I’ve been quietly working on a product idea inspired by conversations with fellow TOG member chebe about her blue LED Matrix Top. I had noticed the different levels of illumination in a row when more then one LED is illuminated. I suggested that using a high-side transistor or special driver chip might resolve the problem for this or future projects.
There are many options for different chips which could be used in a LED matrix display. But no suitable part existed in a form factor compatible with the LilyPad Arduino (or FLORA) sewable micro controller boards. With this deficiency in mind I began investigating and experimenting with different designs for a new add-on board for use with the LilyPad.
The result of this initial work was two sizes of self-etched prototype boards which I called GPIOPAD’s. At the heart of each board was a I2C GPIO expander chip from NXP, the 8-bit PCA9674 and the 16-bit PCA9675. Using these boards I spent a number of nights in August sewing a basic circular and linear pattern of LED’s and resistors onto the back of a polo shirt. This shirt was part of the wearables projects I brought to World Maker Faire in New York in late September.
After World Maker Faire I took a break from wearables to try and finish off some other projects. But I kept thinking about ways to improve on my prototypes and possible new add-on modules.
In November I came back to this project and made a number of changes to the board which should make them easier to work with. These changes include using a consistent arrangement for the VCC, GND, SCL and SDA pins, adding current limiting resistors to each of the GPIO pins on the board, and using solder jumpers to select different I2C addresses.
With all these changes I decided to come up with a different naming convention for these boards. The new boards I’ve called SEWIO8 and SEWIO16.
I sent an order for about 30 of these new designs to be fabricated by the US based OSH Park batch PCB service, which took just over three weeks to arrive in Ireland after placing the order. The circular boards were supplied after tab routing so I had to clean up the remains of the tabs and mouse bite holes with a file. But I’ve been very happy with the results.
So with my trip to 29th Chaos Communication Congress (29c3) in Hamburg rapidly approaching, I started thinking about what I would do or work on during congress. As I was targeting wearables with my new boards and I hadn’t seen wearable projects begin worked on at congress before, I though doing a practical workshop might be interesting.
So the weekend before Christmas I began looked through the components and materials I had at home and TOG. Using these materials I came up with a simpler sewable circuit with a battery, resistor, LED and switch. Over the weekend I self-etched and solder a sewable PCBs to hold a CR1220 batter and another to hold a momentary push button, and made up lots of fabric pieces stiffened with iron on fusing.
The goal of this basic workshop was to concentrate on getting participants familiar with the materials and techniques that can be used in a wearable project. So I used the congress wiki to create a Basic Electronic Fashion workshop page for the second day of the event, which would run for 2 hours and cost €6. I had no idea if people would turn up.
When I arrived at congress I met up with some of my maker type hackers friends and commandeered a small table in the Hardware Hacking Area to show off my wearable pieces and projects and a small piece of paper advertising the workshop. The wearable pieces received a lot of interest with lots of questions and comments about what it was and how it worked. The most common question was “can it be washed?”, my answer was “yes with a careful hand wash”.
The workshop went very well, about 25 took part in the introduction part and 14 stayed for the hands on part. Over the remaining days another 6 people did the hands on part of the workshop which I ran in an ad-hoc manner in the Hardware Hacking Area.
I was also interviewed in English as part of a series of German language articles in the news website Spiegel Online about the activates taking place and some of the people attending 29c3. LED-Kunst auf dem 29C3 (Google Translation).
Hamburg city and the new conference location (CCH) will take a little bit of getting use too but it’s off to a very good start. I’ve collected my photos of 29c3 and Hamburg in this photo album.
Now finally I need to write up product pages for my new SEWIO8 and SEWIO16 boards.