이것은 간단히 Serial 통신을 하는 예제입니다. serial로부터 받은 데이터를 고스란히 다시 반향하여 보내는 것입니다.

아래 예제코드는 으로 만들어져 있습니다.

/*
  Copyright (C) JAEHYUK CHO
  All rights reserved.
  Code by JaeHyuk Cho <mailto:minzkn@minzkn.com>
*/

#include <sys/types.h> 
#include <sys/time.h> 
#include <stdio.h> 
#include <unistd.h> 
#include <fcntl.h> 
#include <malloc.h> 
#include <string.h> 
#include <memory.h> 
#include <signal.h> 
#include <errno.h> 
#include <termios.h> 

#define mz_dump(m_d,m_s) do{int s_o,s_w,s_i;unsigned char s_b[17];if(((void *)(m_d))!=NULL){s_b[16]='\0';s_o=(int)0;\ 
while(s_o<(m_s)){s_w=((m_s)-s_o)<16?((m_s)-s_o):16;printf("%08X",s_o);for(s_i=0;s_i<s_w;s_i++){if(s_i==8)printf(" | ");else printf(" ");\ 
s_b[s_i]=*(((unsigned char *)(m_d))+s_o+s_i);printf("%02X",s_b[s_i]);if((s_b[s_i]&0x80)||(s_b[s_i]<' '))s_b[s_i]='.';}\ 
while(s_i<16){if(s_i==8)printf("     ");else printf("   ");s_b[s_i]=' ';s_i++;}\ 
printf(" [%s]\n",(char *)s_b);s_o+=16;}}else printf("error: dump null\n");}while(0) 

int g_mz_break = 0; 

void mz_my_signal(int s_signal) 
{ 
 switch(s_signal) 
 { 
  case SIGINT: 
       g_mz_break = 1; 
       (void)signal(s_signal, mz_my_signal); 
       break; 
  default: 
       (void)printf("unknown signal ! (%d)\n", s_signal); 
       break; 
 } 
} 

int main(void) 
{ 
 /* configuration */ 
 char *s_device_name = "/dev/ttyS0"; 
 speed_t s_baud = B9600; 
 tcflag_t s_data_bits = CS8; 
 int s_parity_bit = 1; 

 int s_handle, s_index, s_check; 
 struct termios s_prev_termios, s_new_termios; 
 ssize_t s_read_bytes, s_write_bytes; 
 struct timeval s_timeval; 
 fd_set s_fd_in; 
 unsigned char s_buffer[ 4 << 10 ]; 

 (void)signal(SIGINT, mz_my_signal); 

 s_handle = open(s_device_name, O_RDWR | O_NOCTTY); 
 if(s_handle != (-1)) 
 { 
  if(tcgetattr(s_handle, (struct termios *)(&s_prev_termios)) == 0) 
  { 
   (void)memcpy((void *)(&s_new_termios), (void *)(&s_prev_termios), (size_t)sizeof(struct termios)); 

   s_new_termios.c_iflag = IGNBRK | ((s_parity_bit == 0) ? ((tcflag_t)0) : IGNPAR); 
   s_new_termios.c_oflag = (tcflag_t)0; 
   s_new_termios.c_cflag = s_data_bits | CLOCAL | CREAD; 
   s_new_termios.c_lflag = (tcflag_t)0; 
   for(s_index = 0;s_index < NCCS;s_index++)s_new_termios.c_cc[s_index] = (cc_t)0; 
   s_new_termios.c_cc[VMIN] = (cc_t)1; 
   s_new_termios.c_cc[VTIME] = (cc_t)0; 

   if(cfsetispeed((struct termios *)(&s_new_termios), s_baud) == 0 && 
      cfsetospeed((struct termios *)(&s_new_termios), s_baud) == 0) 
   { 
    if(tcsetattr(s_handle, TCSANOW, (struct termios *)(&s_new_termios)) == 0) 
    { 
     if(tcflush(s_handle, TCIOFLUSH) == 0) 
     { 
      (void)printf("Ready serial\n"); 
      do 
      { 
       FD_ZERO(&s_fd_in); 
       FD_SET(s_handle, &s_fd_in); 
       s_timeval.tv_sec = (long)1, s_timeval.tv_usec = (long)0; 
       s_check = select(s_handle + 1, (fd_set *)(&s_fd_in), (fd_set *)0, (fd_set *)0, (struct timeval *)(&s_timeval)); 
       if(s_check > 0) 
       { 
        s_read_bytes = read(s_handle, (void *)(&s_buffer[0]), (size_t)sizeof(s_buffer)); 
        if(s_read_bytes > ((ssize_t)0)) 
        { 
         (void)printf("recv data %d byte(s) {\n", (int)s_read_bytes); 
         mz_dump(&s_buffer[0], s_read_bytes); 
         (void)printf("}\n"); 
#if 1 /* echo part */ 
         s_write_bytes = write(s_handle, (void *)(&s_buffer[0]), (size_t)s_read_bytes); 
         (void)printf("echo %d/%d byte(s)\n", (int)s_write_bytes, (int)s_read_bytes); 
#endif 
        } 
        else if(s_read_bytes == ((ssize_t)0))(void)printf("no data\n"); 
        else (void)perror("read"); 
       } 
       else if(s_check == 0)(void)printf("wait\n"); 
       else (void)perror("select"); 
      }while(g_mz_break == 0); 
      (void)printf("End of serial\n"); 
     } 
     else (void)perror("tcflush"); 
    } 
    else (void)perror("tcsetattr"); 
   } 
   else (void)perror("cfset{i/o}speed"); 
   if(tcsetattr(s_handle, TCSANOW, (struct termios *)(&s_prev_termios)) != 0)(void)perror("tcsetattr(restore)"); 
  } 
  else (void)perror("tcgetattr"); 
  (void)close(s_handle); 
 } 
 else (void)perror("open"); 
 return(1); 
} 

/* vim: set expandtab: */ 
/* End of source */