MicroPython - a lean and efficient Python implementation for microcontrollers and constrained systems
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peter-conalgo and dpgeorge stm32/flashbdev: Fix bug with L4 block cache, dereferencing block size.
The code was dereferencing 0x800 and loading a value from there, trying to
use a literal value (not address) defined in the linker script
(_ram_fs_cache_block_size) which was 0x800.
Latest commit a8736e5 Jul 13, 2018
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docs docs/library/machine: Remove conditional docs for rng function. Jul 18, 2018
drivers drivers/sdcard: Do not release CS during the middle of read operations. Jul 5, 2018
examples examples/embedding: Add code markup and fix typo in README.md. Jun 18, 2018
extmod extmod/vfs_posix: Use DTTOIF if available to convert type in ilistdir. Jul 11, 2018
lib nrf: Upgrade to nrfx 1.1.0 Jul 18, 2018
logo all: Use the name MicroPython consistently in comments Jul 31, 2017
mpy-cross mpy-cross: Make build independent of extmod directory. Jul 10, 2018
ports stm32/flashbdev: Fix bug with L4 block cache, dereferencing block size. Jul 19, 2018
py py/runtime: Use mp_obj_new_int_from_ll when return int is not small. Jul 14, 2018
tests py/objgenerator: Implement __name__ with normal fun attr accessor code. Jul 10, 2018
tools tools/mpy-tool.py: Put frozen bignum digit data in ROM, not in RAM. Jul 9, 2018
.gitattributes .gitattributes: Remove special text handling of stm32 usbdev files. May 11, 2018
.gitignore all: Remove trailing spaces, per coding conventions. Jul 19, 2017
.gitmodules nrf: Replace custom-HAL with nrfx-HAL Jul 18, 2018
.travis.yml travis: Use build stages and parallel jobs under Travis CI. Jul 19, 2018
ACKNOWLEDGEMENTS ACKNOWLEDGEMENTS: Change backer 905 info, replace city with name. Oct 22, 2016
CODECONVENTIONS.md all: Remove trailing spaces, per coding conventions. Jul 19, 2017
CONTRIBUTING.md CONTRIBUTING.md: Link to contrib guidelines and code conventions. May 3, 2015
LICENSE Add license header to (almost) all files. May 3, 2014
README.md README: Update list of ports to include esp32 and nrf. Jul 18, 2018


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The MicroPython project

MicroPython Logo

This is the MicroPython project, which aims to put an implementation of Python 3.x on microcontrollers and small embedded systems. You can find the official website at micropython.org.

WARNING: this project is in beta stage and is subject to changes of the code-base, including project-wide name changes and API changes.

MicroPython implements the entire Python 3.4 syntax (including exceptions, with, yield from, etc., and additionally async/await keywords from Python 3.5). The following core datatypes are provided: str (including basic Unicode support), bytes, bytearray, tuple, list, dict, set, frozenset, array.array, collections.namedtuple, classes and instances. Builtin modules include sys, time, and struct, etc. Select ports have support for _thread module (multithreading). Note that only a subset of Python 3 functionality is implemented for the data types and modules.

MicroPython can execute scripts in textual source form or from precompiled bytecode, in both cases either from an on-device filesystem or "frozen" into the MicroPython executable.

See the repository http://github.com/micropython/pyboard for the MicroPython board (PyBoard), the officially supported reference electronic circuit board.

Major components in this repository:

  • py/ -- the core Python implementation, including compiler, runtime, and core library.
  • mpy-cross/ -- the MicroPython cross-compiler which is used to turn scripts into precompiled bytecode.
  • ports/unix/ -- a version of MicroPython that runs on Unix.
  • ports/stm32/ -- a version of MicroPython that runs on the PyBoard and similar STM32 boards (using ST's Cube HAL drivers).
  • ports/minimal/ -- a minimal MicroPython port. Start with this if you want to port MicroPython to another microcontroller.
  • tests/ -- test framework and test scripts.
  • docs/ -- user documentation in Sphinx reStructuredText format. Rendered HTML documentation is available at http://docs.micropython.org (be sure to select needed board/port at the bottom left corner).

