This ESP32 Bluetooth Page Turner Can’t Get Any Easier

May 27, 2021 by Tom Nardi 8 Comments

Commercial Bluetooth pedals, designed to allow musicians to flip pages of sheet music on a tablet, have the sort of inflated price tag you’d expect for a niche electronic device. Rather than forking as much as $100 USD over for the privilege of hands-free page flipping, [Joonas Pihlajamaa] decided to build his own extremely low cost version using an ESP32 and a cheap foot pedal switch.

In terms of hardware, it does’t get much easier than this. All [Joonas] had to do was hook the pedal up to one of the ESP32’s digital pins, and plug the microcontroller into a USB power bank. From there, it became a software project. With the ESP32-BLE-Keyboard library, it only took a few lines of code to send RIGHT_ARROW or LEFT_ARROW depending on whether the pedal was quickly tapped or held down for a bit; allowing him to navigate back and forth through the pages with just one button.

[Joonas] mentions that the ESP32 development board he’s using is too large to fit inside the pedal itself, though we wonder if the bare module could get slipped in there someplace. Of course you could always build your own pedal with a bit of extra room to fit the electronics, but for less than $2 USD on AliExpress, it’s hard to go wrong with this turn-key unit.

Looking for an alternate approach? We covered a Bluetooth page turner last month that doubled the inputs and packed it all into a handsome wooden enclosure.

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ESP8266 Adds WiFi To A 433 MHz Weather Station

May 26, 2021 by Tom Nardi 7 Comments

There’s no shortage of cheap weather stations on the market that pull in data from several wireless sensors running in the 433 to 900 MHz range and present you with a slick little desktop display, but that’s usually where the flow of information stops. Looking to bridge the gap and bring all that local climate data onto the Internet, [Jonathan Diamond] decided to reverse engineer how his weather station worked.

The first phase of this project involved an RTL-SDR receiver, GNURadio, and a sprinkling of Python. [Jonathan] was able to lock onto the signal and piece together the data packets that reported variables such as temperature, wind speed, and rainfall. Each one of these was a small puzzle in itself, and in the end, there’s still a few bits which he hasn’t quite figured out. But he at least had enough to move onto the next step.

Now at this point, he could have pulled the data right out of the air with his RTL-SDR. But looking to push his skills to the next level, [Jonathan] decided to open up the base station and isolate its receiver. Since he already decoded the packets on the RF side, he knew exactly what he was looking for with his oscilloscope and logic analyzer. Once he was tapped into the feed coming from the radio, the final step was writing some code for the ESP8266 that could listen on the line, interpret the data packets, and push the resulting variables out over the network.

In this case, [Jonathan] decided to funnel all the data into Weather Underground by way of the Personal Weather Station API. This not only let him view the data through their web interface and smartphone application, but brought their hyperlocal forecasting technology into the mix at no extra charge. If you’re not interested in sharing your info with the public, it would be a trivial matter to change the firmware so the data is published to a local MQTT broker, or whatever else floats your proverbial boat.

If you’re really lucky, your own weather station may already have an ESP8266 onboard and is dumping all its collected data to the serial port. But if not, projects like this one that break down how to reverse engineer a wireless signal can be a great source of inspiration and guidance should you decide to try and crack the code.

Teardown: RADICA I-Racer

May 26, 2021 by Tom Nardi 3 Comments

Long before the Oculus Rift and HTC Vive came along, some of the biggest names in gaming tried to develop practical stereoscopic displays. These early attempts at virtual reality (VR) were hindered by the technical limitations of their time, and most never progressed beyond the prototype stage. Of the ones that did make it to retail shelves, none managed to stick around for very long. The best known example is Nintendo’s Virtual Boy, which ended up being a financial disaster upon its release in 1995 and some regard as the gaming giant’s greatest blunder.

Despite these public failures, Radica still felt compelled to throw their hat into the ring. Best known for their line of relatively simplistic LCD handheld games, the company produced several rudimentary stereoscopic stand-alone titles in the late 1990s to try and cash in on the VR fad. Among the later entries in this series was 1999’s NASCAR i-Racer, which at least externally, looks quite a bit like modern VR headset.

Featuring a head-mounted stereoscopic display, a handheld controller, force feedback, and integrated headphones, you’d certainly be forgiven for thinking the i-Racer was ahead of its time. But its reliance on the primitive LCD technology that put Radica on the map, combined with the need to keep the game as cheap as possible, keeps the experience planted firmly in the 1990s. But perhaps there’s something we can do about that.

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High Voltage Gives Metal Balls A Mind Of Their Own

May 25, 2021 by Tom Nardi 19 Comments

Have you ever seen something that’s so fascinating you’re sure there has to be some kind of practical application for it, but you just can’t figure out what? That’s how we feel when watching tiny ball bearings assemble themselves into alien-like structures under the influence of high voltage in the latest Plasma Channel video from [Jay Bowles].

Now to be clear, [Jay] isn’t trying to take credit for the idea. He explains that researchers at Stanford University first documented the phenomenon back in 2015, and that his goal was to recreate their initial results as a baseline and go from there. The process is pretty simple: put small metal ball bearings into a tray of oil, apply high voltage, and watch them self-assemble into “wires” that branch out in search of the ground terminal like a plant’s roots looking for water. With the encouragement of his 500,000 volt Van de Graaff generator, the ball bearings leaped into action and created structures just like in the Stanford study.

