Setting up a C project with multiple source files in MPLAB

Question

I'm using the MPLAB IDE and the XC8 compiler for a C project for PIC18 devices. I'm building a project with multiple source files and don't know how to make the structure.

In the project, I have the following things:

• A file main.c where the main code is located. From here, several files are included:
  • xc.h: to define chip-specific variables and so
  • stdlib.h, stdio.h, plib.h, delays.h: for the compiler's functions
  • enc28j60.h: a homebrew file with definitions and prototypes
• A file enc28j60.c, where the functions of the prototypes in enc28j60.h go

I cannot compile enc28j60.c as standalone file because it depends on definitions in main.c.

I have a few questions on how to set this project up:

1. Should I add enc28j60.c to the source files of my MPLAB project? If I do this, MPLAB tries to compile the file, which fails. If I don't do this, the linker cannot find the symbols that are defined in enc28j60.c and prototyped in enc28j60.h.
2. Should I #include enc28j60.c from somewhere? If not, how does MPLAB know where to get the file?
3. Should I add enc28j60.h to the header files of my MPLAB project?
4. Should I #include enc28j60.h from somewhere? Right now, I do this in main.c, after the definitions enc28j60.h needs in order to run (and not throw #errors).

Answer 1

I managed to get this working by modifying my library and header files a bit.

At first, I added a file main.h where all the prototypes, #defines and #includes would go. Then, in every .h, file, I added this on top:

#ifndef SOME_LIB_IDENTIFIER   // makes sure the lib only gets included once,
#define SOME_LIB_IDENTIFIER   // has to be specific for every lib

#include "main.h"             // to make sure everything's initialized (this line of course not in main.h)

And the last line of every .h file would be:

#endif

I added #include "enc28j60.h" to the top of the enc28j60.c file. This file now can be compiled.

In main.h, I added includes for xc.h, plib.h, stdlib.h, stdio.h and enc28j60.h. I nowhere included .c files.

I added both the main and enc28j60 header and source files to my MPLAB project. The source files get compiled well, both. The result is linked together.

In short

• Add a main.h where all prototypes, #defines and #includes go
• Add a header and footer to all your header file to make sure they're only included once. Also include main.h from these headers, to make sure every file uses the same definitions
• Include a source file's corresponding .h file at the very first line of your source file. Do not include .c files
• Add all header and source files (that are not built into the compiler) to your MPLAB project
• Build (F10) should compile all files and link them together correctly