Hacklet 24 – Raspberry Pi Projects

Experimenting with embedded Linux used to mean reformatting an old PC, or buying an expensive dev board. In February of 2012, the Raspberry Pi was released, and it has proven to be a game changing platform. According to the Raspberry Pi Foundation, over 3.8 million boards have been sold. 3.8 million translates into a lot of great projects. This week’s Hacklet focuses on some of the best Raspberry Pi projects on Hackaday.io!

rpfpvWe start with [richardginus] and the RpiFPV (aka Raspberry Pi First Person View) project. [Richardginus]  is trying to build a low latency WiFi streaming camera system for radio-controlled models using a Raspberry Pi and camera. He’s gotten the system down into a respectable 160 milliseconds on the bench, but in the field interference from the 2.4GHz R/C transmitter drives latency way up. To fix this, [Richardginus] is attempting to control the plane over the same WiFi link as the video stream. We’d also recommend checking out some of those “outdated” 72 MHz R/C systems on the used market.

piholgaNext up is [James McDuffie] and his RPi Holga. Inspired by [Peter’s] Holga camera project, [James] has stuffed a Raspberry Pi model A, a camera module, and a WiFi adapter into a Holga camera body. The result looks like a stock Holga.  We saw this camera up close at the Hackaday 10th Anniversary event, and it fooled us – we thought [James] was just a lomography buff. It was only after seeing his pictures that we realized there was a Pi hiding inside that white plastic body! Definitely check out [James’] instructions as he walks through everything from hardware mods to software installation.

cluster2No Raspberry Pi list would be complete without a cluster or two, so we have [Tobias W.] and his 3 Node Raspberry Pi Cluster. The Raspberry Pi makes for a cheap and efficient platform to experiment with cluster computing. [Tobias] did a bit more than just slap a few Pis on a board and call it a day though. He custom machined an aluminum plate to hold his 3 node cluster. This makes wire management a snap. The Pi’s communicate through a four port Ethernet hub and all run from a single power supply. He even added a key switch, just like on the “old iron” mainframes. [Tobias] has been a bit quiet lately, so if you run into him, tell him we’re looking for an update on that cluster!

pivenaFrom [Tim] comes the PIvena, a Raspberry Pi laptop which takes its styling cues from [Bunnie Huang’s] Novena computer.  Pivena is a bit smaller though, with a 7” HDMI LCD connected to the Pi. The case is made from laser cut wood and a few 3D printed parts. Everything else is just standard hardware. [Tim] kept the PIvena’s costs down by using a wooden kickstand to hold up the screen rather than Novena’s pneumatic spring system. The base plate of the PIvena includes a grid of mounting holes just like the Novena. There is also plenty of room for batteries to make this a truly portable machine.  The end result is a slick setup that would look great at any Hackerspace. We hope [Tim] creates an update to support the new Raspberry Pi B+ boards!

Our Raspberry Pi-based alarm clock is chiming the hour, so that’s about it for this episode of the Hacklet! As always, see you next week. Same hack time, same hack channel, bringing you the best of Hackaday.io!

Keep Tabs on Passing Jets with Pi and SDR

Obviously Software Defined Radio is pretty cool. For a lot of hackers you just need the right project to get you into it. Submitted for your approval is just that project. [Simon Aubury] has been using a Raspberry Pi and SDR to record video of planes passing overhead. The components are cheap and most places have planes passing by; this just might be the perfect project.

We’re not just talking static frames with planes passing through them, oh no. Simon used two hobby servos and some brackets to gimbal his Pi camera board. A DVB dongle allows the rig to listen in on the Automatic Dependent Surveillance Broadcast (ADS-B) coming from the planes. This system is mandated for most commercial aircraft (deadlines for implementation vary). ADS-B consists of positioning data being broadcast from planes using known frequencies and protocols. Once [Simon] locks onto this data he can accomplish a lot, like keeping the plane in the center of the video, establishing which flight is being recorded, and automatically uploading the footage. With such a marvelously executed build we’re certain we will see more people giving it a try.

[Simon] did a great job with the writeup too. Not only did he include a tl;dr, but drilled down through a project summary and right to the gritty details. Well done documentation is itself worth celebrating!

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Custom Raspberry Pi Thermostat Controller

Thermostats can be a pain. They often only look at one sensor in a multi-room home and then set the temperature based on that. The result is one room that’s comfortable and other rooms that are not. Plus, you generally have to get up off the couch to change the temperature. In this day and age, who wants to do that? You could buy an off-the-shelf solution, but sometimes hacking up your own custom hardware is just so much more fun.

