 (20/21) pins, which are pretty close together.
Electromagnetic interference; I've strapped the compass module directly to the Arduino's case in order to keep it parallel to the ground. Could the board be interfering with the detection of the earth's magnetic field?
Thanks, I appreciate any advice.