Propeller takes Step-a-Sketch to a new level

[Mpark's] propeller controlled Etch-a-Sketch is well built and very accurate. He was inspired by the Step-a-Sketch project and he’s carried that design through to a stunning conclusion. The driver board was built around a Parallax Propeller P8X32A microcontroller. But this isn’t just a serial controller board for connecting the hardware to a PC running CNC software. He’s included TV out and a keyboard port so that programming can be done on the chip itself.

In the video after the break you can see how precise the plotting is on the Etch-a-Sketch. It is well mounted but also benefits from some software compensation for the toy’s imprecise controls. [Mpark] has also included an erase function that tilts the frame upside-down a few times. This is used not only to erase a drawing but to hide the line created when moving the stylus into its starting position.


  1. Simonious says:

    Wow fancy, beats mine:
    But then I only just got it working and haven’t learned anything about G-code yet (I’m using EMC2 from over at
    Still, it is a start, the first thing I learned is that when I build a real CNC that it WILL have limit switches!

  2. deathventure says:

    That precision is pretty crazy. I couldn’t draw a straight diagonal line or nice rounded curve like that on an etch a sketch if my life depended on it. Wonder how intricate a design can be for it. Maybe have some kind of drawing file converter for it, decipher into an etch drawing, then have it draw it.

  3. kirov says:


    they already have those (pen plotters) so i’m sure it would be pretty easy to adapt it to the etch a sketch.

  4. svofski says:

    Etch-a-sketches are notoriously sloppy. Probably he did some fine-tuning of the mechanics first. 1000 bonus points for the erase mechanism!

  5. ChrisInAtlanta says:

    I knew that programming in LOGO would come in handy one day…

    That looks like great geeky fun – nice work…


  6. Will says:


    He has a section on his blog post called “Backlash compensation”, it appears he compensated for the sloppy mechanics in software to get that precision.

  7. Agent420 says:

    Having built one of these a while back, I will say that the new EAS toys made in China don’t hold a candle to the old US made units… I went through 6 or 7 before I found one worth using. The problem was not only the backlash, but the knots tied on the internal string mechanism, which caused the unit to ‘twang’ when the knots got caught (and you can’t accommodate for that in software).

    I found an old one at a friends house and it was remarkably more accurate than the new ones I purchased.

  8. M4CGYV3R says:

    Can it print text? That would truly impress me.

  9. Agent420 says:

    ^ as you have no method of lifting the stylus, all ‘objects’ will have a line connecting them. That said, you can still create any geometric symbol such as underlined block print, or script.

  10. 36chambers says:

    How well does it handle rendering monochromatic images with shading?

    If this works as well as I think it does, then you could make a considerable amount of $ by selling these “pieces of art” to customers on a per request basis.

    That, and if the etch a sketch artists arent already doing this secretly it will force them to video the entire process to prove it. LOL… video or fake..haha

    Serioussly even if you were to consider their own artistic interpretation to an image as displayed on the final product, they could have just penciled it, scanned it, and printed it to the EAS using this method or similar and it would “have their distinct style” and seem less like a direct print.

  11. Agent420 says:

    ^ I’ve thought of that, and perhaps one day will persue it (probably make some decent cash in a mall kiosk at Xmas).

    As for faking it, I was thinking you could simply disassemble the unit and freehand the powder from that back of the glass, then re-assemble.

  12. svofski says:

    I tried to find an Etch-a-sketch in a local toy store just a couple of months ago and failed. It’s as if they don’t exist anymore.

  13. Sam says:

    I think the fact that Mpark knows what LOGO and its turtle were dates him. Clearly, it dates me. ;)

  14. svofski says:

    Accidentally, I have a LOGO book lying on a synth next to me. A coincidence?

  15. dougefresh says:

    simply awesome.

  16. Chuck says:

    Excellent project, and it’s good to see some Propeller stuff on here!

  17. Life2Death says:

    I’ve been waiting for Propeller to take off on here!

  18. BeagleBreath says:

    very cool project! i like it. this would be a funny text output to add debug capabilities to the spin software. -or- you could add this on to the spin irc project that won the propeller contest a while back.

  19. vgplayer says:

    I just find it amazing that he can edit and compile all the code on the Propeller itself .without a computer

  20. Urza9814 says:

    What’s this about knowing LOGO dating you? I know LOGO, and I’m 19. We played with it in elementary school. I was never any good at it though.

  21. Jimbo says:

    ‘Joined up’ writing eReader?

  22. that last piece was a bit mc escher.

    very cool.

  23. Agent420 says:

    One of the projects on my never-ending ‘one-day’ list is to move up to an ARM platform that can perform camera input -> outline processing, so that the Etch-A-Sketch can draw what it sees.

  24. bhartley says:

    If you wanted to have it print text, it would be really neat if you could have it print in cursive, spaces and carriage returns would still be a problem though.

  25. Brendan Sleight says:

    Would love to know more about how the backlash was defeated. Very Very Cool.

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