Undefined reference to `main'

Development Platforms
1

This probably a well known build issue, I just need a bit of help to resolve this.

I’ve moved on from a Win10 environment to a Mac environment with the latest VSCode and PIO bits. I can build, run and debug the examples just fine.

I’ve downloaded the BLE LED example from here: PlatformIO Registry

I’ve added the following to my platformio.ini to get the example to build:
build_flags = -DPIO_FRAMEWORK_MBED_RTOS_PRESENT

I’m getting the following linker error:
.pio/build/nrf52_dk/FrameworkMbed/rtos/source/TARGET_CORTEX/TOOLCHAIN_GCC_ARM/mbed_boot_gcc_arm.o: In function __wrap_main': /Users/admin/.platformio/packages/framework-mbed/rtos/source/TARGET_CORTEX/TOOLCHAIN_GCC_ARM/mbed_boot_gcc_arm.c:77: undefined reference to main’

Am I missing another build flag?
Guidance is greatly appreciated.

2

The main() function is right there mbed-os-example-ble-LED - BLE LED control example | Mbed

What are the exact contents of your projects? Can you upload it somewhere for insepction?

3

https://github.com/TerryMcP/mbed_BLE_LED_Project

4

This project doesn’t have any source code files. Can you donwload the repo (here) and add the source/ folder as src/ to the project?

5

https://github.com/TerryMcP/Local-mbed-BLE-LED

how’s this?

6

The two source fiels must be in a folder called src/.

max@max-VirtualBox:~/mbed_BLE_LED_Project$ tree 
.
├── connection.png
├── discovery.png
├── LED_OFF.png
├── LED_ON.png
├── library.json
├── mbed_app.json
├── mbed-os.lib
├── module.json
├── platformio.ini
├── readme.md
├── scan_results.png
├── src
│   ├── LEDService.h
│   └── main.cpp
├── start_scan.png
├── Untitled.code-workspace
├── write_characteristic.png
└── write_pannel.png

compiles for me

max@max-VirtualBox:~/mbed_BLE_LED_Project$ pio run 
[..]
Linking .pio/build/nrf52_dk/firmware.elf
Checking size .pio/build/nrf52_dk/firmware.elf
Building .pio/build/nrf52_dk/firmware.hex
Advanced Memory Usage is available via "PlatformIO Home > Project Inspect"
RAM:   [=====     ]  49.3% (used 32288 bytes from 65536 bytes)
Flash: [=====     ]  47.0% (used 246552 bytes from 524288 bytes)

Note that due to ARM mbed: Compilation of project with long file paths not possible · Issue #2877 · platformio/platformio-core · GitHub, I wasn’t able to get compilation working on Windows, but Linux.

2 Likes
7

Derp! <— me LOL
Many thanks!

yes, issue #2877 is why I moved from Win10 to OS X

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