FFT On The Raspi’s GPU

January 31, 2014 by 17 Comments

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The Raspberry Pi has been around for two years now, and still there’s little the hardware hacker can actually do with the integrated GPU. That just changed, as the Raspberry Pi foundation just announced a library for Fourier transforms using the GPU.

For those of you who haven’t yet taken your DSP course, fourier transforms take a function (or audio signal, radio signal, or what have you) and output the fundamental frequency. It’s damn useful for everything from software defined radios to guitar pedals, and the new GPU_FFT library is about ten times faster at this task than the Raspi’s CPU.

You can get a copy of  the GPU_FFT library by running rpi-update on your pi. If you happen to build anything interesting – something with a software defined radio or even a guitar pedal – you’re more than welcome to send it in to the Hackaday tips line. We’d love to see what you’re up to.

Paintball Picasso Purposely Misses Its Prey

January 31, 2014 by 16 Comments

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We’ve seen quite a few automated paintball marker systems over the years. Generally it’s the same story – a motion detection system used to target and fire upon the opposing team, prowlers, spouses, etc. [Waterloo Labs] decided to take a slightly different approach, and create a system that intentionally misses its target. Paintball Picasso uses a pair of Tippmann A-5 paintball markers to draw an outline around the person in its sights. This is a rather safe project for [Waterloo Labs], considering their previous adventures in car surfing.

The Paintball Picasso system uses a webcam to capture an image of a willing test subject. Picasso then processes the image. The human outline is plotted on a 50×50 grid of paintball pixels. Then the real fun begins. Paintball Picasso uses a National Instruments myRIO to command two paintball markers to simultaneously fire. The markers are fitted with high torque R/C style servos for pan and tilt. At 10 rounds per second the markers quickly draw the human outline. The test subject walks away slightly splattered, but otherwise unscathed. With a matrix of 2500 points, [Waterloo Labs] has enough resolution to draw some basic logos.

We liked the mounting system [Waterloo Labs] created for the markers. Using a mix of 3D printed parts, Lego Tetrix, 80/20 aluminum extrusion, and ball bearings, they fashioned a mount that moved smoothly enough for R/C servos to actuate, yet was strong enough to withstand the kick of firing. We’d love to see the servos swapped for stepper motors and belt drives. While open loop, stepper motors would afford more accuracy and a longer life than PWM driven R/C servos.

Continue reading “Paintball Picasso Purposely Misses Its Prey” →

Immersion: Video Game Biofeedback

January 31, 2014 by 16 Comments

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We’re not sure how scientific the following hack is, but it’s certainly interesting. Designer [Samuel Matson], interested in the correlation between gaming and stress, has pieced together a device that provides biofeedback during gameplay. He referenced this /r/gaming thread—which measured a player’s heart rate during a Halo session—as well as conducted his own tests that monitored the heart rate of gamers. After several iterations, [Samuel] had the above-pictured headset, which features the familiar and hackable pulse sensor placed by the earpiece.

The headset uses a TinyDuino and a Bluetooth TinyShield to communicate to the gamer’s computer in real time. He didn’t stop with simply monitoring heart rates, however; he integrated the signal into the game design. [Samuel] used indie-favorite game engine Unity3d to create a third-person shooter that reacts to the pulse sensor by raising the difficulty level when the player’s heart rate increases. It seems that his goal is to reduce or control stress among players, but we suspect inverting the model may be more effective: have the game cut you some slack when you’re stressed and present a challenge when you’re mellow.

[Thanks Ken]

Help Ithaca Generator Get A Laser Cutter

January 30, 2014 by 42 Comments

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Ithaca Generator, a hackerspace in upstate New York, is running an indiegogo campaign for a laser cutter. With the recent stories of fires, and landlord problems hitting hackerspaces lately, we thought it would be good be to mention a space that is doing well and working to expand their tools. The Generator is looking to purchase a 60 Watt laser cutter. The flexible funding campaign is set for $3000 US, and they are within striking distance of just passed their goal! As any laser veteran will tell you, $3000 isn’t nearly enough for a 60 Watt model from a reputable company. The group already has a donor who will match the campaign final funding amount up to $4000. If the campaign exceeds Now that the campaign has exceeded their goal, the extra funds will go toward a fume extraction systems for the new laser, as well as spare lenses and parts. The group has also added stretch goals for an extended warranty and an upgrade to 90 Watts of laser power.

