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monome eurorack module


  • src: source code for the teletype algorithm
  • module: main.c and additional code for the Eurorack module (e.g. IO and UI)
  • tests: algorithm tests
  • simulator: a (very) simple teletype command parser and simulator
  • docs: files used to generate the teletype manual


See the libavr32 repo for more detailed instructions. You will also need ragel installed and on the path, see below.

Alternatively, if you have Docker installed, you can quickly get building with a Docker image that has all the dependencies set up:

git clone --recursive --config core.autocrlf=input
docker run --rm -it -v"$(pwd)/teletype":/target dewb/monome-build bash

The reasoning behind these options:

  --recursive                   # clone libavr32 and unity submodules
  --config core.autocrlf=input  # if on Windows, avoid adding CRLF line endings that can break compile scripts

  --rm                          # delete the container after exiting it
  -it                           # keep stdin attached, allocate tty
  -v"$(pwd)/teletype":/target  # mount the ./teletype directory at /target inside the container

Make sure that the libavr32 submodule is correctly checked out

cd module
make clean


To run the tests:

cd tests
make clean  # only needed if you've built the module code
make test

In the case of line ending issues make test may fail, in this case make tests && ./tests might work better.


The Ragel state machine compiler is required to build the firmware. It needs to be installed and on the path:

brew install ragel  # Homebrew (OSX)
apt install ragel   # Debian / Ubuntu / WSL (Windows 10)
pacman -Sy ragel    # Arch Linux / MSYS2 (Windows)

Version 6.9 is known to work.

See section 6.3 in the Ragel manual for information on the => scanner constructor used.

Adding a new OP or MOD (a.k.a. PRE)

If you want to add a new OP or MOD, please create the relevant tele_op_t or tele_mod_t in the src/ops directory. You will then need to reference it in the following places:

  • src/ops/op.c: add a reference to your struct to the relevant table, tele_ops or tele_mods. Ideally grouped with other ops from the same file.
  • src/ops/op_enum.h: please run utils/ to generate this file using Python3.
  • src/match_token.rl: add an entry to the Ragel list to match the token to the struct. Again, please try to keep the order in the list sensible.

There is a test that checks to see if the above have all been entered correctly. (See above to run tests.)

Code Formatting

To format the code using clang-format, run make format in the project's root directory. This will only format code that has not been commited, it will format both staged and unstaged code.

To format all the code in this repo, run make format-all.


In order to build the documentation you will need Python 3.6 or greater, Pandoc, as well as the Python libraries specified in the requirements.pip file. In addition, to generate the PDF output you will also require TexLive (or MacTex).

On OSX the dependencies can be installed with brew.

brew install python3
brew install pandoc
brew cask install mactex  # warning, MacTex is a very large install!
cd utils
pip3 install -r requirements.pip

On Linux I would suggest using virtualenv to install all the Python dependencies (including those in the requirements.pip file), and to ensure that the python3 binary is version 3.6 or greater instead of the default of your distro.

To generate the documentation:

cd docs
make               # build both teletype.pdf and teletype.html
make teletype.pdf  # build just teletype.pdf (requires TexLive or MacTex)
make teletype.html # build just teletype.html

Making a Release

To create a file containing:

  • teletype.hex
  • update_firmware.command
  • teletype.pdf

Run make release in the project's root directory

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