micropython/micropython

The MicroPython project

This is the MicroPython project, an implementation of Python 3.x for microcontrollers, embedded systems and other constrained platforms. You can find the official website at micropython.org.

MicroPython implements the entire Python 3.4 syntax (including exceptions, with, yield from, etc., and additionally async/await keywords from Python 3.5 and some select features from later versions). 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 os, sys, time, re, and struct, etc. Some ports have support for _thread module (multithreading), socket and ssl for networking, and asyncio. 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 (.py files) or from precompiled bytecode (.mpy files), in both cases either from an on-device filesystem or "frozen" into the MicroPython executable.

MicroPython also provides a set of MicroPython-specific modules to access hardware-specific functionality and peripherals such as GPIO, Timers, ADC, DAC, PWM, SPI, I2C, CAN, Bluetooth, and USB.

Getting started

See the online documentation for the API reference and information about using MicroPython and information about how it is implemented.

We use GitHub Discussions as our forum, and Discord for chat. These are great places to ask questions and advice from the community or to discuss your MicroPython-based projects.

For bugs and feature requests, please raise an issue and follow the templates there.

For information about the MicroPython pyboard, the officially supported board from the original Kickstarter campaign, see the schematics and pinouts and documentation.

MicroPython design values

"Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away." ―- Antoine de Saint-Exupéry.

For its design and implementation, MicroPython aims to follow a set of values. Although not a strict set of rules, these values and principles serve as a useful guide for new and seasoned contributors, as well as maintainers.

MicroPython is at heart a combination of "Micro" and "Python": it's about resource constrained systems running the Python programming language. Both of these concepts balance off against each other in all parts of MicroPython's design and implementation.

The key concepts that focus the development of MicroPython are:

• Minimalism: do lots with little.
• Efficiency: engineering, build, execution, storage, power consumption.
• Consistency: the whole system feels like it was designed at once.

When using MicroPython, the Python language is used as the human interface to a system, giving fine control over the entities attached to that system. In a hardware setting, MicroPython aims to give the user a bare-metal feeling: one should feel like they have complete control over the system, with very little between the programmer and the physical world.

MicroPython recognises that systems can be very complex. The existing Python libraries in combination with the MicroPython-specific libraries provide a user-friendly way to harness the complexity of a system.

Python language compatibility is very important to MicroPython, and at first glance MicroPython should look just like regular Python. In the first instance, most Python scripts should run unchanged on MicroPython, even on devices with very tight resources. Beyond that, there are ways to extend MicroPython if needed to better match Python. The provided built-in modules are an efficient subset of the corresponding Python ones, without duplication of functionality, and allow extension in Python if needed.

Contributing

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.

About this repository

This repository contains the following components:

• 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/ -- platform-specific code for the various ports and architectures that MicroPython runs on.
• lib/ -- submodules for external dependencies.
• tests/ -- test framework and test scripts.
• docs/ -- user documentation in Sphinx reStructuredText format. This is used to generate the online documentation.
• extmod/ -- additional (non-core) modules implemented in C.
• tools/ -- various tools, including the pyboard.py module.
• examples/ -- a few example Python scripts.

"make" is used to build the components, or "gmake" on BSD-based systems. You will also need bash, gcc, and Python 3.3+ available as the command python3. Some ports (rp2 and esp32) additionally use CMake.

Supported platforms & architectures

MicroPython runs on a wide range of microcontrollers, as well as on Unix-like (including Linux, BSD, macOS, WSL) and Windows systems.

Microcontroller targets can be as small as 256kiB flash + 16kiB RAM, although devices with at least 512kiB flash + 128kiB RAM allow a much more full-featured experience.

The Unix and Windows ports allow both development and testing of MicroPython itself, as well as providing lightweight alternative to CPython on these platforms (in particular on embedded Linux systems).

Over twenty different MicroPython ports are provided in this repository, split across three MicroPython Support Tiers.

Tier 1 Ports

👑 Ports in Tier 1 are mature and have the most active development, support and testing:

An asterisk indicates that the port has ongoing financial support from the vendor.

Tier 2 Ports

✔ Ports in Tier 2 are less mature and less actively developed and tested than Tier 1, but still fully supported:

Tier 3 Ports

Ports in Tier 3 are built in CI but not regularly tested by the MicroPython maintainers:

Additional Ports

In addition to the above there is a Tier M containing ports that are used primarily for maintenance, development and testing:

• The "bare-arm" port is an example of the absolute minimum configuration that still includes the compiler, and is used to keep track of the code size of the core runtime and VM.

• The "minimal" port provides an example of a very basic MicroPython port and can be compiled as both a standalone Linux binary as well as for ARM Cortex-M4. Start with this if you want to port MicroPython to another microcontroller.

• The qemu port is a QEMU-based emulated target for Cortex-A, Cortex-M, RISC-V 32-bit, RISC-V 64-bit, and PowerPC 64-bit architectures.

The MicroPython cross-compiler, mpy-cross

Most ports require the MicroPython cross-compiler to be built first. This program, called mpy-cross, is used to pre-compile Python scripts to .mpy files which can then be included (frozen) into the firmware/executable for a port. To build mpy-cross use:

$ cd mpy-cross
$ make

External dependencies

The core MicroPython VM and runtime has no external dependencies, but a given port might depend on third-party drivers or vendor HALs. This repository includes several submodules linking to these external dependencies. Before compiling a given port, use

$ cd ports/name
$ make submodules

to ensure that all required submodules are initialised.