Android Hacks

417 Articles

Start Gaming Early With IKEA High (Score) Chair

November 29, 2015 by 18 Comments

If you want your kid to be really great at something, you have to start them out early. [Phil Tucker] must want his kid to be a video gamer pretty badly. [Phil’s] build starts with a $20 IKEA high chair. He likes these chairs because at that price point, tearing into them isn’t a big risk. What’s more is you can buy extra trays so you can use it as a modular project with different trays serving different purposes.

The chair has two joysticks and two buttons, looking suspiciously like a video game controller. The current incarnation (see video, below) uses an Arduino Uno to trigger an Akai MPC1000 synthesizer via the MIDI interface.

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Object Oriented State Machine Operating System Goes Open Source

November 14, 2015 by 19 Comments

On a desktop computer, you think of an operating system as a big piece of complex software. For small systems (like an Arduino) you might want something a lot simpler. Object Oriented State Machine Operating System (OOSMOS) is a single-file and highly portable operating system, and it recently went open source.

OOSMOS has a unique approach because it is threadless, which makes it easy to use in memory constrained systems because there is no stack required for threads that don’t exist. The unit of execution is a C++ object (although you can use C) that contains a state machine.

You can read the API documentation online. Just remember that this is not an end user OS like Windows or Linux, but an operating environment for managing multiple tasks. You can, though, use OOSMOS under Windows or Linux as well as many other host systems.

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Your First GNU Radio Receiver With SDRPlay

November 12, 2015 by 25 Comments

Although GRC (the GNU Radio Companion) uses the word radio, it is really a graphical tool for building DSP applications. In the last post, I showed you how you could experiment with it just by using a sound card (or even less). However, who can resist the lure of building an actual radio by dragging blocks around on a computer screen?

For this post and the accompanying video, I used an SDRPlay. This little black box has an antenna jack on one end and a USB port on the other. You can ask it to give you data about a certain area of the RF spectrum and it will send complex (IQ) data out in a form that GRC (or other DSP tools) can process.

The SDRPlay is a great deal (about $150) but if you don’t want to invest in one there are other options. Some are about the same price (like the HackRF or AirSpy) and have different features. However, you can also use cheap TV dongles, with some limitations. The repurposed dongles are not as sensitive and won’t work at lower frequencies without some external help. On the other hand, they are dirt cheap, so you can overlook a few little wrinkles. You just can’t expect the performance you’ll get out of a more expensive SDR box. Some people add amplifiers and converters to overcome these problems, but at some point it would be more cost effective to just spring for a more expensive converter.

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Bicycle Heads Down Display Shows You The Way

October 28, 2015 by 10 Comments

On a bicycle you’re typically looking ahead and slightly down to make sure you don’t ride over any potholes. While a speedometer is great on the handlebars, what if you could project your speed and other information onto the road ahead? Well, it turns out if you have a smartphone and a bit of ingenuity, you can do just that!

We’ve seen this hack done before with a pico projector, but that’s a pretty big investment for your bicycle. So [Peter] had another idea. What if you could just use your cellphone as is and a bit of optics? It turns out you can buy some pretty cheap “cell phone projectors” from China or Amazon — it’s basically a little cardboard box that your phone fits into, with a cheap plastic lens to project your image. Lumen output is pretty miserable, but if you’re riding at night, it is enough to see by!

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Toy Television’s Dreams Come True

October 21, 2015 by 12 Comments

A couple of years ago, [Alec]’s boss brought him a souvenir from Mexico City—a small mid-century console television made of scrap wood and cardboard. It’s probably meant to be a picture frame, but [Alec] was determined to give it a better life.

As it turns out, the screen of [Alec]’s old Samsung I9000 was a perfect fit for the cabinet with room to spare. It was on its way to becoming a real (YouTube) TV once [Alec] could find a way to control it remotely. A giant new-old stock remote that’s almost bigger than the TV was just the thing. There’s enough room inside the remote for a non-LE Bluefruit module, which is what the I9000 will accept as input without complaint.

Trouble is, Bluefruit doesn’t support matrix keypads, so [Alec] used a bare ATMega328 running on the internal clock. Since the Bluefruit board provides voltage regulation, the remote was able to keep its native 9V power. [Alec] is happy with the results, though he plans to refine his button choices and maybe make a new overlay for the remote. Stay tuned for a tiny TV tour.

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Etch-A-SDR

October 4, 2015 by 3 Comments

What do you get if you cross a software defined radio (SDR) and an iconic children’s drawing toy that we are sure is a trademarked name? If you are [devnulling], you wind up with the Etch-A-SDR. The box uses an Odroid C1, a Teensy, and the ubiquitous RTL-SDR.

The knobs work well as control knobs (as you can see in the video below). When you are bored listening to the radio, you can reset the box and go into Etch-a… um, drawing mode. The knobs work like you’d expect and you can even erase the screen with a vigorous shake.

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Resistance Is… There’s An Augmented Reality App For That!

September 12, 2015 by 68 Comments

Like many engineers of a certain age I learned the resistor color code using a mnemonic device that is so politically incorrect, only Tosh might venture to utter it in public today. When teaching kids, I have to resort to the old Radio Shack standby: Big Boys Race Our Young Girls But Violet Generally Wins. Doesn’t really roll off the tongue or beg to be remembered. Maybe: Bad Beer Rots Our Young Guts But Vodka Goes Well. But again, when teaching kids that’s probably not ideal either.

Maybe you can forget all those old memory crutches. For one thing, the world’s going surface mount and color coded resistors are becoming a thing of the past. However, if you really need to read the color code, there’s at least three apps on the Google Play Store that try to do the job. The latest one is ScanR, although there is also Resistor Scanner and Resistor Scan. If you use an iPhone, you might try this app, although not being an Apple guy, I can’t give you my feedback on that one.

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