하이퍼 터미널에 숫자 1을 치면 led 불이 켜졋다 꺼지고 숫자 2를 치면 fnd가 작동 되는 코딩인데 주석을 달고 싶은데 책만 보고 베낀거라 하나두 몰라서요.. 혹시 조금이라도 주석 달아주실수 있는분 계신가요? 







#include <avr/io.h>

#include <stdio.h>

#include <util/delay.h>

#include <avr/interrupt.h>

 

#define DDR_LED DDRB

#define PORT_LED PORTB

 

#define DDR_FND DDRA

#define PORT_FND PORTA

 

#define UART_RX_BUFLEN 128

 

#define BS 0x08

#define CR 0x0D

 

volatile unsigned int tic_time;

 

ISR(TIMER0_OVF_vect,ISR_NOBLOCK)

{

tic_time++;

TCNT0 = 6;

}

 

void uart_send_byte(unsigned char byte)

{

while(!(UCSR0A & (1<<UDRE0)));

  UDR0 = byte;

}

 

void uart_send_string(unsigned char *str, unsigned char len)

{

int i;

 

for(i=0;i<len;i++)

{

if(!(*(str + i)))

{

break;

}

uart_send_byte(*(str + i));

}

}

 

unsigned char uart_recv_byte(void)

{

while(!(UCSR0A & (1<<RXC0)));

return UDR0;

}

 

void uart_recv_string(unsigned char *str)

{

unsigned char len = 0;

unsigned char byte;

 

for(;;)

{

if(len>= UART_RX_BUFLEN - 1)

{

break;

}

 

byte = uart_recv_byte();



if(byte==CR)

{

uart_send_byte('\n');

uart_send_byte('\r');

break;

}

else if(byte==BS)

{

if(len)

{

len--;

}

uart_send_byte(byte);

uart_send_byte(' ');

uart_send_byte(byte);

}

else

{

str[len++] = byte;

uart_send_byte(byte);

}

}

str[len] = 0;

return len;

}

 

void menu_display(void)

{

uart_send_string("\n\r 1. LED test", 15);

uart_send_string("\n\r 2. FND test", 15);

uart_send_string("\n\r Input number(1-2) : ", 25);

}

 

void Putch1(unsigned char data)

{

while (!(UCSR0A & (1 << UDRE0)));

UDR0 = data;

}

 

char Getch1(void)

{

while(!(UCSR0A & (1 << RXC0)));

return UDR0;

}

 

int main(void)

{

unsigned char fnd[10] = {0x3F,0x06,0x5B,0x4F,0x66,0x6D,0x7D,0x27,0x7F,0x6F};

 

FILE *fp;

fp = fdevopen(Putch1, Getch1);

 

unsigned char buf[UART_RX_BUFLEN];

unsigned int i;

 

DDR_LED = 0xFF;

PORT_LED = 0xFF;

 

DDR_FND = 0xFF;

DDRC = 0x0F;

PORT_FND = 0xFF;

 

TCCR0 = (1<<CS02) | (0<<CS01) | (0<<CS00);

TCNT0 = 6;

TIMSK = (1<<OCIE0) | (1<<TOIE0);

 

UBRR0L = 103;

UBRR0H = 0;

UCSR0C = (0<<UPM1) | (0<<UPM0) | (0<<USBS) | (1<<UCSZ1) | (1<<UCSZ0);

UCSR0B = (1<<TXEN) | (1<<RXEN) | (0<<UCSZ2);

 

sei();

 

for(;;)

{

menu_display();

uart_recv_string(buf);

 

switch(atoi(buf))

{

case 1:

for(i=0;i<8;i++)

{

PORT_LED = ~(1 << i);

_delay_ms(10000);

}

PORT_LED = 0xFF;

uart_send_string("OK.\r\n",5);

break;

case 2:

for(i=0;i<10;i++)

{

PORT_FND = fnd[i];

_delay_ms(500);

}

PORTC = 0xFC;

PORT_FND = 0xFF;

uart_send_string("OK.\r\n",5);

break;

default:

uart_send_string("Invalidarguments.\r\n",20);

break;

}

 

}

return 1;

}





아 그리고 마지막으로 하이퍼터미널에서 1을 입력하면 OK가 나오던데 OK가 출력되는 원리가 뭔가요?