Better Stepping With 8-Bit Micros

The electronics for motion control systems, routers, and 3D printers are split into two camps. The first is 8-bit microcontrollers, usually AVRs, and are regarded as being slower and incapable of cool acceleration features. The second camp consists of 32-bit microcontrollers, and these are able to drive a lot of steppers very quickly and very smoothly. While 32-bit micros are obviously the future, there are a few very clever people squeezing the last drops out of 8-bit platforms. That’s what the Buildbotics team did with their ATxmega chip — they’re using a clever application of DMA as counters to drive steppers.

The usual way of driving steppers quickly with an ATMega or other 8-bit microcontroller is abusing the hardware timers. It’s quick, but there is a downside. It takes time for these timers to start and stop, and if you’re doing it two hundred times per second with four stepper motors, that clock jitter will ruin your CNC machine. The solution is to use a DMA channel to count down, with each count sending out a pulse to a stepper. It’s a clever abuse of the hardware, and the only drawback is the micro can’t send more than 2¹⁶ pulses per any 5ms period. That’s not really an issue because that would mean some very, very fast acceleration.

The Buildbotics team currently has a Kickstarter running for their four-axis CNC controller using this technique. It’s designed for Taig mills, 6040 routers, K40 lasers, and other various homebrew robots. It’s an interesting solution to the apparent end of the of the age of 8-bit microcontrollers in CNC machines and certainly worth checking out.

Building a Working Game of Tetris in Conway’s Game of Life

If you haven’t been following along with Conway’s Game of Life, it’s come a long way from the mathematical puzzle published in Scientific American in 1970. Over the years, mathematicians have discovered a wide array of constructs that operate within Life’s rules, including many that can be leveraged to perform programming functions — logic gates, latches, multiplexers, and so on. Some of these creations have gotten rather huge and complicated, at least in terms of Life cells. For instance, the OTCA metapixel is comprised of 64,691 cells and has the ability to mimic any cellular automata found in Life.

A group of hackers has used OTCA metapixels to create a Tetris game out of Life elements. The game features all 7 shapes as well as the the movement, rotation, and drops one would expect. You can even preview the next piece. The game is the creation of many people who worked on individual parts of the larger program. They built a RISC computer out of Game of Life elements, as well as am assembler and compiler for it, with the OTCA metapixels doing the heavy lifting. (The image at the top of the post is the program’s data synchronizer.

Check out the project’s source code on GitHub, and use this interpreter. Set the RAM to 3-32 and hit run.

For a couple of other examples of Life creations, check out the Game of Life clock and music synthesized from Life automata we published earlier.

Hackaday Links: September 17, 2017


Mergers and acquisitions? Not this time. Lattice Semiconductor would have been bought by Canyon Bridge — a private equity firm backed by the Chinese government — for $1.3B. This deal was shut down by the US government because of national security concerns.

[Jan] is the Internet’s expert in doing synths on single chips, and now he has something pretty cool. It’s a breadboard synth with MIDI and CV input. Basically, what we’re looking at is [Jan]’s CVS-01 chip for a DCO, DCF, and DCA), a KL5 chip for an LFO, and an envelope chip. Tie everything together with a two-octave captouch keyboard, and you have a complete synthesizer on a breadboard.

As an aside relating to the above, does anyone know what the cool kids are using for a CV/Gate keyboard controller these days? Modular synths are making a comeback, but it looks like everyone is running a MIDI keyboard into a MIDI-CV converter. It seems like there should be a –simple, cheap– controller with quarter-inch jacks labeled CV and Gate. Any suggestions?

World leaders are tweeting. The Canadian PM is awesome and likes Dark Castle.

Way back in July, Square, the ‘POS terminal on an iPad’ company posted some data on Twitter. Apparently, fidget spinner sales peaked during the last week of May, and were declining through the first few weeks of summer. Is this proof the fidget spinner fad was dead by August? I have an alternate hypothesis: fidget spinner sales are tied to middle schoolers, and sales started dropping at the beginning of summer vacation. We need more data, so if some of you could retweet this, that would be awesome.

Remember [Peter Sripol], the guy building an ultralight in his basement? This is going to be a five- or six-part video build log, and part three came out this week. This video features the installation of the control surfaces, the application of turnbuckles, and hardware that is far too expensive for what it actually is.

Hackaday Prize Entry: You Can Tune A Guitar, But Can You Reference REO Speedwagon?

Just for a second, let’s perform a little engineering-based thought experiment. Let’s design a guitar tuner. First up, you’ll need a 1/4″ input, and some op-amps to get that signal into a microcontroller. In the microcontroller, you’re going to be doing some FFT. If you’re really fancy, you’ll have some lookup tables and an interface to switch between A440, maybe A430, and if you’re a huge nerd, C256. The interface is simple enough — just use a seven-segment display and a few LEDs to tell the user what note they’re on and how on-pitch they are. All in all, the design isn’t that hard.

