Emulating ARM On An 8-pin AVR

April 17, 2012 by Brian Benchoff 9 Comments

Falling on the heels of some fabulous ‘lets see what we can emulate on an AVR’ builds we’ve seen, [Dimitri] emulated an ARM Cortex-M0 on an 8-pin ATtiny85.

The emulator is written entirely in AVR assembly. Unfortunately, the instruction set of ATtinys don’t have a multiply instruction, so that had to emulated in a separate piece of code. Even with this addition, the emulator is very small; the core is just over 1300 instructions and small enough to fit on the Flash of the very small ‘tiny85.

Unlike the ATMega running Linux we saw last month, [Dimitri] won’t be doing anything crazy like making the tiniest and worst Linux computer ever. The Cortex-M0 doesn’t have a MMU, so Linux is out of the question. [Dimitri] could go with μCLinux, with the addition of a I2C EEPROM and RAM, but don’t expect a speed demon for an emulated ARM running at 200kHz.

[Dimitri] put all the code up on his webpage, and the installation is just running ‘make.’ It looks easy enough to get up and running very quickly, so we’re sure some bored hardware guru will come up with something interesting to do with this code.

Playing Zork On The Arduino

April 15, 2012 by Brian Benchoff 5 Comments

If you’re looking for something to do on a boring Sunday afternoon, how about dusting off your Arduino and playing a text adventure? [Louis] wrote in to tell us about his project called AZIP, an app that will let you play classic 1980s text adventures on your Arduino.

The famous Infocom text adventure games such as Zork and Hitchhiker’s Guide to the Galaxy (reputed to be better than the book, by the way) all ran on a virtual machine called a ZMachine. We’ve seen a few unsuccessful attempts to run a ZMachine on an Arduino, but these builds usually end up going with a Linux-based single board computer. As far as we’re aware, [Louis]’ build is the first time classic text adventures have been available on the Arduino.

[Louis] based his build on the popular Jzip ZMachine. The required hardware is fairly minimal – just an Arduino with an SD card. Right now the limitations of Flash and RAM on the Arduino means [Louis] needed to remove the game save and restore functions, but with a little clever coding and continued development those functions can be restored. Very cool indeed.

QArt Codes, The Better Way To Put Picture In A QR Code

April 13, 2012 by Brian Benchoff 22 Comments

[Russ Cox], current Googler and formerly of Bell Labs, posted an awesome guide to putting images in a QR code. Unlike this terrible attempt I wrote last August, [Russ]’s method does much more than simply paste an image into a QR code and hope the error correction passes. This new method generates a unique URL to be encoded for each QR code. In other words, the embedded image is actually part of the QR code and not just a copy and paste attempt.

The basis of [Russ]’ hack is the ability to change the message contained in a QR code to be made of either ASCII/UTF-8 or decimal numbers coded as binary. By appending an anchor tag (i.e. http://swtch.com/pjw/#123456789...) to the URL that will be encoded, [Russ] can change a whole bunch of pixels in a QR code to make just about any image.

With a few tricks like building new Reed-Solomon encoded blocks, [Russ] can change where in the pixels required by the QR code are placed. This allows for the full-width image of PJW’s binary likeness to be displayed in the QR code.

[Russ] put up a QArt coder that allows anyone to put a pixelated image in any QR code. [Luke Shumaker] (thanks for sending this in, [Luke]) took this tool and put the ‘ol skull ‘n wrenches inside a QR code pointing to hackaday.com. Very nice work from [Russ], and puts my work to shame. I’ll go cry in a corner now.

Building A Word Clock With Genetic Algorithms

April 10, 2012 by Brian Benchoff 22 Comments

Maybe it was a language barrier he ran into, or possibly an inclination to do things the hard and smart way, but we really like [Alessio]’s take on building the display for his word clock. Instead of relying on a pre-designed word layout, he made his own word pattern with a genetic algorithm.

While looking at other word clock builds on the Internet, [Alessio] noticed all the DIY copies used the same pattern of letters as the original QLOCKTWO word clock. There are obvious reasons for this, laziness chief among them, but [Alessio] decided to do one better. Armed with JGAP, he made a 10×10 German language word clock and a 11×11 English language word clock.

