raspberry pi

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Fly A Pi On Your Next Model Rocket

July 5, 2019 by 6 Comments

From time to time, we see electronics projects for model rocket instrumentation. Those who have been involved in the hobby for many years may remember when 8-bit microcontrollers like the PIC16F84 were the kind of hardware you might fly on a mission. These days, however, there’s little reason not to send a high-powered processor. This is exactly what [Mohamed Elhariry] has done with his PiX project, which turns a Raspberry Pi Zero W into a neat little flight data recorder.

The hardware has what you might expect from a flight recorder, including accelerometer, gyroscope, and pressure sensor. In addition, it carries temperature and humidity sensors, and of course, a camera. A 64 GB microSD card provides the storage, while a LiPo SHIM board allows the whole thing to run from a 150 mAh battery. All of the components are off-the-shelf breakouts, which makes assembly as easy as soldering a few connections and securing the modules with a little tape.

The project is in GitHub, including python code, schematics for the hardware, and detailed instructions. If you ever wanted to get started with instrumenting a model rocket, this looks like a great resource. Also in the repo is a captured video from an actual flight [34 MB GIF] if you just want to see the view from one launch.

Using commercial modules seems pretty convenient, but if custom hardware is more your thing, check out these 22 mm round PCBs designed to fit inside rockets.

Raspberry Pi Catches The Early Bird

July 4, 2019 by 11 Comments

If you live in an area with high bird activity, setting up a bird feeder and watching some hungry little fellows visit you can be a nice and relaxing pastime. Throw in a Raspberry Pi with some sensors and it can also be the beginning of your next IoT project, as it was the case for [sbkirby] with his Bird Feeder Monitor project.

To track the arrival and departure times of his avian visitors, [sbkirby] attached a set of capacitive touch sensors to each side of his bird feeder, and hooked them up to a Raspberry Pi Zero W via a CAP1188 breakout board. The data is published via MQTT to another Raspberry Pi that serves as backend and stores the data, as well as to an optional additional camera-equipped Pi that will take a picture of each guest along the way. Taking into account that precipitation might affect the sensor readings, he also checks the current weather situation to re-calibrate the sensors if necessary, and also to observe a change in the birds’ presence and eating behavior based on weather conditions.

It seems that sensor-based animal feeding will always serve as inspiration for some new projects, whether feeding the animal itself is the goal, like most recently this fish feeder has shown, or whether the eating behavior is monitored and used for further research such as this squirrel-based weather forecast system.

Exploring Basement Humidity With A Raspberry Pi

July 1, 2019 by 16 Comments

Sometimes a hack isn’t about building something cool. Sometimes it’s more tactical, where the right stuff is cobbled together to gather the information needed to make decisions, or just to document some interesting phenomenon.

Take this impromptu but thorough exploration of basement humidity undertaken by [Matthias Wandel]. Like most people with finished basements in their homes, [Matthias] finds the humidity objectionable enough to warrant removal. But he’s not one to just throw a dehumidifier down there and forget about it. Seeking data on how well the appliance works, [Matthias] wired a DHT22 temperature/humidity sensor to a spare Raspberry Pi to monitor room conditions, and plugged the dehumidifier into a Kill-A-Watt with a Pi camera trained on the display to capture data on electrical usage.

His results were interesting. The appliance does drop the room’s humidity while raising its temperature, a not unexpected result given the way dehumidifiers work. But there was a curious cyclical spike in humidity, corresponding to the appliance’s regular defrost cycle driving moisture back into the room. And when the dehumidifier was turned off, room humidity gradually increased, suggesting an unknown source of water. The likely culprit: moisture seeping up through the concrete slab, or at least it appeared so after a few more experiments. [Matthias] also compared three different dehumidifiers to find the best one. The video below has all the details.

We always appreciate [Matthias]’ meticulous approach to problems like these, and his field expedient instrumentation. He seems to like his creature comforts, too – remember the target-tracking space heater from a few months back?

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Building A DIY Desktop-Sized Arcade Machine

June 29, 2019 by 10 Comments

Full-sized arcade cabinets are undeniably cool, but take up a lot of space and can be somewhat of a handful. [PleaseNoFisticuffs] desired something a little more fun-sized, and so built a desktop arcade machine that has some serious style.

It’s a build that’s remarkably accessible for even the inexperienced builder. Paper templates are used to cut out the plywood parts for the cabinet, and the electronic components are all off-the-shelf items. Assembly is readily achievable with high-school level woodworking and soldering skills. Like most similar builds, it relies on the Raspberry Pi running RetroPie, meaning you’ll never run out of games to play.

