Generate python protocol buffer files with nanopb

[Caleb]

Hi, 

Is it possible to use nanopb to also generate python protocol buffer files, i.e. _pb2.py? I am trying to add the custom option of --python-out= but i get the following error:

 Usage: nanopb_generator.py [options] file.pb ...

nanopb_generator.py: error: no such option: --python_out

For some added context I am running nanopb through platform.io and hoping to automatically generate both c and python protocol buffer files everytime i build the project. 

This is what my platformio .ini files looks like:

[env:teensy41]

platform = teensy

board = teensy41

framework = arduino

lib_deps =

    nanopb/Nanopb

custom_nanopb_protos =

    +<../proto/packet_config.proto>

custom_nanopb_options =

    --error-on-unmatched -I.pio/libdeps/teensy41/generator/proto/google/protobuf --python_out=.

build_flags = -D USB_RAWHID

Any help would be much appreciated!

Thanks,

Caleb

[Petteri Aimonen]

Hi,

Well, normally you would use protoc --python_out= separately for that.

But looks like this works to generate both outputs:

nanopb_generator --protoc-opt="--python_out=." test.proto

--
Petteri

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[Caleb]

Thank you for such a quick reply, that has worked a treat!

Is there any particularly reason why it would normally be called separately? It seems in the situation where you have a pc running python sending messages to a microcontroller you would always want the corresponding pb files generated at the same time, and conveniently with the platformio plugin it only calls this command on build if the proto file has changed since last generation.

Im sure others will use platformio and nanopb in the future so for reference, if you are wanting to generate both nanopb-c and python protocol buffer files with the nanopb plugin in platformio the .ini file should look like this:

[env:teensy41]

platform = teensy

board = teensy41

framework = arduino

lib_deps =

    nanopb/Nanopb

custom_nanopb_protos =

    +<../proto/packet_config.proto>

custom_nanopb_options =

    --error-on-unmatched --protoc-opt="--python_out=<path_to_where_you_want_your_python_pb_files>"

build_flags = -D USB_RAWHID

The _.pb.c and _.pb.h files that nanopb generates get put in the .pio/build/teensy41/nanopb/generated-src folder, and can be included as you normally would in your project files.