Add buffers and bleeder diodes between the PIC and the stepper! Then the (single-coil) stepping is simple: step coil1 coil2 1 forward nothing 2 nothing forward 3 backward nothing 4 nothing backward BTW all 3.5 inch drive steppers I saw used part of the drive's frame as second bearing for the stepper shaft. Do you have a stepper which has both bearings in the stepper housing? regards, Wouter. ---------- > From: Lynx {Glenn Jones} > To: PICLIST@MITVMA.MIT.EDU > Subject: [OT]: Bi-Polar stepper motors > Date: Saturday, February 06, 1999 03:02 > > Hello everyone, > sorry for the OT-edness of this post, but i have a little stepper > motor which i got from a 3.5" disk drive which was used to move the > read/write heads. The problem is that its bipolar. I plan to drive this > motor using 4 pic pins connected to buffers, with each buffer's output > going to one of the 4 wires. then ill set two adjacent pins opposite to > get a differential. However, in which order should i set and reset the > pins? btw, i did search the internet for this info, but to no avail, > everything dealt with unipolar steppers. thanks alot. > > ---------------------------------------------------------------------------- -- > A member of the PI-100 Club: > 3.1415926535897932384626433832795028841971693993751 > 058209749445923078164062862089986280348253421170679