Undefined reference to fds_init(); Despite having included fds.h, and setting fds_enabled to 1.

[SamPenn]

I asked a question on here couple of days ago, but I resolved that issue and have stumbled into a more concise and in the right direction.

I am using ble_app_uart as my code base. 

I am working with an nRF52840 dev kit and nRF15.3.0_59ac345 SDK. 

As stated in the title I am trying to call fds_init in the main() in main.c. Despite having included fds.h and enabled fds_enable it continues to give me 'undefined reference to 'fds_init' here is my debug log: 

c:/users/sam/appdata/roaming/xpacks/@gnu-mcu-eclipse/arm-none-eabi-gcc/8.2.1-1.7.1/.content/bin/../lib/gcc/arm-none-eabi/8.2.1/../../../../arm-none-eabi/bin/ld.exe: _build/nrf52840_xxaa/main.c.o: in function `main':
C:\Users\sam\Desktop\project_work\nRF5_SDK_15.3.0_59ac345\nRF5_SDK_15.3.0_59ac345\examples\ble_peripheral\ble_app_uart\project\s140\armgcc/../../../main.c:757: undefined reference to `fds_init'
collect2.exe: error: ld returned 1 exit status
make: *** [C:\Users\sam\Desktop\project_work\nRF5_SDK_15.3.0_59ac345\nRF5_SDK_15.3.0_59ac345/components/toolchain/gcc/Makefile.common:294: _build/nrf52840_xxaa.out] Error 1
C:\Users\sam\Desktop\project_work\nRF5_SDK_15.3.0_59ac345\nRF5_SDK_15.3.0_59ac345\examples\ble_peripheral\ble_app_uart\project\s140\armgcc>

Am I missing something? Are there more items to enable in the sdk_config file?

[SamPenn]

Found the answer. It turns out that you do need to add the .c files into SRC_FILES in the makefile.