Many of the donation perks include free membership to the hackerspace. [Vic Aprea], a member of The Generator board told us that out-of-town donors can gift these memberships to anyone local to the hackerspace. A membership would be a great gift for a Cornell or Ithaca college student. For more information on the generator and the campaign check out their website and the video after the break.

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Drilling Custom Standoffs

January 30, 2014 by 29 Comments

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Every electronics project of sufficient complexity needs standoffs – little plastic or metal cylinders – to mount boards to one another. Keeping hundreds of little plastic trinkets around doesn’t really fit with the hacker mentality, though: it would be far simpler to keep some Delrin rod stock around to drill and cut standoffs as needed. [HomeCSP] created a device to do just that, allowing him to turn 1/4″ Delrin rod stock into any size standoff he needs.

Before building this device, [HomeCSP] was taking plastic rods to the drill press fitted with a very tiny drill bit for a #2 screw. The problems with that technique should be evident to anyone. The new solution uses an old cordless drill and a 6 inch piece of linear rail, effectively turning some bits of scrap into a horizontal drill press with a stationary bit.

The end result is a machine that can bore a hole straight down a 1/4″ rod. With a box of screws these homebrew plastic rods are much cheaper than off-the-shelf parts and can be made in any length desired.

Pan Flute Hero

January 30, 2014 by 21 Comments

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The latest creation in the never-ending collection of “____ Hero” instruments is this Raspi-infused pan flute, built by [Sven Andersson] and his team at the 2013 WOW Hackathon. The flute itself consists of varying lengths of bamboo from a local flower shop, cut short enough to be hand-held while still hiding the Pi from the front side. In the spirit of other ‘Hero’ instruments, the pan flute has no real musical functionality. Each pipe houses what appears to be an electret microphone breakout board, which they kept in place by sealing off the end of the pipe with glue.

The sensors connect to the GPIO connector on the Raspi, which communicates to a local TCP/IP server the team ran as a controller hub. The game is also their original creation, written entirely in LUA. They turned to Spotify to find suitable material for the player to experience, creating playlists with actual pan flute songs and using the libspotify SDK to access the music. You can see the end result of the project in a short demo video below.

Continue reading “Pan Flute Hero” →

Fail Of The Week: Reverse Engineering A Wireless Energy Monitor

January 30, 2014 by 58 Comments

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[Afonso] picked up a cheap energy use monitor a few years back. He really like the data it displays about his home’s electricity, using a sensor to gather this info and a display that communicates with it wirelessly. But there is no option to log or dump the data. He set out to reverse engineer the wireless protocol in order to extend the use of the system. As the name of this column implies, he failed to get this working.

The hardware above is a 433Mhz transceiver that he rigged up as test hardware. It sounds like he’s assuming the monitor works on this band, which could have been his first misstep (we really don’t know). The speaker is there to give audible confirmation that he’s receiving something from the transmitter. This is where things start to get pretty weird. White noise was coming from the speaker, but when he stepped away from the bench it stopped. He was able to measure a regular pattern to the noise, and proceeded to place the speaker next to his computer MIC so that he could record a sample for further analysis.

Fail of the Week always aims to be a positive experience. In this case we’d like to have a conversation about the process itself. We agree that connecting a speaker (or headphones) should help get your foot in the door because your ear will recognize a rhythmic pattern when it is received. But with this noise, measuring the timing and recording a sample we’re not so sure about. Given the situation, how would you have soldiered on for the best chance at successfully sniffing out the communication scheme used by this hardware? Leave a comment below!

2013-09-05-Hackaday-Fail-tips-tileFail of the Week is a Hackaday column which runs every Wednesday. Help keep the fun rolling by writing about your past failures and sending us a link to the story — or sending in links to fail write ups you find in your Internet travels.