Month: September 2015

There’s A Bug In My Robot

September 17, 2015 by 15 Comments

What has six legs, 25 LEDs, a Microchip CPU, can be sewn into clothing, and even plugged into a Raspberry Pi? The answer, it turns out, is the CodeBug–a low cost computer board aimed at the educational market. These board were crowdfunded and are now available for general purchase. [Mike Redrobe] took one of the boards, connected a few servos and used the CodeBug’s Scratch-like language to create a small robot.

You can see the robot in the video below. Programs download via USB (the board looks like a USB drive). You can also send commands over USB to operate in tether mode, or you can directly plug the board into a Raspberry Pi.

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Circular Saw + Innovative Fence = Unique DIY Table Saw

September 17, 2015 by 26 Comments

A table saw is often the first machine the aspiring woodworker wants for the shop. But even a lightweight contractor’s saw is not cheap, and a really good cabinet saw is both expensive and incredibly heavy. And any table saw is an intimidating machine that can liberate your fingers from your hand in a trice. Looking for a solution to all of these problems, [Seumas] has come up with a unique table saw conversion for a circular saw that improves safety and lowers the barrier to table saw ownership.

Flipping a low-cost circular saw upside down and attaching it to a table is old hat – we’ve seen plenty of examples of that before, including this recent post. Where [Seumas]’s idea shines is in the integration of the fence and the table. A typical fence needs to stay perfectly parallel to the blade while being dead square to the table, but still needs to be moved to adjust the width of cut. In [Seumas]’s design, the fence is fixed to the table, and the whole table slides left and right on high-pressure laminate rails. In theory, the fence will never go out of true, and the width of cut can be a lot wider than the typical table saw – an impressive 3 feet to the right of the blade.

As for safety, [Seumas] shows off quite a selection of DIY attachments in the video after the break. He builds his own Lexan blade guard, anti-kickback pawls, and stock hold-downs. Add in the little touches like shop-made clamps for locking the table, extending outfeed support, and built-in dust collection, and you can make yourself a pretty capable machine at the fraction of the cost of buying.

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Hardware Virtualization In Microcontrollers

September 17, 2015 by 36 Comments

Look at any sufficiently advanced CNC machine or robot, and you’ll notice something peculiar. On one hand, you have a computer running a true operating system for higher-level processing, be it vision or speech recognition, or just connecting to the Internet. On the other hand, you have another computer responsible only for semi-real-time tasks, like moving motors, servos, and reading sensors and switches. You won’t be doing the heavy-lifting tasks with a microcontroller, and the Raspberry Pi is proof enough that real-time functions aren’t meant for a chip running Linux. There are many builds that would be best served with two processors, but that may be changing soon.

Microchip recently announced an addition to the PIC32 family of microcontrollers that will support hardware virtualization. This addition comes thanks to the MIPS M5150 Warrior-M processor, the first microcontroller to support hardware visualization.

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Tiny Headless Servers Everywhere

September 17, 2015 by 30 Comments

Quick, what do “cloud compute engines” and goofy Raspberry Pi Internet of Things hacks have in common? Aside from all being parody-worthy buzzword-fests, they all involve administering remote headless (Linux) installations. It’s for exactly that reason that a new Ubuntu distribution flavor, Ubuntu (Snappy) Core, targets both the multi-bazillion-dollar Amazon Elastic Compute Cloud and the $55 BeagleBone Black.

If that combination seems unlikely to you, you’re not alone. But read on as we hope to make a little more sense of it all.
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Retro Games On ArduinoCade Just Shouldn’t Be Possible

September 17, 2015 by 26 Comments

Making retro video games on today’s micro controllers brings many challenges, especially when using only the micro controller itself to handle the entire experience. Complex graphics, sound, game logic and input is taxing enough on the small chips, toss in NTSC color graphics and you have a whole different bear on your hands.

[rossum] set out making the Arduinocade retro game system using an overclocked Arduino Uno, and not much more. Supporting 4 voice sound and IR game controllers, the system also boasts 27 simultaneous colors all in software. These colors and the resolution feel like they’re impossible without a graphics chip to offload some of the work. While doing all of this the ATmega328p is also playing some faithful reproductions of classic arcade games.

The uses a couple of interesting tricks. Color is generated with NTSC color artifacts, where the screen is really black and white, but thanks to a delay or two in the signal generation the bits are out of phase from the reference “color burst” signal and appear on-screen as unique colors. This approach was used in the 8 bit Apple II personal computers to generate its colors, and also on the early IBM PC’s with CGA cards to drastically increase color depth. In this case, the chip is overclocked with a 28.6363 MHz crystal (a multiple of NTSC timing) and the SPI hardware leveraged to shift out all the necessary pixels. Check out how great it looks and sounds after the break.

It’s good to see an old trick on a new project and we are off to play some games!

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The Ubiquitous Atari Punk Console

September 17, 2015 by 11 Comments

The Atari Punk Console (APC) is a dual 555 (or single 556) based synth. Designed by the famous (and somewhat infamous) Forrest Mims in 1980 and originally simply named “Sound Synthesizer”, the circuit gained it’s more recent popularity when re-dubbed the “Atari Punk Console” by Kaustic Machines. The circuit however doesn’t bear much relation to the Atari 2600 which didn’t contain a 555 timer chip. However we assume the 2600 produced a similarly glitchy square wave audio output.

a2The circuits operation is easy to grasp and uses only 9 components. This ease of design and construction has allowed builders to focus more on the aesthetics of its construction, hacking it into interesting, and often unlikely enclosures and systems. One such hack is the “Atari Punk Bucket” (shown here) where the APC along with a simple amp was hacked into an old rusted bucket. The APC was built up on strip-board along with a simple amp and reclaimed speakers. [Farmer glitch] has used this as a prop in live sets and it both looks and sounds awesome. Continue reading “The Ubiquitous Atari Punk Console” →

Visualizing The Fourier Transform

September 17, 2015 by 56 Comments

If you do any electronics work–especially digital signal processing–you probably know that any signal can be decomposed into a bunch of sine waves. Conversely, you can generate any signal by adding up a bunch of sine waves. For example, consider a square wave. A square wave of frequency F can be made with a sine wave of frequency F along with all of its odd harmonics (that is, 3F, 5F, 7F, etc.). Of course, to get a perfect square wave, you need an infinite number of odd harmonics, but in practice only a few will do the job.

Like a lot of abstract concepts, it is easy to understand the basic premise and you could look up any of the mathematical algorithms that can take a signal and perform a Fourier transform on it. But can you visualize why the transform works the way it does? If you can’t (or even if you can), you should check out [Mehmet’s] MATLAB visualization of harmonic circles. If you don’t have MATLAB yourself, you can always check out the video (see below).

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