//Displaying Overflow Timer on LEDs of PORTA for Project Board with HCS12 MCU Module and CodeWarrior
//Modified by Mazidi from Example 9-28 in HCS12 textbook by Mazidi & Causey
 
//In CodeWarrior,MAKE sure you are in TBDML Mode before downloading 
//Press F7 (to Make), then F5(Debug) to downLOAD,and F5 once more to start the program execution

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



void main(void) 
{
  /* put your own code here */
  
      unsigned char overflow = 0; 



    DDRA = 0xFF;    //PORTA as output since LEDs are connected to it
    DDRP = DDRP | 0b00010000;  //on Project Board, the lower 4 bits of PA3-PA0 are connected to LEDs(LED1-LED4) permanently
    PTP = PTP & 0b11101111;    //and must be enabled by clearing bit P4 of PORTP
                 //on Project Board,we need to connect 4 wires from LED5-LED8 (J10) to pins PA4-PA7 via J6 connector (pins 25,27,29,31)
   TSCR1 = 0x80;  //enable timer
   TSCR2 = 0x4;  //Prescaler=16 (Try 0-7 values to see changes on LEDs) 
  	   
   for(;;)
    { 
      TFLG2 = 0x80;  
      
      while (!(TFLG2 & TFLG2_TOF_MASK));  //wait for Timer Overflow
      overflow = overflow + 1;            //keep adding the overflows
      PORTA = overflow;                   //and dump it PORTA to see
    }                         // Notice the LEDs of LED1-LED4 on Project Board are arranged in awkward manner.
                              //LED1 should have been connected to the PA0 pin of CPU ,but instead it is connected to PA3.
                              //that is the reason the counter looks awkward.
               
    
 
}