Computer Control for the Table

A few months ago I bought some hardware for interfacing my computer with the outside world along with a relay card and stepper motor card. I had some time over the weekend (actually I just couldn’t put it off any longer) to finish soldering the main board together and hook it up to the computer and table.

I’ve started out with a Velleman K8000 (rev 3) board which hooks to the computer through the parallel port. I purchased it from ApogeeKits for $129 plus another $40 for a stepper motor board and enclosure.

I’ve got the two shutters hooked in at the bottom through two of the nine analog outputs. I’m still researching how to hook up the sensors (although my light meter can be hooked directly to the board, simplifying my work there) but I’ve done enough to show that the board works and to start working on connection and software design.

Basic controller designs

  • 1 DAC for 11mW laser shutter.
  • 1 DAC for 30mW laser shutter.
  • 1 TTL? input for 11mW laser light sensor.
  • 1 TTL? input for 30mW laser light sensor.
  • 1 TTL input for manual switching of 11mW laser.
  • 1 TTL input for manual switching of 30mW laser.
  • 1 TTL? output for light showing when the lasers are on.
  • 1 TTL? output for light showing when an exposure is settling/in-progress.

Something for sound/speech output for alerting the humans to when an exposure is immenent.

I’ll be writing all the code in C++ most likely although I’m giving serious consideration to making an HTTP server out of the code so I can monitor and control the table from any thin client inside the house.

Initially I’ll run everything on my regular machine and check on it through WinVNC but there’s something that just feels wrong about that much overhead (and yes, I’ll grant that there’s not really that much with vnc).

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Published by

Michael Harrison

Husband, Programmer, Irish dancer, tinkerer, astronomer, layabout (as much as possible)

One thought on “Computer Control for the Table”

  1. read your stuff at You said you were thinking about interfacing to a printer port. A not bad freeware program with source code can be found at:
    I haven’t gotten involved with holography yet. CNC’s are still eating up all my extra money 🙂 It’s just been a subject I’ve been interested in for a long time

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