Garrett's blog

Musical Fish (MSP430 Captouch & Bare Conductive Paint)

This is a short article demonstrating an experiment with Bare conductive ink and the MSP430's capacitive sensing hardware.

I've experimented with various capacitive sense methods previously; the most common uses one pin to charge up an electrode, while using another pin to measure the amount of time needed to charge up to the logic high threshold level of an input pin. A couple of similar approaches are illustrated here:

An alternate method is available on several of the MSP430 value line microcontrollers (G2xx2, G2xx3, FR58xx, FR59xx). In addition to the typical pin peripheral functions, they include a relaxation oscillator circuit that includes pin capacitance to set the frequency. By measuring the number of oscillations in a given time period, a small change in capacitance can be measured...enough to detect whether a finger is touching an electrode.

Photo Jan 04, 1 43 12 AM (HDR)

Bare Conductive makes a carbon-bearing paint that is fairly conductive, and available in pen form. Combined with capacitive sensing, it is possible to draw an interface on a sheet of paper, and use it as input to a microcontroller. For this experiment, we used it to play a few notes from a speaker and make a very basic piano-like instrument.

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Submitted by Garrett on Sun, 01/19/2014 - 13:58.

Dallas Makerspace

Dallas Makerspace Laser Cutter

In the SF Bay Area, I had access to a number of places (TechShop, Noisebridge, Hacker Dojo) to work on projects that weren't appropriate for my garage or a spare bedroom. Tools like engine lathes and laser cutters are expensive to own, bulky, and require the proper infrastructure. It's also good to have a place to meet with like-minded people and share ideas. I just moved to Dallas and hoped to find something similar.

The nearest TechShop is about three hours away, in Austin. So I decided to check out the local Dallas Makerspace.

They seem to hold a middle ground between a typical hackerspace and a corporate-run workshop like TechShop. Hackerspaces usually attempt to remain completely open to the public, and shy away from creating rules whenever possible. This leads to a more intense environment where amazing things can rise from the chaos, but often leads to conflicts and drama. TechShops have a very strong divide between members and employees, and require adhering to a set of rules and certifications in order to use the equipment. Dallas Makerspace seems to have achieved an interesting midpoint where the feeling of members creating the space is still there, but many problems are forestalled by a small set of rules regarding the space, member behavior, and equipment.

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Submitted by Garrett on Sun, 01/12/2014 - 21:58.

Front driveway snail



Submitted by Garrett on Sun, 02/22/2009 - 03:15.

FedEx Email Support: Useless

So the next shipment of ShiftBrites was delayed in Alaska Customs again. Last time, I had to call and provide an EIN or social security number, I hoped they had that on file. Also, they never billed me for duties and eventually sent a collection agency after me. That always looks good on a credit report. Anyway, I used their online support contact form to ask for help:  Read more»

Submitted by Garrett on Wed, 10/29/2008 - 11:42.

TGIMBOEJ: Microbox


What happens when you mix electronics, chain-letters, and awkward acronyms? You get TGIMBOEJ, or The Great Internet Migratory Box Of Electronics Junk. A nefarious plot to obtain more junk under the guise of giving away junk, hatched up by Windell at Evil Mad Scientist Laboratories (with whom I occasionally cross paths at TechShop).

The idea is to recieve a TGIMBOEJ, pick out some interesting parts, put some more of your own electronics miscellany back in the box, and send it along to the next person. There are now several boxes circulating; you can track their progress and get yourself on the request list by visting the TGIMBOEJ wiki. Be warned there's a little vandalism on that site, so it may not be what you expect by the time you visit.  Read more»

Submitted by Garrett on Sat, 07/19/2008 - 03:09.

It worked, ok?

Homebrew PCB saw with dust removal

This was pretty ugly. I needed to cut a bunch of copper-clad FR4 into thin strips for my LED array project. 144 1/4" strips, to be precise. I wasn't going to use the metal shear at TechShop, since fiberglass is pretty abrasive. I was also worried the pinching effect would wrap copper around the edges and short the two sides. Anyway, I lashed together a mini table saw with a Dremel, diamond wheel, hot glue, plywood, and duct tape. Note the Shop Vac dust removal system. It actually worked quite well, cutting about 120 feet of PCB material and I didn't notice any decline in cutting ability.  Read more»

Submitted by Garrett on Sun, 04/27/2008 - 01:18.

Maker Faire Bay Area 2008

Maker Faire. HID Portal

Ahh, it's that time of year again. Maker Faire Bay Area 2008 is coming up quickly, and I'm in a rush to get my projects done. Worst case, I finish them while at the Faire, which could be interesting too! Above is a photo from last year's Maker Faire here in San Mateo (only a couple miles from where I live and work). My project was a device that makes it easy to send custom keyboard, mouse, or joystick input to a computer over USB. The demo was a model airplane with accelerometers, controlling the same airplane in a flight simulation game. It was really popular, we had people lined up to play the game! Some were actually interested in the hardware behind it.  Read more»

Submitted by Garrett on Sat, 04/26/2008 - 02:03.

Maker Faire Project Update: Grow Lamps

Over at Darker Technologies they're making good progress on the Maker Faire projects that we're exhibiting in the same booth this May. The first LED grow lamp array has been built and tested. It uses red and blue LEDs, since those are the wavelengths plants absorb (they reflect green, so no need to waste power emitting that color). He'll be testing the arrays on live plants this month, using other light sources as a control. If you're in the SF Bay Area this May, stop by the Maker Faire in San Mateo and check out all the great projects and exhibits! There's a lot to do! It's fun!

Submitted by Garrett on Fri, 04/04/2008 - 14:59.

Ball throwing robot

I like this ball throwing robot and the dog operating it. Unfortunately I can't find any build details, it looks like a lot of work was invested in the mechanism and controller.

Submitted by Garrett on Mon, 03/17/2008 - 10:12.

Silicon Valley Electronics Flea Market

I took a trip down to De Anza College for the monthly electronics flea market. Lots of interesting parts, gizmos, tools, and random clutter. Click on the photo above to view my Flickr set of the event!

Submitted by Garrett on Sat, 03/08/2008 - 20:25.