#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#define F_CPU 14745600UL // 14.7456 MHz
#include <util/delay.h>
#include <stdio.h>

void SpiTx (unsigned char Data)
{
USIDR = Data;
USISR |= (1<<USIOIF);
USISR = (USISR & 0xF0);
TCCR0B = 0x03; //start timer
while(!(USISR & (1<<USIOIF))); // wait for transmission
}

ISR(TIMER0_OVF_vect)
{
TCNT0 = 0x83; //set count
}

int main(void)
{
PORTB=0b00000000;
DDRB=0b11010001;
TCCR0B = 0x00; //stop timer
TCNT0 = 0x83; //set count
OCR0A = 0x84; //set count
OCR0B = 0x84; //set count
TCCR0A = 0x00; //start timer
TCCR0B = 0x03; //start timer

// Universal Serial Interface initialization
// Mode: Three Wire (SPI)
// Clock source: Reg. & Cnt.=Timer/Counter 0 Ovf.
// USI Counter Overflow Interrupt: Off
USICR=0x14;//00010100

TIMSK = 0x02;
SpiTx(0b10101010);

asm("sei");

while(1)
{
asm("nop");
}
return 0;
}

void SPIWriteData(unsigned char data)
{
unsigned char i;

for(i=0;i<8;i++) {
        SPI_CLK_low;
        if (data & 0x80) SPI_DATA_high; else SPI_DATA_low;
        data <<= 1;
        SPI_CLK_high;
        }
NOP();
SPI_CLK_low;
}

//SPI генератор
#define SPI_CLK_high PORTC |= BIT(PC6)
#define SPI_CLK_low PORTC &= ~BIT(PC6)
#define SPI_DATA_high PORTC |= BIT(PC7)
#define SPI_DATA_low PORTC &= ~BIT(PC7)

data = (unsigned char)(long_data);
SPIWriteData(data);