MicroPython libraries


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.

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 the micropython-lib repository.

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 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. For example, import json will first search for a file json.py or directory json and load that package if it is found. If nothing is found, it will fallback to loading the built-in ujson module.