lucas,

The dump circuit is unnecessary for recirculating mode standby. By definition the attack slope is steeper than the decay slope in this mode.

By the way H500's 06-12-2011, 09:43 AM post scope pictures show pronounced notches at the full-step locations (sin 0, 90, 180, etc.). This is due to an overly long reset pulse applied to the time-base counter. The reset pulse synchronizes the PWM to the step pulse frequency at the full-step rate. The purpose is to prevent beat frequencies between the step rate and the PWM frequency. An overly long reset duration introduces such artifacts.

Mariss