Stepper Motor Controller Card
This board is based on the Universal Controller Board.
First you need an assembled UniversalControllerBoard.
There is very little work needed to take a universal controller board with all the common components and to turn it into a stepper controller. All you need to do is to add the following components, which are shown in the magnified part of the picture:
These form the synchronisation link between the stepper control boards.
In addition, the stepper motor connector (P9, top right of the picture) has two capacitors (C5 and C6) beside it for an extruder controller. These are not needed for a stepper controller, but you should put dabs of solder over the holes where they would have connected on the reverse of the board. This is because those connections have to carry a high current, and the drilled holes increase their resistance slightly.
Bolt a heatsink to the L298N (U2). Any heatsink that will handle about 10oC per watt or better will do. Put a little thermally-conducting silicone grease between the chip tab and the heatsink before you tighten it up.
You need three of these boards for the X, Y, and Z stepper motors respectively. Label them X, Y, and Z with a felt-tipped pen so you don't forget which will be which.
For details of the stepper motors RepRap uses follow this link.
Program three PIC 16F628 chips with the files in ~your-id/workspace/firmware/build/16f628/stepmotor/stepmotor.hex (X axis), ~your-id/workspace/firmware/build/16f628/stepmotorb/stepmotorb.hex (Y axis), and ~your-id/workspace/firmware/build/16f628/stepmotorc/stepmotorc.hex (Z axis).
The programs in each are identical exept for one number - the address of the corresponding PIC in the token ring.
It's also convenient to label the PICs. I find that the best way to do this is to put a dab of typewriter correction fluid on each one, then to write X, Y, or Z on that when it's dry. (Mystery: there's hardly a typewriter left on the planet; so how is it that everywhere still has typewriter correction fluid?)
The boards are now ready for attaching to your RepRap machine.
-- Main.ZachSmith - 11 Feb 2007