Build and Flash MicroPython
micro:bit V1
This applies to MicroPython for the micro:bit V1, the source of which can be found here: bbcmicrobit/micropython.
Dependencies
Build MicroPython
The yotta tool is used to build MicroPython, but before that takes place additional files have to be generated by the Makefile in preparation for the build, and additional data is added to the hex file after.
Clone the repository and change directory to it:
$ git clone https://github.com/bbcmicrobit/micropython
$ cd micropython
Configure yotta to use the micro:bit target:
yotta target bbc-microbit-classic-gcc-nosd@https://github.com/lancaster-university/yotta-target-bbc-microbit-classic-gcc-nosd
Run yotta update to fetch remote assets:
yotta up
Start the build using the makefile:
make all
The resulting firmware.hex
can be found in the build/
directory which can then be copied to the micro:bit.
The Makefile does some extra preprocessing of the source, which is needed only
if you add new interned strings to qstrdefsport.h
. The Makefile also puts
the resulting firmware at build/firmware.hex, and includes some convenience
targets.
Preparing MicroPython with a Python program
Using tools/makecombinedhex.py
you can combine the MicroPython firmware
with a Python script and produce a hex file ready for uploading to the
micro:bit.:
./makecombinedhex.py <firmware.hex> <script.py> [-o <combined.hex>]
The script will output to stdout
if no output option (-o
) is provided.
Using tools/hexlify.py
you can turn a Python script into Intel HEX format
to be concatenated at the end of the MicroPython firmware.hex. A simple header
is added to the script.:
./hexlifyscript.py <script.py>
It also accepts data on standard input.
micro:bit V2
This applies to MicroPython for the micro:bit V2, the source of which can be found here: microbit-foundation/micropython-microbit-v2.
The repository also contains a history of MicroPython firmware builds.
Dependencies
Build MicroPython
Clone the repository and change directory to it:
$ git clone https://github.com/microbit-foundation/micropython-microbit-v2
$ cd micropython-microbit-v2
Update the submodules:
$ git submodule update --init
Then build the MicroPython cross-compiler:
$ make -C lib/micropython/mpy-cross
After setting up, go to the src/ directory and build:
$ cd src
$ make
The resulting firmware will be MICROBIT.hex
in the src/
directory which can be copied to the micro:bit.
Flashing the micro:bit
The micro:bit mounts itself as a USB mass storage device named MICROBIT
.
When it detects that a .hex file has been copied to the USB drive, it will
flash it, and start running the program.