bfreeOrgan2

Drawbar Organ Synthesizer

By Franco Caspe (francocaspe@hotmail.com)

bfreeOrgan2 is a C++ coded, synchronous tonewheel organ synthesizer for the STM32F4 Discovery board and Linux, based on the flexYnth development library.

Video Presentation

Introduction

I love the Hammond Organ! but as June 2019 there was no open-source homebrew box that implements a nice Drawbar Organ, so I decided to code one myself.

In the efforts of doing so, I learned a lot of efficient programming on C++ so I opted to create a base library to modularize the code, and to allow me to easily expand this project in the future, or to develop new synths! Thus creating flexYnth and bfreeOrgan2.

Scope

This project implements a modularly-coded tonewheel drawbar organ synthesizer, implemented on two different flexYnth Engines, each one in different branches.

1. A Linux/ALSA testbench implementation.
2. A STM32F4 Discovery Board Implementation.

Features

• 10 voice Polyphony.
• Real time 9 Drawbar control.
• Chorus effect with adjustable Rate and Amplitude.
• Envelope and Optional Click Generator.
• Commands are controled over MIDI CC's. (See the MIDI mapping in utils/vmpk.ins)
• 16bit@48Khz Mono output.

Build it!

For the Discovery STM32F407

FIRST switch to the Discovery STM32F407 Board branch.

1. Run: 'git checkout discovery_f4'

NOTE: Make sure the arm-gcc toolset path is set in the PATH enviroment variable when you run make.
Get ARM GCC Toolset

For Flashing the discovery, the makefile uses texane/stlink toolThe latest version that is currently working fine for the STM32F4 Discovery board is 1.3.0. Get Texane's stlink utility

2. Run: 'make'
3. Connect the STM32F4 Discovery Board to the PC.
4. Run: 'make flash'

After the Discovery Board is flashed, connect the User USB Port to your computer. It will recognize a MIDI Device. Route a controller to the MIDI input of the Board. The audio output is provided by the 3.5mm Jack of the Discovery Board.

On Linux/ALSA:

NOTE: Make sure you have the Alsa Development Libs installed.

FIRST switch to the linux_alsa branch:

1. Run: 'git checkout linux_alsa'
2. Run 'make'
3. Execute the testbench: './bin/testbench'

An ALSA MIDI port will open for you to connect your favorite controller! ( I use alsaconnectgui )

License

Released under Apache V2.0 License.