Where this project really shines, however, is the graphics. Cribbed from Mortal Kombat II and looking resplendent in purple, they’re key to making this cabinet a truly stunning piece. The attention to detail is excellent, too, with the marquee and screen getting acrylic overlays for that classic shine, as well as proper T-moulding being used to finish the edges.

We’d love to have something like this on our desk, though we’d likely get far less work done in such an event. For another take on an arcade build, check out this impressive Undertale pinball cabinet.

 

Accurate Time On Your Pi, The Extreme Way

June 26, 2019 by 27 Comments

The Raspberry Pi is an extremely versatile little computer, but even its most ardent fans would acknowledge that there are some areas in which its hardware is slightly lacking. One of these is in the field of timing, the little board has no real-time clock. Users must rely on the on-board crystal oscillator, which is good enough as a microprocessor clock but subject to the vagaries of temperature as it is, not so much as a long-term timepiece.

[Manawyrm] has tackled this problem in a rather unusual way, by dispensing entirely with the crystal oscillator on an older Pi model and instead using a clock derived from a GPS source. The source she’s used is a Leo Bodnar mini precision GPS reference clock, which includes a low-jitter synthesiser that can be set to the Pi’s 19.2 MHz required clock. Unexpectedly this also required a simple LC low-pass filter which was made on a sheet of PCB material, because the Pi at first appeared to be picking up a harmonic frequency. The Pi now has a clock that’s sufficiently stable for tasks such as WSPR transmission without constant referral to NTP or other timing sources to keep it on-track.

It’s a short write-up, but it brings with it a further link to a discussion of different time synchronisation techniques on a Pi including using a kernel module to synchronise with the more common GPS-derived 1PPS signal. We’ve not seen anyone else do this particular mod to a Pi before, but conversely we’ve seen a Pi provide an RF time reference to something else.

The Cheese Grater In Fusion 360

June 25, 2019 by 34 Comments

By now you will all have heard so much about the grille on Apple’s new “Cheese grater” Mac Pro that you might think there was nothing more to say. Before we move on though there’s one final piece of work to bring to your attention, and it comes from [Andy Pugh]. He’s replicated the design in Fusion 360, and used it to produce rather an attractive Raspberry Pi case.

It seems that for Fusion 360 users the problem lies in that package’s method of placing spheres which differs from that of some other CAD software. Using the page linked in our previous coverage of the grille he’s taken its geometry information and produced a video detailing every step in recreating it for Fusion 360. This is where following someone who really knows your CAD package pays dividends, because we suspect it would take us days to figure out some of the tricks he shows us.

The result is the Raspberry Pi case, which is for the Pi 3 and others like it. Sadly we couldn’t break our embargo and tell him about the Pi 4 and its different connector layout, but we’re guessing a halfway competent CAD operator could put together a Pi 4 case. Andy’s files can be found on Thingiverse, so you can all make one for yourselves.

Andy’s appeared here before a few times, not least for his Ner-A-Car motorcycle, and for designing a Robot Wars robot.

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Raspberry Pi 4 Just Released: Faster CPU, More Memory, Dual HDMI Ports

June 23, 2019 by 260 Comments

The Raspberry Pi 4 was just released. This is the newest version of the Raspberry Pi and offers a better CPU and more memory than the Raspberry Pi 3, dual HDMI outputs, better USB and Ethernet performance, and will remain in production until January, 2026.

There are three varieties of the Raspberry Pi 4 — one with 1GB of RAM, one with 2GB, and one with 4GB of RAM — available for $35, $45, and $55, respectively. There’s a video for this Raspberry Pi launch, and all of the details are on the Raspberry Pi 4 website.

A Better CPU, Better Graphics, and More Memory

The CPU on the new and improved Raspberry Pi 4 is a significant upgrade. While the Raspberry Pi 3 featured a Broadcom BCM2837 SoC (4× ARM Cortex-A53 running at 1.2GHz) the new board has a Broadcom BCM2711 SoC (a quad-core Cortex-A72 running at 1.5GHz). The press literature says this provides desktop performance comparable to entry-level x86 systems.

Of note, the new Raspberry Pi 4 features not one but two HDMI ports, albeit in a micro HDMI format. This allows for dual-display support at up to 4k60p. Graphics power includes H.265 4k60 decode, H.264 1080p60 decode, 1080p30 encode, with support for OpenGL ES, 3.0 graphics. As with all Raspberry Pis, there’s a component  composite video port as well tucked inside the audio port. The 2-lane MIPI DSI display port and 2-lane MIPI CSI camera port remain from the Raspberry Pi 3.

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