Yarns – Open source

Yarns is open-source. The code and hardware files can be found in the yarns directory in our Eurorack modules git repository.

After having cloned the repository, don’t forget to run git submodule init && git submodule update to make sure the sub-projects referenced in the code are also pulled.

Firmware hacking


To build Yarns’ code, an ARM EABI toolchain must be installed. We recommend jsnyder scripts (which include a lot of useful extras).

The path to the toolchain binaries must be specified in the TOOLCHAIN_PATH variable in makefile.inc.

To build the code, use the following command:

make -f yarns/makefile

If you modify lookup tables and want the big resources.cc file to be regenerated:

touch yarns/resources/resources.py && make -f yarns/makefile resources

Updating the firmware

A first solution is to simply use the firmware update procedure. A .syx file for firmware upgrade can be generated with:

make -f yarns/makefile syx

The firmware can then be loaded into the module using the procedure described in the manual.

Past this point, we assume you know what you are doing and we are not responsible for any damage to your module!

Another solution for firmware updating is to use a JTAG interface and openOCD. We recommend Olimex’ ARM-USB-OCD-H devices. Their older ARM-USB-OCD product is also known to work – and is in the fact used for factory programming. Configuration data for both are listed in stmlib/programming/jtag/interface.cfg – uncomment the one which is not needed.

An adapter must also be purchased for the mini-JTAG connector used by Yarns.

Upload the firmware with:

make -f yarns/makefile upload_combo_jtag_no_erase

Note that the upload_combo_jtag_no_erase command is used to prevent the FLASH to be entirely erased at each update – keeping the precious calibration data in place!

Hardware hacking

Schematics, board layout and panel files can be found in the yarns/hardware_design directory of the github repository.

The hardware description files are released under a cc-by-sa-3.0 license. The source code is released under the MIT license.

Olivier Gillet, Mutable instruments SARL 2011-2017. Except where otherwise noted, content on this site is licensed under a cc-by-sa 3.0 license.