Doesn't build

[skrat]

I followed the intruction in README. I'm building an esp32 port. After adding gen_mpy to py/py.mk, I get this error:

~/W/m/micropython master• 2m 29.2s $ make -C mpy-cross
make: Entering directory '/home/skrat/Workspace/m5paperS3/micropython/mpy-cross'
Use make V=1 or set BUILD_VERBOSE in your environment to increase build verbosity.
LVGL-GEN build/lvgl/lv_mpy.c
Traceback (most recent call last):
  File "/home/skrat/Workspace/m5paperS3/micropython/mpy-cross/../lib/lv_binding/gen/gen_mpy.py", line 436, in <module>
    ast = parser.parse(s, filename="<none>")
  File "/home/skrat/Workspace/m5paperS3/micropython/lib/lv_binding/gen/../pycparser/pycparser/c_parser.py", line 147, in parse
    return self.cparser.parse(
           ~~~~~~~~~~~~~~~~~~^
            input=text,
            ^^^^^^^^^^^
            lexer=self.clex,
            ^^^^^^^^^^^^^^^^
            debug=debug)
            ^^^^^^^^^^^^
  File "/home/skrat/Workspace/m5paperS3/micropython/lib/lv_binding/gen/../pycparser/pycparser/ply/yacc.py", line 331, in parse
    return self.parseopt_notrack(input, lexer, debug, tracking, tokenfunc)
           ~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/skrat/Workspace/m5paperS3/micropython/lib/lv_binding/gen/../pycparser/pycparser/ply/yacc.py", line 1199, in parseopt_notrack
    tok = call_errorfunc(self.errorfunc, errtoken, self)
  File "/home/skrat/Workspace/m5paperS3/micropython/lib/lv_binding/gen/../pycparser/pycparser/ply/yacc.py", line 193, in call_errorfunc
    r = errorfunc(token)
  File "/home/skrat/Workspace/m5paperS3/micropython/lib/lv_binding/gen/../pycparser/pycparser/c_parser.py", line 1931, in p_error
    self._parse_error(
    ~~~~~~~~~~~~~~~~~^
        'before: %s' % p.value,
        ^^^^^^^^^^^^^^^^^^^^^^^
        self._coord(lineno=p.lineno,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                    column=self.clex.find_tok_column(p)))
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/skrat/Workspace/m5paperS3/micropython/lib/lv_binding/gen/../pycparser/pycparser/plyparser.py", line 67, in _parse_error
    raise ParseError("%s: %s" % (coord, msg))
pycparser.plyparser.ParseError: ../lib/lv_binding/lvgl/src/widgets/bar/../label/lv_label.h:100:67: before: __attribute__
make: *** [../py/py.mk:40: build/lvgl/lv_mpy.c] Error 1
make: *** Deleting file 'build/lvgl/lv_mpy.c'
make: Leaving directory '/home/skrat/Workspace/m5paperS3/micropython/mpy-cross'

[StephenDone]

I am experiencing the same issue, but for rp2.

I am not 100% sure, but I think the instructions for adding lvgl bindings to a micropython build are completely out of date.
I searched the current master of lv_micropython and found none of the file changes suggested in the readme.md.
It appears that you need to add the bindings at /micropython/user_modules/lv_binding_micropython instead of /lib/lv_binding and then completely ignore all the files changes suggested.

This allowed me to build a firmware. However, the firmware I now have gives a syntax error on reboot. So now I am trying different version of the bindings and mp, to see if I can find a combination that gives me a working build.

For anyone maintaining the repo, these are the instructions that are all wrong:
It would be nice if, as well as correcting the instructions, you could provide a version of bindings and version of micropython that play well together at the time of writing.

Adding MicroPython Bindings to a project

An example project of "MicroPython + lvgl + Bindings" is lv_mpy. Here is a procedure for adding lvgl to an existing MicroPython project. (The examples in this list are taken from lv_mpy):

• Add lv_bindings as a sub-module under lib.
• Add lv_conf.h in lib
• Edit the Makefile to run gen_mpy.py and build its product automatically. Here is an example.
• Register lvgl module and display/input drivers in MicroPython as a builtin module. An example.
• Add lvgl roots to gc roots. An example.
• Configure lvgl to use Garbage Collection by setting several LV_MEM_CUSTOM_* and LV_GC_* macros example lv_conf.h was moved to lv_binding_micropython git module.
• Make sure you configure partitions correctly in partitions.csv and leave enough room for the LVGL module.
• Something I forgot? Please let me know.

[StephenDone]

Hi @skrat,

I thought it was going to be another evening of swearing, but I got a result.
Note that I haven't tested the build, but at least I got a REPL prompt!!!

MicroPython v1.24.1-dirty on 2026-01-31; Raspberry Pi Pico with RP2040
Type "help()" for more information or .help for custom vREPL commands.

>>>

This worked for me. Hope it helps you:

Get the version of Micropython that we want

Clone the Micropython repo

git clone https://github.com/micropython/micropython.git

Fetch the available tagged versions

git fetch --tags

List the choices

git tag

Select the tagged version we want

git checkout tags/v1.24.1

Link in a matching version of LVGL bindings...

The user modules directory does not exist by default

mkdir user_modules
cd user_modules

Add the submodule for LVGL bindings with the same version as the Micropython above

git submodule add -b update/micropython_v1.24.1 https://github.com/lvgl/lv_binding_micropython.git ./lv_binding_micropython`
cd ..

Follow the lv_micropython build instructions for your target

I'm not sure about ESP32, but the BOARD names were wrong in the instructions for Raspberry Pi Pico - they had been updated since the instructions were written.

git submodule update --init --recursive user_modules/lv_binding_micropython
make -C ports/rp2 BOARD=RPI_PICO clean
make -C ports/rp2 BOARD=RPI_PICO submodules
make -j -C mpy-cross
make -j -C ports/rp2 BOARD=RPI_PICO USER_C_MODULES=../../user_modules/lv_binding_micropython/bindings.cmake