Reading from serial port in C - serial-port

Question

I'm trying to read from Arduino (who's sending char '4' constantly) with XBee.
I have tried writing from the PC to Arduino, and it works, so the connection is correct.
When I execute de following code, the terminal doesn't show anything and don't finish the program, so it gets stuck on reading.
#include <stdio.h> // Standard input / output functions
#include <stdlib.h>
#include <string.h> // String function definitions
#include <unistd.h> // UNIX standard function definitions
#include <fcntl.h> // File control definitions
#include <errno.h> // Error number definitions
#include <termios.h> // POSIX terminal control definitions
#define XBEE "/dev/ttyUSB0"
#define BAUDRATE B9600
int main(int argc,char** argv)
{
struct termios tio;
struct termios stdio;
struct termios old_stdio;
int tty_fd = open(XBEE , O_RDWR| O_NOCTTY);
cfsetospeed(&tio,BAUDRATE);
cfsetispeed(&tio,BAUDRATE); // Baudrate is declared above
tcsetattr(tty_fd,TCSANOW,&tio);
// for(i;i<5;i++){
// write(tty_fd,&c,1); //If new data is available on the console, send it to the serial port
// write(tty_fd,&o,1); //If new data is available on the console, send it to the serial port
// }
int n=0;
char buf = '\0';
/* Whole response*/
do
{
n = read( tty_fd, &buf, sizeof(char) );
}
while( n > 0);
if (n < 0)
{
printf("ERROR READING");
}
else if (n == 0)
{
printf("Read nothing!");
}
else
{
printf("Response: %c",buf);
}
close(tty_fd);
tcsetattr(STDOUT_FILENO,TCSANOW,&old_stdio);
return EXIT_SUCCESS;
}
How do I solve this?
UPDATE
I tried this other code and receive a warning: turning off output flushing and then the terminal froze.
#include <stdio.h> // Standard input / output functions
#include <stdlib.h>
#include <string.h> // String function definitions
#include <unistd.h> // UNIX standard function definitions
#include <fcntl.h> // File control definitions
#include <errno.h> // Error number definitions
#include <termios.h> // POSIX terminal control definitions
#define XBEE "/dev/ttyUSB0"
#define BAUDRATE B9600
int main(int argc,char** argv)
{
struct termios tio;
struct termios stdio;
struct termios old_stdio;
struct termios options;
int tty_fd = open(XBEE , O_RDWR | O_NOCTTY | O_NDELAY);
cfsetospeed(&tio,BAUDRATE);
cfsetispeed(&tio,BAUDRATE); // Baudrate is declared above
tcsetattr(tty_fd,TCSANOW,&tio);
options.c_cflag &= ~PARENB;
options.c_cflag &= ~CSTOPB;
options.c_cflag &= ~CSIZE;
options.c_cflag |= CS8;
// for(i;i<5;i++){
// write(tty_fd,&c,1);//if new data is available on the console, send it to serial port
// write(tty_fd,&o,1);//if new data is available on the console, send it to serial port
// }
int n=0;
char buf = '1';
int i = 1;
/* Whole response*/
while(i==1){
n = read( tty_fd, &buf, sizeof(char) );
if (n < 0)
{
printf("ERROR READING");
}
else if (n == 0)
{
printf("Read nothing!");
}
else
{
printf("Response: %c",buf);
close(tty_fd);
break;
}
}
tcsetattr(STDOUT_FILENO,TCSANOW,&old_stdio);
return EXIT_SUCCESS;
}

Answer 1

If you're going to be using C to communicate with XBee modules, you might want to check out this Open Source XBee Host library. You could just use the serial driver from it in your code, or take a look at the xbee_term sample program as a simple terminal.

Answer 2

If you are printing data, why are you using printf? You must use the Serial.print() syntax w.r.t the Arduino IDE.