// проверка кнопок
    CButton* pb = &btn[shift_cntr];
    if((PINA & BT1) != 0)
        {
        // отпущена
        pb->PressTime = SysTime;
        if(pb->Pressed != RELEASED)
            pb->Pressed = ((BTN_PROC)pgm_read_word_near(&BtnProc[shift_cntr]))(RELEASED);
        }
    else
        {
        // нажата
        if(pb->Pressed != PRESSED && SysTime - pb->PressTime > 50)
            pb->Pressed = ((BTN_PROC)pgm_read_word_near(&BtnProc[shift_cntr]))(PRESSED);
        }
    }

typedef struct tagCButton
{
uint8_t    Pressed;
uint16_t    PressTime;
uint8_t    pad;
enum { RELEASED = 0, PRESSED, WAITING };
} CButton;

/************************************************************************/
/*                                                                      */
/*                      Debouncing 8 Keys                               */
/*                      Sampling 4 Times                                */
/*                      With Repeat Function                            */
/*                                                                      */
/*              Author: Peter Dannegger                                 */
/*                      danni@specs.de                                  */
/*                                                                      */
/************************************************************************/

#include <stdint.h>
#include <avr/io.h>
#include <avr/interrupt.h>

#ifndef F_CPU
#define F_CPU           1000000                   // processor clock frequency
#warning kein F_CPU definiert
#endif

#define KEY_DDR         DDRB
#define KEY_PORT        PORTB
#define KEY_PIN         PINB
#define KEY0            0
#define KEY1            1
#define KEY2            2
#define ALL_KEYS        (1<<KEY0 | 1<<KEY1 | 1<<KEY2)

#define REPEAT_MASK     (1<<KEY1 | 1<<KEY2)       // repeat: key1, key2
#define REPEAT_START    50                        // after 500ms
#define REPEAT_NEXT     20                        // every 200ms

#define LED_DDR         DDRA
#define LED_PORT        PORTA
#define LED0            0
#define LED1            1
#define LED2            2

volatile uint8_t key_state;                                // debounced and inverted key state:
                                                  // bit = 1: key pressed
volatile uint8_t key_press;                                // key press detect

volatile uint8_t key_rpt;                                  // key long press and repeat


ISR( TIMER0_OVF_vect )                            // every 10ms
{
  static uint8_t ct0, ct1, rpt;
  uint8_t i;

  TCNT0 = (uint8_t)(int16_t)-(F_CPU / 1024 * 10e-3 + 0.5);  // preload for 10ms

  i = key_state ^ ~KEY_PIN;                       // key changed ?
  ct0 = ~( ct0 & i );                             // reset or count ct0
  ct1 = ct0 ^ (ct1 & i);                          // reset or count ct1
  i &= ct0 & ct1;                                 // count until roll over ?
  key_state ^= i;                                 // then toggle debounced state
  key_press |= key_state & i;                     // 0->1: key press detect

  if( (key_state & REPEAT_MASK) == 0 )            // check repeat function
     rpt = REPEAT_START;                          // start delay
  if( --rpt == 0 ){
    rpt = REPEAT_NEXT;                            // repeat delay
    key_rpt |= key_state & REPEAT_MASK;
  }
}

///////////////////////////////////////////////////////////////////
//
// check if a key has been pressed. Each pressed key is reported
// only once
//
uint8_t get_key_press( uint8_t key_mask )
{
  cli();                                          // read and clear atomic !
  key_mask &= key_press;                          // read key(s)
  key_press ^= key_mask;                          // clear key(s)
  sei();
  return key_mask;
}

///////////////////////////////////////////////////////////////////
//
// check if a key has been pressed long enough such that the
// key repeat functionality kicks in. After a small setup delay
// the key is reported beeing pressed in subsequent calls
// to this function. This simulates the user repeatedly
// pressing and releasing the key.
//
uint8_t get_key_rpt( uint8_t key_mask )
{
  cli();                                          // read and clear atomic !
  key_mask &= key_rpt;                            // read key(s)
  key_rpt ^= key_mask;                            // clear key(s)
  sei();
  return key_mask;
}

///////////////////////////////////////////////////////////////////
//
uint8_t get_key_short( uint8_t key_mask )
{
  cli();                                          // read key state and key press atomic !
  return get_key_press( ~key_state & key_mask );
}

///////////////////////////////////////////////////////////////////
//
uint8_t get_key_long( uint8_t key_mask )
{
  return get_key_press( get_key_rpt( key_mask ));
}

int main( void )
{
  KEY_DDR &= ~ALL_KEYS;                // konfigure key port for input
  KEY_PORT |= ALL_KEYS;                // and turn on pull up resistors

  TCCR0 = (1<<CS02)|(1<<CS00);            // divide by 1024
  TIMSK |= 1<<TOIE0;                // enable timer interrupt

  LED_PORT = 0xFF;
  LED_DDR = 0xFF;                    

  sei();

  while(1){
    if( get_key_short( 1<<KEY1 ))
      LED_PORT ^= 1<<LED1;

    if( get_key_long( 1<<KEY1 ))
      LED_PORT ^= 1<<LED2;

                                                  // single press and repeat

    if( get_key_press( 1<<KEY2 ) || get_key_rpt( 1<<KEY2 )){
      uint8_t i = LED_PORT;

      i = (i & 0x07) | ((i << 1) & 0xF0);
      if( i < 0xF0 )
        i |= 0x08;
      LED_PORT = i;      
    }
  }
}