Important summary of this section:
- Pycopy implements a subset of Python functionality for each module.
- To ease extensibility, Pycopy versions of standard Python modules
u(“micro”) prefix, e.g.
- Any particular
Pycopy portor variant may miss any feature/function described in the general documentation (due to resource constraints or other limitations).
- More complete and compatible with CPython modules are available via
This chapter describes modules (function and class libraries) which are built into Pycopy. 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 Pycopy extensions to the Python standard libraries.
- Modules specific to a particular
Pycopy portand thus not portable to other ports.
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 Pycopy project. However, Pycopy is highly configurable, and each port to a particular board/embedded system makes available only a subset of Pycopy 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 Pycopy 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
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 Pycopy
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 Pycopy. 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
pycopy-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 (
import json will first search for a file
json.py (or package
json) and load that module if it is found. If nothing is found,
it will fallback to loading the built-in
ujson module. This behavior is
deprecated and not compatible with other platforms on which Pycopy runs.
Please do not rely on it.
- Builtin types, functions and exceptions (
cmath– mathematical functions for complex numbers
gc– control the garbage collector
math– mathematical functions
sys– system specific functions
uarray– arrays of numeric data
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
urandom– pseudo-random number generation
ure– simple regular expressions
uselect– wait for events on a set of streams
usocket– socket module
ussl– SSL/TLS module
ustruct– pack and unpack primitive data types
utime– time related functions
uzlib– zlib decompression
_thread– multithreading support
Functionality specific to the Pycopy implementation is available in the following libraries.
btree– simple BTree database
framebuf— frame buffer manipulation
machine— functions related to the hardware
pycopy– access and control Pycopy internals
network— network configuration
ubluetooth— low-level Bluetooth
ucryptolib– cryptographic ciphers
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 Unix port¶
The following libraries are specific to the
Pycopy Unix port.
Libraries specific to the pyboard¶
The following libraries are specific to the pyboard.
Libraries specific to the WiPy¶
The following libraries and classes are specific to the WiPy.
Libraries specific to the ESP8266 and ESP32¶
The following libraries are specific to the ESP8266 and ESP32.