[redditseph] did exactly that by modifying his home thermostat to be controlled by a Raspberry Pi. The temperature is controlled by a simple web interface that runs on the Pi. This way, [redditseph] can change the temperature from any room in his home using a computer or smart phone. He also built multi-sensor functionality into his design. This means that the Pi can take readings from multiple rooms in the home and use this data to make more intelligent decisions about how to change the temperature.

The Pi needed a way to actually talk to the thermostat. [redditseph] made this work with a relay module. The Pi flips one side of the relays, which then in turn switches the buttons that came built into the thermostat. The Pi is basically just emulating a human pressing buttons. His thermostat had terminal blocks inside, so [redditseph] didn’t have to risk damaging it by soldering anything to it. The end result is a functional design that has a sort of cyberpunk look to it.

[via Reddit]

A Raspberry Pi in a Game Boy Advance SP

It’s not the biggest use of a Raspberry Pi, but running emulators for old game systems is by far the most visible use of the Pi. In fact, putting Pis inside old game systems has led to a resurgence of case modding not seen since the heyday of the Mini-ITX craze of the early ‘aughts.

You’d think every possible Pi casemod had been done by now, but [frostedfires] is still raising the bar with a Pi casemod that stuffs a clone of everyone’s favorite credit card sized computer into a Game Boy Advance SP.

[frostedfires] isn’t using a real Raspi from The Foundataion. Instead, he found the Odroid W, a raspi compatible board that’s about half the size of a model B. It still has everything needed to complete the build – analog video out, a reasonable Linux system, and enough processing power to run Quake III. Right now, [frostedfires] has the screen working – that was taken from a car backup camera. Other than that, the only portion of the build left to go is a few buttons.

This is officially the smallest derivative casemod we’ve ever seen. the previous record holder was the still tiny Game Boy Pocket build from last summer. That build required heavy modifications to the Model B board, though, so if you’re aiming for a smaller build, the Odroid is the way to go.

Thanks to the Bacman forums for yet another great build.

RasPiCommPlus, An Expansion Board For Expansion Boards

The easiest way to connect a GSM module to a Raspberry Pi would be to buy a breakout module, install some software, and connect to a mobile network with a Pi. Need GPS, too? That’s a whole other module, with different software. The guys behind RasPiCommPlus are working on a better solution – a breakout board for breakout boards that takes care of plugging a ton of modules into a Pi and sorts out the kernel drivers to make interfacing with these modules easy.

Right now, the team has a GPS and GSM module, digital in and out modules, an analog input module, and RS-232 and -485 modules. They’re working on some cool additions to the lineup, including a breakout for Sharp memory displays, a 9-axis IMU, a stepper motor driver, and a 1-wire breakout module.

Some of the RasPiCommPlus team showed up to the Hackaday Munich party and were kind enough to sit down for a demo video. You can check that out below.

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Bricked Raspberry Pi Displays History

[eN0Rm’s] Raspberry Pis are much more than just another brick in the wall. He’s used the popular embedded Linux platform to build several small rear projection screens in a brick wall (Imgur link). Brick shaped metal enclosures were mortared into the wall of the building. Each rear projection screen is illuminated by a DLP projector which sits inside the metal enclosure. The Raspberry Pis sit on a shelf below all this.  The bricks are in a building in the Aker Brygge section of Oslo, Norway, and show historical facts and short videos about the local area.

[eN0Rm] could have used a PC for this task, the price for a low-end PC with a few graphics cards probably wouldn’t have been much more expensive than several Raspberry Pi’s with cases. However, this system has to just work, and a PC would represent a single point of failure. Even if one Raspberry Pi goes down, the others will continue running.

The current installation is rather messy, but it’s just a test setup.  [eN0Rm] has already been taken to task for the lack of cable management in his Reddit thread.  As [eNoRm] says – first get it working, then make it pretty.

Throwing Pis into the Stratosphere

It’s always exciting to see the photos from High Altitude Ballooning (HAB) outings. While it’s no surprise that the Raspi is a popular choice—low cost, convenient USB jacks, etc.—this is the first build we’ve seen that uses an OLED during the trip to show real-time data on-screen to be picked up by the on-board webcam. (Though you may have to squint to see it at the bottom middle of the above image).

[Fabrice’s] payload made it to 26,000m, and the screen he chose, an ILSOFT OLED, performed admirably despite the extreme conditions suffered (temperatures can reach -50C). The last time we saw a near-space Raspi payload was a couple of years ago, when [Dave Akerman] was closing in on UK balloon altitude records. [Dave] hasn’t stopped launching balloons, either, testing new trackers and radio modules, as well as his most recent build that sent a Superman action figure to the skies—all recorded in glorious HD.

Check out both [Dave] and [Fabrice’s] blogs for loads of pictures documenting the latest in High Altitude Ballooning, and stay with us after the jump for a quick video of [Fabrice’s] OLED in action.

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