>From: "Govinda Parida" <[EMAIL PROTECTED]>
>To: [email protected]
>Subject: communicating with serial port
>Date: Wed, 7 Mar 2007 17:14:46 +0530
>
>Hi
>I am using gtkmm for GUI. My operating system is Obuntu.
>In my application i need like this.
>I have to open a window which contain a label "swipe the card", I have
>magnetic swipe card reader which is connected to serial port after that it
>reads data from serial port. if it will read correctly then new window will
>be open.So please help me.
>Thanks in advance.
Those are the functions I use to open serial ports ( I have almost
copy&paste the functions so maybe there are some class functions not listed
here , as for example the error printing functions ... ).
int libreria_serie::tty_open(char *line, int baudios, char *par, char *bits,
int stop,int hw_flow, int sw_flow)
{
int puerto; // Port descriptor
char devname[100], error_mens[80];
int modo;
modo = (O_RDWR | O_NONBLOCK | O_EXCL);
//modo = (O_RDWR);
if ((puerto = open(line, modo)) <0) {
sprintf(error_mens,"Cant open %s: %s", devname, strerror(puerto));
this->tty_error(error_mens); // Error printing function
return(-1);
}
if(isatty(puerto) == 0) {
sprintf(error_mens,"%s not a tty\n", devname);
this->tty_error(error_mens);
return(-1);
}
// Save the port attributtes to save then during close
if(tcgetattr(puerto, &this->termios_original) < 0)
this->tty_error("Error while doing tcgetattr\n");
// configure the serial port
this->tty_m_setparms(puerto, baudios, par, bits, stop, hw_flow, sw_flow);
return(puerto);
}
void libreria_serie::tty_m_setparms(int fd, int newbaud, char *par, char
*bits, int stop,int hwf, int swf)
{
int spd = -1;
int bit = bits[0];
struct termios tty;
tcgetattr(fd, &tty);
/* We generate mark and space parity ourself. */
if (bit == '7' && (par[0] == 'M' || par[0] == 'S'))
bit = '8';
// Marcamos la velocidad
newbaud=newbaud/100;
switch(newbaud) {
case 0:
spd = 0; break;
case 3: spd = B300; break;
case 6: spd = B600; break;
case 12: spd = B1200; break;
case 24: spd = B2400; break;
case 48: spd = B4800; break;
case 96: spd = B9600; break;
case 192: spd = B19200; break;
case 384: spd = B38400; break;
case 576: spd = B57600; break;
case 1152: spd = B115200; break;
}
if (spd != -1) {
cfsetospeed(&tty, (speed_t)spd);
cfsetispeed(&tty, (speed_t)spd);
}
switch (bit) {
case '5':
tty.c_cflag = (tty.c_cflag & ~CSIZE) | CS5;
break;
case '6':
tty.c_cflag = (tty.c_cflag & ~CSIZE) | CS6;
break;
case '7':
tty.c_cflag = (tty.c_cflag & ~CSIZE) | CS7;
break;
case '8':
default:
tty.c_cflag = (tty.c_cflag & ~CSIZE) | CS8;
break;
}
/* Set into raw, no echo mode */
tty.c_iflag = IGNBRK;
tty.c_lflag = 0;
tty.c_oflag = 0;
tty.c_cflag |= CLOCAL | CREAD;
// Para permitir poner 1 o 2 bits de stop
if(stop==2) tty.c_cflag|=CSTOPB;
tty.c_cc[VMIN] = 0;
tty.c_cc[VTIME] = 10;
if (swf)
tty.c_iflag |= IXON | IXOFF;
else
tty.c_iflag &= ~(IXON|IXOFF|IXANY);
tty.c_cflag &= ~(PARENB | PARODD);
if (par[0] == 'E')
{
tty.c_cflag |= PARENB;
}
else if (par[0] == 'O')
{
tty.c_cflag |= PARENB;
tty.c_cflag |= PARODD;
}
tcsetattr(fd, TCSANOW, &tty);
// m_setrts(fd);
this->tty_m_sethwf(fd, hwf);
}
/************************************** m_sethwf
*****************************/
/* Set hardware flow control. */
void libreria_serie::tty_m_sethwf(int fd, int on){
struct termios tty;
tcgetattr(fd, &tty);
if (on)
tty.c_cflag |= CRTSCTS;
else
tty.c_cflag &= ~CRTSCTS;
tcsetattr(fd, TCSANOW, &tty);
}
Using those function we can open a serial port has follows :
int desc;
SigC::Connection conexion;
// Open /dev/ttyS0 at 9600baud 8N1 no hw/sw flow control
if(desc = tty_open("/dev/ttyS0",9600,'N','8',1,0,0)<0)
{
// ERROR
}
// Now we have a valid descriptor for the port let start reading from it
if(conexion.connected())
conexion.disconnect();
// Activate callback
conexion =
Glib::signal_io().connect(SigC::slot(*this,&class_name::callback_funcion),
Glib::IOChannel::create_from_fd(desc),
Glib::IO_IN,Glib::PRIORITY_HIGH);
if(!conexion.connected())
{
// ERROR
}
With this callback_funcion is called whenever is something to be read on the
serial port.
bool class_name:callback_funcion(Glib::IOCondition io)
{
// Reading buffer
gchar c[TAM_BUFFER];
// Recogemos todo lo que haya hasta ese momento
gint res = -1;
res = read(c,TAM_BUFFER);
// Now res has the number of chars readed from the port
if(res>0) // Todo bien
do_what_you_need_with_data(c,res); // Pass the chars to the needed
function
else if(res<0) // Error
{
// ERROR, something failed when reading the data
}
else // (res==0)
{
// ERROR or WARNING there where no data on the port
}
return true; // We continue active
}
If you need to write data to the port just use
write(file_desc,char_buffer*,char_count);
Also remenber to close the port on exit :-)
Hope it helps, ( or at least dont confuse you even more ;-) )
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