//Getting data from push-button SW1-SW4 and sending it to LED1-LED4 for HCS12G128 Tower Module using CodeWarrior 
//On TWR-S12G128 Tower board, 4 LEDs (LED4-LED1)are connected to PT7-PT4 pins. PT7=LED4,.., PT4=LED1
//LED1-LED4 are active LOW.  See TWR-HCS12G128 schematic 
//The 4-pins of PAD7-PAD4 are also connected to the push-button (debounce) switches (SW4-SW1)
//SW4-SW1 are active LOW (normally HIGH) See TWR-HCS12G128 schematic
//There are 8 jumpers allowing the connection of the SW1-Sw4 and LED1-LED4 to the CPU pins.
//If you use LEDs and SWs make sure the jumpers for them are set.  

//Notice the PAD7-PAD4 pins are normally used for Analog-to-Digital converter (ADC).
//To use them for digital input via SW4-SW1, we must write 1 to ATDDIEN register bits. See Chap 12 of the HCS12G Ref. Manual.
 
//Chapter 2 of HCS12G Ref. Manual describes all the ports of HCS12G128
//Sections 2.4.3.49 through 2.4.3.64 give the details of registers associated with PAD 

 
//As you press the push-button Sw, an LED is turned on (LEDs shows the status of SW).


//Modified and tested by Mazidi from Example 7-10 of Mazidi & Causey HCS12 textbook

  
//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 MSDelay(unsigned int);
void main(void) 
{
  /* put your own code here */
  
    
    unsigned char mybyte;
    DDRT = 0xF0;              //PT7-PT4 as output for LED4-LED1 
    ATDDIEN = 0x00F0;	      //Make PAD7-PAD4 as digital Input for SW4-Sw1. (The default is analog for ADC)   
    PER1AD = 0xF0;	      //Enable internal pull-ups for the PAD4-PAD7 pins
    DDR1AD= DDR1AD | 0x00;     //Make PAD7-PAD4 pins as input. Optional since the default is input.
	  

	  
    for(;;) 			
      {
        mybyte=PT1AD;         //Get data from push button SW
        mybyte=mybyte&0xF0;   //Mask the unwanted bits
        PTT = mybyte;         //and send it to LEDs on PortT
        MSDelay(1);           //Optional
      }
 
}


 void MSDelay(unsigned int itime)
  {
    unsigned int i; unsigned int j;
    for(i=0;i<itime;i++)
      for(j=0;j<1000;j++);    //1 msec. NOT tested yet using Scope
  }