Multiple definition of a variable in a multi-file sketch

Projects Programming
11

Thanks, gfvalvo, I will now read your provided link.

I sincerely apologize, AWOL, if I was difficult. Here is the latest version of my code:

/* FILE: multi_file.ino */

#include "multi_file.h"

void setup() {
}

void loop() {
  fnc_1();
  fnc_2();
}

/* FILE: multi_file.h */

#ifndef multi_file_h
#define multi_file_h

#include "Arduino.h"

extern byte var_1;
void fnc_1( void );
extern byte var_2;
void fnc_2( void );

#endif

/* FILE: fnc_1.cpp */

#include "multi_file.h"

void fnc_1( void ) {
  var_1 = 1;
}

/* FILE: fnc_2.cpp */

#include "multi_file.h"

void fnc_2( void ) {
  var_2 = 1;
}