Arduino ZX Spectrum AY Player

#include <avr/io.h>
#include <avr/sfr_defs.h>
#include <compat/ina90.h>
#include <avr/interrupt.h>
#include <stdlib.h>
#include <avr/sleep.h>

#ifndef cbi
#define cbi(sfr, bit) (_SFR_BYTE(sfr) &= ~_BV(bit))
#endif
#ifndef sbi
#define sbi(sfr, bit) (_SFR_BYTE(sfr) |= _BV(bit))
#endif

volatile int bit_counter=0;
volatile int byte_counter=0;
volatile int half=0;

unsigned char data_card[5][8] = {{0xFF,0xC5,0x38,0x2D,0x19,0xD1,0xC9,0x5A},    //test
                                {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF},     // other cards
				{0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF},    
				{0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF},    
				{0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF}};    

unsigned char data[8];

void delay_ms(int ms) {              // 1.000 MHz
  int i;
  for (i=0; i < ms; i++) {
	TCNT0=0;
	while (TCNT0 <  125);
  }
}

ISR(SIG_OUTPUT_COMPARE1A){
    TCNT1=0;

//      if(byte_counter==0) sbi(PORTB,PD1);
//        else cbi(PORTB,PD1);

	if (((data[byte_counter] << bit_counter)&0x80)==0x00) {
	    if (half==0) cbi(PORTB,PB1);
	    if (half==1) sbi(PORTB,PB1);
	}
	else {
	    if (half==0) sbi(PORTB,PB1);
	    if (half==1) cbi(PORTB,PB1);
	}
    
	half++;
	if (half==2) {
	    half=0;
	    bit_counter++;
	    if (bit_counter==8) {
	        bit_counter=0;
	        byte_counter=(byte_counter+1)%8;
		}
	}
}

 
int main(void) {
  int i;
  DDRB=0xFF;
  DDRC=0x00;
  DDRD=0x00;
  PORTC=0x00;

  TCCR0 = 2;             // timer0 clock/8 
//  TCCR1B = 2;		 // timer1 clock/8
  TCCR1B = 3;

//  OCR1A = 254;
//  OCR1A = 32;   //32           

  unsigned char sel = (PINC >> 1) & 0x07;
  OCR1A = 30 + sel;
  
//  for (i=0;i<8;i++) data[i]=data_card[sel][i];
  for (i=0;i<8;i++) data[i]=data_card[0][i];
  
  sbi(TIMSK, OCIE1A);	 // timer1 Output Compare A match

  sei();

  while (1) {

  }
    return 0;  
}

MCU=atmega8
CC=avr-gcc
OBJCOPY=avr-objcopy
PROJECT=rfid
CFLAGS=-g -mmcu=$(MCU) -Wstrict-prototypes -Os -mcall-prologues -Wall

#-------------------
all: $(PROJECT).hex
#-------------------
$(PROJECT).hex : $(PROJECT).out 
	$(OBJCOPY) -R .eeprom -O ihex $(PROJECT).out $(PROJECT).hex 
$(PROJECT).out : $(PROJECT).o 
	$(CC) $(CFLAGS) -o $(PROJECT).out -Wl,-Map,$(PROJECT).map $(PROJECT).o 
$(PROJECT).o : $(PROJECT).c 
	$(CC) $(CFLAGS) -Os -c $(PROJECT).c
asm : $(PROJECT).c 
	$(CC) $(CFLAGS) -O -S $(PROJECT).c
# you need to erase first before loading the program.
# load (program) the software into the EEPROM:
load: $(PROJECT).hex
	avrdude -c butterfly -P /dev/ttyUSB0 -b 115200 -p m8 -U flash\:w\:$(PROJECT).hex\:a
#	uisp --erase --upload --verify if=$(PROJECT).hex -dprog=avr910 -dserial=/dev/ttyUSB0 -dspeed=115200 -dpart=auto  -v=3 --hash=12 

#-------------------
#	different programmers and fuse programming if necessary
#	uisp -dserial=/dev/ttyUSB0 -dspeed=115200 --erase --upload --verify if=$(PROJECT).hex -dprog=avr910  -v=3 --hash=12 -dpart=auto
#	uisp --erase --upload --verify if=$(PROJECT).hex -dprog=dapa  -v=3 --hash=12 
#	uisp -dprog=dapa --wr_fuse_l=0x5f --wr_fuse_h=0xd9 -v=3
#-------------------
clean:
	rm -f *.o *.map *.out *.hex
#-------------------