Author: Elliot Williams

1434 Articles

No Windows Drivers? Boot Up A Linux VM!

August 4, 2015 by 46 Comments

[Voltagex] was fed up with BSODs on his Windows machine due to a buggy PL2303 USB/serial device driver. The Linux PL2303 driver worked just fine, though. A weakling would simply reboot into Linux. Instead, [Voltagex] went for the obvious workaround: create a tiny Linux distro in a virtual machine, route the USB device over to the VM where the drivers work, and then Netcat the result back to Windows.

OK, not really obvious, but a cool hack. Using Buildroot, a Linux system cross-compilation tool, he got the size of the VM down to a 32Mb memory footprint which runs comfortably on even a small laptop. And everything you need to replicate the VM is posted up on Github.

Is this a ridiculous workaround? Yes indeed. But when you’ve got a string of tools like that, or you just want an excuse to learn them, why not? And who can pass up a novel use for Netcat?

Embed With Elliot: The Static Keyword You Don’t Fully Understand

August 4, 2015 by 70 Comments

One of our favorite nuances of the C programming language (and its descendants) is the static keyword. It’s a little bit tricky to get your head around at first, because it can have two (or three) subtly different applications in different situations, but it’s so useful that it’s worth taking the time to get to know.

And before you Arduino users out there click away, static variables solve a couple of common problems that occur in Arduino programming. Take this test to see if it matters to you: will the following Arduino snippet ever print out “Hello World”?

void loop()
{
	int count=0;
	count = count + 1;
	if (count > 10) {
		Serial.println("Hello World");
	}
}

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RIP: HitchBot

August 3, 2015 by 59 Comments

Equal parts art project and social media experiment, with a dash of backyard hackery “robotics” thrown in for good measure, hitchBot was an experiment in the kindness of strangers. That is, the kindness of strangers toward a beer bucket filled with a bunch of electronics with a cute LED smiley face.

The experiment came to a tragic end (vandalism, naturally) in Philadelphia PA, after travelling a month across Canada, ten days in Germany, and yet another month across the Netherlands. It survived two weeks in the USA, which is more than the cynics would have guessed, but a few Grand Canyons short of the American Dream.

Professors [David Smith] and [Frauke Zeller] built hitchBot to see how far cuteness and social media buzz could go. [Smith], a former hitchhiker himself, also wanted hitchBot to be a commentary on how society’s attitudes toward hitching and public trust have changed since the 70s. Would people would pick it up on the side of the street, plug it in to their own cigarette lighters, and maybe even take it to a baseball game? Judging by hitchBot’s Twitter feed, the answer was yes. And for that, little bucket, we salute you!

But this is Hackaday, and we don’t pull punches, even for the recently deceased. It’s not clear how much “bot” there was in hitchBot. It looks like it had a GPS, batteries, and a solar cell. We can’t tell if it took its own pictures, but the photos on Twitter seem to be from another perspective. It had enough brains inside to read out Wikipedia entries and do some rudimentary voice recognition tasks, so it was a step up from Tweenbots but was still reassuringly non-Terminator.

Instead, hitchBot had more digital marketing mavens and social media savants on its payroll than [Miley Cyrus] and got tons of press coverage, which seems to have been part of the point from the very start. And by writing this blog post, we’re playing right into [Smith] and [Zeller]’s plan. If you make a robot / art project cute enough to win the hearts of many, they might just rebuild it. [Margaret Atwood] has even suggested on Twitter that people might crowdfund-up a hitchBot 2.0.

Our suggestion? Open-source the build plans, and let thousands of hitchBots take its place.

Shinewave Gamecube Controller Reacts To Smash Brothers

August 2, 2015 by 8 Comments

[Garrett Greenwood] plays Smash Brothers, and apparently quite seriously. So seriously that he needed to modify his controller with five Neopixels so that it flashed different color animations according to the combo he’s playing on the controller; tailored to match the colors of the moves of his favorite character, naturally.

All of this happens with an ATtiny85 as the brains, which we find quite ambitious. Indeed, [Garrett] started out thinking he could simply read each of the inputs from the controller directly into the microcontroller at the heart of the whole thing, but then counted up how many wires that would be, and looked at how many pins he had free (six), and thought up a better solution.

[Garrett]’s routine instead reads the single line that the Gamecube controller uses to send back to the console. The protocol is well understood, using long-short and short-long signals to encode bits. The only trick is that each bit is sent in four microseconds, so the decoding routine has to be fairly speedy. To make it work he had to do quite a bit of work. More about that, and the demo video, after the break.

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DIY Punch Card System Despite Hanging Chads

July 30, 2015 by 8 Comments

Sometimes you just have parts lying around and want to make something out of them. [Tymkrs] had a robot paper cutter, so naturally they made punch cards. But then, of course, they needed a punch card reader, so they made one of those too. All with stuff lying around the shop.

The Silhouette Portrait paper cutter is meant for scrapbooking, but what evokes memories of the past more than punchcards? To cut out their data, rather than cute kittens or flowers, they wrote some custom code to turn ASCII characters into rows of dots. And the cards are done — you just have to clean up the holes that didn’t completely cut. These are infamously known as hanging chads.

The reader is made up of a block of wood, with a gap for the cards and perpendicular holes drilled for LEDs and photoresistors. This is cabled to a Propeller dev board with some simple firmware. We would have used photodiodes or phototransistors, because that’s what’s in our junk box (and because they have faster reaction time), but when you’ve got lemons, make lemonade.

OK, now that you’ve got a punch card reader and writer, what do you do with it? Password storage comes to mind.

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Say It With Me: Input Impedance

July 29, 2015 by 37 Comments

In the “Say It with Me” series, we’ll take a commonly used concept out of electronics and explain it the best we can. If there’s something that’s been bugging you, or a certain term or concept that keeps cropping up in your projects, let us know. We’ll write about it!

What’s up with input impedance? You hear people talking about it, but why does it matter? And impedance matching? Let’s break it all down.

First of all, impedance is the frequency-dependent sister of resistance, so for intuition we’ll first work through the cases of purely resistive impedance. And that’s almost fine if you’re only ever working at one frequency. We’ll hint at the full-blown impedance = resistance + reactance version at the end, but it’s really its own topic. For now, pretend that your circuits aren’t reactive.

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Embed With Elliot: There Is No Arduino “Language”

July 28, 2015 by 157 Comments

This installment of Embed with Elliot begins with a crazy rant. If you want to read the next couple of paragraphs out loud to yourself with something like an American-accented Dave-Jones-of-EEVBlog whine, it probably won’t hurt. Because, for all the good Arduino has done for the Hackaday audience, there’s two aspects that really get our goat.

(Rant-mode on!)

First off is the “sketch” thing. Listen up, Arduino people, you’re not writing “sketches”! It’s code. You’re not sketching, you’re coding, even if you’re an artist. If you continue to call C++ code a “sketch”, we get to refer to our next watercolor sloppings as “writing buggy COBOL”.

And you’re not writing “in Arduino”. You’re writing in C/C++, using a library of functions with a fairly consistent API. There is no “Arduino language” and your “.ino” files are three lines away from being standard C++. And this obfuscation hurts you as an Arduino user and artificially blocks your progress into a “real” programmer.

(End of rant.)

Let’s take that second rant a little bit seriously and dig into the Arduino libraries to see if it’s Arduinos all the way down, or if there’s terra firma just beneath. If you started out with Arduino and you’re looking for the next steps to take to push your programming chops forward, this is a gentle way to break out of the Arduino confines. Or maybe just to peek inside the black box.

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