During last week’s python class we got to the part in our wonderful textbook where the concept of recursion is introduced.  My friend Susan posted a witty line to my facebook feed regarding the teaching of recursion:

I normally teach recursion by checking to see whether they understand recursion, and if not, teaching recursion.

Within the class we have a variety of levels of experience with programming in general, and recursion in particular.  I’m curious to hear peoples’ favourite recursion teaching tools, examples, or other witticisms.  What’s your favourite programming problem to solve recursively?

-Leigh

After a few hours or hacking the old Red Roomba, and failing to fix or workaround the cliff hanger sensor it was time to get some success.

Elmood went out and got me a ULN2803AP chip, which I could use to glue together the Arduino and the tri colour LED bar. I then used some of the arduino examples to pulse and colour and mess around a bit.

The next step, perhaps using I2C to control individual bars (I have 10) and line them up on the stairway!

We now have a webcam pointed at the sign….
Live Broadcasting by Ustream

Andrew has written a detailed blog post about making the LED sign work.

Check it out.

Andrew Kilpatrick: Moving Sign 2

LED Sign from hypatia on Vimeo.

moar LED sign awesomeness from hypatia on Vimeo.

Download the video

We’ve started a Hacklab project to bring utility to some surplus LED sign panels that have been hanging around the HackLab! These panels use a high-speed digital serial interface, which has been reverse-engineered by Dan and Andrew. It’s a very complicated and strange system. If you’re interested in digital logic, ask us to explain how it works.

In order to make the panels easy to use for members, we’re going to permanantly mount them on the wall over the stairs.  They’re going to be attached to a nice painted piece of plywood (steev!) and wired up to a server.  We’re going to do some circuitry to allow the sign’s power to be automatically controlled.

We’re going to interface the LED panels with a host computer using an Arduino.  Our previous efforts pushed the limits of the Arduino’s performance, but we were running completely unoptmized code.  Hopefully with a few tweaks, and by getting a bit more low level, we can move the serial data fast enough for an adquite scan rate.

The Arduino’s USB Serial interface will be used to interface the sign with the host computer, which will most likely be running BMix with a custom output plugin.  BMix is software developed by Andrew, Dan and Jonathan for the Blinkenlights project in Toronto, and is very good at controlling a matrix of lights.  It will allow the display to be operated using a standard UDP protocol which already has lots of language support, and will also allow it to be easily shared between a number of users and applications at the lab.  There’s even a video game API.

This is the start of the project and the basic design… More information, photographs, and geeky details will be coming as we dig deeper.

There’s a new JUG in town!

Jonathan, Andrew and I are starting a new Java Users Group in Toronto. Our group is meant to
hold better appeal for geeks/hackers, to actually hold a meeting every month, and to put a bigger emphasis on socialization with and contributions from all group members. Through 5-minute lightning talks (impromptu and prepared are always welcome), we hope everyone will have a chance to participate.

Vital stats:

Meeting night: 3rd Thursday of each month
Start time: 7:15
Location: the hacklab
Web Site: http://tjug.ca

The monthly agenda will include:

* group discussion of recent Java-related headlines
* lightning talks from anyone who has something to show&tell
* a robocode battle
* at most one longer-format prepared talk (30-45 minutes max)
* a visit to a nearby pub!

We hope you’ll join us for a fun evening of Java!

Notacon is coming up, and it would be cool to get a bunch of people from Toronto to come along.

NOTACON, an annual conference held in Cleveland, Ohio, explores and showcases technologies, philosophy and creativity often overlooked at many “hacker cons”. Our desire is not to supplant other events, but complement them and strike a balance that has gone unnoticed in our community for far too long.

With each new year we build upon the successes and knowledge of the previous years. Our goal is to enlighten, educate, and entertain attendees, presenters, and staff alike. We do this by finding new ways to apply technology to graphics, art, music, or social interaction.

Notacon espouses an ethos of exploration, participation and positive contributions. Hence, while some of the material we may cover is controversial or potentially “black hat” in nature, we feel it is important to openly discuss all topics so that others can learn from the experience and create something good, fun or interesting from it.

Events during Notacon run from Friday morning through Sunday afternoon. These include over 40 presentations, contests such as “Anything but Ethernet”, game shows, prize giveaways and a whole lot of who-knows-what. Anything can happen, and usually does. New in 2009 we will be offering a Thursday night sampler, which will be free of charge and open to the public. More information will be posted as it becomes available.

If you would like to join the community, please explore our getting involved section. Be sure to check out our archives from previous years, featuring information and recordings of our past content.

Last year we had multiple cars head down (it’s only a 5 hour drive to Cleveland), and good times were had by all. It would be great if we could organize a caravan this year and bring as many people as we can to show support for this excellent event.

There will be a “temporary hackerspace” set up at Notacon, with help from people from other spaces including NYC Resistor, HacDC, and the not-yet-opened Pumping Station One. This will include representing and showing off the hacklab: our space, what we’re doing, our projects. Anyone who’d like to help out, whether just by attending or by putting something together to show off, would be very welcome!

A challenge has also been thrown down from people in these other spaces: we should show them (and everyone else) some of the cool things we can do by participating in the Anything But Ethernet competition. This can be the place for us to show off and engage in some friendly competition with our friends in hacker spaces across North America… anyone want to submit something?