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[Julien] is one of those cool dads who shows his love with time invested rather than money spent. His daughter plays the harp, and you would not believe the price of concert harps. Even the cheap ones are several thousand USD. So naturally, he decided he would build her a MIDI concert harp from the ground up.

This plucky work in progress uses a strain gauge and an AD620 amplifier on every string to detect the tension when plucked. These amplifiers are connected to Arduinos, with an Arduino every nine strings. The Arduinos send MIDI events via USB to a Raspberry Pi, which is running the open synth platform Zynthian along with Pianoteq.

The harp is strung with guitar strings painted with silver, because he wanted capacitive touch support as well. But he scrapped that plan due to speed and reliability issues. Strain past the break to check out a brief demo video.

[Julien] used strings because he wanted to anchor the harpist in tactility. But you’re right; many if not most MIDI harps use lasers.

If you treat your Pi as a wearable or a tablet, you will already have a battery. If you treat your Pi as a desktop you will already have a plug-in power supply, but how about if you live where mains power is unreliable? Like [jwhart1], you may consider building an uninterruptible power supply into a USB cable. UPSs became a staple of office workers when one-too-many IT headaches were traced back to power outages. The idea is that a battery will keep your computer running while the power gets its legs back. In the case of a commercial UPS, most generate an AC waveform which your computer’s power supply converts it back to DC, but if you can create the right DC voltage right to the board, you skip the inverting and converting steps.

Cheap batteries develop a memory if they’re drained often, but if you have enough space consider supercapacitors which can take that abuse. They have a lower energy density rating than lithium batteries, but that should not be an issue for short power losses. According to [jwhart1], this quick-and-dirty approach will power a full-sized Pi, keyboard, and mouse for over a minute. If power is restored, you get to keep on trucking. If your power doesn’t come back, you have time to save your work and shut down. Spending an afternoon on a power cable could save a weekend’s worth of work, not a bad time-gamble.

We see what a supercap UPS looks like, but what about one built into a lightbulb or a feature-rich programmable UPS?

The great irony of the social media revolution is that it’s not very social at all. Users browse through people’s pictures in the middle of the night while laying in bed, and tap out their approval with all the emotion of clearing their spam folder. Many boast of hundreds or thousands of “friends”, but if push came to shove, they probably couldn’t remember when they had last seen even a fraction of those people in the real world. Assuming they’ve even met them before in the first place. It’s the dystopian future we were all warned about, albeit a lot more colorful than we expected.

But what if we took social media tropes like “Likes” and “Follows”, and applied them to the real world? That’s precisely what [Tuang] set out to do with the “Social Touch Suit”, a piece of wearable technology which requires a person actually make physical contact with the wearer to perform social engagements. There’s even a hefty dose of RGB LEDs to recreate the flashy and colorful experience of today’s social media services.

Every social action requires that a specific and deliberate physical interaction be performed, which have largely been designed to mimic normal human contact. A pat on the shoulder signifies you want to follow the wearer, and adding them as a friend is as easy as giving a firm handshake. These interactions bring more weight to the decisions users make. For example, if somebody wants to remove you as a friend, they’ll need to muster up the courage to look you in the eye while they hit the button on your chest.

The jacket uses an Arduino to handle the low level functions, and a Raspberry Pi to not only provide the slick visuals of the touch screen display, but record video from the front and rear integrated cameras. That way you’ve even got video of the person who liked or disliked you. As you might expect, there’s a considerable energy requirement for this much hardware, but with a 5200 mAh LiPo battery in the pocket [Tuang] says she’s able to get a run time of 3 to 4 hours.

Considering how much gadgetry is packed into it, the whole thing looks remarkably wearable. We wouldn’t say it’s a practical piece of outerwear when fully decked out, but most of the electronic components can be removed if you feel like going low-key. [Tuang] also points out that for a garment to be functional it really needs to be washable as well, so being able to easily strip off the sensitive components was always an important part of the design in her mind.

The technology to sensors wearable and flexible is still largely in its infancy, but we’ve very excited to see where it goes. If projects like these inspire you, be sure to check out the presentation [Kitty Yeung] gave at the Hackaday Supercon where she talks about her vision for bespoke wearable technology.

Students at the University of Illinois at Urbana-Champaign have a brain-computer interface that can measure brainwaves. What did they do with it? They gave it to Alma, a golden labrador, as you can see in the video below. The code and enough info to duplicate the electronics are on GitHub.

