How-to: Programmable Logic Devices (CPLD)

December 11, 2008 by Ian 57 Comments

Complex programmable logic devices (CPLDs) contain the building blocks for hundreds of 7400-serries logic ICs. Complete circuits can be designed on a PC and then uploaded to a CPLD for instant implementation. A microcontroller connected to a CPLD is like a microcontroller paired with a reprogrammable circuit board and a fully stocked electronics store.

At first we weren’t sure of the wide appeal and application of CPLDs in hobbyist projects, but we’ve been convinced. A custom logic device can eliminate days of reading datasheets, finding the ideal logic IC combination, and then waiting for chips to arrive. Circuit boards are simpler with CPLDs because a single chip with programmable pin placement can replace 100s of individual logic ICs. Circuit mistakes can be corrected by uploading a new design, rather than etching and stuffing a new circuit board. CPLDs are fast, with reaction times starting at 100MHz. Despite their extreme versatility, CPLDs are a mature technology with chips starting at $1.

We’ve got a home-etchable, self programming development board to get you started. Don’t worry, this board has a serial port interface for working with the CPLD, and doesn’t require a separate (usually parallel port) JTAG programmer.

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Simulated Annealing

December 10, 2008 by Eliot 24 Comments

annealing

Here’s an update on our earlier post about genetic programming. Altered Qualia has posted a new implementation of [Ron Alsing]’s idea. It starts with 50 polygons and then randomly changes one parameter with each optimization step. If the the change results in fewer differences from the target image, it’s kept as the new best DNA. This search method is similar to simulated annealing. The image above is the result of 1500 good mutations out of 35900 possible. The implementation lets you choose any image, but smaller means the fitness calculation is faster. It’s written in JavaScript using the <canvas> environment. You’ll definitely get better performance using newer browser builds.

[Original image by R Stevens]

[via Waxy]

WordPress 2.7 Upgrade In One Line

December 10, 2008 by Eliot 43 Comments

BadPoetry WordPress 2.7 has just been released and features a complete interface overhaul. Hack a Day runs on WordPress MU hosted by WordPress.com, so we got this update last week. We run standard WordPress.org on all of our personal blogs though. We recommend it because it’s free, has a massive userbase, and if you host it yourself, you can do whatever you want with it.

To make the upgrade process as simple as possible (and for the sheer rush of ‘rm -rf’), we use a one line command.

$ curl http://wordpress.org/latest.zip -o "wp.zip" && unzip wp.zip && rm -rf ./wordpress/wp-content/ && cp -r ./wordpress/* ~/www/

curl downloads the latest version from wordpress. unzip unpacks all of the files into a directory called ‘wordpress’. rm -rf removes everything in the ‘wp-content’ directory. Otherwise, you will overwrite your images, themes, and plugins. cp -r copies everything to your http document root, overwriting the previous install.

Naturally, you should back up your current install and database beforehand. We tend to use the one-liner with reckless abandon. If you’re wondering about the terseness, it was designed to fit inside the 140 character limit of Twitter.

[Thanks, Chris Finke]

Edge-lit Holiday Cards

December 10, 2008 by Eliot 8 Comments

edgelit

Got 30 minutes for a holiday project and don’t want to get wrangled into some sort of decoupage disaster? Evil Mad Scientist Laboratories can show you just how easy it is to do edge lighting effects. Pictured above are three holiday cards constructed using scored plastic. You can use many different types of clear plastic for this, not just acrylic. The lighting is just an LED on a coincell. Black tape is used to prevent light leaking from the edges. The red and green version above is two stacked layers. This looks like something fun to scale up for a larger project or just to kill some time.

22″ Binocular Telescope

December 9, 2008 by Caleb Kraft 16 Comments

binocular

This is the worlds largest known visual binocular. Why binocular and not just a regular telescope? Well, it all has to do with clarity. Apparently when you can use both eyes, you can see much more detail and pick up light better. The author states in one story that he was able to see a spiral galaxy clearly with a binocular telescope, but couldn’t see it at all with a monocular telescope of the same power.

There is information on several models on the site. Look in the right hand column as well for useful links to parts distributors.

[via Hacked Gadgets]

Genetic Programming

December 8, 2008 by Eliot 46 Comments

monalisa

[Ron Alsing] wanted to try out some genetic programming, so he created a simple test problem: Could you render the Mona Lisa using just 50 semitransparent polygons? The program starts with a random DNA sequence. It then mutates and compares itself to the original image. If the mutation is closer, it becomes the new sequence. The final image he shows looks pretty good after 904,314 iterations.

[prunesquallor] pointed out a genetic algorithm project of his own. It’s a flash program to evolve a car. The car tries to get as far as possible on a set terrain without the passenger circles hitting the ground. The wheel size and positions can change along with the spring length, constant, and damping. A graph tracks the best performance along with the mean. He’s planning on building a version that lets you change the parameters.

[via Waxy]

Simple Laser Projector

December 8, 2008 by Eliot 21 Comments

laserscanner

[kap4001] built what has to be the simplest laser scanner possible. It’s two servos strapped together with zip ties plus a 5V laser module. They’re connected to a Pololu serial servo controller. The laser is pulsed by switching the DTR line. You could use it to draw images like the one above… except that’s an 85 second exposure.