I'm wondering what the feasability of not using the stepper control circuits and "directly" driving the stepper windings from the Arduino firmware would be.
I know the Arduino can't directly drive the windings, I would be using a darlington pair plus protection diodes for each winding. What I'm interested in is bypassing the more expensive driver boards and using 4 pins per motor to do the stepping.
I know that I would have to make code changes to the grbl firmware for the Arduino. I'm interested to know if it would be a fairly isolated change or if it would be a very difficult thing to do.