I read Rich's tutorial regarding the l298 h bridge which is prompting this question. There was a spin off link that Rich directed me too that actually showed a bit of code to control a stepper motor. I need to set up something like that, and so what I would like to do is set D1 on and off rapidly creating an actual pulse. PWM will not work in this situation. Anyways my controller is looking for 5vdc to fire a optoisolator (led). I am powering my ezb4 via 12vdc. The output of the D0 ports is 12vdc Correct? What voltage would come out of the white wire, if any? My stepper controller is a bit different than the l2d8 requiring only a pulse on one input and a on/off voltage for direction. The controller can work on 12vdc but requires the addition of 820ohm resistors on these inputs. Thanks for the help.