Important summary of this section
- MicroPython implements a subset of Python functionality for each module.
- To ease extensibility, MicroPython versions of standard Python modules
- Any particular MicroPython variant or port may miss any feature/function described in this general documentation, due to resource constraints.
This chapter describes modules (function and class libraries) which are built into MicroPython. There are a few categories of modules:
- Modules which implement a subset of standard Python functionality and are not intended to be extended by the user.
- Modules which implement a subset of Python functionality, with a provision for extension by the user (via Python code).
- Modules which implement MicroPython extensions to the Python standard libraries.
- Modules specific to a particular port and thus not portable.
Note about the availability of modules and their contents: This documentation in general aspires to describe all modules and functions/classes which are implemented in MicroPython. However, MicroPython is highly configurable, and each port to a particular board/embedded system makes available only a subset of MicroPython libraries. For officially supported ports, there is an effort to either filter out non-applicable items, or mark individual descriptions with “Availability:” clauses describing which ports provide a given feature. With that in mind, please still 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 board. 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 port.
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
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. Some modules below use a standard Python name, but prefixed with “u”,
ujson instead of
json. This is to signify that such a module is
micro-library, i.e. implements only a subset of CPython module functionality.
By naming them differently, a user has a choice to write a Python-level module
to extend functionality for better compatibility with CPython (indeed, this is
what done by the
micropython-lib project mentioned above).
On some embedded platforms, where it may be cumbersome to add Python-level
wrapper modules to achieve naming compatibility with CPython, micro-modules
are available both by their u-name, and also by their non-u-name. The
non-u-name can be overridden by a file of that name in your package path.
import json will first search for a file
json and load that package if it is found. If nothing is found,
it will fallback to loading the built-in
- Builtin functions and exceptions
array– arrays of numeric data
gc– control the garbage collector
math– mathematical functions
sys– system specific functions
ubinascii– binary/ASCII conversions
ucollections– collection and container types
uerrno– system error codes
uhashlib– hashing algorithms
uheapq– heap queue algorithm
uio– input/output streams
ujson– JSON encoding and decoding
uos– basic “operating system” services
ure– simple regular expressions
uselect– wait for events on a set of streams
usocket– socket module
ustruct– pack and unpack primitive data types
utime– time related functions
uzlib– zlib decompression
Functionality specific to the MicroPython implementation is available in the following libraries.
Libraries specific to the OpenMV Cam¶
The following libraries are specific to the OpenMV Cam.
pyb— functions related to the board
- class ADC – analog to digital conversion
- class CAN – controller area network communication bus
- class DAC – digital to analog conversion
- class ExtInt – configure I/O pins to interrupt on external events
- class I2C – a two-wire serial protocol
- class LED – LED object
- class Pin – control I/O pins
- class PinAF – Pin Alternate Functions
- class RTC – real time clock
- class Servo – 3-wire hobby servo driver
- class SPI – a master-driven serial protocol
- class Timer – control internal timers
- class TimerChannel — setup a channel for a timer
- class UART – duplex serial communication bus
- class USB_VCP – USB virtual comm port
time— tracking elapsed time
sensor— camera sensor
image— machine vision
- class HaarCascade – Feature Descriptor
- class Similarity – Similarity Object
- class Histogram – Histogram Object
- class Percentile – Percentile Object
- class Threhsold – Threshold Object
- class Statistics – Statistics Object
- class Blob – Blob object
- class Line – Line object
- class Circle – Circle object
- class Rect – Rectangle Object
- class QRCode – QRCode object
- class AprilTag – AprilTag object
- class DataMatrix – DataMatrix object
- class BarCode – BarCode object
- class Displacement – Displacement object
- class kptmatch – Keypoint Object
- class ImageWriter – ImageWriter object
- class ImageReader – ImageReader object
- class Image – Image object
gif— gif recording
- class Gif – Gif recorder
mjpeg— mjpeg recording
- class Mjpeg – Mjpeg recorder
lcd— lcd shield driver
fir— thermopile shield driver (fir == far infrared)
cpufreq— easy cpu frequency control