Important summary of this section
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 extended from Python code 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 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 REPL:
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 micropython-lib.
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.
array– arrays of numeric data
asyncio— asynchronous I/O scheduler
binascii– binary/ASCII conversions
builtins– builtin functions and exceptions
cmath– mathematical functions for complex numbers
collections– collection and container types
errno– system error codes
gc– control the garbage collector
gzip– gzip compression & decompression
hashlib– hashing algorithms
heapq– heap queue algorithm
io– input/output streams
json– JSON encoding and decoding
math– mathematical functions
os– basic “operating system” services
platform– access to underlying platform’s identifying data
random– generate random numbers
re– simple regular expressions
select– wait for events on a set of streams
socket– socket module
ssl– SSL/TLS module
struct– pack and unpack primitive data types
sys– system specific functions
time– time related functions
zlib– zlib compression & decompression
_thread– multithreading support
Functionality specific to the MicroPython implementation is available in the following libraries.
bluetooth— low-level Bluetooth
btree– simple BTree database
cryptolib– cryptographic ciphers
deflate– deflate compression & decompression
framebuf— frame buffer manipulation
machine— functions related to the hardware
micropython– access and control MicroPython internals
neopixel— control of WS2812 / NeoPixel LEDs
network— network configuration
uctypes– access binary data in a structured way
The following libraries provide drivers for hardware components.
In some cases the following port/board-specific libraries have functions or
classes similar to those in the
machine library. Where this occurs, the
entry in the port specific library exposes hardware functionality unique to
Libraries specific to the pyboard¶
The following libraries are specific to the pyboard.
pyb— functions related to the board
stm— functionality specific to STM32 MCUs
lcd160cr— control of LCD160CR display
Libraries specific to the WiPy¶
The following libraries and classes are specific to the WiPy.
wipy– WiPy specific features
- class ADCWiPy – analog to digital conversion
- class ADCChannel — read analog values from internal or external sources
- class TimerWiPy – control hardware timers
- class TimerChannel — setup a channel for a timer
Libraries specific to the ESP8266 and ESP32¶
The following libraries are specific to the ESP8266 and ESP32.
Libraries specific to the RP2040¶
The following libraries are specific to the RP2040, as used in the Raspberry Pi Pico.
Libraries specific to Zephyr¶
The following libraries are specific to the Zephyr port.
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
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 micropython-lib, see Package management 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
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 = ()
from time import *
sys.path = _path
The result is that
time.py contains all the globals of the built-in
module, but adds
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 time. For example,
time.py on the filesystem could
from utime import *
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