Monday, April 14, 2014

Rotating Perspective

The Holocon software is finally running. Since I had four individually-controllable RGB pixels, it just seemed too much of a shame not to animate them. So I wanted to write a routine that "spun" (that is, a chase circuit) with a pulse superimposed on that, with a color shift superimposed on that.

Took forever to work it out. Yesterday, I managed to board BART out towards TechShop without my grenade plans (or a book to read) or even a pen. And worked out the software routine I needed in my head.

(This being the internet age, once I arrived at TechShop I logged in to one of the freely available workstations, navigated to Instructables and after searching out my own Instructable on the grenade, scribbled down the measurements I needed on a scrap of paper.)

The big thing that made the routine finally simple enough to write was realizing the LEDs were changing too quickly for me to bother with actually fading the chase part up and down. Between the hysteresis of the light, and the persistence of vision of the eye, just blinking them in a 25%, 50%, 75%, full-on pattern would be sufficient.

Now I just need to solder up a "naked" ATtiny circuit and hook it back to the rest of the Holocron. The last part will be figuring out how to close the lid properly. And once that is done, I can finish the Instructable and earn another class.

Another bit of perspective. I had to use a different lathe than the one I normally reserve, and I found to my dismay it was a bit out of alignment. I was pretty much ranting about how bad it was; over five thous off of plumb (measured over three inches from the face of the chuck out along the workpiece). Using the three-jaw chuck, I had a wobble at the end of my billet that was on the order of twenty thou.

Yeah. About that. A thou is a thousandth of an inch. The worst error the lathe was throwing at me was maybe 1/32nd of an inch. Put another way, the lead on my mechanical pencil is bigger. Even using the edge of the lead, I could not draw a line with the accuracy I'm usually shooting for with the lathe (2-3 thousandths of an inch).

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