Zephyr Micropython module

Overview

This project adds Micropython as a submodule to zephyr, and exposes it as it using zephyr's shell and filesystem. The Micropython instance is run in a shell thread, and input/output is passed directly between the shell backend using zephyr shell bypass feature.

This approach differs from the existing zephyr port as we are adding Micropython as an addition to a zephyr application, rather than building a Micropython application using zephyr.

The overhead of littlefs + minimal micropython is about 120K ROM and 20K RAM, this is without optimizing readline and stdio which duplicate a lot of the logic of zephyr's shell module.

Setup

• Follow the official Getting Started guide.

• Set up a new zephyr workspace using the following commands

  west init -m https://github.com/bjarki-andreasen/zephyr-micropython
  west update
  

• Build and flash the sample application. If you want to be able to execute a python script from the filesystem, set up a filesystem partition for your board and enable CONFIG_FILE_SYSTEM. For examples see zephyr-micropython/samples/micropython/shell/boards/

  Overlays and configs for native_sim/native and nrf54l15dk/nrf54l15/cpuapp have been added for quick testing.

  west build -p -b <board> zephyr-micropython/samples/micropython/shell/
  west flash
  

Usage

Open a terminal emulator or whichever method you use to access the zephyr shell. To start a normal REPL, use the python command.

uart:~$ python
MicroPython aceafd9e98 on 2025-12-14; nrf54l15dk with nrf54l15/cpuapp
>>>

Press CTRL+D to exit, or import sys and call sys.exit().

uart:~$ python
MicroPython aceafd9e98 on 2025-12-14; nrf54l15dk with nrf54l15/cpuapp
>>> import sys
>>> sys.exit()
uart:~$

To run a python script from the filesystem, use the python command and pass a path to the script as the only argument. A simple hello world script can be written to a file using zephyr's fs shell commands.

uart:~$ fs write /storage/test.py 70 72 69 6e 74 28 22 68 65 6c 6c 6f 20 77 6f 72 6c 64 22 29 d a
uart:~$ fs cat /storage/test.py
print("hello world")
uart:~$ python /storage/test.py
hello world
uart:~$