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, the built-in modules can be extended from Python code loaded onto the device.
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
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
hashlib– hashing algorithms
heapq– heap queue algorithm
io– input/output streams
json– JSON encoding and decoding
math– mathematical functions
os– basic “operating system” services
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
uasyncio— asynchronous I/O scheduler
zlib– zlib 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
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
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¶
In most cases, the above modules are actually named
umodule rather than
module, but MicroPython will alias any module prefixed with a
u to the
u version. However a file (or frozen module) named
module.py will take precedence over this alias.
This allows the user to provide an extended implementation of a built-in library
(perhaps to provide additional CPython compatibility). The user-provided module
module.py) can still use the built-in functionality by importing
umodule directly. This is used extensively in micropython-lib. See
Distribution packages, package management, and deploying applications for more information.
This applies to both the Python standard libraries (e.g.
but also the MicroPython libraries too (e.g.
The main exception is the port-specific libraries (
Other than when you specifically want to force the use of the built-in module, we recommend always using ``import module`` rather than ``import umodule``.