Just saw your project on the Hackaday website - absolutely incredible!
Just a question about the software and it’s compatibility with DIY midi controllers…
I’m currently working on a Digital Trombone project on Hackaday.io and I’m wondering if I could incorporate Zynthian.
The concept is to have an on-board Pi rocking a JustBoom amp and dac hats connected to a speaker housed in the end of the instrument.
For input I am planning on using an Arduino microcontroller connected to the Pi via USB.
The Arduino will read data from some potentiometers, a ping sensor and an air pressure sensor and use the values to determine midi data.
Do you think it could work??
Amazing, thank you @mheidt.
I think I’ll aim to use something like this library: https://www.arduino.cc/en/Tutorial/MidiDevice
This will give the Pi a native midi input device and should work nicely.
In order to capture the trombone-like input I’m going to be using an pressure sensor to pick up airflow (as sending a note on/note off value as the instrument is played) two potentiometers to determine velocity and range and a ping sensor on the slide to determine the actual note.
I should be able to use a pro micro with all of these inputs without running out of pins, which is compatible with the above midi library.
Good times!
I don’t thing a ping (ultrasonic range finder) sensor has the resolution and the speed you need to handle this task. Been there, done that, and eventually we had to revert to a mechanical sensor.
Have you considered using an IR position sensor, similar to those used in mouses?
You only have to build a small capsule (where the air flows-in from your mouth) with some kind of membrane (a kid’s ballon will do the task) and measure the deformation of the membrane with the sensor.
It works very very well, have a good precision and reacts very fast to changes in the air pressure. Finally, it’s ludicrous cheap. I think it’s perfect for your application
A friend of mine used this method for building a couple of MIDI-sax and the resultant instruments are incredibly playable … believe me!! I will try to get some photo or video.
Thank you so much for the feedback! @Axeman - thanks for the heads up about that. I was hoping it would be responsive enough to track slide movement but was wart that it maybe quite the task to calculate it rapidly. @jofemodo - thanks for the suggestion buddy!
It sounds perfect; I’m looking for something small enough I can conceal it inside a normal trombone mouthpiece ideally, or even between the mouthpiece and the instrument. This way a player could use their piece of choice and still be able to tear it up on the digital trombone
I’m really looking forward to getting this project up and running. Hopefully on Saturday I’ll be able to stick the software on the Pi and begin configuring it to run as intended, and also set up a breadboard to start testing the midi input arduino.
The “Pro Micro” Arduino clones are one of the cheapest way to produce a USB MIDI interface, they use the ATmega32U4 processor with built in USB like the Leonardo.
The Teensy boards are an example of 32 bit processors with USB MIDI libraries.
(I would not use bit banged USB code that some projects use with more standard Arduinos)
Another input device candidate is a Wii Numchuck whick has an I2C interface Arduino boards know It gives an analog joystick, 2 pushbuttons and an accelerometer.
Thanks @MaxMaxis - I have a handful of Pro Micro clones at work. I’m going to grab one tomorrow and see what I can come up with.
The Wii nunchuk is a great shout too, although I’m not sure how is accurately capture it’s position on the slide in order to dictate the note being played.
Hopefully in the coming weeks I’ll be getting my hands on an old pBone (a plastic trombone) to serve as the frame of my build.
Once I have that I’ll be able to start trying out various combos of sensors to try and get that accurate capture I need.
