Effect Cape for Bela Mini

Effect Cape for Bela Mini

A programmable open-platform effect pedal based on the Bela framework.

The objective of this project was to create a customizable guitar effects pedal using Bela's embedded computing framework. The pedal allows guitarists to design and run their own effects on dedicated audio hardware. To achieve this, an extension cape has been developed, integrating essential components such as rotary encoders, switches, and audio inputs/outputs onto a single circuit. Additionally, a software framework has been created using Pure Data, providing all the necessary functions for utilizing the device.

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.)