micropython-samples/micropip/README.md

0. Installing MicroPython library modules

Paul Sokolovsky, the author of most of the micropython library and major contributor to MicroPython, has forked the MicroPython project. This is the pycopy fork.

Official firmware may be found on micropython.org. Each firmware build has its own library. Some modules in the Pycopy library are incompatible with the official firmware.

Libraries may be installed by copying files from the appropriate library repository to the target device. However this requires some attention to detail where there are dependencies or where modules are organised as Python packages.

Each version has a tool known as upip for installing library and user contributed modules modelled on Python's pip. This handles dependencies and builds the correct directory structure on the target.

Note that pip and pip3 cannot be used for MicroPython modules. This is because the file format is nonstandard. The file format was chosen to enable the installer to run on targets with minimal resources.

1. Contents

0. Installing MicroPython library modules
1. Contents
2. Users of Pycopy firmware
3. Users of official MicroPython
   3.1 micropip Runs on a PC
4. Overriding built in library modules

Main README

2. Users of Pycopy firmware

The library for the pycopy fork may be found here. Library modules located on PyPi are correct for the pycopy firmware.

The upip tool may be found in the tools directory of pycopy. This version should be used as it installs exclusively from PyPi.

For hardware which is not network enabled, upip may be run under the Unix build of MicroPython to install to an arbitrary directory on a PC. The resultant directory structure is then copied to the target using a utility such as rshell.

Usage of upip is documented in the official docs.

3. Users of official MicroPython

The library at micropython-lib is compatible with the official firmware. As of version 1.11 the included version of upip will install the correct library module for use with this firmware, searching for modules in the official library before searching PyPi.

Users of non-networked hardware such as the Pyboard 1.x can use upip with the Unix build of MicroPython to install a library module to an arbitrary directory on a PC, from where the files and directories can be copied to the target hardware. This approach has the drawback of requiring the Unix build, which has to be built from source.

For those unable or unwilling to do this, micropip.py in this repo may be employed.

3.1 micropip

This runs under Python 3.2 or above. Library and user modules are installed to the PC for transfer to the target. It is cross-platform and has been tested under Linux, Windows and OSX.

Help may be accessed with

micropip.py --help

or

python3 -m micropip --help

Example invocation line:

$ micropip.py install -p ~/rats micropython-uasyncio

Contents

4. Overriding built in library modules

Some firmware builds include library modules as frozen bytecode. On occasion it may be necessary to replace such a module with an updated or modified alternative. The most RAM-efficient solution is to rebuild the firmware with the replacement implemented as frozen bytecode.

For users not wishing to recompile there is an alternative. The module search order is defined in sys.path.

>>> import sys
>>> sys.path
['', '/flash', '/flash/lib']

The '' entry indicates that frozen modules will be found before those in the filesystem. This may be overridden by issuing:

>>> import sys
>>> sys.path.append(sys.path.pop(0))

This has the following outcome:

>>> sys.path
['/flash', '/flash/lib', '']

Now modules in the filesystem will be compiled and executed in preference to those frozen as bytecode.

Contents

Main README