Hi! Over the past few months, I have been developing an effect cape for Bela Mini.
My goal was to create a customizable guitar effects pedal that allows guitarists to design and run their own effects on this dedicated audio hardware. This project forms an integral part of my Master's thesis which I am currently writing at the Institute for Electronic Music and Acoustics in Graz. The primary objective of my thesis is to assess the feasibility of utilizing Bela for developing real-time guitar effects, while also conducting a comparative analysis with other reprogrammable effect pedals constructed on similar platforms.
The circuit board was designed using KiCad, and manufactured with Eurocircuits. The cape is conceived as a stompbox incorporating four rotary encoders, each equipped with a switch, as well as two footswitches, all of which can be assigned based on personal preferences. It incorporates a 6.3 mm mono jack socket for audio input and two identical sockets for audio output, a 3.5 mm stereo jack socket for headphones output, and a 6.3 mm stereo jack socket for expression pedal input. To provide visual feedback for various modes, changes, and the status of each rotary encoder, I incorporated a bicolor LED and an OLED screen into the board. Additionally, to ensure compatibility with pedal board power supplies, I included a DC Barrel Jack that enables external power (5V/100mA) using 2.1 mm or 2.5 mm plugs with a negative polarity.
I also made an example project (Delay_Chain) that serves as a demonstration of utilizing the effect_cape in a multi-effect configuration and provides all the necessary frameworks to operate the hardware. With the exception of a custom render.cpp file dedicated to reading the values from the rotary encoders, all software components were developed exclusively using Pure Data.
The audio effects included are as follows: (their order is interchangeable in the _main patch)
[scanner] Hammond's Scanner Vibrato simulator with an adjustable rate, depth, and mix.
[tapedelay] Tape delay simulator with variable-speed tape and saturation.
[freeverb] Schroeder reverberator implementation using the Freeverb algorithm.
[looper] Looper with overdub capability and clock synchronized to the first layer.
(For more information on each patch, see the content within.)
The project is released under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, so if you want to build your own version, you can get all the files and information from this repository. https://github.com/leheltorok/effect_cape_for_bela_mini
The documentation is still in progress but the important stuff is mainly there. (a case is also under development)
I look forward to hearing your thoughts, suggestions, and comments on the outcome. Feel free to share your ideas and give feedback on the result.