This is the documentation for the latest development branch of MicroPython and may refer to features that are not available in released versions.

If you are looking for the documentation for a specific release, use the drop-down menu on the left and select the desired version.

Getting Started¶

This guide covers a step-by-step process on setting up version control, obtaining and building a copy of the source code for a port, building the documentation, running tests, and a description of the directory structure of the MicroPython code base.

Source control with git¶

MicroPython is hosted on GitHub and uses Git for source control. The workflow is such that code is pulled and pushed to and from the main repository. Install the respective version of Git for your operating system to follow through the rest of the steps.

Note

For a reference on the installation instructions, please refer to the Git installation instructions. Learn about the basic git commands in this Git Handbook or any other sources on the internet.

Note

A .git-blame-ignore-revs file is included which avoids the output of git blame getting cluttered by commits which are only for formatting code but have no functional changes. See git blame documentation on how to use this.

Get the code¶

It is recommended that you maintain a fork of the MicroPython repository for your development purposes. The process of obtaining the source code includes the following:

Fork the repository https://github.com/micropython/micropython
You will now have a fork at <https://github.com/<your-user-name>/micropython>.
Clone the forked repository using the following command:

$ git clone https://github.com/<your-user-name>/micropython

Then, configure the remote repositories to be able to collaborate on the MicroPython project.

Configure remote upstream:

$ cd micropython
$ git remote add upstream https://github.com/micropython/micropython

It is common to configure upstream and origin on a forked repository to assist with sharing code changes. You can maintain your own mapping but it is recommended that origin maps to your fork and upstream to the main MicroPython repository.

After the above configuration, your setup should be similar to this:

$ git remote -v
origin       https://github.com/<your-user-name>/micropython (fetch)
origin       https://github.com/<your-user-name>/micropython (push)
upstream     https://github.com/micropython/micropython (fetch)
upstream     https://github.com/micropython/micropython (push)

You should now have a copy of the source code. By default, you are pointing to the master branch. To prepare for further development, it is recommended to work on a development branch.

$ git checkout -b dev-branch

You can give it any name. You will have to compile MicroPython whenever you change to a different branch.

Compile and build the code¶

When compiling MicroPython, you compile a specific port, usually targeting a specific board. Start by installing the required dependencies. Then build the MicroPython cross-compiler before you can successfully compile and build. This applies specifically when using Linux to compile. The Windows instructions are provided in a later section.

Required dependencies¶

Install the required dependencies for Linux:

$ sudo apt-get install build-essential libffi-dev git pkg-config

For the stm32 port, the ARM cross-compiler is required:

$ sudo apt-get install gcc-arm-none-eabi libnewlib-arm-none-eabi

See the ARM GCC toolchain for the latest details.

Python is also required. Python 2 is supported for now, but we recommend using Python 3. Check that you have Python available on your system:

$ python3
Python 3.5.0 (default, Jul 17 2020, 14:04:10)
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>

All supported ports have different dependency requirements, see their respective readme files.

Building the MicroPython cross-compiler¶

Almost all ports require building mpy-cross first to perform pre-compilation of Python code that will be included in the port firmware:

$ cd mpy-cross
$ make

Note

Note that, mpy-cross must be built for the host architecture and not the target architecture.

If it built successfully, you should see a message similar to this:

LINK mpy-cross
   text          data    bss     dec     hex filename
 279328          776     880  280984   44998 mpy-cross

Note

Use make -C mpy-cross to build the cross-compiler in one statement without moving to the mpy-cross directory otherwise, you will need to do cd .. for the next steps.

Building the Unix port of MicroPython¶

The Unix port is a version of MicroPython that runs on Linux, macOS, and other Unix-like operating systems. It’s extremely useful for developing MicroPython as it avoids having to deploy your code to a device to test it. In many ways, it works a lot like CPython’s python binary.

To build for the Unix port, make sure all Linux related dependencies are installed as detailed in the required dependencies section. See the Required dependencies to make sure that all dependencies are installed for this port. Also, make sure you have a working environment for gcc and GNU make. Ubuntu 20.04 has been used for the example below but other unixes ought to work with little modification:

$ gcc --version
gcc (Ubuntu 9.3.0-10ubuntu2) 9.3.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.then build:

$ cd ports/unix
$ make submodules
$ make

If MicroPython built correctly, you should see the following:

LINK micropython
   text         data     bss     dec     hex filename
 412033         5680    2496  420209   66971 micropython

Now run it:

$ ./micropython
MicroPython v1.13-38-gc67012d-dirty on 2020-09-13; linux version
Use Ctrl-D to exit, Ctrl-E for paste mode
>>> print("hello world")
hello world
>>>

Building the Windows port¶

The Windows port includes a Visual Studio project file micropython.vcxproj that you can use to build micropython.exe. It can be opened in Visual Studio or built from the command line using msbuild. Alternatively, it can be built using mingw, either in Windows with Cygwin, or on Linux. See windows port documentation for more information.

Building the STM32 port¶

Like the Unix port, you need to install some required dependencies as detailed in the Required dependencies section, then build:

$ cd ports/stm32
$ make submodules
$ make

Please refer to the stm32 documentation for more details on flashing the firmware.

Note

See the Required dependencies to make sure that all dependencies are installed for this port. The cross-compiler is needed. arm-none-eabi-gcc should also be in the $PATH or specified manually via CROSS_COMPILE, either by setting the environment variable or in the make command line arguments.

You can also specify which board to use:

$ cd ports/stm32
$ make BOARD=<board> submodules
$ make BOARD=<board>

See ports/stm32/boards for the available boards. e.g. “PYBV11” or “NUCLEO_WB55”.

Building the documentation¶

MicroPython documentation is created using Sphinx. If you have already installed Python, then install Sphinx using pip. It is recommended that you use a virtual environment:

$ python3 -m venv env
$ source env/bin/activate
$ pip install -r docs/requirements.txt

Navigate to the docs directory:

$ cd docs

Build the docs:

$ make html

Open docs/build/html/index.html in your browser to view the docs locally. Refer to the documentation on importing your documentation to use Read the Docs.

Running the tests¶

To run all tests in the test suite on the Unix port use:

$ cd ports/unix
$ make test

To run a selection of tests on a board/device connected over USB use:

$ cd tests
$ ./run-tests.py -t /dev/ttyACM0

Folder structure¶

There are a couple of directories to take note of in terms of where certain implementation details are. The following is a break down of the top-level folders in the source code.

py

Contains the compiler, runtime, and core library implementation.

mpy-cross

Has the MicroPython cross-compiler which pre-compiles the Python scripts to bytecode.

ports

Code for all the versions of MicroPython for the supported ports.

lib

Low-level C libraries used by any port which are mostly 3rd-party libraries.

drivers

Has drivers for specific hardware and intended to work across multiple ports.

extmod

Contains a C implementation of more non-core modules.

docs

Has the standard documentation found at https://docs.micropython.org/.

tests

An implementation of the test suite.

tools

Contains scripts used by the build and CI process, as well as user tools such as pyboard.py and mpremote.

examples

Example code for building MicroPython as a library as well as native modules.