Sunday, 7 April 2013

Arduino "shield"

After getting the extruder stepper motor driver and temperature sensor set up, I found myself with a bird's nest of wires. Four 10-wire strips that split off, crossing and re-crossing, plus several more for the sensor, plus power and other bits and pieces. The wires plugged into to the Arduino were apt to fall out, even with a proper connector on them, and I didn't know if there were shorts in random places (at least nothing smokes). So I decided to make a little "shield" for the Arduino, putting proper plugs onto the 10-wire strips (except I managed to again order the wrong size from Eibtron, their pages are really confusing). This is how it turned out (people who care about the √¶stethics of electronics might want to avert their eyes):

4-stepper-motor-driver shield mounted on Arduino.

Rear side of shield, with the fixed connections done in wire. From left to right to top-right: Z, Y, X stages and Extruder. Ground goes around the left and along the bottom.
Two ends were deliberately left loose, so I can later plug them in where I want them, if it turns out I need to have min/max for the X/Y stages or be able to enable/disable more of the motors. I have hardwired (literally) enable/disable and min opto endstop for the Z stage, since it will be idle most of the time and need be able to position itself right over the plate.

The pins for the Arduino are now:
  1. RX - used to program the Arduino.
  2. TX - used to program the Arduino.
  3. ExStep - Extruder Direction
  4. ExDir - Extruder Step
  5. XStep - X stage Step
  6. XDir - X stage Direction
  7. YStep - Y stage Step
  8. YDir - Y stage Direction
  9. ZStep - Z stage Step
  10. ZDir - Z stage Direction
  11. ZOff - Z stage Enable (off on high)
  12. Heat - Heater on
  13. ZMin - Z stage minimum opto endstop
  14. GND
Finally got the right crimp header for the four control wires for the extruder stepper motor driver, and soldered them on. Happy to see that the crimp pins were properly Murphyized[1]. My notes on this blog came in handy here, as I didn't have to re-test what the ordering of the wires should be.

Also trimmed a bit of the extruder-holding plate (which is a pain, as that requires unmounting the extruder, which is fiddly to remount) so as to avoid yet another collision with the edge of the Z stage. *sigh*

Decided to desolder the connector to the v. 1.1 stepper motor driver I got from +Tim Hatch - I would rather have all four driver connectors be of the same kind.

It's fun to sit here and hack on my little project while three Ultimakers are running full tilt in the background. I realize my Monster will never be as speedy or probably even as stable, but it's mine.

For next time (tomorrow?): Bring new power supply of my own, buy crimp-on headers locally if possible, and bring/buy some 10-wire strip. Then I can redo the old driver and mount it all together!

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