MicroPython libraries

Warning

Important summary of this section

  • MicroPython implements a subset of Python functionality for each module.
  • To ease extensibility, MicroPython versions of standard Python modules usually have u (“micro”) prefix.
  • Any particular MicroPython variant or port may miss any feature/function described in this general documentation (due to resource constraints or other limitations).

This chapter describes modules (function and class libraries) which are built into MicroPython. There are a few categories of such 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 MicroPython port and thus not portable.

Note about the availability of the modules and their contents: This documentation in general aspires to describe all modules and functions/classes which are implemented in MicroPython project. 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 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:

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 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. Some modules below use a standard Python name, but prefixed with “u”, e.g. 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 library path (sys.path). For example, import json will first search for a file json.py (or package directory json) and load that module if it is found. If nothing is found, it will fallback to loading the built-in ujson module.

Libraries specific to the OpenMV Cam

The following libraries are specific to the OpenMV Cam.

Third-party libraries on the OpenMV Cam

The following third-party libraries are built-in to your OpenMV Cam’s firmware:

bno055IMU Driver

Examples scripts are located in OpenMV IDE under the IMU Shield examples folder.

tb6612Stepper Motor Driver

Examples scripts are located in OpenMV IDE under the Motor Shield examples folder.

vl53l1xToF Distance Sensor Driver

Examples scripts are located in OpenMV IDE under the Distance Shield examples folder.

modbusmodbus protocol library

Examples scripts are located in OpenMV IDE under the Modbus examples folder.

mqttmqtt protocol library

Examples scripts are located in OpenMV IDE under the WiFi Shield examples folder.