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[personal profile] maradydd
Since my last update, I've picked up the necessary hardware to build a SpiffChorder, Mikkel Holm Olsen's homebrew AVR-based chording keyboard. The circuit is now mostly breadboarded, and one of my winter gloves has been converted into a prototype that looks scarily like something out of Serial Experiments Lain. ph34r my wire tentacles!

I have also fallen madly in love with the art of wire-wrapping. It's not a technique people use very often anymore, since soldering is so convenient and cheap, and almost nobody prototypes CPUs with discrete components these days -- we have FPGAs for that. However, it's a great way to hook up components that need a flexible connexion, such as glove-mounted switches that need to tie in to a breadboard. Wrap a lead, then wrap a single header pin, and voila -- breadboardable glove-mounted switch. (Also handy for connecting panel-mount components to a breadboard, using the same header trick. This worked great for the USB-B jack.)

[livejournal.com profile] joel tells me that I'm not the only one doing my part to keep wire-wrapping alive -- Steve Chamberlin did prototype his own CPU with discrete components, showed it off at Maker Faire, and taught Joel (and presumably many more people) how to wire-wrap. Keep the dream alive, Steve!

Now to figure out what I did with those 82-ohm resistors, finish that breadboarding job, and try loading Mikkel's hex image onto my ATMega8. Cross your fingers for me -- I want to take this to the hackerspace meeting tonight.

ETA: hm, that's strange, the ISP pins are definitely lined up correctly (my multimeter tells me so!), there's a 2.2k pullup on the RESET line, but I still get the blinky red LED of no love from the AVR-ISPmkII. Actually, first it's the solid red LED of no love which isn't mentioned in the manual, then when I try to load up the image via avrdude it's the blinky red LED of no love. Downloading AVR Studio now, we'll see if the official tools give a more useful error.

(no subject)

Date: 2009-06-30 03:21 pm (UTC)
From: [identity profile] anaisdjuna.livejournal.com

Is there a chance of seeing pictures of this geekery?

(no subject)

Date: 2009-06-30 03:32 pm (UTC)
From: [identity profile] maradydd.livejournal.com
Sure, I can bust out the camera later tonight. I'm going to take the breadboard with me to the hackerspace meeting and see if someone there can help me figure out what's going on with the uC, but I've been wanting to take some HOWTO shots of wirewrapping anyway, so pics of the board should be no problem.

(no subject)

Date: 2009-06-30 07:08 pm (UTC)
From: [identity profile] cadmus.livejournal.com
I should have been an electrical engineer, like my grandfather before me. Instead, I have my shiny Humanities degrees.

(no subject)

Date: 2009-07-01 12:50 pm (UTC)
From: [identity profile] maradydd.livejournal.com
Both my degrees are in linguistics.

(no subject)

Date: 2009-07-01 12:00 am (UTC)
From: [identity profile] deeptape.livejournal.com
+1 Lain reference

(no subject)

Date: 2009-07-01 03:30 am (UTC)
From: [identity profile] ch.livejournal.com
you should also consider ugly style over a ground plane. i thought it was bogus until i tried it. also see the related dead bug style.

c.f. http://www.qrp.pops.net/ugly.asp

(no subject)

Date: 2009-07-01 12:50 pm (UTC)
From: [identity profile] maradydd.livejournal.com
I love ground plane construction. It looks like ass, but when you need to knock something together fast, there's nothing better.

The main reason for using wire-wrap for the production version of this project is size and flexibility. I can fit the whole thing (less the mini-USB connector and the switches) into two 28-pin sockets, and since this is going into a glove, I can put one on the front of the wrist and one on the back and it'll fit beautifully, even with my tiny little wrists. Now I just need to wait for my sockets to show up at the Local Electronics Store.

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