Hot Swappable Raspberry Pi Rack

June 1, 2015 by Chad Lawson 29 Comments

The Raspberry Pi has inspired many a hacker to take the inexpensive (~$35) microcomputer to the enterprise level. From bitcoin miners to clusters, the Raspberry Pi has found itself at the heart of many large-scale projects.

On hackaday.io [Dave] served up his own contribution with his Raspberry Pi Rack. Inspired by enterprise blade servers, he wanted to house multiple Raspberry Pi boards in a single enclosure providing power and Ethernet. The spacing between the blades and the open sides allow for each Pi to cool without the additional power and cost of fans.

Starting with an ATX power supply and Ethernet switch, Dave created a base that housed the components that would be shared by all the Pis. Using a 3D model of a Pi he found online, he began working on the hotswap enclosures. After “dozens of iterations” he created a sled that would hold a Pi in place with clips rather than screws and slide into his rack to connect to power and Ethernet.

Like most projects, some mistakes were made along the way. In his write up [Dave] describes how after printing the bottom plate he realized he hadn’t accounted for the holes for the Ethernet cable runs. Instead the cables run along the back wall in a way he now prefers.

You can find all the details and download the 3D models on his project page.

Itemizing Water Consumption At Home

May 29, 2015 by James Hobson 79 Comments

For a while now [Florian] has wanted to itemize his water usage at home to keep better track of where his water bill is coming from — and to help him develop water conscious habits. He’s not done yet, but has had a pretty good start.

The problem with measuring the water usage of everything in your house is that the plumbing involved to install sensors is a rather big job — so instead he assumed constant flow in some places and just used sensors on the valves to determine how long the valve was open for, which gives him a fairly accurate number for water usage.

On the right is his kitchen faucet which features a super quick arcade button hack to keep track of it being on or off.

The toilet was a bit trickier. He ended up designing a 3D printed mount attached to the lever on the inside of the tank — it’s pretty universal so he’s included the .STL files on his website if anyone wants to try implementing this system.

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Eye-Controlled Wheelchair Advances From Talented Teenage Hackers

May 28, 2015 by Anool Mahidharia 19 Comments

[Myrijam Stoetzer] and her friend [Paul Foltin], 14 and 15 years old kids from Duisburg, Germany are working on a eye movement controller wheel chair. They were inspired by the Eyewriter Project which we’ve been following for a long time. Eyewriter was built for Tony Quan a.k.a Tempt1 by his friends. In 2003, Tempt1 was diagnosed with the degenerative nerve disorder ALS and is now fully paralyzed except for his eyes, but has been able to use the EyeWriter to continue his art.

This is their first big leap moving up from Lego Mindstorms. The eye tracker part consists of a safety glass frame, a regular webcam, and IR SMD LEDs. They removed the IR blocking filter from the webcam to make it work in all lighting conditions. The image processing is handled by an Odroid U3 – a compact, low cost ARM Quad Core SBC capable of running Ubuntu, Android, and other Linux OS systems. They initially tried the Raspberry Pi which managed to do just about 3fps, compared to 13~15fps from the Odroid. The code is written in Python and uses OpenCV libraries. They are learning Python on the go. An Arduino is used to control the motor via an H-bridge controller, and also to calibrate the eye tracker. Potentiometers connected to the Arduino’s analog ports allow adjusting the tracker to individual requirements.

The web cam video stream is filtered to obtain the pupil position, and this is compared to four presets for forward, reverse, left and right. The presets can be adjusted using the potentiometers. An enable switch, manually activated at present is used to ensure the wheel chair moves only when commanded. Their plan is to later replace this switch with tongue activation or maybe cheek muscle twitch detection.

First tests were on a small mockup robotic platform. After winning a local competition, they bought a second-hand wheel chair and started all over again. This time, they tried the Raspberry Pi 2 model B, and it was able to work at about 8~9fps. Not as well as the Odroid, but at half the cost, it seemed like a workable solution since their aim is to make it as cheap as possible. They would appreciate receiving any help to improve the performance – maybe improving their code or utilising all the four cores more efficiently. For the bigger wheelchair, they used recycled car windshield wiper motors and some relays to switch them. They also used a 3D printer to print an enclosure for the camera and wheels to help turn the wheelchair. Further details are also available on [Myrijam]’s blog. They documented their build (German, pdf) and have their sights set on the German National Science Fair. The team is working on English translation of the documentation and will release all design files and source code under a CC by NC license soon.

The Biggest Game Boy Ever?