With the basic pieces now in place, [Jay] starts to push the envelope. He experiments with various oils to see how their viscosity impacts the ball’s ability to assemble, finding that olive oil seems to be the ideal candidate (at least of those he’s tried so far). He also switches up the size and shape of the tray, to try and find how far the balls can realistically stretch out on their own.

In the end we’re no closer to finding a practical application for this wild effect than the good folks at Stanford were back in 2015, but at least we got to watch the little fellows do their thing in glorious 4K and with the exceptional production value we’ve come to expect from Plasma Channel. That said, [Jay] does hint at his ongoing efforts to turn the structures into works of art by “freezing” them with clear resin, so keep your eyes out for that.

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RAM Fiddling Turns VGA Converter Into Video Synth

May 25, 2021 by Tom Nardi 2 Comments

If you’re interested in circuit bent video but not sure where to start, the excellent guide [LoFi Future] has come up with for modifying the cheap and readily available GBS-8100 VGA to composite converter would be a great first step. While we wouldn’t call it an easy modification, the circuit documentation and demonstration video below go a long way to making it as accessible as possible to new players.

While other video converters have all-in-one chipsets that are much harder to work with, [LoFi Future] explains that the separate EM636165TS DRAM chip on the GBS-8100 provides an ideal spot to tap in and wreak some technicolor havoc. By mapping out the pins and studying how the video output is corrupted by grounding them out or connecting them to each other, he’s been able to come up with fairly repeatable “recipes” for different effects.

In the most basic form, once you’ve soldered the pins of the DRAM chip up to the plug board interface, you’d technically be done. But [LoFi Future] takes it a step further and pairs the GBS-8100 with a separate composite to VGA converter. This provides some additional effects in the form of feedback loops and hue adjustment, but more practically, allows the device to handle composite on both the input and output. It’s a lot of hardware to cram into the enclosure, but thanks to little touches like the printed panel graphics, the final product does looks very professional.

Aside from the occasional modified NES Zapper, most of the circuit bent hardware we see is of the audio variety. But with projects like this one and the MIDI controlled SNES we covered last year as inspiration, we might see a balancing of the scales. Continue reading “RAM Fiddling Turns VGA Converter Into Video Synth” →

Running Modern Linux From A Single Floppy Disk

May 24, 2021 by Tom Nardi 34 Comments

There was a time when booting Linux from a floppy disk was the norm, but of course, those days are long gone. Even if you still had a working 3.5 inch drive, surely the size of the modern kernel alone would far exceed the 1.44 MB capacity of the disks, to say nothing of all the support software required to create a usable operating system. Well that’s what we thought, anyway.

But then [Krzysztof Krystian Jankowski] dropped Floppinux, a live Linux OS that boots from just a single floppy. There’s even a few hundred KB left over on the disk, allowing the user to tuck a few of their own programs and scripts onboard before booting it up. But most impressively, the project doesn’t rely on ancient software releases like so many other embedded systems do. Every component of Floppinux is pulled directly from the cutting edge, including version 5.13.0-rc2 of the Linux kernel which is literally just a few days old.

Of course some concessions had to made in order cram the latest Linux kernel and build of BusyBox into slightly north of 1 MB, so Floppinux certainly isn’t what anyone would call a daily driver. The kernel is stripped down the absolute minimum, and is targeted for the decidedly poky i486. [Krzysztof] had to be very selective about which programs actually made the cut as well, so once the system is booted, there’s not a whole lot you can do with it outside of writing some shell scripts. But then, that was sort of the goal to begin with.

If you’re wondering how [Krzysztof] pulled it off, you don’t have to. He walks you though the entire process, down to the commands he used to do everything from pull down and compile the source code to creating the final disk image. Even if you don’t own a floppy drive, it’s well worth following his guide and booting the image up in QEMU just to say you’ve officially built a Linux system from scratch. It’s good for more than just bragging rights; learning how all the components of a minimal install like this fits together will no doubt come in handy the next time you find yourself poking around inside an embedded Linux device.

Optical Sensor Keeps Eye On Wandering Saw Blade

May 24, 2021 by Tom Nardi 17 Comments

Over the last year or so, we’ve been checking in on the progress [Andrew Consroe] has been making with his incredible CNC scroll saw project. While we were already impressed with his first prototype version, he somehow manages to keep pushing the envelope forward with each new upgrade, and we’re always excited when one of his progress reports hits the inbox.

Recently he’s been struggling with the fact that the considerable flexing of the scroll saw’s ultra-thin blade introduces positional errors while cutting. To combat this, he’s developed an ingenious sensor that can track the movement of the blade in two dimensions without actually touching it. Utilizing the Raspberry Pi HQ camera, a 3D printed framework, and some precisely placed mirrors, [Andrew] says his optical sensor is able to determine the blade’s position to within 10 microns.

In the video below [Andrew] goes over how his “Split Vision Periscope” works, complete with some ray traced simulations of what the Pi camera actually sees when it looks through the device. After experimenting with different lighting setups, the final optical configuration presents the camera with two different perspectives of the saw blade set on a black background. That makes it relatively easy to pick out the blade using computer vision, and turn that into positional information.

The periscope arrangement is particularly advantageous here as it allows the camera and lens to be placed under the work surface and well away from the actual cutting, though we’re interested in seeing how it fares against the dust and debris that will inevitably be produced as the saw cuts. While he hit all of his design goals, [Andrew] does note that his mirrors do leave some room for improvement; but considering he hand cut them out of old hard drive platters we think the results are more than acceptable.

An incredible amount of progress has been made since the first time we saw the CNC scroll saw, and we’re eager to see this new sensor fully integrated into the next version of [Andrew]’s impressive long-term project.

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