Additional components:

  • ports/bare-arm/ -- a bare minimum version of MicroPython for ARM MCUs. Used mostly to control code size.
  • ports/teensy/ -- a version of MicroPython that runs on the Teensy 3.1 (preliminary but functional).
  • ports/pic16bit/ -- a version of MicroPython for 16-bit PIC microcontrollers.
  • ports/cc3200/ -- a version of MicroPython that runs on the CC3200 from TI.
  • ports/esp8266/ -- a version of MicroPython that runs on Espressif's ESP8266 SoC.
  • ports/esp32/ -- a version of MicroPython that runs on Espressif's ESP32 SoC.
  • ports/nrf/ -- a version of MicroPython that runs on Nordic's nRF51 and nRF52 MCUs.
  • extmod/ -- additional (non-core) modules implemented in C.
  • tools/ -- various tools, including the pyboard.py module.
  • examples/ -- a few example Python scripts.

The subdirectories above may include READMEs with additional info.

"make" is used to build the components, or "gmake" on BSD-based systems. You will also need bash, gcc, and Python (at least 2.7 or 3.3).

The Unix version

The "unix" port requires a standard Unix environment with gcc and GNU make. x86 and x64 architectures are supported (i.e. x86 32- and 64-bit), as well as ARM and MIPS. Making full-featured port to another architecture requires writing some assembly code for the exception handling and garbage collection. Alternatively, fallback implementation based on setjmp/longjmp can be used.

To build (see section below for required dependencies):

$ git submodule update --init
$ cd ports/unix
$ make axtls
$ make

Then to give it a try:

$ ./micropython
>>> list(5 * x + y for x in range(10) for y in [4, 2, 1])

Use CTRL-D (i.e. EOF) to exit the shell. Learn about command-line options (in particular, how to increase heap size which may be needed for larger applications):

$ ./micropython --help

Run complete testsuite:

$ make test

Unix version comes with a builtin package manager called upip, e.g.:

$ ./micropython -m upip install micropython-pystone
$ ./micropython -m pystone

Browse available modules on PyPI. Standard library modules come from micropython-lib project.

External dependencies

Building MicroPython ports may require some dependencies installed.

For Unix port, libffi library and pkg-config tool are required. On Debian/Ubuntu/Mint derivative Linux distros, install build-essential (includes toolchain and make), libffi-dev, and pkg-config packages.

Other dependencies can be built together with MicroPython. This may be required to enable extra features or capabilities, and in recent versions of MicroPython, these may be enabled by default. To build these additional dependencies, first fetch git submodules for them:

$ git submodule update --init

Use the same command to get the latest versions of dependencies, as they are updated from time to time. After that, in the port directory (e.g. ports/unix/), execute:

$ make deplibs

This will build all available dependencies (regardless whether they are used or not). If you intend to build MicroPython with additional options (like cross-compiling), the same set of options should be passed to make deplibs. To actually enable/disable use of dependencies, edit ports/unix/mpconfigport.mk file, which has inline descriptions of the options. For example, to build SSL module (required for upip tool described above, and so enabled by dfeault), MICROPY_PY_USSL should be set to 1.

For some ports, building required dependences is transparent, and happens automatically. They still need to be fetched with the git submodule command above.

The STM32 version

The "stm32" port requires an ARM compiler, arm-none-eabi-gcc, and associated bin-utils. For those using Arch Linux, you need arm-none-eabi-binutils, arm-none-eabi-gcc and arm-none-eabi-newlib packages. Otherwise, try here: https://launchpad.net/gcc-arm-embedded

To build:

$ git submodule update --init
$ cd ports/stm32
$ make

You then need to get your board into DFU mode. On the pyboard, connect the 3V3 pin to the P1/DFU pin with a wire (on PYBv1.0 they are next to each other on the bottom left of the board, second row from the bottom).

Then to flash the code via USB DFU to your device:

$ make deploy

This will use the included tools/pydfu.py script. If flashing the firmware does not work it may be because you don't have the correct permissions, and need to use sudo make deploy. See the README.md file in the ports/stm32/ directory for further details.


MicroPython is an open-source project and welcomes contributions. To be productive, please be sure to follow the Contributors' Guidelines and the Code Conventions. Note that MicroPython is licenced under the MIT license, and all contributions should follow this license.