//Toggling 8 LEDs on PORTA using Freescale Student Project board with HCS12 MCU Module from Axiom  
//HCS12 MCU Modules come with USB-BDM. This code is for CodeWarrior IDE only


//Notice the following facts about the Student Project Board
//a) the lower 4 bits of PA3-PA0 are connected to LEDs(LED1-LED4 on J10) permanently 
//b) they must be enabled by clearing bit P4 of PORTP. 
//c) ON the Project Board, MAKE SURE jumper for these LEDs is set. LED JUMPER is part of group of jumpers called UFEA right next to the Buzzer
//d) We also need to connect 4 wires from LED5-LED8 (J10) to pins PA7-PA4 via J6 connector(pins 25,27,29,31)


//On HCS12 MCU Module itself,
//a)MAKE SURE ALL the jumpers for PORTB are removed.(SW3-1...SW3-4 and LED1-LED4) 
//b)The 8 Jumpers (SW3-1...SW3-4 and LED1-LED4) on HCS12 MCU module connect the PORTB to SW and LEDs of the Module itself.  
//c)The PORTB can be either used by the HCS12 MCU Module itself or the Project Board, but not both of them at the same 

//WE USE THIS LAB EXTENSIVELY IN FUTURE LABs. SO KEEP THE LEDs CONNECTED TO PORTA7-PORTA4. THIS WAY WE HAVE 8 LEDs

//See Chapter 7 of Mazidi & Causey HCS12 textbook
 
//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 MSDelay(unsigned int);
void main(void) 
{
  /* put your own code here */
  

    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)

      
    for(;;) 			
      {
        PORTA = 0x55;
        MSDelay(500);    //1/2 sec delay
        PORTA = 0xAA;
        MSDelay(500);
      }
 
}


//The HCS12 MCU Module works with XTAL=4MHz 
//Freq. for Instruction Clock Cycle (Bus Freq.) is 2MHz (1/2 of 4MHz). 
 void MSDelay(unsigned int itime)
  {
    unsigned int i; unsigned int j;
    for(i=0;i<itime;i++)
      for(j=0;j<313;j++);    //1 msec. tested using Scope
  }