[avr-gcc-list] volatile with winavr2010

[Leiu]

Thanks all, But i can't find bug, Here is my full code
#include <avr/io.h>
#include <avr/interrupt.h>
#ifndef F_CPU
#define F_CPU 8000000
#endif
#include <util/delay.h>
volatile uint8_t first_edge = 'A';

void usart_initiation() {
        UCSRA = 0;   //Control register initiation, double transfer rate
        UCSRB = (1<<TXEN)|(1<<RXEN);   // enable transmitter and receiver
        UBRRH = 0;
        UBRRL = 51;   // set baud rate = 9600
        UCSRC = (1<<URSEL)|(1<<UCSZ1)|(1<<UCSZ0);       // 8 bit data, 1 stop 
bit
}

void avr2pc(uint8_t data)
{
        loop_until_bit_is_set(UCSRA,UDRE);
        UDR = data;
}

void timer1_init()
{
                TCCR1A = 0x83;  //Fast PWM 10 bit
                TCCR1B = 0x45;  //set prescale = 1024
                TIMSK = 0x24;   //enable timer1 overflow interrupt
                TCNT1H = 0x00;  //clear counter
                TCNT1L = 0x00;
                ICR1H = 0x00;   //clear input capture
                ICR1L = 0x00;
                OCR1AH = 0xff;  //set max pwm
                OCR1AL = 0xff;
}

ISR(TIMER1_OVF_vect)
{
        if(first_edge <= 'Z')
        {
                avr2pc(first_edge);
                ++first_edge;
        }else
        {
                first_edge = 'A';
        }

}

int main()
{
        //char data;
        PORTD = 0x00;
        DDRD = (1<<PD1);
        PORTA = 0xff;
        DDRA = 0xff;
        timer1_init();
        usart_initiation();
        sei();
        while(1)
        {
                ;
        }
        return 0;
}



Result : i can show 'A'! why?
Please help me!