Of course, the dog doesn’t directly generate speech. Instead, the circuit watches her brainwaves via an Arduino and feeds the raw data to a Raspberry Pi. A machine learning algorithm determines Alma’s brainwave state and plays prerecorded audio expressing Alma’s thoughts.

Alma’s collar duplicates — to some degree — the fictional collar from the movie Up. Of course, Dug was a bit more loquacious. It isn’t very clear from the video how many states the program classifies. A quick peek at the code reveals five audio clips but only one appears to be wired to the recognizer — the one for a treat. We think it might be a harder problem to figure out when the dog does not want a treat.

The last time we saw a talking dog collar it was phone-controlled. If you really want to probe a brain — canine or human — you could do worse than to check out OpenHardwareExG.

Oh. By the way. Good dog! Very good dog!

If you are a Harry Potter fan, you might remember that one of the movies showed an Isle of Lewis chess set whose pieces moved in response to a player’s voice commands. This feat has been oft replicated by hackers and [amoyag00] has a version that brings together a Raspberry Pi, Arduino, Android, and the Stockfish chess engine in case you want to play by yourself. You can see a video of the game, below.

Interestingly, the system uses Marlin — the 3D printing software — to handle motion using the Arduino. We suppose moving chess pieces over a path isn’t much different than moving a print head. It is certainly a novel use of GCode.

There are a lot of pieces integrated to make this work. There is a Bluetooth connection between the Android and Pi. We saw code in Java, Python, C++, at least. We were sad to read that the team that built it can’t modify it anymore as it was a school project and the parts have been recycled for a new class of students. On the other hand, maybe someone else will make a copy and extend it further.

We are always surprised we haven’t seen more Harry Potter paraphernalia. There was the magic wand at this year’s Superconference. We also liked the Mad Eye Moody. There have been others, of course, but not as many as you’d think given the franchise’s popularity.

At the risk of putting too fine a point on it, Hackaday exists because people are out there building and documenting open source gadgets. If the person who built a particular gizmo is willing to show the world how they did it, consider us interested. Since you’re reading this, we’ll assume you are as well. Over the years, this mentality has been spreading out from the relatively niche hacker community into the greater engineering world, and we couldn’t be happier.

Case in point, the Poseidon project created at the California Institute of Technology. Developed by students [Sina Booeshaghi], [Eduardo Beltrame], and [Dylan Bannon], along with researcher [Jase Gehring] and professor [Lior Pachter], Poseidon consists of an open source digital microscope and syringe pump which can be used for microfluidics experiments. The system is not only much cheaper than commercial offerings, but is free from the draconian modification and usage restrictions that such hardware often comes with.

Of course, one could argue that major labs have sufficient funding to purchase this kind of gear without having to take the DIY route. That’s true enough, but what benefit is there to limiting such equipment to only the established institutions? As in any other field, making the tools available to a wider array of individuals (from professionals to hobbyists alike) can only serve to accelerate progress and move the state of the art forward.

The Poseidon microscope consists of a Raspberry Pi, touch screen module, and commercially available digital microscope housed in a 3D printed stage. This device offers a large and clear view of the object under the microscope, and by itself makes an excellent educational tool. But when running the provided Python software, it doubles as a controller for the syringe pumps which make up the other half of the Poseidon system.

Almost entirely 3D printed, the pumps use commonly available components such as NEMA 17 stepper motors, linear bearings, and threaded rods to move the plunger on a syringe held in the integrated clamp. Controlled by an Arduino and CNC shield, these pumps are able to deliver extremely precise amounts of liquid which is critical for operations such as Single-cell RNA sequencing. All told a three pump system can be built for less than $400 USD, compared to the tens of thousands one might pay for commercially available alternatives.

The Poseidon project joins a relatively small, but very exciting, list of DIY biology projects that we’ve seen over the years. From the impressive open source CO2 incubator we saw a few years ago to the quick and dirty device for performing polymerase chain reaction experiments, there’s little doubt about it: biohacking is slowly becoming a reality.

Drone racing is nifty as heck, and a need all races share is a way to track lap times. One way to do it is to use transponders attached to each racer, and use a receiver unit of some kind to clock them as they pass by. People have rolled their own transponder designs with some success, but the next step is ditching add-on transponders entirely, and that’s exactly what the Delta 5 Race Timer project does.

