Since I discover Bela platform a year ago, It seems I solved all my issues related to the disconection between my instrument and the processings on my computer. I was using Teensy and Arduino having a lot of issues to integrate everything in a unique mobile format.
Bela is an open-source embedded platform for real-time, ultra-low-latency audio and sensor processing on the BeagleBone Black.
Here I would like to share some fundamental tips that I wish I could know when I started to learn bela:
1. The correct power supply
Note that in order for the speaker amp to work, Bela needs to be powered from the barrel jack.
2. If you send the output to your interface, use line
3. When conecting to speakers, keep in mind to send to 8 Ohm.
The speaker amps are rated for 1.1W on 8ohms, which sets the upper limit on the current that can be provided. This means that when loading it with a 4ohm speaker, you would have to make sure the current does not exceed the one that would be provided on a 8ohm load. Ultimately, if you need more power, you'd be better off using some off-board components such as a MAX9744 breakout or similar. I was using https://opencircuit.nl/Product/2-Kanaals-3W-PAM8403-Audio-Amplifier-Module
But at the moment, I decide to keep simple connecting 2x 2 speakers of 4 ohm in series, having in total 4 speakers but stereo. For more information about this connection:
4. Piezo mics
You need 1 pair of resistors (2MOhm) for each piezo. If you group them together they will all be mixed together so you would get only one trigger from the 8 piezos (see figure bellow). If you don't have 1.8M resistors, you can just about any value between 22k and 2.2M (as long as it is the same on both sides). On the lower end of that you will have less low-frequency response but that may not matter in your application.
5. (For collider users) Spare CPU using C++ and efficiency in UGENS In order to spare CPU, make sure to organize your information in your patch by sending messages to OSCdef functions
A special thanks to Marije Baalman, Jonathan Reus and the Bela team for the support and the contribution for this product development.