[Jake M]

I implemented a globals.h file to handle all variables that need to be accessed across multiple .c files, and a handy macro that can make all these declarations in a single statement, which makes things easy if you need to add more variables, or change the name of an existing one.

/********************************************************************************
* FILE NAME: globals.h
*
* DESCRIPTION: 
*  This file contains the definitions of global variables, used by multiple
*  modules in the robot program. A macro is used to resolve the separate 
*  definition of each variable, in each module. Simply include this file in
*  all of your C Source files, but also make sure to insert the line
*     #define MAIN_C
*  in your main.c file.
*  
********************************************************************************/

/* GLOBAL_VAR(Type, Name, Initial Value); */
#ifdef MAIN_C
#define GLOBAL_VAR(t, n, v) t n = v
#else
#define GLOBAL_VAR(t, n, v) extern t n
#endif

/* example */
GLOBAL_VAR(unsigned char, test, 0);

In addition, I came up with a similar macro to deal with the relays.

#define drt_hand_piston_fwd  relay2_fwd
#define drt_hand_piston_rev  relay2_rev

...

#define RELAY_FWD  1
#define RELAY_OFF  0
#define RELAY_REV  -1

#define Generate_Relay(r)\
         {\
          r##_fwd = 0;\
          r##_rev = 0;\
          if(r == 1)\
            r##_fwd = 1;\
          else if(r == -1)\
            r##_rev = 1;\
         }

...

GLOBAL_VAR(char, drt_hand_piston, 0);

...

Generate_Relay(drt_hand_piston);

I also tried to use the EEPROM to make the arm_position self-calibrating, but seeing how I only got the robot for programming late on Monday, I didn't have enough time to make it work.