Notes:

• Works with virtually any bipolar stepper motor, including 4-, 6- or 8-wire motors wired as bipolar.
• Set the driver for minimum motor current (with pot on board).
• The driver is shown wired for full steps.  Half, quarter and eighth steps can also be accomodated. See the A3967 datasheet.
• Because the driver responds to a change of state on the STEP input only, the motor registers every other frequency comparator phase slip, and φ in the error calculation* becomes 1/500000 S (2 µS). Refer back to the Frequency Comparator article for more on this calculation.

*Frequency Offset = dNφ/dt = dN x 1/500000 x 1/dt.