[Alessio]’s algorithm takes a list of regular expressions – ‘five past four’ and ‘four five’ are both valid expressions for 4:05 – and combines solutions together for a hopefully optimal solution. One added bonus of [Alessio]’s method is the ability to generate non-square word clocks. On his project page, [Alessio] put up examples for round, triangular, and diamond-shaped word clocks.

[Alessio] ended up building a 10×10 square German language word clock with an Arduino Nano, DS1307 real-time clock, RGB LEDs, and a few shift registers. Very nice work for a custom-designed word clock.

Getting 12 Year Olds To Learn Assembly Programming

April 8, 2012 by Brian Benchoff 72 Comments

[notch], the mastermind behind Minecraft, is working on a new game. It’s called 0x10c (pronounced ‘trillek’, we think) and promises to teach an entire new generation the joys of assembly programming on a 1980s-era computer.

The setup for the game is nerdy/awesome enough to make [Douglas Adams] blush; a ‘deep sleep core’ was invented in 1988 that attached to the 16-bit computers of the day. This core was big endian, where the DCPU-16 (the computer in the game) was little endian. What was supposed to be a one-year hibernation turned into a 281 Trillion year coma, the Universe is dying, and everyone from 1988 is just waking up.

The game features a fully functional 16-bit CPU that controls every aspect of your spaceship. The specs for the DCPU-16 have been released and there are several emulators available.

Already, a few communities have been set up around the web to discuss how to program the DCPU-16: the official forum of 0x10c, the 0x10c subreddit, and another dedicated to programming the in-game computer. Already there’s a C-like language that compiles executables for the DCPU and a Game of Life implementation.

We know this isn’t a usual Hackaday post. Despite this, we’re fairly certain a good percentage of our readership will be programming a DCPU-16 in the next year. It just might be time to crack the books and learn how to build a compiler and OS. The dragon book (Compilers Principles, Techniques, and Tools, Aho, Sethi, Ullman, 1985) is very good, and [Andy Tanenbaum]’s Operating Systems Design and Implementation is how [Linus Torvalds] got his start.

One more thing: we’re going to be running a contest for the best physical implementation of the DCPU-16 in a few months. We’ll wait until the in-game hardware is nailed down, along with any peripherals [notch] plans to add. Right now the prizes are some HaD schwag, but that may change. Further info with updates pending, but you’re free to start working now.

Putting Multitasking On An AVR

March 26, 2012 by Brian Benchoff 15 Comments

[vinod] wanted to familiarize himself with AVR assembly programming, but wanted to do something a little more ambitious than simply blinking an LED. While the completed build does blink a few LEDs, we love that e decided to implement multitasking on his microcontroller.

The program [vinod] came up with uses round robin scheduling to give one of the seven programmed tasks a little bit of compute time every time a timer is triggered. Although it’s extremely simple compared to “real-life” real-time operating systems like VxWorks, it’s still an impressive achievement.

In the video after the break, [vinod] shows off his task-switching with seven LEDs. The white LED is a PWM task, while the six other LEDs are simple toggling tasks that switch a LED on and off at set intervals independent of each other. This would be hard – if not impossible – to do without some sort of scheduling. Nice work, [vinod].

Continue reading “Putting Multitasking On An AVR” →

Kinect For Windows Resources

March 22, 2012 by Brian Benchoff 10 Comments

Despite having been out for nearly two months, the world has yet to see a decent guide to the Kinect for Windows. While the Xbox and Windows versions of the Kinect use basically the same hardware, there are subtle but important differences. Thanks to [Matthew Leone] and his awesome summary of developer resources, getting your Kinect project up and running is now a lot easier.

After getting the SDK from the Microsoft Kinect for Windows site, you might want to check out the Microsoft Programming Guide. The Windows Kinect can only be used with Visual Studio, but with that inflexibility comes a few added features. Both versions of the Kinect have a microphone array that allows for determining the direction of a sound source. The Open Source driver has very little support for audio input, but the official Microsoft version has all the APIs for audio capture, source localization, and speech recognition ready to go.

At $250, the Kinect for Windows is a fairly hefty investment. A used Xbox Kinect can be had for around $80, so we’re pretty certain the hacker community is going to steer itself away from the Windows version. Still, if you’re ever paid to develop something for the Kinect you might want the friendly APIs and features not found in the XBox version.