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Build Status

Common code shared between Monome Eurorack firmwares:

Getting starting with development

If you want to build your own copy of any of the firmwares you'll need the Atmel AVR-32 toolchain installed.


If you're on OSX you can use the avr32-toolchain repo to build your own. You'll need Homebrew installed.

To install on OSX in ~/avr32-tools:

brew install mpfr gmp libmpc texinfo dfu-programmer
git clone
cd avr32-toolchain
PREFIX=$HOME/avr32-tools make install-cross
# go make a cup of tea, this will take a while...

If you encounter an error make sure you have the Xcode command line tools installed. They can be installed by typing xcode-select --install (if they are already installed it will print an error message).


If you're on Linux, download the toolchain and the headers from Atmel. You need to dowload:

  • Atmel AVR 32-bit Toolchain 3.4.3 - Linux 64-bit (avr32-gnu-toolchain-
  • Atmel 32-bit Toolchain (3.4.3) - Header Files (

The headers need to be installed in the correct location.

To install on Linux in ~/avr32-tools:

tar xvfz avr32-gnu-toolchain-
mv avr32-gnu-toolchain-linux_x86_64 $HOME/avr32-tools
unzip -d $HOME/avr32-tools/avr32/include

You should also install dfu-programmer from your package manager.


Install bash:

Install dependencies to compile the toolchain (unzip and gperf needed to compile toolchain, but aren't listed as dependencies in the README):

sudo apt update
sudo apt upgrade
sudo apt install curl flex bison libgmp3-dev libmpfr-dev autoconf build-essential libncurses5-dev libmpc-dev texinfo
sudo apt install gperf unzip

Install clang-format:

sudo apt install clang-format

Compile the toolchain (this will take a few hours, the tar steps can take a while and won't print anything to screen):

git clone
cd avr32-toolchain
PREFIX=$HOME/avr32-tools make install-cross

Install ragel and compile the firmware:

sudo apt install ragel
export PATH="$HOME/avr32-tools/bin:$PATH"
git clone --recursive  # change to repo of your preference
cd teletype
cd module

Building a firmware

Let's build and upload a copy of the teletype firmware

First clone the repo, we need to clone recursively to bring in the libavr32 submodule.

git clone --recursive
cd teletype

Let's build it, we need to make sure that avr32-gcc and company are available on our path. Assuming they are installed in ~/avr32-tools:

export PATH="$HOME/avr32-tools/bin:$PATH"
cd module

You should now have a teletype.hex file in the src directory.

To upload it, you'll need a USB A-A cable, then:

  1. Power on your module with no USB cables attached, while holding down the front panel button
  2. Connect the USB A-A cable to your computer and the module
  3. Run ./ in the module directory
  4. The firmware should upload and verify itself. If it can't find the device, try repeating the steps.
  5. Disconnect the USB A-A and power cycle the module to re-enable normal USB mode (otherwise your grid or keyboard will not be detected)

You cannot overwrite the bootloader if you update via USB

Serial port

Each of the modules has an unpopulated UART header on the rear, when populated it can be used with an FTDI cable or breakout board for print / trace debugging.

The following cables are known to work:

When connecting, align the black cable with the gnd pin. Breakout boards are also available. 3.3V should work too.

Newer versions of OSX and Linux include builtin drivers for the FTDI cable. On OSX the simplest way to connect to the serial port is to use the cu program (type ~. to quit), e.g.

sudo cu -s 115200 -l <device>

On Linux and OSX, you can also use the screen command (type C-a \, or C-a :quit to quit), e.g.

sudo screen <device> 115200

The value of <device> depends on the adaptor being used and the OS, try the following 2 commands to identify it:

ls /dev | grep -i ttyusb   # should work on Linux
ls /dev | grep -i tty.usb  # should work on OSX


This folder contains the Atmel software framework, if you wish to make changes here, please make them using the diet-asf repo.

AVR32 development

The modules use AVR32 MCUs from Atmel, either the AT32UC3B0512 or the AT32UC3B0256.

module MCU RAM ROM default stack size default NVRAM size
ansible, teletype AT32UC3B0512 96kb 512kb 8kb 256kb
earthsea, meadowphysics, whitewhale AT32UC3B0256 32kb 256kb 4kb 128kb

Useful AVR32 documents

(very) In depth AVR32 documentation

There is a lot of overlap between these documents, the table of contents is at the back.

RAM and ROM usage

In short run avr32-size -A <module name>.elf. All free RAM is allocated to the .heap. ROM size is approximately .data + .rodata + .text. NVRAM is given by .flash_nvram. See here for a more in depth discussion.

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