Undefined reference for all of my functions

Hi! I’ve been trying to build this code that I’m working on. I believe that I got all of the actual bugs out, so it should build, but I’m having issues building anything that’s a function made by me. Specifically, I get this error in the build process:

.pio\build\teensy35\src\main.cpp.o: In function `setup’:

It will do this for the loop as well, and then will mention any function I’ve made in any other library.

I then decided to see if it was an issue with the entire platform, or if it was just my code, so I reworked the main file to just be minimal code, it builds. it’s only when I put my own functions in that it doesn’t. What should I do?


What’s the project file structure? What is path to the file that contains the function that you’re getting an undefiend reference to?

It’s the predefined file structure, I have all of the functions in libraries in the include folder, and the main in src. And I know that the main can see the libraries in the include folder, as it’s able to see an include that’s in one of them; it’s specifically <liquidcrystal.h>, which is in my lcd.h library, not my main, but in my main, I have

void setup()



    lcd.begin(16, 2);


And it works perfectly fine.

And it’s not just one function, it’s every function in a different library file. None of the ones I’ve made work.

The include folder is for includes, header files. None of the files in include/ are getting compiled. Place source files in src/.

Ahh, I see, thanks, I’ll try that right now!

That did the trick, finally compiled! Now I can melt some metal!