A sample Delta 5 Race Timer build (Source: ET Heli)

The open-sourced design has a clever approach. In drone racing, each aircraft is remotely piloted over a wireless video link. Since every drone in a race already requires a video transmitter and its own channel on which to broadcast, the idea is to use the video signal as the transponder. As a result, no external hardware needs to be added to the aircraft. The tradeoff is that using the video signal in this way is trickier than a purpose-made transponder, but the hardware to do it is economical, accessible, and the design is well documented on GitHub.

The hardware consists of RX508 video receiver PCBs modified slightly to enable them to communicate over SPI. Each RX508 is attached to its own Arduino, which takes care of low-level communications. The Arduinos are themselves connected to a Raspberry Pi over I2C, allowing the Pi high-level control over the receivers while it serves up a web-enabled user interface. As a bonus, the Pi can do much more than simply act as a fancy stopwatch. The races themselves can be entirely organized and run through the web interface. The system is useful enough that other projects using its framework have popped up, such as the RotorHazard project by [PropWashed] which uses the same hardware design.

While rolling one’s own transponders is a good solution for getting your race on, using the video transmission signal to avoid transponders entirely is super clever. The fact that it can be done with inexpensive, off the shelf hardware is just icing on the cake.

Even on the go, there is no substitute for a physical keyboard with buttons that move and click. Sure, you could solder a bunch of tactile switches to some perfboard, but how about going all out and making something robust as [Anthony DiGirolamo] did for his Teensy Thumboard. Everything is insertion-mount so it is an approachable project for anyone who knows the dangerous end of a soldering iron, and that also makes it easy to hack on.

Each pin of the Teensy has an adjacent empty hole tied to it for easy access, and the serial data pins are exposed at the top of the board. All the holes use standard 0.1″ (2.54mm) spacing. The I/O points used by the keyboard are labeled, and the rest of them can use the space under the controller where proto-board style holes add some extra space for an IMU or whatever sensors suit your slant.

Most impressive is the shell, which is freely available on Thingiverse, where you can also find a bill of materials with links to everything you will need in case you don’t have drawers full of those tactile switches.

If this looks familiar, you have probably seen the PocketCHIP, and it is no secret that this project is an homage to that versatile pocket computer. We appreciate this kind of love for PocketCHIP, especially since they are now a limited commodity.

Machine learning is starting to come online in all kinds of arenas lately, and the trend is likely to continue for the forseeable future. What was once only available for operators of supercomputers has found use among anyone with a reasonably powerful desktop computer. The downsizing isn’t stopping there, though, as Microsoft is pushing development of machine learning for embedded systems now.

The Embedded Learning Library (ELL) is a set of tools for allowing Arduinos, Raspberry Pis, and the like to take advantage of machine learning algorithms despite their small size and reduced capability. Microsoft intended this library to be useful for anyone, and has examples available for things like computer vision, audio keyword recognition, and a small handful of other implementations. The library should be expandable to any application where machine learning would be beneficial for a small embedded system, though, so it’s not limited to these example applications.

There is one small speed bump to running a machine learning algorithm on your Raspberry Pi, though. The high processor load tends to cause small SoCs to overheat. But adding a heatsink and fan is something we’ve certainly seen before. Don’t let your lack of a supercomputer keep you from exploring machine learning if you see a benefit to it, and if you need more power than just one Raspberry Pi you can always build a cluster to get your task done just a little bit faster, too.

Thanks to [Baldpower] for the tip!

A Raspberry Pi Zero (W) and Arduino are very different animals, the prior has processing power and connectivity while the latter has some analog to digital converters (ADCs) and nearly real-time reactions. You can connect them to one another with a USB cable and for many projects that will happily wed the two. Beyond that, we can interface this odd couple entirely through serial, SPI, I2C, and logic-level signaling. How? Through a device by [cburgess] that is being called an Arduino shield that supports a Pi0 (W). Maybe it is a cape which interfaces with Arduino. The distinction may be moot since each board has a familiar footprint and both of them are found here.

Depending on how they are set up and programmed, one can take control over the other, or they could happily do their own thing and just exchange a little information. This board is like a marriage counselor between a Raspberry Pi and an Arduino. It provides the level-shifting so they don’t blow each other up and libraries so they can speak nicely to one another. If you want to dig a bit deeper into this one, design files and code examples are on available.

Perhaps we’ll report on this board at the heart of a pinball machine retrofit, a vintage vending machine restoration, or maybe a working prop replica from the retro bar in Back to the Future II.



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