How to have more than one source file with C18 in MPLAB?

Question

In many languages, such as C++, having lots of different source files is normal, but it doesn't seem like this is the case very often with PIC microcontroller programs -- at least not with any of the tutorials or books I've read.

I'm wondering how I can have a source (.c) file with a bunch of routines, global variables and defines in it that can be used by my main.c file. Is this even possible?

Thanks for your advice!

Answer 1

This is absolutely possible with PIC development. Size is certainly a concern both from a code and data perspective but it's still just C code meaning most (see compiler documentation for exceptions) of the rules of C apply including having multiple source files that get compiled and linked into a single output (usually .hex file). For example, in a separate C file from your main.c like test.c:

int AddNumbers(int a, int b)
{
  return a + b;
}

You could then define that in a header file test.h:

int AddNumbers(int a, int b);

Include test.h at the top of your main.c file:

#include "test.h"

You should then be able to call AddNumbers(4,5) from main.c. I have not tested this code but provide it simply as an example of the process.