On Sat, 12 Feb 2005 09:27:15 -0500, Vic Fraenckel wrote: > I believe both the CMP03 and the Vector 2x mentioned in my previous post > have provisions in their firmware to allow user to do soft iron calibration > to handle the problem of near-by iron objects. I suggest RTFM for each. Don't remember who made my friend's compass -- wasn't my money spent -- but it did indeed have an ambient magnetic calibration routine. It worked great for the motors, wires, batteries, etc, but when the robot moved ten feet, the magnetic profile of the rebar underneath it had changed (can we say recalibrate? Oh, wait, we need a reference to North to do that -- Foiled again!) Yes, datasheets are created for a purpose, and the more you read, the more you savor the really good ones . . . but they don't always solve inherent problems. the calibration is good for cutting out, say, the frame of a car or a nearby engine block/motor, but if this is a small vehicle (again, I havn't seen Padu's design) or mounted near the ground, then metal moving relative to the compass may strongly affect the measurements -- something we desire independance from! Dan Crews, E.I.T. (crews.dan@gmail.com) <>< -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist