Lecture /dev/ttyUSB0 en C

bool readMessage(int file, unsigned int nCountMax)
{
    int i;
    size_t nbytes;
	ssize_t bytes_read;
 
    if (file != -1)
    {
	    i = 0;  
	    char message[100];
	    char data[100];
		while (i<nCountMax && data != ".")
		{
		    if (read(file, data, 1) == -1)
		    {
			    printf("reception error\n");
			    printf("code errno = %d\n", errno);
			    return false;
		    }
		    else
		    {   
				nbytes = sizeof(data);
				bytes_read = read(file, data, nbytes);
			    message[i] = *data;
			    printf("%c", message[i]);
			    i++;
		    }
		}
	    message[i] = 0;
	    return true;
    }
};

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#include <stdio.h>
#include <stdlib.h>
#include <termios.h>
#include <sys/fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include "serial_port.h"

void read_Serial_Port(const char* DEVICE_PORT)
{
    int file;
    struct termios options;
    unsigned int nCountMax = 60;
    bool b;

    file = open(DEVICE_PORT, O_RDONLY | O_NOCTTY | O_NDELAY);

    if(file == -1){perror("Unable to open the serial port\n");}
    printf("Serial port open successful !\n");

    tcgetattr(file, &options);          
    cfsetispeed(&options, B9600);                   
    cfsetospeed(&options, B9600);                   
    options.c_cflag |= (CLOCAL | CREAD);              
    options.c_cflag |= PARENB;                                          
    options.c_cflag |= PARODD;                                          
    options.c_cflag &= ~CSIZE;                      
    options.c_cflag |= CS8;                                             


    printf("Reading serial port ...\n\n"); 
    b = readMessage(file, nCountMax);

    if (b == 0){printf("Error while reading serial port\n");}
    else printf("\nSerial port read successful\n");

    close(file);
    printf("Serial port closed\n");
};

bool readMessage(int file, unsigned int nCountMax)
{
    int i;
    size_t nbytes;
    ssize_t bytes_read;

    if (file != -1)
    {
        i = 0;  
        char message[100] = {0};
        char data[1] = "";
        nbytes = sizeof(data);

        while (i<nCountMax)
        {
            bytes_read = read(file, data, nbytes);
            if (bytes_read < 0)
            {
                printf("read failed, errno code = %d [%s]\n", errno, strerror(errno));
                return false;
            }
            else
            {   
                message[i] = *data;
                printf("%c", message[i]);
                i++;
            }
        }
        message[i] = 0;
        return true;
    }
}

bytes_read = read(file, data, 1);
if (bytes_read > 0)
{   
    message[i] = *data;
    printf("%c", message[i]);
    i++;
}

bytes_read = read(file, data, nbytes);
if (bytes_read > 0)
{
   for (j=0;j<bytes_read;j++) printf("%c", data[j]);
   i+=bytes_read;
...

bool readMessage(int file, unsigned int nCountMax) 
{ 
    int i; 
    size_t nbytes; 
 ssize_t bytes_read; 
     
    if (file != -1) 
    { 
     i = 0;   
     char message[100] = {0}; 
     char data[1] = ""; 
     nbytes = sizeof(data); 
      
  while (i<nCountMax) 
  { 
   bytes_read = read(file, data, 1); 
      if (bytes_read >0) 
      {    
       message[i] = *data; 
       printf("%c", message[i]); 
       i++; 
      } 
  } 
     message[i] = 0; 
     return true; 
    } 
}

Start read_Serial_Port function ...
Serial port open successful !
Reading serial port ...

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Serial port read successful
Serial port closed

int main()
{
	const char* DEVICE_PORT = "/dev/ttyUSB0";
	
	printf("Start read_Serial_Port function ...\n");
   	read_Serial_Port(DEVICE_PORT);
}

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#include <stdio.h>
#include <stdlib.h>
#include <termios.h>
#include <sys/fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include "serial_port.h"

void read_Serial_Port(const char* DEVICE_PORT)
{
	int file;
	struct termios options;
	unsigned int nCountMax = 60;
	bool b;
	
	file = open(DEVICE_PORT, O_RDONLY | O_NOCTTY | O_NDELAY);
	
	if(file == -1){perror("Unable to open the serial port\n");}
	printf("Serial port open successful !\n");
	  
	tcgetattr(file, &options); 			
	cfsetispeed(&options, B9600); 					
	cfsetospeed(&options, B9600); 					
	options.c_cflag |= (CLOCAL | CREAD); 			  
	options.c_cflag |= PARENB; 					
	options.c_cflag |= PARODD; 						 					
	options.c_cflag &= ~CSIZE; 						
	options.c_cflag |= CS8;			
	 
	printf("Reading serial port ...\n\n"); 
	b = readMessage(file, nCountMax);
	
	if (b == 0){printf("Error while reading serial port\n");}
	else printf("\nSerial port read successful\n");
	
	close(file);
	printf("Serial port closed\n");
};

bool readMessage(int file, unsigned int nCountMax)
{
    int i,j;
	ssize_t bytes_read;
    
    if (file != -1)
    {
	    i = 0;
	    char data[1] = "";
	    
		while (i<nCountMax)
		{
			bytes_read = read(file, data, sizeof(data));
			if (bytes_read > 0)
			{
			   	printf("%c", data[0]);
			   	i += bytes_read;
			}
		}
	    return true;
    }
};