keypad.c

#include "keypad.h"


const static unsigned char keymap[NO_OF_ROW][No_OF_COL] = {
{ '1', '2', '3', 'A'},
{ '4', '5', '6', 'B'},
{ '7', '8', '9', 'C'},
{ '*', '0', '#', 'D'},
};

void KEYPAD_Init(void){
	
	 SET_BIT((SYSCTL->RCGCGPIO),2); // Enable clock to PORTC
	 SET_BIT((SYSCTL->RCGCGPIO),4); // Enable clock to PORTE
	 (KEYPAD_PORT_C)->CR  |= 0xF0;  // Allow settings for all pins of PORTC
	 (KEYPAD_PORT_E)->CR  |= 0x0F; 	// Allow settings for all pins of PORTE
	 (KEYPAD_PORT_C)->DEN |= 0xF0;  // Set PORTC as digital pins
	 (KEYPAD_PORT_E)->DEN |= 0x0F;  // Set PORTE as digital pins
	 (KEYPAD_PORT_C)->DIR |= 0xF0;  // Set pins of PORTC as digital output
	 (KEYPAD_PORT_E)->DIR |= 0x00;  // Set pins of PORTE as digital input
	 (KEYPAD_PORT_E)->PDR |= 0x0F;  //Enable pull down resistor on PORTE
}

uint8_t KEYPAD_Getkey(void){
	
		while(1){
			
			for(int i = 0; i < 4; i++)    //Scan columns loop
			{
				(KEYPAD_PORT_C)->DATA = (1U << (i+4));
				 delayUs(1);
				
				   for(int j = 0; j < 4; j++)  //Scan rows
				   {
					     if(BIT_IS_SET(((KEYPAD_PORT_E)->DATA),j))
					     {
					      delayMs(250);
						    return keymap[j][i];
					     }
				   }
			}
	
		}
}