micropython/docs/library/index.rst

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.. _micropython_lib:
MicroPython libraries
=====================
.. warning::
Important summary of this section
* MicroPython provides built-in modules that mirror the functionality of the
:ref:`Python standard library <micropython_lib_python>` (e.g. :mod:`os`,
:mod:`time`), as well as :ref:`MicroPython-specific modules <micropython_lib_micropython>`
(e.g. :mod:`bluetooth`, :mod:`machine`).
* Most Python standard library modules implement a subset of the
functionality of the equivalent Python module, and in a few cases provide
some MicroPython-specific extensions (e.g. :mod:`array`, :mod:`os`)
* Due to resource constraints or other limitations, some ports or firmware
versions may not include all the functionality documented here.
* To allow for extensibility, some built-in modules can be
:ref:`extended from Python code <micropython_lib_extending>` loaded onto
the device filesystem.
This chapter describes modules (function and class libraries) which are built
into MicroPython. This documentation in general aspires to describe all modules
and functions/classes which are implemented in the MicroPython project.
However, MicroPython is highly configurable, and each port to a particular
board/embedded system may include only a subset of the available MicroPython
libraries.
With that in mind, please be warned that some functions/classes in a module (or
even the entire module) described in this documentation **may be unavailable**
in a particular build of MicroPython on a particular system. The best place to
find general information of the availability/non-availability of a particular
feature is the "General Information" section which contains information
pertaining to a specific :term:`MicroPython port`.
On some ports you are able to discover the available, built-in libraries that
can be imported by entering the following at the :term:`REPL`::
help('modules')
Beyond the built-in libraries described in this documentation, many more
modules from the Python standard library, as well as further MicroPython
extensions to it, can be found in :term:`micropython-lib`.
.. _micropython_lib_python:
Python standard libraries and micro-libraries
---------------------------------------------
The following standard Python libraries have been "micro-ified" to fit in with
the philosophy of MicroPython. They provide the core functionality of that
module and are intended to be a drop-in replacement for the standard Python
library.
.. toctree::
:maxdepth: 1
array.rst
asyncio.rst
binascii.rst
builtins.rst
cmath.rst
collections.rst
errno.rst
gc.rst
gzip.rst
hashlib.rst
heapq.rst
io.rst
json.rst
math.rst
os.rst
platform.rst
random.rst
re.rst
select.rst
socket.rst
ssl.rst
struct.rst
sys.rst
time.rst
zlib.rst
_thread.rst
.. _micropython_lib_micropython:
MicroPython-specific libraries
------------------------------
Functionality specific to the MicroPython implementation is available in
the following libraries.
.. toctree::
:maxdepth: 1
bluetooth.rst
btree.rst
cryptolib.rst
deflate.rst
framebuf.rst
machine.rst
micropython.rst
neopixel.rst
network.rst
uctypes.rst
The following libraries provide drivers for hardware components.
.. toctree::
:maxdepth: 1
wm8960.rst
Port-specific libraries
-----------------------
In some cases the following port/board-specific libraries have functions or
classes similar to those in the :mod:`machine` library. Where this occurs, the
entry in the port specific library exposes hardware functionality unique to
that platform.
To write portable code use functions and classes from the :mod:`machine` module.
To access platform-specific hardware use the appropriate library, e.g.
:mod:`pyb` in the case of the Pyboard.
Libraries specific to the pyboard
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The following libraries are specific to the pyboard.
.. toctree::
:maxdepth: 2
pyb.rst
stm.rst
lcd160cr.rst
Libraries specific to the WiPy
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The following libraries and classes are specific to the WiPy.
.. toctree::
:maxdepth: 2
wipy.rst
machine.ADCWiPy.rst
machine.TimerWiPy.rst
Libraries specific to the ESP8266 and ESP32
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The following libraries are specific to the ESP8266 and ESP32.
.. toctree::
:maxdepth: 2
esp.rst
esp32.rst
.. toctree::
:maxdepth: 1
espnow.rst
Libraries specific to the RP2040
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The following libraries are specific to the RP2040, as used in the Raspberry Pi Pico.
.. toctree::
:maxdepth: 2
rp2.rst
Libraries specific to Zephyr
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The following libraries are specific to the Zephyr port.
.. toctree::
:maxdepth: 2
zephyr.rst
.. _micropython_lib_extending:
Extending built-in libraries from Python
----------------------------------------
A subset of the built-in modules are able to be extended by Python code by
providing a module of the same name in the filesystem. This extensibility
applies to the following Python standard library modules which are built-in to
the firmware: ``array``, ``binascii``, ``collections``, ``errno``, ``gzip``,
``hashlib``, ``heapq``, ``io``, ``json``, ``os``, ``platform``, ``random``,
``re``, ``select``, ``socket``, ``ssl``, ``struct``, ``time`` ``zlib``, as well
as the MicroPython-specific ``machine`` module. All other built-in modules
cannot be extended from the filesystem.
This allows the user to provide an extended implementation of a built-in library
(perhaps to provide additional CPython compatibility or missing functionality).
This is used extensively in :term:`micropython-lib`, see :ref:`packages` for
more information. The filesystem module will typically do a wildcard import of
the built-in module in order to inherit all the globals (classes, functions and
variables) from the built-in.
In MicroPython v1.21.0 and higher, to prevent the filesystem module from
importing itself, it can force an import of the built-in module it by
temporarily clearing ``sys.path`` during the import. For example, to extend the
``time`` module from Python, a file named ``time.py`` on the filesystem would
do the following::
_path = sys.path
sys.path = ()
try:
from time import *
finally:
sys.path = _path
del _path
def extra_method():
pass
The result is that ``time.py`` contains all the globals of the built-in ``time``
module, but adds ``extra_method``.
In earlier versions of MicroPython, you can force an import of a built-in module
by appending a ``u`` to the start of its name. For example, ``import utime``
instead of ``import time``. For example, ``time.py`` on the filesystem could
look like::
from utime import *
def extra_method():
pass
This way is still supported, but the ``sys.path`` method described above is now
preferred as the ``u``-prefix will be removed from the names of built-in
modules in a future version of MicroPython.
*Other than when it specifically needs to force the use of the built-in module,
code should always use* ``import module`` *rather than* ``import umodule``.