On Tue, Apr 17, 2012 at 11:44 PM, Sean Breheny wrote: > The behavior you describe may be possible if the commutation sequence > is wrong (e.g., if you have phases swapped on the motor). There are a > number of possible relationships between hall sensor outputs and > appropriate phase drive. Some combinations will not run at all. Some > will run with a different back-EMF constant. Some will run but only if > you give the motor a push to start and then they will have very little > torque. It may be that your commutation sequence is offset by 60 > degrees in one direction so that, for one direction of motion you are > 60 degrees off but for the other direction you are 120 degrees off. > > Sean I agree with Sean. Check that your sensor and phase drive is correct. Trigger off each of your three sensors in turn, and with your scope in chop mode, fixed channel triggering, look at the drive signals. All three sets should look identical. If you have a mismatched phase, the 3 sets will look different. R --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .