keypad.h

this is keypad driver for 4x4 matrix keypad for ATMEGA32 Microcontroller from Atmel

#ifndef _KEYPAD_INCLUDED_
#define _KEYPAD_INCLUDED_ 

/***************************************************************************************************
  Description
***************************************************************************************************/
/*
    Keypad is connected to PORTC
    Timer Used = Timer 2;
    
*/




/***************************************************************************************************
  Keyboard Key Definition
***************************************************************************************************/
#define KEY_0          '0'
#define KEY_1          '1'
#define KEY_2          '2'
#define KEY_3          '3'
#define KEY_4          '4'
#define KEY_5          '5'
#define KEY_6          '6'
#define KEY_7          '7'
#define KEY_8          '8'
#define KEY_9          '9'
#define KEY_STAR       '*'
#define KEY_GATE       '#'
#define KEY_UP         'A'
#define KEY_DOWN       'B'
#define KEY_CONNECT    'C'
#define KEY_DISCONNECT 'D'




/***************************************************************************************************
  Keypad Related Constants
***************************************************************************************************/
#define FIRST_COLUMN     0x80    // 0b10000000
#define LAST_COLUMN      0x10    // 0b00010000
#define KEYIN            PINC
#define KEYOUT           PORTC
#define KEYPAD_PRESCALAR 256
#define KEYPAD_RATE      500    // 500 scan per second
#define KEYPAD_TIMER_SET (0x100-(FCLK/KEYPAD_PRESCALAR/KEYPAD_RATE))

/***************************************************************************************************
  Function prototypes
***************************************************************************************************/
interrupt [TIM2_OVF] void timer2_int(void);
unsigned char keypad_read(void);
void keypad_init(void);

#endif