If you’re one of those people who started making electronics for music, this Raspberry Pi RP2040-based audio DSP project [DatanoiseTV] May be of interest. EuroRac provides a freeRTOS template application for creating compatible synthesizers, effects processors, and similar DSP-based audio widgets.
The hardware platform has a simple EuroRock connection with MIDI in, control voltage (CV) and a simple 5V-compatible trigger. An audio output is provided to send audio to a system mixer or any other analog module. Additionally, a rotary encoder, a few push buttons and a connection for an OLED display are provided to allow the module to build a primary user interface, if required.
The application template is generic enough, but the project is intended for use with the Vault DSP Transcompiler. Vault is a high-level programming language designed to enable the creation of audio synthesizers and the like easily, generating C ++ code as the output of the compilation process. It is then wrapped with RTOS goodies (although you don’t actually need them) in the usual way, for easy downloading to RP2040 via USB-C port. So, if you want to access DSP-based Eurorac modules for your Homebrew Synth rack, this might be a good place to start.
Just as the RP2040 is not the most obvious choice for a DSP application, neither is the ESP32, but who cares? Many modern micro nowadays are more capable than audio DSPs, with or without dedicated functionality.