May 25, 2015 by James Hobson 8 Comments

Feeling nostalgic? Miss the solid feel of an original Nintendo Game Boy? You could smash a window with one and keep playing Pokemon the whole time! Well, [Raz] was, and he built what might just be the biggest Gameboy ever. Gameboy XXL: The Texas Edition.

Actually, it was commissioned for a Belgian music festival called Nintendoom — picture video game music + rave. Anyway, the organizer thought it would be so cool to have a giant functional Game Boy, so [Raz] got to work. He made it out of 10 square meters of 3mm thick MDF, which he laser cut into shape at the Brussels FabLab. The electronics inside consist of a 19″ LCD monitor, a Raspberry Pi, and a few jumbo size buttons.

It’s pretty freaking awesome. It runs Retropie which allows you to play pretty much whatever game you want. Check it out after the break.

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Raspberry Pis And A Video Triptych

May 19, 2015 by Brian Benchoff 20 Comments

A filmmaker friend of [Thomas] mentioned that she would like to display a triptych at the 2015 Venice Art Walk. This is no ordinary triptych with a frame for three pictures – this is a video triptych, with three displays each showing a different video, and everything running in sync. Sounds like a cool engineering challenge, huh?

The electronics used in the build were three Raspberry Pi 2s and a trio of HDMI displays. Power is provided by a 12V, 10A switching supply with 5V stepdown converters for the Pis. The chassis is a bunch of aluminum bars and U channel encased in an extremely well made arts and crafts style frame. So far, nothing out of the ordinary.

Putting three monitors and three Pis in a frame isn’t the hard part of this build; getting three different displays all showing different videos is. For this, [Thomas] networked the Pis through an Ethernet hub, got the videos to play independently on a RAM disk with omxplayer. One of the Raspberry Pis serves as the master, commanding the slaves to start, stop, and rewind the video on cue. According to [Thomas], it’s a somewhat hacky solution with a bunch of sleep statements at the beginning of the script to allow the boot processes to finish. It’s a beautiful build, though, and if you ever need to command multiple monitors to display the same thing, this is how you do it.

LED Notification Cube Is A Good First Project

May 10, 2015 by Rick Osgood 5 Comments

Two years ago, [Matt] made a move away from his software hacks and into the physical world. He was part of a pilot program to provide mentorship to children as part of the Maker Education Initiative. This program gave him access to 3D printers, CNC machines, and laser cutters within the New York Hall of Science makerspace. [Matt] chose to build an illuminated notification cube for his first physical project. The idea being that smart phones have so many alerts, many of which are unimportant. His project would help him to visualize and categorize each alert to better understand its importance.

The brain of the system is a Raspberry Pi. [Matt] found a Python library that allowed him to directly control an RGB LED strip based on the LPD8806 chip. He wired the data pins directly to the Pi and used an old 5V cell phone charger to power the LEDs. The strip was cut into smaller strands. Each face of the cube would end up with three strands of two LEDs each, or six LEDs per side. [Matt] found a mount for the Pi on Thingiverse and used a 3D printer to bring it into existence. The sides were made of frosted laser cut acrylic. The frosted look helps to diffuse the light from the LEDs.

Over time [Matt] found that the cube wasn’t as useful as he originally thought it would be. He just didn’t have enough alerts to justify the need. He ended up reprogramming the Pi to pull weather information instead, making use of the exact same hardware for another, more useful purpose.

Raspberry Preserve – A BitTorrent Sync Client In A Mason Jar

May 9, 2015 by Anool Mahidharia 17 Comments

[Matt Reed] used a few off-the-shelf parts and built a Raspberry-Pi based BitTorrent Sync client to help backup files. What makes it stand out is the idea of using a Mason Jar as the enclosure and the nice build finish. Mason Jars have long been used to preserve food. [Matt] wanted to use the Mason Jar to help preserve family memories.

Basically, he just stuffed a Raspberry Pi inside a jar with some LED’s and put BitTorrent Sync on it. He started off with a nice, square piece of wood and mounted the lid on it. Holes were drilled to fix the four LED’s and faux crystal drawer pull knobs. The Pi was connected to power and Ethernet and the LED’s wired up. The software is quite straightforward – just install BitTorrent Sync on the Raspberry Pi. He wrote a Node.js script to constantly check if BitTorrent Sync is transferring any data, and if it is, blink the LED’s so it looks cool. If no data is being transferred, the LED’s just glow solid red. Once it is plugged into power and connected to the internet, any photo or video (or any file for that matter) that is put inside a special folder called “Preserve” on any of his devices, gets sync’ed and copied to the “Raspberry Preserve” – preserved for posterity.