Hello everyone,
really I don’t understand what’s wrong.
Simple folder tree:
- Development
  - CMakeLists.txt       (1)
  - main.cpp
  - hwconfig.c
  - pico_sdk_import
  - build
  - lib
    - CMakeLists.txt      (2)
    - pico-ds3231
       - examples
       - lib
          - CMakeLists.txt    (3)
          - ds3231.c
          - include
             - ds3231.h
(1)
… raspberry pi pico stuff
add_subdirectory(lib)
add_executable(${PROJECT_NAME}
main.cpp
hw_config.c
)
target_include_directories(app PRIVATE
lib/pico-ds3231/lib/include
)
target_link_libraries(${PROJECT_NAME}
pico_stdlib
hardware_rtc
pico-ds3231
)
(2)
add_subdirectory(pico-ds3231/lib)
(3)
add_library(pico-ds3231 INTERFACE)
target_sources(pico-ds3231 INTERFACE
${CMAKE_CURRENT_LIST_DIR}/ds3231.c
${CMAKE_CURRENT_LIST_DIR}/include/ds3231.h
)
target_include_directories(FatFs_SPI INTERFACE
include
)
target_link_libraries(pico-ds3231 INTERFACE
hardware_i2c
pico_stdlib
)
The error is always
[build] [78/79 98% :: 2.912] Linking CXX executable app.elf
[build] FAILED: app.elf
undefined reference to `ds3231_init(i2c_inst*, unsigned char, unsigned char, ds3231_rtc*)’
any suggestion?