user14761: I am completely lost here, I have no idea what I am doing wrong. I am using Eclipse Mars using the Eclipse C++ Arduino extension. I am also using the COSA library, this is where the problem comes in. I can use all of the core COSA libraries but I can not figure out how to include the other libraries that are supplied with COSA specifically the ST7920.h file that is located in the libraries folder. Does anyone have any experience with this?
I have tried setting the path using the Project->C/C++ General->Preprocessor include paths and setting it there to no avail.
One thing that I am concerned about is in these separate libraries they are including files that are in other libs using only the header file, for example in the ST7920.hh file it has:
#include "Cosa/LCD.hh"
#include <HD44780.h>

I need to configure things so that the HD44780.h file needs to be found also. That file is located at "../HD44780/HD44780.h". How do I tell the compiler to search the "libraries" folder for files?
Also I tried to simply add the libraries folder as a linked folder in my project, that also did not work.
the only code I have is the #include  and the compiler come back with that it can't find the file.

user18478: I would advice to use the arduino eclipse plugin and not use the eclipse C++ arduino extension.  
The eclipse C++ arduino extension is still very much in development. 
The Arduino eclipse plugin has been around for years and contains far more features. 
If you use V3 (that is still the nightly at the time of writing) you can use the boards manager and the cosa json file to import the cosa boards.
Importing a lib is a matter of typing 
#include "libname"

and saving.

14761: <p>I am completely lost here, I have no idea what I am doing wrong. I am using Eclipse Mars using the Eclipse C++ Arduino extension. I am also using the COSA library, this is where the problem comes in. I can use all of the core COSA libraries but I can not figure out how to include the other libraries that are supplied with COSA specifically the ST7920.h file that is located in the libraries folder. Does anyone have any experience with this?</p>

<p>I have tried setting the path using the Project->C/C++ General->Preprocessor include paths and setting it there to no avail.</p>

<p>One thing that I am concerned about is in these separate libraries they are including files that are in other libs using only the header file, for example in the ST7920.hh file it has:</p>

<pre><code>#include "Cosa/LCD.hh"
#include &lt;HD44780.h&gt;
</code></pre>

<p>I need to configure things so that the HD44780.h file needs to be found also. That file is located at "../HD44780/HD44780.h". How do I tell the compiler to search the "libraries" folder for files?</p>

<p>Also I tried to simply add the libraries folder as a linked folder in my project, that also did not work.</p>

<p>the only code I have is the #include  and the compiler come back with that it can't find the file.</p>
 18478: <p>I would advice to use the arduino eclipse plugin and not use the eclipse C++ arduino extension.  </p>

<p>The eclipse C++ arduino extension is still very much in development. </p>

<p>The Arduino eclipse plugin has been around for years and contains far more features. </p>

<p>If you use V3 (that is still the nightly at the time of writing) you can use the boards manager and the cosa json file to import the cosa boards.</p>

<p>Importing a lib is a matter of typing </p>

<pre><code>#include "libname"
</code></pre>

<p>and saving.</p>
