I have recently been performing some experiments interfacing HMC6352 breakouts to an arduino unohttps://www.sparkfun.com/products/7915https://dlnmh9ip6v2uc.cloudfront.net/images/products/1/1/0/2/1/11021-01a.jpg
in my experiments, I have taken each compass breakout, and wired it to an arduino uno 1 foot away. This is to make sure they are unaffected by any metal on the board, or the power source on the board. The arduinos are secured to the board with zip ties, and the compasses are secured with foam tape. I have taken the compasses outside, and taken readings every 4 seconds, in between which I rotate the setup 90 degrees. Most of the modules rotate the same number of degrees, however, a few of the modules seem to have compounded decreased readings up to 270 degrees (360 degrees by the other compasses) when rotated to the 90 degree point, the compasses seem to be accurate again. Some of the compasses seem to have compressed reading differences around what should read as 180-360 degrees.
I am trying to figure out why this is. Does anyone have any suggestions on what it might be? Or where to begin looking for what might be causing this?
any help is much appreciated. Thanks!