Getting MIDI Under Control

When [Mr. Sobolak] started his DIY Midi Fighter he already had experience with the MIDI protocol, and because it is only natural once you have mastered something to expand on the success and build something more impressive, more useful, and more button-y. He is far from rare in this regard. More buttons mean more than extra mounting holes, for example an Arduino’s I/O will fill up quickly as potentiometers hog precious analog inputs and button arrays take digital ones. Multiplexing came to the rescue, a logic-based way to monitor or control more devices, in contrast to the serial protocols used by an IO expander.

Multiplexing was not in [Mr. Sobolak]’s repertoire, but it was a fitting time to learn and who doesn’t love acquiring a new skill by improving upon a past project? All the buttons were easy enough to mount but keeping the wires tidy was not in the scope of this project, so if you have a weak stomach when it comes to a “bird’s nest” on the underside you may want to look away and think of something neat. Regardless of how well-groomed the wires are, the system works and you can listen to a demo after the break. Perhaps the tangle of copper beneath serves a purpose as it buoys the board up in lieu of an enclosure.

We are looking forward to the exciting new versions where more solutions are exercised, but sometimes, you just have to tackle a problem with the tools you have, like when the code won’t compile with the MIDI and NeoPixel libraries together so he adds an Uno to take care of the LEDs. Is it the most elegant? No. Did it get the job done? Yes, and if you don’t flip over the board, you would not even know.

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Midiboy, The Portable Gaming Console With MIDI

The ArduBoy is a tiny little gaming console that’s also extremely simple. It’s only a small, cheap, monochrome OLED display, a microcontroller with Arduino-derived firmware, and a few buttons. That’s it, but with these simple ingredients the community around the ArduBoy has created a viable gaming platform. It has cartridges now, and one version has a crank. Now, the MIDIboy is bringing something like the ArduBoy to the world of electronic music.

Inside the MIDIboy is what you would expect from any review of the ArduBoy schematics. There are six buttons, a speaker, a USB port, and a SPI OLED display. In addition to all of this are two big chonkin’ DIN-5 ports for MIDI in and MIDI out, and yes, the MIDI in port has an optoisolator.

As for what you can do with a tiny little game console connected to MIDI, there are already a few choice apps — the MIDI Chords app creates chords, obviously, and the MIDImon sketch is a MIDI monitor. There are some controllers for MIDI synths, and of course this device is completely open source. If you’ve ever wanted a DIY controller for your favorite MIDI synth, this is what you need.

If an ArduBoy with MIDI doesn’t sound exciting, just check out Little Sound DJ. That’s a Game Boy cartridge that turns your old brick Game Boy into a music production workstation. Yes, it sounds great and there’s a lot of potential in a pocket game console with MIDI ports.

MIDI-Gurdy, MIDI-Gurdy, MIDI-Gurdy Man

The hurdy gurdy is the perfect musical instrument. It’s an instrument with a crank, and a mechanical wonderment of drone strings and weird chromatic keyboards. No other musical instrument combines the sweet drone of bagpipes with the aural experience of an eight-year-old attempting to play Hot Cross Buns on a poorly tuned violin.

Now, the hurdy gurdy is going digital. The Digi-Gurdy is [XenonJohn]’s entry into this year’s Hackaday Prize, and it’s exactly what it says on the tin: it’s a musical instrument that drones on and on, with keys plunking out a melody.

If you’re not familiar with a hurdy gurdy, this video is a varily good introduction. It’s a box with somewhere between four and six strings mounted on the outside. The strings vibrate by means of a wooden wheel powered by a crank. There’s a keyboard of sorts along the body of the instrument that ‘fret’ a single string providing the melody; all the other strings are drone strings that sound continuously. I think it was in, like, a Led Zeppelin video, man.

While it’s a slightly complicated build to make an analog hurdy gurdy, delving into the digital domain is easy: [XenonJohn] is building a hurdy gurdy that simply outputs MIDI commands with some buttons and a Teensy 3.6 microcontroller. The parts are 3D printed, and since this hurdy gurdy is completely digital, you can change the tuning of the drone strings without actually tuning them. Awesome.

DIY Raspberry Pi Multi FX Stomp Box

From building your own analog effects pedal to processing audio through micro controllers, a lot of musicians love building their own boxes of sound modification. In his entry for the 2019 Hackaday Prize, [Craig Hissett] has a project to build an all-in-one multi-effects stomp box.

At the center of the box is a Raspberry Pi with an AudioInjector stereo sound card.  The card takes care of stereo in and out, and passing the signal to the Pi. The software is Modep, an open source audio processor that allows the setup of a chain of digital effects plugins to be run on the Pi. After finding some foot switches, [Craig] connected them to an Arduino Pro Micro which he set up as a MIDI device that sends MIDI messages to the Modep software running on the Pi.

There are still a few steps to go, but [Craig] has the basic layout covered. Next up is wiring it up and building a proper case for it, as well as working on latency. A few years ago, another multi-effects stomp box was featured in the Hackaday Prize, and last year, this multi-effects controller was featured.


