Monday, October 21, 2013

Keyboard Hoodie Project part 1

So, I'm kinda' excited. I have a new project in the works and I'm already making good progress. Next month is NaNoWriMo, which every year I aspire to participate in and every year but one I've fallen flat on my face. What happened that one year? Well, I had a lovely commute every day on the light rail which was an enforced 30 min of writing (by hand). I find my thinking is clearest when I'm not just sitting on my computer at home-- when I'm not sitting at all in fact. That's why I've been inspired to do a keyboard hoodie. I've tried voice dictation stuff, and typing on a phone, but in the end my fingers on keys are like magic. Speed of thought, yo!

The basic idea is there's a hoodie I can shrug on (zipper down the middle), plug my phone into a sort of pocket on the right forearm, tuck my hands into the hoodie pockets, and BAM! I'm typing.

Years ago I picked up a cheap USB keyboard with the cute idea of removing the key covers and replacing them with some embroidered buttons... HORRIBLE idea in retrospect- high-use keyboards get super dirty around me. I can just imagine now how gross the smudged and worn embroidered D and J buttons would look. Ugh. BUT! The important thing is that I kept the keyboard. This Sunday I settled down with it and popped out each and every key. I tore it apart until I had access to the traces sheet, which I scanned and backwards engineered. Photoshop Flood Bucket FTW. (I had to set the tolerance to 20px to prevent leaking between the traces)

I'm only trying to grab the bare minumum of keys so numbers and functions and whatnot are out. Shift, enter, delete, space, and some punctuation [,.?"] are what I'm aiming for. Mapping it out on a sheet of paper I then plugged the bare board into the computer (about half the size of a cell phone at the end of a long usb cable) and then proceeded to short pairs of pins to ground. Thanks to this keyboard tester site, I found that my sample set of mappings proved to be correct! Go me! It's exhilarating to short some exposed pins with bits of wire and see "z" and "n" show up on screen as expected.

My initial joy was temporarily dampened by the prospect of breaking out the lines for the 27 pin connector.... Turns out that really thin connector style isn't called a "ribbon cable" but instead a "flat flex" connector, and hacking on the cable itself was a no go- too delecit and tiny. However! I found that soldering little lines to where the connector met the board turned out to be super easy. Yay for not having to lay down new solder myself.

I spent a lot of today thinking about how to make the buttons... Wikipedia helped me name my problem-- I wanted a switch that would let me ground 2 lines at the same time and it turns out what I wanted was a DPST (double pole, single throw) switch. But not just any switch, a really tiny push button switch... for which initial Googling did not yield any results. So I eventually abandoned the idea of buying something and turned my thoughts to constructing one myself.

I'm very excited with my initial solution. I'm going to be making ~40 buttons so something simple and cheap is nice, which this is. The idea comes from the original keyboard which has 2 sheets of plastic separated by a 3rd sheet. The button you press forces them to contact each other and a grounded metal plate in the back. My version is a segment of foam with a hole-punched circle taken out of the middle. I then run 3 lines of conductive thread through the foam at different levels such that they all cross. When I press with my finger, the lines touch and everything lights up.

Interestingly if I place a popped key atop it and press, the lines do no cross-- much like a real keyboard button the slightly convex shape of my finger is required to actually force contact (the keyboard has a nubben) . A flat surface bearing down on them is not enough (assuming the correct amount of tension remains on the conductive thread)

My next step is to acquire a hoodie and begin placing pieces. I've got new finer soldering irons tips in the mail, as well as a USB OTG adapter which will let the "keyboard" talk to the phone- a horribly vital piece that I pray just... works. I've also got to construct a set of buttons and ensure I can actually wire them up next to each other at close enough proximity... Praise be to my random purchasing habits! Having a hardly used spool of conductive thread on hand is super helpful!

Here's hoping I can get it done before Nov 1st...

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