A Parts Bin MIDI Controller In 24 Hours

October 20, 2024 by 9 Comments

Part of the reason MIDI has hung on as a standard in the musical world for so long is that it is incredibly versatile. Sure, standard instruments like pianos and drums can be interfaced with a computer fairly easily using this standard, but essentially anything can be converted to a MIDI instrument with the right wiring and a little bit of coding. [Jeremy] needed to build a MIDI controller in a single day, and with just a few off-the-shelf parts he was able to piece together a musical instrument from his parts bin.

The build is housed in an off-brand protective case from a favorite American discount tool store, but the more unique part of the project is the choice to use arcade buttons as the instrument’s inputs. [Jeremy] tied eight of these buttons to an Arduino Uno to provide a full octave’s worth of notes, and before you jump to the comments to explain that there are 12 notes in an octave, he also added a button to the side of the case to bend any note when pressed simultaneously. An emergency stop button serves as a master on/off switch and a MIDI dongle on the other side serves as the interface point to a computer.

After a slight bit of debugging, the interface is up and running within [Jeremy]’s required 24-hour window. He’s eventually planning to use it to control a custom MIDI-enabled drum kit, but for now it was fun to play around with it in some other ways. He’s also posted the project code on a GitHub page. And, if this looks a bit familiar, this was not [Jeremy]’s first MIDI project. He was also the creator of one of the smallest MIDI interfaces we’ve ever seen.

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Forget Flipper, How About Capybara?

October 20, 2024 by 26 Comments

One of the hacker toys to own over the last year has been the Flipper Zero, a universal wireless hacking tool which even caused a misplaced moral panic about car theft in Canada. A Flipper is cool as heck of course but not the cheapest of devices. Fortunately there’s now an alternative in the form of the CapibaraZero. It’s a poor-hacker’s Flipper Zero which you can assemble yourself from a heap of inexpensive modules.

At the center is an ESP32-S3 board, which brings with it that chip’s wireless and Bluetooth capabilities. To that is added an ST7789 TFT display, a PN532 NFC reader, an SX1276 LoRa and multi-mode RF module, and an IR module. The firmware can be found through GitHub. Since the repo is nearly two years old and still in active development, we’re hopeful CapibaraZero will gain features and stability.

If you’re interested in our coverage of the Canadian Flipper panic you can read it here, and meanwhile if you’re using one of those NFC modules, consider tuning it.

Behold A First-Person 3D Maze, Vintage Atari Style

October 20, 2024 by 15 Comments

[Joe Musashi] was inspired by discussions about 3D engines and decided to create a first-person 3D maze of his own. The really neat part? It could have been done on vintage Atari hardware. Well, mostly.

He does admit he had to do a little cheating to make this work; he relies on code for the ARM processor in the modern Atari VCS do the ray casting work, and the 6507 chip just handles the display kernel. Still, running his demo on a vintage Atari 2600 console could be possible, but would definitely require a Melody or Harmony cartridge, which are special reprogrammable cartridges popular for development and homebrew.

Ray casting is a conceptually simple method of generating a 3D view from given perspective, and here’s a tutorial that will tell you all you need to know about how it works, and how to implement your own.

[Joe]’s demo is just a navigable 3D maze rather than a game, but it’s pretty wild to see what could in theory have run on such an old platform, even if a few modern cheats are needed to pull it off. And if you agree that it’s neat, then hold onto your hats because a full 3D ray casting game — complete with a micro physics engine — was perfectly doable on the Commodore PET, which even had the additional limitation of a monochrome character-based display.

Ideal Diodes And How To Build Them

October 19, 2024 by 17 Comments

[Julian] knows that real diodes you can buy don’t work exactly like we say they do. That’s actually pretty common. We routinely ignore things like wire resistance and source resistance in batteries. Diodes have problems that are harder to ignore, such as the forward voltage drop. So, while a real diode will only pass current in one direction, it will also drop some of the voltage. [Julian] shows you how you can get simulated ideal diodes and why you might want them in a recent video you can see below.

The video starts with a simple demonstration and enumerates some of the practical limitations. Then, he pulls out some ideal diode modules. These typically don’t solve every problem, so they aren’t really ideal in the theoretical sense. But they typically appear to have no forward voltage drop.

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Fundamentals Of FMCW Radar Help You Understand Your Car’s Point Of View

October 19, 2024 by 3 Comments

Pretty much every modern car has some driver assistance feature, such as lane departure and blind-spot warnings, or adaptive cruise control. They’re all pretty cool, and they all depend on the car knowing where it is in space relative to other vehicles, obstacles, and even pedestrians. And they all have another thing in common: tiny radar sensors sprinkled around the car. But how in the world do they work?

If you’ve pondered that question, perhaps after nearly avoiding rear-ending another car, you’ll want to check out [Marshall Bruner]’s excellent series on the fundamentals of FMCW radar. The linked videos below are the first two installments. The first covers the basic concepts of frequency-modulated continuous wave systems, including the advantages they offer over pulsed radar systems. These advantages make them a great choice for compact sensors for the often chaotic automotive environment, as well as tasks like presence sensing and factory automation. The take-home for us was the steep penalty in terms of average output power on traditional pulsed radar systems thanks to the brief time the radar is transmitting. FMCW radars, which transmit and receive simultaneously, don’t suffer from this problem and can therefore be much more compact.

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Inside The RLL Hard Drive Protocol

October 19, 2024 by 19 Comments

If you are younger than a certain age, RLL probably doesn’t mean much to you. Old consumer-grade hard drives used MFM (modified frequency modulation like a floppy disk uses) and soon went to IDE (integrated drive electronics). There was a brief period when RLL (run length limited) drives were the way to get a little more life out of the MFM technology. [W1ngsfly] has an RLL drive on his bench and uses his scope and some other gear to put it through its paces. You can watch over his shoulder in the video below.

The hardware interface and drive are the same for an MFM and an RLL drive. However, an RLL-aware controller can pack more bits on the same platter by using the newer modulation scheme. Some older disks were good enough for MFM but too sloppy to successfully take an RLL format, but — in theory — any MFM drive could be an RLL drive and vice versa.

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Make Your Own Remy The Rat This Halloween

October 19, 2024 by 10 Comments

[Christina Ernst] executed a fantastic idea just in time for Halloween: her very own Remy the rat (from the 2007 film Ratatouille). Just like in the film Remy perches on her head and appears to guide her movements by pulling on hair as though operating a marionette. It’s a great effect, and we love the hard headband used to anchor everything, which also offers a handy way to route the necessary wires.

Behind Remy are hidden two sub-micro servos, one for each arm. [Christina] simply ties locks of her hair to Remy’s hands, and lets the servos do the rest. Part of what makes the effect work so well is that Remy is eye-catching, and the relatively small movements of Remy’s hands are magnified and made more visible in the process of moving the locks of hair.

Originally Remy’s movements were random, but [Christina] added an MPU6050 accelerometer board to measure vertical movements of her own arm. She uses that sensor data to make Remy’s motions reflect her own. The MPU6050 is economical and easy to work with, readily available on breakout boards from countless overseas sellers, and we’ve seen it show up in all kinds of projects such as this tiny DIY drone and self-balancing cube.

Want to make your own Remy, or put your own spin on the idea? The 3D models and code are all on GitHub and if you want to see more of it in action, [Christina] posts videos of her work on TikTok and Instagram.

[via CBC]