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Firmware for the OWL programmable effects pedal.

All code licensed under the Gnu GPL unless otherwise stated.

The OwlWare firmware in this repository has been superceded by OpenWare. For more details see, the community forum, or refer to for documentation.


First you need to get the OwlWare source code into a directory of your choice. We will refer to this as the OwlWare directory.

If you have or create a account then you can always get the latest version of the software with git.

  • Clone this github repository with git clone
  • Open a terminal or command window in the cloned repository OwlWare (the OwlWare directory)
  • Do a git submodule init and git submodule update to get the required submodules

If you are not familiar with git, you can also download the source code as a zip file.

You will then also have to manually download OwlPatches and unzip in the OwlWare/Libraries directory.

GNU Tools for ARM Embedded Processors

Download the GNU ARM toolchain for your operating system. Unzip in the OwlWare/Tools directory.

If you want to install it elsewhere, edit in the OwlWare directory to point to the right TOOLROOT directory.

DFU Util

To upload firmware over USB, you will also need dfu-util which you can download from here. Unzip the binaries (or compile them) in the OwlWare/Tools/dfu-util directory.

Recommended for most users. OwlNest can also be used.

ST Util

For those who want to upload firmware using an STLINKv1 or STLINKv2 programmer (such as those on the ST Discovery boards). Download stlink from here and install it in the OwlWare/Tools/stlink directory..

For most users, this will not be required.


To build and deploy the project using the provided Makefiles you will need some version of the make utility, for example GNU make.

For Windows users, we recommend installing Cygwin.



Open a terminal or command window in the OwlWare directory and type in:

  • make to build Builds/OwlWare.elf
  • make bin to build Builds/OwlWare.bin
  • make clean all to rebuild all intermediary files

Build Options

The default configuration builds an OWL Pedal debug build. To build the release version (no debug information, apprx 2x performance) add CONFIG=Release. To build the OWL Modular version, add PLATFORM=Modular. Make sure to do a make clean after changing build options.


In the OwlWare directory, type in:

  • make dfu to build the bin file and upload to an OWL device in DFU mode, connected by USB
  • make debug to build the elf file and upload to an OWL device connected with st-util using an stlink programmer