An idea that came up during the 31C3. The guys from VisualPhi had some motion sensors lying around and wanted to use them to control their VJ-software. That’s why I built them a Motion-Sensor-to-MIDI-Converter.

As usual it all starts on a breadboard. Most of the times I draw the schematics parallel to building the circuit on a breadboard. Guess that’s the usual way.




The circuit itself is rather unspectacular. 8 inputs are polled from a 74HC165. Then there’s a little bit of logic implemented within an Arduino and then there’s 16 LEDs, a rotary encoder and MIDI out.






This project is the first one to benefit from my new 3D Printer. Due to the fact that I don’t have a dedicated toolshed anymore it’s kind of impossible to reliably manufacture the case anymore. Seems as if I don’t need one from now on.



I really think the fixation of the rotary encoder is one of the smartest pieces ever done by mankind. Ever =)





The LEDs are driven via Charlieplexing. It’s rather easy to implement but you really need to concentrate while soldering. By the way: If everything else fails I guess I’ll become a Soldering-Artist one day.



The function of the device is easy to explain. Every input is triggered when the state of a connected switch changes. This is indicated by the red LED below the channel. The green LEDs indicate the channel that’s influenced by the rotary enoder: The encoder gives the possibility to set the time that has to pass from the moment the input is triggered until it can be retriggered again. Something like a ‘Retrigger Threshold’. The value can be set to values between 0 and ~2 seconds. When the lower / upper limit of the value is reached the green LED flashes. Pressing the rotary encoder (it has a built-in switch) switches to the next input.

A triggered input sends a MIDI note.










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2 Responses to Motion-Sensor-to-MIDI-Converter

  1. JOnny says:

    Hello! Cheers for this amazing project, I’m building a similar system and only now i came across this website 😀 😀
    I tried to use HCsr04 sensors to send MIDI CC messages but it failed long way, maybe could u help for the code please? the system im building is much simpler so i wish i could adapt it, I commissioned such work (with hcsr04s) to a said professional but even he returned me the money back saying it was impossible for him to do
    thanks a lot, Jonny

    • Andy Fischer says:

      Hey JOnny, the description of your project sounds like something completely different to me =). Maybe you’ll want to contact me via mail and we’ll have a chat about your project.

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