Custom user C module can not import on rpi (LCD driver)

[boognevatz]

Hi,

I have a Waveshare LCD 2" rp2350 board:
https://www.waveshare.com/wiki/RP2350-Touch-LCD-2

Features:

• 16MB flash
• 2" lcd
• camera

There is an example C code on their wiki:
https://files.waveshare.com/wiki/RP2350-Touch-LCD-2/RP2350-Touch-LCD-2.zip

I managed to compile the UF2 file. What it does is display the camera image on the LCD in real time.

I want to port the LCD driver from this example project.

I uploaded my code to this github repo:
https://github.com/boognevatz/lcd_2in

It compiles without error, along with the official two "cexample" and "cppexample" modules.
On the target device (the uf2 boots) there I can issue:

import cexample
import cppexample

And it works. However import lcd does not work.
Here is the modules list:

>>> help('modules')
__main__          builtins          lwip              socket
_asyncio          cexample          machine           ssl
_boot             cmath             math              struct
_boot_fat         collections       micropython       sys
_onewire          cppexample        mip/__init__      time
_rp2              cryptolib         neopixel          tls
_thread           deflate           network           uasyncio
_webrepl          dht               ntptime           uctypes
array             ds18x20           onewire           urequests
asyncio/__init__  errno             os                vfs
asyncio/core      framebuf          platform          webrepl
asyncio/event     gc                random            webrepl_setup
asyncio/funcs     hashlib           re                websocket
asyncio/lock      heapq             requests/__init__
asyncio/stream    io                rp2
binascii          json              select
Plus any modules on the filesystem
>>> 

Also here is the micropython.cmake file:

# Create an INTERFACE library for our C module.
add_library(usermod_lcd INTERFACE)

# Add our source files to the lib
target_sources(usermod_lcd INTERFACE
    ${CMAKE_CURRENT_LIST_DIR}/DEV_Config.c
    ${CMAKE_CURRENT_LIST_DIR}/LCD_2in.c
)

# Add the current directory as an include directory.
target_include_directories(usermod_lcd INTERFACE
    ${CMAKE_CURRENT_LIST_DIR}
)


# Link to the Pico SDK
target_link_libraries(usermod_lcd INTERFACE
    pico_stdlib
    hardware_spi
)

# Link our INTERFACE library to the usermod target.
target_link_libraries(usermod INTERFACE usermod_lcd)

This is the command line option I built with:

make -C micropython/ports/rp2/ BOARD=RP2350_TOUCH_LCD_2 USER_C_MODULES=../../../modules/micropython.cmake

The custom board definition is here:
https://github.com/boognevatz/micropython/tree/rp2350_touch_boot_failure/ports/rp2/boards/RP2350_TOUCH_LCD_2

Also I needed to add a file under pico-sdk too:

micropython/lib/pico-sdk/src/boards/include/boards/waveshare_rp2350_touch_lcd_2.h

The general project structure:

modules/cexample
modules/cppexample
modules/lcd
micropython
micropython/lib/pico-sdk

These are the directories I modified. My module what I want to build is modules/lcd directory.

It compiles without error. I can see compiled .o files under:

micropython/ports/rp2/build-RP2350_TOUCH_LCD_2/CMakeFiles/firmware.dir/home/boognevatz/Desktop/newprojects/rp2350-boognevatz/modules/lcd

DEV_Config.c.o
DEV_Config.c.o.d
LCD_2in.c.o
LCD_2in.c.o.d

directory.

However the .module files are missing under micropython/ports/rp2/build-RP2350_TOUCH_LCD_2/genhdr/module directory.

What am I missing? Any help is greatly appreciated.
I attached the buildlog, and also the resulted .uf2 file.
buildlog.txt
firmware.uf2.zip

[shariltumin]

Your "lcd" module needs to be written in a special structure and registered with the firmware. Here is a minimum example:

#include "py/obj.h"
#include "py/runtime.h"

// Function to return a constant
STATIC mp_obj_t mymod_hello(void) {
    return mp_obj_new_str("Hello from C!", 14);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_0(mymod_hello_obj, mymod_hello);

// Module globals
STATIC const mp_rom_map_elem_t mymod_globals_table[] = {
    { MP_ROM_QSTR(MP_QSTR_hello), MP_ROM_PTR(&mymod_hello_obj) },
};
STATIC MP_DEFINE_CONST_DICT(mymod_module_globals, mymod_globals_table);

// Module definition
const mp_obj_module_t mymod_user_cmodule = {
    .base = { &mp_type_module },
    .globals = (mp_obj_dict_t *)&mymod_module_globals,
};

// Register the module to make it available in Python
MP_REGISTER_MODULE(MP_QSTR_mymod, mymod_user_cmodule);

Here, we register the module "mymod," which has one function, "hello."

We can then do the following in a MicroPython script:

from mymod import hello
print(hello())  # Output: Hello from C!

So, you need to wrap all your "lcd" functions, register them in the module globals table, and register "lcd" as a module, as shown in the simple example above.

I don't see a structure like that in your "LCD_2in.c" file.