rti.c

/*********************************************
                    rti.h
**********************************************/
#ifndef RTIH
#define RTIH
#include <hidef.h>      /* common defines and macros */
#include "derivative.h" 

extern volatile unsigned int rtiCount; // global counter incremented each time
//Note: extern just means that this variable exists but is defined elsewhere
extern volatile unsigned int rtiInterval; // How freqently (in ms) to run the callback

void RTIInit(void); //Set up RTI for 1 ms intervals, enable interrupts
void RTICallback(void(*fp)(void), unsigned int count); //Tell the RTI to call a function when triggered

#endif

/*********************************************
                    rti.c
**********************************************/
#include "rti.h"
#include <hidef.h>      /* common defines and macros */
#include "derivative.h" 
#include "swled.h"

//These were declared in my .h, here's my definitions
volatile unsigned int rtiCount = 0;
volatile unsigned int rtiInterval = 1;
void (*rtiHandler)(void) = 0;

void RTIInit(void)
{
    //Set RTI to decimal, divider 2000, mod8 counter (1 ms)
    RTICTL = 0b10010111;
    //Enable my interrupts
    CRGINT |= CRGINT_RTIE_MASK;
}

//Set a handler that will get called every RTI count
void RTICallback(void(*fp)(void), unsigned int count)
{
    rtiHandler = fp; //Function to run
    rtiInterval = count; // How many milliseconds between runs
}

//Special syntax for interupt handlers (unique to CodeWarrior, not standard C)
interrupt VectorNumber_Vrti void Vrti_ISR(void)
{
    CRGFLG = CRGFLG_RTIF_MASK; //clear flag;
    ++rtiCount;
    if (!(rtiCount % rtiInterval))
    {   //If I have a valid pointer to a handler, call it.
        if (rtiHandler) rtiHandler();
        rtiCount = 0;
    }
}

/*********************************************
                    main.c
**********************************************/
#include <hidef.h>      /* common defines and macros */
#include "derivative.h"      /* derivative-specific definitions */
#include "pll.h"
#include "swled.h"
#include "rti.h"

void LightsToggle(void);

void main(void) {
  
  PLL_To20MHz();
  SWL_Init();
  RTIInit();
  RTICallback(LightsToggle, 200); //toggle lights every 200 ms
  EnableInterrupts;
  for(;;) {
    //No reason to stay awake in between interrupts.
    asm wai;
  } /* loop forever */
  /* please make sure that you never leave main */
}

void LightsToggle(void)
{
    SWL_ToggleLEDs(eAllLEDs);
}