|Making a digital watch, part II
||[Mar. 16th, 2009|09:09 am]
Last time, I described why I started this project and how I managed to design my first PCB.
I should have taken some pictures of the board when it first arrived in its bubble-wrapped envelope. It was pristine. Sharp, clean corners. Delicate, interwoven traces. Innumerate pads of just the right size and shape and position. Perfectly-formed vias. A green solder-mask, thin but covering all the right places. A father's opinion is never impartial, but this was a damn sexy board. I couldn't restrain myself long enough to do the photoshoot it deserved; I attacked it immediately with solder and flux.
Parts went on. Parts broke, and came back off again. I ripped up pads. I managed somehow to dissolve certain areas of the soldermask, exposing scandalous traces underneath. I drilled extra through-holes. I cut some traces with an X-Acto knife and drew some new ones with a conductive pen. I let flux get dry and sticky in the crevices. I pried up pins, then pried them back down again. I added whitewires that were neither white nor, in some cases, actually wires. I probed the board's every secret with ammeter and ohmmeter, with oscilloscope and microscope.
In short, I thoroughly abused and mistreated this board, in equal parts accidentally and on purpose, for about a month and a half. And how did it repay me?
|Pretty damn well.|
Unfortunately, that 9-volt isn't just for scale -- it's providing the bias voltage for the OLED panel. The next task is to shrink and apply my voltage booster circuit so that the whole thing can run off of the 3.7V Lithium-polymer battery that's exactly the size of the board. Also I still need to mount the accelerometer, and write a fair bit more software (no, that's not the real date and time, but it does tick up approximately correctly). I'll probably end up with at least one more board revision: this one doesn't include space for a 32Khz crystal, which I've recently discovered could save me a whole lot of power.
Finally, I need to build some kind of case and attach wrist straps. Hmm, maybe I need a makerbot....