Circuit Bending Those Adorable Voices

Leapfrog make some pretty awesome kids electronics. Especially admirable is the low cost, the battery life, and the audio quality of these devices. This circuit bending hack takes advantage of those audio circuits by turning the Alphabet Pal into your lead vocalist. The performance in the demo video begins with some impressive tricks, but just wait for it because by the end the little purple caterpillar proves itself an instrument worthy of a position beside that fancy Eurorack you’ve been assembling.

The image above provides a great look inside the beastie. [Jason Hotchkiss] mentions he’s impressed by the build quality, and we have to agree. Plus, look at all of those inputs — this is begging to leave toyland and join the band. With an intuitive sense that can only be gained through lots of circuit-bending experience, he guessed that the single through-hole resistor on the PCB was used to dial in the clock speed. That made it easy to throw in a trimpot for pitch-bending and he moved on to figure out individual note control.

All of those caterpillar feet are arranged in a keyboard matrix to detect button presses. After pulling out the oscilloscope for a bit of reverse engineering, [Jason] grabbed a PIC microcontroller and added it to the same solder points as the stock ribbon connector. The result is that the buttons on the feet still work, but now the Alphabet Pal also has MIDI control.

Take a look at the writeup for full details, and the video after the break to hear it in action. If you’re a fan of circuit-bent toys, this pretty pink keyboard hack always impressed us, especially the spring reverb that was added!

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Repairdown: Disklavier DKC500RW Control Unit

If you’ve been kind enough to accompany me on these regular hardware explorations, you’ve likely recognized a trend with regards to the gadgets that go under the knife. Generally speaking, the devices I take apart for your viewing pleasure come to us from the clearance rack of a big box retailer, the thrift store, or the always generous “AS-IS” section on eBay. There’s something of a cost-benefit analysis performed each time I pick up a piece of gear for dissection, and it probably won’t surprise you to find that the least expensive doggy in the window is usually the one that secures its fifteen minutes of Internet fame.

DKC500RW installed on right side.

But this month I present to you, Good Reader, something a bit different. This time I’m not taking something apart just for the simple joy of seeing PCB laid bare. I’ve been given the task of repairing an expensive piece of antiquated oddball equipment because, quite frankly, nobody else wanted to do it. If we happen to find ourselves learning about its inner workings in the process, that’s just the cost of doing business with a Hackaday writer.

The situation as explained to me is that in the late 1990’s, my brother’s employer purchased a Yamaha Mark II XG “Baby Grand” piano for somewhere in the neighborhood of $20,000. This particular model was selected for its ability to play MIDI files from 3.5 inch floppy disks, complete with the rather ghostly effect of the keys moving by themselves. The idea was that you could set this piano up in your lobby with a floppy full of Barry Manilow’s greatest hits, and your establishment would instantly be dripping with automated class.

Unfortunately, about a month or so back, the piano’s Disklavier DKC500RW control unit stopped reading disks. The piano itself still worked, but now required a human to do the playing. Calls were made, but as you might expect, most repair centers politely declined around the time they heard the word “floppy” and anyone who stayed on the line quoted a price that simply wasn’t economical.

Before they resorted to hiring a pianist, perhaps a rare example of a human taking a robot’s job, my brother asked if he could remove the control unit and see if I could make any sense of it. So with that, let’s dig into this vintage piece of musical equipment and see what a five figure price tag got you at the turn of the millennium.

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Please Meet ‘Capability Inquiry’, Part Of The MIDI 2.0 Standard

It may have passed you by in the news, but the MIDI Manufacturers Association (MMA) has recently unveiled more details about the upcoming MIDI 2.0 standard. Previously we covered the prototyping phase start of this new standard. The original Musical Instrument Digital Interface standard was revealed all the way back in August of 1983, as a cooperation between companies including Moog Music, Roland, Yamaha, Korg, Kawai and others. It was the first universal interface that allowed one to connect and control all kinds of musical instruments.

Over the years, MIDI has seen use with the composing of music, allowing instruments to be controlled by a computer system and to easily share compositions between composers. Before MIDI such kind of control was limited to a number of proprietary interfaces, with limited functionality.

The MMA lists the key features of MIDI 2.0 as: Bidirectional, Backwards Compatible, and the enhancing of MIDI 1.0 where possible. Using a new technology called MIDI Capability Inquiry (MIDI-CI), a MIDI 2.0 device can exchange feature profiles and more with other 2.0 devices. 1.0 is the fallback if MIDI-CI finds no new functionality. MIDI-CI-based configuration can allow 2.0 devices to automatically configure themselves for their environment.

Suffice it to say, MIDI 2.0 is a far cry from the original MIDI standard. By transforming MIDI into a more versatile, bidirectional protocol, it opens new ways in which it can be used to tie musical devices and related together. It opens the possibility of even more creative hacks, many of which were featured on Hackaday already. What will you make with MIDI 2.0?

See a brief demonstration of this feature of MIDI 2.0 in the below video:

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