//Toggling PORTT in C Language for TWR-HCS12G128 Tower module using CodeWarrior 
//On TWR-S12G128 Tower module, 4 green LEDs are connected to PT7-PT4 
//They are active LOW. Make sure the jumers for all 4 LEDs are set

//This program uses Timer Overflow for Delay. 
//Two ways to control Delay size. (1)Prescaler value, (2)SIZE value 


//Modified by Mazidi from Example 7-7 and 9-28 of Mazidi & Causey HCS12 book


//Use F7 to Make, F5 (Debug) to download, and F5 (Start) to run the program
//In CodeWarrior,make sure you are in Open Source BDM when downloading and running. 

#include <hidef.h>      /* common defines and macros */
#include "derivative.h"      /* derivative-specific definitions */


void BigTimerDelay(unsigned int);
void main(void) 
{
  
    unsigned int SIZE=1;	 //one way to control Delay size

    DDRT = 0xF0;    //PT7-PT4 as output since LEDs are connected to it
    for(;;) 			
      {
        PTT = 0x50;
        BigTimerDelay(SIZE);    
        PTT = 0xA0;
        BigTimerDelay(SIZE);
      }
 
}

void BigTimerDelay(unsigned int ttime)
  {
   unsigned int i;    
   TSCR1 = 0x80;  //enable timer 
   TSCR2 = 0x01;  //Prescaler=1 (2nd way to control Delay size is using 0 to 7) 
          
       for(i=0;i<ttime;i++) 
        {
    
         TFLG2 = 0x80;  //clear the TOF flag
     
         while (!(TFLG2 & TFLG2_TOF_MASK));  //wait for Timer Overflow
	 //while ((TFLG2 &0x80)==0);          //you can use this line instead					
        }
   
  }