I have a "standard" 4 amp TB6600-based stepper driver (happens to be a Winsinn)and I'm using it with a motor that can deliver 8 foot-pounds of torque. I want to find the "zero position" my moving the motor until the carriage hits a zero switch, but even with a unity screw this motor can generate at least 400 pounds of force, and with a less aggressive screw it could be ten times that. The "standard" device only allows the selection of a lower current mode by activation of a DIP switch, so of course that cannot be done under programmatic control. The driver has two optoisolated inputs for step and direction, but it also has a third called "enable" (which I suppose should have been "disable" but I'm carping a little). The question I have is can I feed a PWM output from the MCU to drive the enable input to reduce the average torque? I'd probably set the cycle time at about 2 kHz (can only be factor-of-four one way or the other), I figure so long as it's much slower than the step rate it should work OK, and if I lose a step or two that's OK too because I'm just trying to find zero and not rip the bracket right off its mounting screws. Is that how the TB6600 chip and that input work? Does it just cause the back EMF to drive the "free" end of the half-bridge into the body diode and supply rail of the other output? Any insight into how this chip works in this regards would be appreciated, I don't seem to find this level of detail on either the Toshiba data sheet or the vendor's website.