Airflute is a home-made flute synthesizer over bluetooth, that was realized as part of the ARTISHOW project at Télécom Paris. It has the shape of a flute, and uses the MIDI protocol and a Bluetooth Lower Energy (BLE) connection to send notes to your favourite synthesiser software on your computer.
It can be used to:
- Play almost any instrument you like while only knowing how to play the flute.
- Learn music without causing bleeding ears to everyone (because you can use your headphones on your computer, and you'll be the only one to hear your awful music)
It was created using the Zephyr RTOS Project on the Nordic XIAO BLE SENSE board.
We used:
- a XIAO BLE SENSE
- some phototransistors (We couldn't find the exact ref on Vishay, here are the exact ones we used).
- an I/O expander PCF8574
- A 3.7V 250mAh Lithium Battery to power the flute.
- a 3D printer, and some additionnal crafting stuffs
To detect the fingers on the holes of the flute, we uses the phototransistors. A regular flute should have 10 holes. The thing is, on a real flute overlay, some holes are very very close to each other. This is why we decided only to use 8 sensors, and to modify the real fingerings to something that whould fit on 8 holes (you can see them here).
However, 8 GPIO pins only for this would be kind of overkill, and it was also interesting for use to experiment with i2c, which is the reason why we actually use a I/O expander controled with i2c. In case you want to add more holes, you only have to chain the expanders (up to 8), and rewrite a portion of the code.
We also needed to know if somebody is blowing into the flute or note. We decided to make our own sensor, inspired by this youtube video by KontinuumLAB, using the phototransistors and a membrane made of balloon. If you blow, the membrane expands and is closer to the phototransistor. We then read the sensor using the ADC, and can, with calibration, decide the intensity of the blow.
As it began to be hard to fit everything in the flute (there were lots of wires due to the number of sensor, and the expander), we decide to make a PCB, on which we welded all the components. You can find it here. Please note this PCB is distributed under the CC BY 4.0 license as stated in the License section.
Of course, we want our flute to look like one, and not just sensors wired to a board, so we 3D printed the mouthpiece mouthpiece.stl, a body body.stl, and a horn horn.stl. Alternatively, you can use a PVC pipe for the body.
Note: The project was developed using Zephyr RTOS v.3.6 and SDK v0.16.5-1. If you encounter any issues with other versions, please try using this version.
Here are the steps to build the project for the Nordic XIAO BLE SENSE board:
- Clone the repository:
git clone https://github.com/paulmialane/airflute.git- Navigate to the zephyr project directory:
cd path/to/zephyrproject- Source the Zephyr environment:
On Linux or MacOS:
source path/to/zephyr-env/bin/activateOn WindowsPowerShell:
path/to/zephyr-env\Scripts\Activate.ps1- Build the project:
west build -b xiao_ble_sense path/to/airflute- Flash the project:
On the XIAO BLE SENSE board, press the reset button twice to enter the
bootloader mode. Then, copy the generated zephyr.uf2 file of the build
folder to the device.
You can use the shell or you can directly drag and drop the zephyr.uf2 file
to the device using the file explorer.
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Install a synthesizer on your computer that can connect to MIDI devices. Depending on the software you might need to install a soundfont to get the flute sound. For a simple use on Linux we recommend installing QSynth and adding the soundfont of your choice.
Alternatively, you can use an android app that can connect to MIDI devices. We recommend using FluidSynth MIDI Synthesizer available on the Play Store.
Note: We also tested on MAC OS with GarageBand but had some latency problem we didn't have on QSynth. We didn't test on Windows.
Fun part : Don't restrict yourself to flute sounds, you can use any soundfont you like. You can play the trumpet, the saxophone, the piano, the drums, etc. The flute acts as a synthesizer and can play any sound you want.
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Be sure the flute is powered on, whether it is connected to the computer with the USB cable or powered by a battery.
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Connect to the XIAO BLE SENSE board using Bluetooth on your device. The device should appear as
Airflutein the list of available devices. -
Open the synthesizer software and select the MIDI device as the input.
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Have fun playing the flute !
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Optionally, if you are connected to the computer with the USB cable, you can also use the serial port to see the logs and debug the project.
Note: Sadly, we were not able to make the Bluetooth connection work on Windows. If you have any idea on how to make it work, feel free to contribute.
As mentionned in the Building the flute section, we are not really creating a flute, as the layout isn't the right one. Instead of using 10 holes, we are only using 8 holes, and so the fingerings are a bit different from a regular flute. Actually, it's inspired from a saxophone (still with some modifications).
Here are the fingerings implemented (the octave key at the back of the flute isn't pictured):
You can actually create your own fingerings by modifying the combinationToMidi.c file.
The code if this project is licensed under the MIT License.
The PCB and the 3D models, created as part of the ARTISHOW project at Télécom Paris, are licensed under
If you have any questions, suggestions, or feedback regarding this project, feel free to reach out to us through GitHub issues or discussions. However, if you don't receive a response, you can also contact us directly at our academic email addresses:
- Justine OGER: justine.oger@telecom-paris.fr
- Lucas MICHEL: lucas.michel@telecom-paris.fr
- Paul MIALANE: paul.mialane@telecom-paris.fr
Please note that while we welcome your messages, we cannot guarantee a prompt response due to our academic commitments. We appreciate your understanding.