How to include a file from another (parent) directory

Question

This is my structure

program/
  src/
    Makefile
    main.ino
    test.h
    ...
  lib/
    i2c.h

In main.ino I include test.h and in test.h I'm trying to include i2c.h but it is just not working, I keep getting:

make: *** No rule to make target 'i2c.h', needed by 'build-uno/main.ino.o'.  Stop.

I tried including like this

// test.h
#include "../lib/i2c.h"

I also tried making a symlink to my lib folder in arduino libraries and adding it as a library in Makefile

sudo ln -s /home/pi/program/lib /usr/share/arduino/libraries/GAVR

# Makefile
ARDUINO_DIR = /usr/share/arduino
BOARD_TAG = uno
ARDUINO_PORT = /dev/ttyAMA0
ARDUINO_LIBS = GAVR
include /usr/share/arduino/Arduino.mk

I also tried making a symlink to lib inside the src directory

ln -s /home/pi/program/lib /home/pi/program/src/lib

None of the above had any effect, the error message stays the same.

How can I include a file from another directory in my program?

php_nub_qq · Accepted Answer · 2020-11-19T12:17:30.643

This is definitely on the hacky side and not a proper solution to the problem, but it works nevertheless so I'm sharing it.

After making a symlink in the /usr/share/arduino/libraries directory you must make sure that there is a header file with the exact name of the directory, apparently that's how arduino is set up to include them.

In my case my symlink was named GAVR, so I had to create a GAVR.h file inside my lib directory, which would then go ahead and include my i2c.h file and possibly any other file that I'd need.

~~Also in test.h or anywhere I need to use i2c.h I must include <GAVR.h> instead.~~
Turns out Also 1 is false, you just need to include <GAVR.h> once in the .ino file and its members will be available everywhere, just like any other library.

Also 2, now that ARDUINO_LIBS is not empty in the Makefile you will need to manually declare all libraries that your code is using.

How to include a file from another (parent) directory

1 Answers1