Now let’s design a tuner for blind musicians. This makes things a bit more interesting. That LED interface isn’t going to work, and you’ve got to figure out a better way of telling the musician they’re on-pitch. This is the idea of [Pepijn]’s Accessible Guitar Tuner. It’s a finalist in The Hackaday Prize Assistive Technology round, and a really interesting problem to solve.

Most of [Pepijn]’s tuner is what you would expect — microcontrollers and FFT. The microcontroller is an ATMega, which is sufficient enough for a simple guitar tuner. The real trick here is the interface. [Pepijn] modulating the input from the guitar against a reference frequency. The difference between the guitar and this reference frequency is then turned into clicks and played through headphones. Fewer clicks mean the guitar is closer to being in tune.

This is one of those projects that’s a perfect fit for the Hackaday Prize Assistive Technology round. It’s an extremely simple problem to define, somewhat easy to build, and very useful. That doesn’t mean [Pepijn] isn’t having problems — he’s having a lot of trouble with the signal levels from a guitar. He’s looking for some help, so if you have some insights in reading signals that range from tiny piezos to active humbuckers, give him a few words of advice.

Word Clock Five Minutes At A Time

As this clock’s creator admits, it took far more than five minutes to put together, but it does display the time in five minute increments.

After acquiring five 4-character, 16 segment display modules that were too good to pass up, they were promptly deposited in the parts pile until [JF] was cajoled into building something by a friend. Given that each display’s pins were in parallel, there was a lot of soldering to connect these displays to the clock’s ATMega328P brain. On the back of the clock’s perfboard skeleton, a DS1307 real-time clock and coin cell keep things ticking along smoothly. The case is laser cut out of acrylic with an added red filter to up the contrast of the display, presenting a crisp, crimson glow.

Troubleshooting — as well as procrastination — proved to be the major stumbling block here. Each of the displays required extensive troubleshooting because — like Christmas lights of yore — one bad connection would cause all the other displays to fail. Furthermore, there isn’t any easy way to change the time, so the clock needs to be reprogrammed once in a while

We love word clocks because there are so many ways to configure them and for the oddities. That isn’t to say radial clocks are any less creative.

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3D Prints That Fold Themselves

3D printing technologies have come a long way, not only in terms of machine construction and affordability but also in the availability of the diverse range of different printing materials at our disposal. The common consumer might already be familiar with the usual PLA, ABS but there are other more exotic offerings such as PVA based dissolvable filaments and even carbon fiber and wood infused materials. Researchers at MIT allude to yet another possibility in a paper titled “3D-Printed Self-Folding Electronics” also dubbed the “Peel and Go” material.

The crux of the publication is the ability to print structures that are ultimately intended to be intricately folded, in a more convenient planar arrangement. As the material is taken off the build platform it immediately starts to morph into the intended shape. The key to this behavior is the use of a special polymer as a filler for joint-like structures, made out of more traditional but flexible filament. This special polymer, rather atypically, expands after printing serving almost like a muscle to contort the printed joint.

Existing filaments that can achieve similar results, albeit after some manual post-processing such as immersion in water or exposure to heat are not ideal for electronic circuits. The researchers focus on this new materials potential use in manufacturing electronic circuits and sensors for the ever miniaturizing consumer electronics.

If you want to experiment printing extremely intricate structures, check out how [_primoz_] brilliant technique revolutionized how the 3D printing community prints thin fibers, bristles, and lion sculptures.

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Take a Time-Lapse or Bake a Cake with this Kitchen Timer Panning Rig

Seems like the first thing the new GoPro owner wants to do is a time-lapse sequence. And with good reason – time-lapses are cool. But they can be a bit bland without a little camera motion, like that provided by a dirt-cheap all-mechanical panning rig.

Let’s hope [JackmanWorks]’ time-lapse shots are under an hour, since he based his build on a simple wind-up kitchen timer, the likes of which can be had for a buck or two at just about any store. The timer’s guts were liberated from the case and a simple wooden disc base with a 1/4″-20 threaded insert for a tripod screw was added. The knob, wisely left intact so the amount of time left in the shot is evident, has a matching bolt for the camera’s tripod socket. Set up the shot, wind up the timer, and let it rip at 1/60 of an RPM. Some sample time-lapse shots are in the video below.

Turning this into a super-simple powered slider for dollying during a time-lapse wouldn’t be too tough — if you’ve already got a nice pantograph slide rig built.

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