MIDI to CV/Gate The Easy Way

Let’s say you’ve got a modular synthesizer. You’re probably a pretty cool person. But all your cool laptop DJ friends keep showing off their MIDI-controlled hardware, and you’re getting jealous. Well, [little-scale] has the build for you.

The Teensy 3.6 is the current top-of-the-line Teensy from PJRC, and it’s [little-scale]’s weapon of choice here. With USB-MIDI and two 12-bit DACs on board, it’s made creating an interface between the worlds of analog and digital music into a remarkably simple job. Control voltages for pitch and velocity are pushed out over the analog pins, while pin 29 is used for gate signals.

It’s a testament to the amount of development that has gone into the Teensy platform that such projects can be built with virtually no off-board components. The build is a further step forward in simplicity from [little-scale]’s previous work, using a Teensy 2 with an offboard DAC to generate the output voltages.

Here at Hackaday, we’ve always been big fans of adding computer control to analog hardware. This CNC mod to a guitar pickup winding machine is a great example.

Hackaday Links: September 17, 2017


Mergers and acquisitions? Not this time. Lattice Semiconductor would have been bought by Canyon Bridge — a private equity firm backed by the Chinese government — for $1.3B. This deal was shut down by the US government because of national security concerns.

[Jan] is the Internet’s expert in doing synths on single chips, and now he has something pretty cool. It’s a breadboard synth with MIDI and CV input. Basically, what we’re looking at is [Jan]’s CVS-01 chip for a DCO, DCF, and DCA), a KL5 chip for an LFO, and an envelope chip. Tie everything together with a two-octave captouch keyboard, and you have a complete synthesizer on a breadboard.

As an aside relating to the above, does anyone know what the cool kids are using for a CV/Gate keyboard controller these days? Modular synths are making a comeback, but it looks like everyone is running a MIDI keyboard into a MIDI-CV converter. It seems like there should be a –simple, cheap– controller with quarter-inch jacks labeled CV and Gate. Any suggestions?

World leaders are tweeting. The Canadian PM is awesome and likes Dark Castle.

Way back in July, Square, the ‘POS terminal on an iPad’ company posted some data on Twitter. Apparently, fidget spinner sales peaked during the last week of May, and were declining through the first few weeks of summer. Is this proof the fidget spinner fad was dead by August? I have an alternate hypothesis: fidget spinner sales are tied to middle schoolers, and sales started dropping at the beginning of summer vacation. We need more data, so if some of you could retweet this, that would be awesome.

Remember [Peter Sripol], the guy building an ultralight in his basement? This is going to be a five- or six-part video build log, and part three came out this week. This video features the installation of the control surfaces, the application of turnbuckles, and hardware that is far too expensive for what it actually is.

Augmented Reality Pinball

Pinball machines are fascinating pieces of mechanical and electrical engineering, and now [Yair Moshe] and his students at the Israel Institute of Technology has taken the classic game one step further.  Using computer vision and a projector, this group of engineers has created an augmented reality pinball game that takes pinball to a whole new level.

Once the laptop, webcam, and projector are set up, a course is drawn on a whiteboard which the computer “sees” to determine the rules of the game. Any course you can imagine can be drawn on the whiteboard too, with an interesting set of rules that no regular pinball game could take advantage of. Most notably, the ball can change size when it hits certain types of objects, which makes for a very interesting and unconventional style of play.

The player uses their hands to control the flippers as well, but not with buttons. The computer watches the position of the player’s hands and flips the flippers when it sees a hand in the right position. [Yair] and his students recently showed this project off at DLD Tel Aviv and even got [Shimon Perez], former President of Israel, to play some pinball at the conference!

Flocking behavior using Mindstorm robots


Do you ever wonder why geese always fly together in a V-shape? We’re not asking about the fact that it makes the work load much less for all but the lead goose. We mean how is it that all geese know to form up like this? It’s is the act of flocking, and it’s long been a subject of fascination when it comes to robotics. [Scott Snowden] researched the topic while working on his degree a few years ago. Above you can see the demonstration of the behavior using LEGO Mindstorm robots. That’s certainly interesting and you’ll want to check out the video after the break. But his offering doesn’t end with the demo. He also posted a huge article about his work that will provide days of fascinating reading.

We can’t begin to scratch the surface of all that he covers, but we can give you a quick primer on his Mindstorm (NXT) setup. He uses these three bots along with a central brick (the computer part of the NXT hardware) which communicates with them. This lets him use a wide range of powerful tools like MatLab and Processing to recognize each robot with a top-down camera, passing it data based on info harvested with computer vision. From there it’s a wild ride of modeling the behavior as a set of algorithms.

Continue reading “Flocking behavior using Mindstorm robots”

MIDI Swiss Army Knife built from an MSP430

Hot off the heels of his web server for the TI MSP430, [Rob] shared a MIDI booster pack for the MSP430 LaunchPad, an exceedingly inexpensive and ever more capable microcontroller that is getting somewhat of a cult following.

[Rob]’s MIDI booster pack contains a MIDI in and out port as well as just about whatever MIDI manipulation apps his mind can dream up. So far, [Rob] has a MIDI arpeggiator, a harmonizer, an echo, filter, s MIDI monitor that displays incoming messages on a Nokia LCD, and a controller that interfaces with a light sensor or joystick to manipulate MIDI variables.

Back in the 80s (and 90s, and even into the aughts), a dedicated MIDI arp or harmonizer was a crazy expensive piece of kit, especially considering how simple the device is. Those dedicated rackmount boxes can now be replaced with a TI LaunchPad and [Rob]’s booster pack.

You can check out the arp and harmonizer in action after the break.

Continue reading “MIDI Swiss Army Knife built from an MSP430”

CV Sequencer with a TV out

[gijs] sent in the control voltage sequencer he’s been working on that uses the TVout Arduino library to provide a graphical interface.

The sequencer doesn’t produce any sound on its own. Instead, it outputs a Control Voltage so other synths can be sequenced with [gijs]’ TVSCV. Before MIDI came around, CV was the standard to connect synthesizers and drum machines together. Even today, a lot of boutique synths have at least one jack for CV. [gijs]’ build is really interesting because of the user interface – the TVout Arduino library was used in conjunction with a tiny CRT to change values, timing and speed of the CV output. The TVSCV is able to sequence two different channels of CV at 10 bit resolution with 16 steps per bank.

From the video after the break, the TVSCV sounds like it can produce what would be the trippiest soundtrack ever conceived for an Atari or NES game. It’s a great bit of kit, especially when connected to an Atari punk console or a TR-808 and a glitch delay.

Continue reading “CV Sequencer with a TV out”