Learn ARM Assembly With The Raspberry Pi

September 20, 2018 by Al Williams 41 Comments

We live in a time when you don’t have to know assembly language to successfully work with embedded computers. The typical processor these days has resources that would shame early PCs and some of the larger ones are getting close to what was a powerful desktop machine only a few years ago. Even so, there are some cases where you really want to use assembly language. Maybe you need more speed. Or maybe you need very precise control over timing. Maybe you just like the challenge. [Robert G. Plantz] from Sonoma State University has an excellent book online titled “Introduction to Computer Organization: ARM Assembly Langauge Using the Raspberry Pi.” If you are interested in serious ARM assembly language, you really need to check out this book.

If you are more interested in x86-64 assembly and Linux [Plantz] has you covered there, too. Both books are free to read on the Internet, and you can pick up a printed version of the Linux book for a small payment if you want.

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Touch Anything And Everything

September 19, 2018 by Brian McEvoy 10 Comments

Powering IoT devices is often a question of batteries or mains power, but in rare exceptions to this rule there is no power supply (PDF Warning). At the University of Wisconsin-Madison and the University of California, San Diego, researchers have gone the extra mile to make advanced backscatter devices, and these new tags don’t need the discrete components we have seen in previous versions. They are calling it LiveTag, and it doesn’t need anything aside from a layer of foil printed or etched on a flexible ceramic-PTFE laminate. PTFE is mostly seen in the RF sector as a substrate for circuit boards.

We have seen some of the wild creations with wifi backscatter that range from dials to pushbuttons. RF backscatter works by modulating the RF signals in which we are continuously swimming. Those radio waves power the device and disrupt the ambient signals, which disruption can be detected by a receiver. With a BOM that looks like a statement more than a list, integration with many devices becomes a cost-effective reality. Do not however broadcast important data because you cannot expect great security from backscatter.

[Via IEEE Spectrum]

Advanced Techniques For Using Git With KiCAD

September 19, 2018 by Kerry Scharfglass 4 Comments

For most developers “distributed version control” probably means git. But by itself git doesn’t work very well with binary files such as images, zip files and the like because git doesn’t know how to make sense of the structure of an arbitrary blobs of bytes. So when trying to figure out how to track changes in design files created by most EDA tools git doesn’t get the nod and designers can be trapped in SVN hell. It turns out though KiCAD’s design files may not have obvious extensions like .txt, they are fundamentally text files (you might know that if you’ve ever tried to work around some of KiCAD’s limitations). And with a few tweaks from [jean-noël]’s guide you’ll be diffing and merging your .pro’s and .sch’s with aplomb.

There are a couple sections to the document (which is really meant as an on boarding to another tool, which we’ve gotten to in another post). The first chunk describes which files should be tracked by the repo and which the .gitignore can be configured to avoid. If that didn’t make any sense it’s worth the time learning how to keep a clean repo with the magic .gitignore file, which git will look for to see if there are any file types or paths it should avoid staging.

The second section describes how you can use two nifty git features, cleaning and smudging, to dynamically modify files as they are checked in and out of the repo. [jean-noël]’s observation is that certain files get touched by KiCAD even if there are no user facing changes, which can clutter patch sets with irrelevant changes. His suggested filters prevent this by stripping those changes out as files get checked in. Pretty slick.

Electric Wheelbarrow Makes Hauling Big Loads Easier

September 19, 2018 by Richard Baguley 20 Comments

Gardening involves a depressing amount of physical activity: haul this over here, dump it there and then cover it with this. Things like wheelbarrows are still damn hard work, especially for people like who are somewhat physically compromised. That’s why we love this build from [Karl Gesslein]. He usually makes electronic bikes, adding motors to bicycles to roam the streets faster. But this time he applied his expertise to a wheelbarrow. He added a 3000W motor to the wheelbarrow, which drives the front wheel when triggered by the accelerator on the handle.

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Voice Controlled Stereo Balance With ESP8266

September 19, 2018 by Tom Nardi 13 Comments

A stereo setup assumes that the listener is physically located between the speakers, that’s how it can deliver sound equally from both sides. It’s also why the receiver has a “Balance” adjustment, so the listener can virtually move the center point of the audio by changing the relative volume of the speakers. You should set your speaker balance so that your normal sitting location is centered, but of course you might not always be in that same position every time you listen to music or watch something.

[Vije Miller] writes in with his unique solution to the problem of the roving listener. He’s come up with a system that can adjust the volume of his speakers without having to touch the receiver’s setup, in fact, he doesn’t have to touch anything. By leveraging configurable voice control software running on his computer, his little ESP8266-based devices do all the work.

Each speaker has its own device which consists of a NodeMCU ESP8266 and X9C104 digital potentiometer inside of a 3D printed case. The audio terminal block on the gadget allows him to connect it inline between the speaker and the receiver, giving [Vije] the ability to adjust the volume through software. The source code, which he’s posted on the Hackaday.io project page, uses a very simple REST-style API to change speaker volume based on HTTP requests which hit the ESP8266’s IP address.

The second part of the project is a computer running VoiceAttack, which lets [Vije] assign different actions based on what the software hears. When he says the appropriate command, the software goes through and fires off HTTP requests to the nodes in the system. Everything is currently setup for two speakers, but it shouldn’t be too difficult to expand to more speakers (or even rooms) with some adjustment to the software.

It’s not the first voice controlled speaker we’ve ever seen, but it does solve a very specific problem in a unique way. We’d be interested in seeing the next logical step, which would see this technology integrated into the speaker itself.

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‘SHE BON’ Is An Artful, Wearable, Sensual, Sensing Platform

September 19, 2018 by Donald Papp 16 Comments

SHE BON (that’s the French bon, or “good”) is an ambitious project by [Sarah Petkus] that consists of a series of wearable electronic and mechanical elements which all come together as a system for a single purpose: to sense and indicate female arousal. As a proponent of increased discussion and openness around the topic of sexuality, [Sarah]’s goal is to take something hidden and turn it into something obvious and overt, while giving it a certain artful flair in the process.

The core of the system is a wearable backpack in the shape of a heart, from which all other sensors and feedback elements are connected. A lot of thought has gone into the design of the system, ensuring that the different modules have an artistic angle to their feedback while also being comfortable to actually wear, and [Sarah] seems to have a knack for slick design. Some of the elements are complete and some are still in progress, but the system is well documented with a clear vision for the whole. It’s an unusual and fascinating project, and was one of the finalists selected in the Human Computer Interface portion of the 2018 Hackaday Prize. Speaking of which, the Musical Instrument Challenge is underway, so be sure check it out!

Industrial 3D Printing Uses Layers Like We’ve Never Seen Before

September 19, 2018 by Mike Szczys 20 Comments

We’ve seen FDM printers lay down layers by extruding plastic in a line. We’ve seen printers use sintering and lithography to melt or cure one layer at a time before more print medium moves into place for the next layer. What we’ve never seen before is a printer like this that builds parts from distinct layers of substrate.

At the International Manufacturing Technology Show last week I spoke with Eric of Impossible Objects. The company is using a “sheet lamination process” that first prints each layer on carbon fiber or fiberglass, then uses a hydraulic press and an oven to bake the part into existence before bead-blasting the excess substrate away. Check out my interview with Eric and join me below for more pictures and details.

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