Shop Stuff: May 2011 Archives

Dead bug construction

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So I thought I was pretty proud of myself for building a PIC based stepper driver. There was a small defect in the final board layout that required me to solder a couple resistors to the back side instead of through the top like all the rest of the components, however, in testing the board with a 555 based step generator, it worked!

That is, until I tried using the signals from the parallel port. Since electrical engineering is not my profession, I'm not 100% sure why the signals didn't work, but my guess is the 3V from the parallel port was not strong enough for the PIC to register the logic Highs. So I had to some transistors to convert the 3V inputs to 5V for the PIC.

The problem was the boards were already etched and soldered. Building new boards from scratch when I only needed the 2 boards I had started did not excite me. So I utilized a tried and true method of "Dead Bug Construction" to add the 4 resistors and 2 transistors to each board. The results, while not pretty, do work.

Dead bug PIC driver

CNC - Parallel port breakout board - with Lights!

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I need a clean way to break out the pins from the parallel port to the various stepper drivers, etc. I had a rats nest on a breadboard for a long time, and for almost as long of a time, I had an Eagle file that would make a nice breakout board with status lights. The plan was to mill the PCB board, but I have been having too much fun laser printing the negatives onto magazine paper, ironing them onto PCB. Anyhow, for those who are interested, this is what the board looks like:

Parallel port breakout board

The LEDS are in 3 groups of 4 pins, they pass through the header to the LED / resister for status. Beside the big connector is 4 input pins for home signals, etc.

Parallel port breakout board - backside

This is the back side.

And for those interested, here is the LED_SIGNAL_V2.brd.