//*********************************************************
//Title:    Keypad input is sent to LED4-LED1 of TWR-S12G128 Tower module 
//          Based on Example 12.4C                        *
//          HCS12 Microcontroller And Embedded Systems    *
//          Using Assembly and C with CodeWarrior         *
//          1st Edition                                   *
//          by Mazidi & Causey          
//Modified and tested by Mazidi 
//with contribution from Travis Chandler and Shu-Jen Chen                               
//Platform: Axiom Peripheral board on TWR-S12G128 Tower module board                 *
//Compiler: Feescale CodeWarrior IDE v5.9.0               

//*********************************************************
//On TWR-S12G128 Tower module, 4 green LEDs of LED4-LED1 are connected to PT7-PT4 
//They are active LOW. Make sure the jumers for all 4 LEDs are set

//Make sure the Axiom Peripheral board is connected to Tower Elavator correctly
//The J1 primary side of the Axiom peripheral board must be on the WHITE side of elevator
//On Axiom Peripheral board, the rows and columns of 4x4 keypad are connected to PORTA. 

//On the Axiom TWR-DEV-PERIPH board make sure you have jumpers: JP1 set on the left, JP2 is set, and JP3,JP4, and JP5 on the right. 
//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. 

//As you press any key the binary value for the key is placed on the LED4-LED1 of HCS12 Tower Module


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

void mSDelay(unsigned int);

const unsigned char keypad[4][4] =
{
 0x01,0x02,0x03,0x0A,
 0x04,0x05,0x06,0x0B,
 0x07,0x08,0x09,0x0C,
 0x2A,0x00,0x23,0x0D      //Notice 0x2A is ASCII for '*' and 0x23 for '#'
};
unsigned char column,row,mykey;

/**************MAIN*******************************/
void main(void){                          //OPEN MAIN
   DDRT = 0xF0;                           //MAKE UPPER 4-BIT OF PORTT OUTPUT
   DDRA = 0x0F;                           //MAKE ROWS INPUT AND COLUMNS OUTPUT
      
   
   
 
   while(1){                              //OPEN WHILE(1)
      do{                                 //OPEN do1
         PORTA = PORTA | 0x0F;            //COLUMNS SET HIGH
         row = PORTA & 0xF0;              //READ ROWS
      }while(row == 0x00);                //WAIT UNTIL KEY PRESSED //CLOSE do1



      do{                                 //OPEN do2
         do{                              //OPEN do3
            mSDelay(1);                   //WAIT
            row = PORTA & 0xF0;           //READ ROWS
         }while(row == 0x00);             //CHECK FOR KEY PRESS //CLOSE do3
         
         mSDelay(15);                     //WAIT FOR DEBOUNCE
         row = PORTA & 0xF0;
      }while(row == 0x00);                //FALSE KEY PRESS //CLOSE do2

      while(1){                           //OPEN while(1)
         PORTA &= 0xF0;                   //CLEAR COLUMN
         PORTA |= 0x01;                   //COLUMN 0 SET HIGH
         row = PORTA & 0xF0;              //READ ROWS
         if(row != 0x00){                 //KEY IS IN COLUMN 0
            column = 0;
            break;                        //BREAK OUT OF while(1)
         }
         PORTA &= 0xF0;                   //CLEAR COLUMN
         PORTA |= 0x02;                   //COLUMN 1 SET HIGH
         row = PORTA & 0xF0;              //READ ROWS
         if(row != 0x00){                 //KEY IS IN COLUMN 1
            column = 1;
            break;                        //BREAK OUT OF while(1)
         }

         PORTA &= 0xF0;                   //CLEAR COLUMN
         PORTA |= 0x04;                   //COLUMN 2 SET HIGH
         row = PORTA & 0xF0;              //READ ROWS
         if(row != 0x00){                 //KEY IS IN COLUMN 2
            column = 2;
            break;                        //BREAK OUT OF while(1)
         }
         PORTA &= 0xF0;                   //CLEAR COLUMN
         PORTA |= 0x08;                   //COLUMN 3 SET HIGH
         row = PORTA & 0xF0;              //READ ROWS
         if(row != 0x00){                 //KEY IS IN COLUMN 3
            column = 3;
            break;                        //BREAK OUT OF while(1)
         }
         row = 0;                         //KEY NOT FOUND
      break;                              //step out of while(1) loop to not get stuck
      }                                   //end while(1)

      if(row == 0x10){
         mykey=keypad[0][column];         
 	 PTT = ~(mykey<<4);    	//shift left 4 times and OUTPUT TO upper 4-bit of PORTT LED
 				//We invert it since LED4-LED1 are active LOW	
      }
      else if(row == 0x20){
         mykey=keypad[1][column];
         PTT = ~(mykey<<4); 	//shift left 4 times and OUTPUT TO upper 4-bit of PORTT LED
				//We invert it since LED4-LED1 are active LOW
      }
      else if(row == 0x40){
         mykey=keypad[2][column];
         PTT = ~(mykey<<4); 	//shift left 4 times and OUTPUT TO upper 4-bit of PORTT LED
 				//We invert it since LED4-LED1 are active LOW
      }
      else if(row == 0x80){
         mykey=keypad[3][column];
         PTT = ~(mykey<<4);     //shift left 4 times and OUTPUT TO upper 4-bit of PORTT LED
 				//We invert it since LED4-LED1 are active LOW
      }

      do{
         mSDelay(15);
         PORTA = PORTA | 0x0F;            //COLUMNS SET HIGH
         row = PORTA & 0xF0;              //READ ROWS
      }while(row != 0x00);                //MAKE SURE BUTTON IS NOT STILL HELD
   }                                      //CLOSE WHILE(1)
}                                         //CLOSE MAIN



/**********************SUBROUTINES***********/

void mSDelay(unsigned int itime){
unsigned int i; unsigned int j;
   for(i=0;i<itime;i++)
      for(j=0;j<1000;j++);
}