Install the software

See also How to prepare a Raspberry Pi Zero to drive the plotter, which gives step-by-step directions specifically for using a Pi Zero as the plotter engine.

brachiograph.py requires a few additional components, and needs to be run in a Python 3 environment, using Python 3.6 or later.

Install system packages

You may have some of these installed already, but that shouldn’t matter.

sudo apt install -y python3-venv pigpiod libjbig0 libjpeg-dev liblcms2-2 libopenjp2-7 libtiff5 libwebp6 libwebpdemux2 libwebpmux3 libzstd1 libatlas3-base libgfortran5 git

The packages include:

  • venv, for managing virtual environments under Python 3

  • PIGPIO, an excellent library that provides hardware control of the Pi’s GPIO pins - important for accurate timing of pulses. It comes with a Python interface to the lower-level code.

  • various system libraries required by the Pillow Python imaging library

  • libatlas3-base and libgfortran5, required by the Numpy Python mathematics library

  • Git

Set up a virtual environment

Create and activate a Python virtual environment to work in:

python3 -m venv env
source env/bin/activate

You will need to ensure the environment is activated by running source env/bin/activate - in this directory - if you return to it later.

Install Python packages

Pinned versions of the Python packages are listed in requirements.txt; install with:

pip install -r requirements.txt

This will install:

  • Numpy, a Python mathematics library

  • PIGPIO’s Python library

  • Pillow, the most widely-used Python imaging library.

  • tqdm, for the progress indicator while drawing

  • readchar, to allow the BrachioGraph.drive() methods to accept user input

Clone the BrachioGraph repository

Clone the BrachioGraph repository:

git clone git@github.com:evildmp/BrachioGraph.git

You will need to have set up a public key using ssh-keygen and added your public key to your GitHub account for this to work. Or, you can use HTTPS instead:

git clone https://github.com/evildmp/BrachioGraph.git