LiniStepper TestDrive Board Tested

Working toward a CNC machine, I decided to use the LiniStepper as my Stepper motor driver.  It is inexpensive, has a good feature set, is based on the Microchip 16F638A and open source.  I have build two LiniSteppers to date (need 1, maybe 2 more).  To test the stepper drivers, 4 control lines have to be set and a step clock function provided. A simple 555-based oscillator with some DIP switches will do. (You can buy a complete kit from James Newton for $19. That’s what I did, but I had a small soldering incident that destroyed the board–hence this project.)

Here’s the LinStepper driving a small stepper motor at 12V.

And here’s a close up of the Stepper Tester.

 If you want to build one of your own, here’s the schematic and circuit board (600dpi) artwork.  I used a 470 ohm resistor for the LED, 10K ohm resistors for the pull-ups, 2 500K pots for frequency and duty cycle adjustment and a .1 microfarad capacitor for the timing cap.  The 7 pin header matches the layout of the LiniStepper.  The upper 2-pin jumper in the photo is power input to the regulator circuit; the lower 2-pin header is for additional 5V supply (here I am powering the circuit directly from my bench supply).