Tuesday, February 06, 2007


Configurable Stepper Controller

Here you will observe several ideas I'd mentioned in my last post; modular jacks for board-to-board serial connections -- which work, by the way -- and a MOLEX connector for 12V and 5V power from any PC-compatible supply. Oddly enough, I'm using the 12V for logic, regulating it to clean 5V with a 7805 so I can use the 5V rail to drive my 5V stepper. The four transistors are TIP110 power darlington's of the same sort used to drive the heater current, and the last important bit is the DIP switch module. It chooses the order.

I've always hated swapping stepper wires all the time, I can never get it right twice in a row; I've let the PIC choose the order instead. Of the 24 possible combinations of wires, 19 are reflections or rotations of other sequences, boiling down to 5 unique orderings if I've worked this out right.

The rightmost switch enables half-stepping, and the leftmost activated switch tells it to use sequence 5/5.

Correction, four combinations. A,D,B,C is both a reflection and a rotation of A,C,B,D. This is convenient as it only takes two bits to try all unique combinations.
Do you have code for this with some explanation? Sounds handy.
Sure, I'll post it. Just give me a bit to clean it up and add comments. I'll try to have it up tomorrow.
I've put the source up here as 0011-ustepper.c. I've tried to document it heavily, but I'm not especially great at that; any questions, ask away.
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