| webquinty |
01-08-2016 04:21 AM |
Why serial port /dev/ttyS1 after a while only send data and doesn't receive?
Hello,
I have kernel 3.6.11 with real time support (ingo molnar patch) and my app use serial port to connect access door control.
When app start, all works fine, but after a while ( 1 day or one week ) serial port doesn't receive anything but it is possible to send data.
Code:
n_bytes = read(fd_485, &byte_485, 1);
The function above always return me -1 and interrupt doesn't increase.
This is very strange, it's like driver doesn't reset flag interrupt, but I can't check or I don't known how to check it from user space.
This is init function where configure and open port:
Code:
int openserial(char *devicename)
{
int fd;
struct termios attr;
struct serial_struct serial;
if ((fd = open(devicename, O_RDWR | O_NOCTTY | O_NDELAY)) == -1)
perror("openserial(): open()");
if (tcgetattr(fd, &oldterminfo) == -1)
perror("openserial(): tcgetattr()");
attr = oldterminfo;
attr.c_oflag = 0;
//**************************************************************************************
//**************************************************************************************
cfsetispeed(&attr, B19200);
cfsetospeed(&attr, B19200);
cfmakeraw(&attr); //--> OBTENER LOS DATOS EN RAW
attr.c_cflag |= PARENB; //--> HABILITAMOS LA PARIDAD
attr.c_cflag &= ~PARODD; //--> HABILITAMOS LA PARIDAD PAR
attr.c_cflag &= ~CSTOPB; //--> UN BIT DE STOP
attr.c_cflag &= ~CSIZE; //--> ACTIVAMOS 8 BITS DE DATOS
attr.c_cflag |= CS8;
attr.c_cflag &= ~CRTSCTS; //--> NO HAY CONTROL DE FLUJO DE HARDWARE
attr.c_iflag &= ~(IXON | IXOFF | IXANY); //--> NO HAY CONTROL DE FLUJO DE SOFTWARE
attr.c_cflag |= (CLOCAL | CREAD); //--> ENABLE RECEIVER AND SET LOCAL MODE
attr.c_cc[VMIN] = 1; //--> LECTURA MINIMA DE CARACTERES DEL BUFFER
attr.c_cc[VTIME] = 10; //--> TIMEOUT DE LECTURA DE CARACTERES, EN PASOS DE 0.1 SEG
ioctl(fd, TIOCGSERIAL, &serial);
serial.flags |= ASYNC_LOW_LATENCY; // (0x2000)
ioctl(fd, TIOCSSERIAL, &serial);
//**************************************************************************************
//**************************************************************************************
if (tcflush(fd, TCIOFLUSH) == -1)
perror("openserial(): tcflush()");
if (tcsetattr(fd, TCSANOW, &attr) == -1)
perror("initserial(): tcsetattr()");
return fd;
}
And this is a function where I read all data avaible in serial port:
Code:
while (1)
{
n_bytes = read(fd_485, &byte_485, 1);
if (n_bytes < 0)
{
error_rs485_negative = n_bytes;
}
else if (n_bytes == 0)
{
error_rs485_zero ++;
}
else
{
buffer_485[commEnd] = byte_485;
commEnd = ( commEnd + 1 ) BUFFER_RS485;
commItems ++;
}
// Tiempo de espera para no dejar la CPU tostada
//********************************************************
usleep(2000); // Se ejecuta cada 1 ms, si no , peta la CPU con carga al 100%
counter_rs485 ++;
}
and cat /proc/tty/driver/serial
Code:
0: uart:16550A port:000003F8 irq:4 tx:0 rx:0
1: uart:16550A port:000002F8 irq:3 tx:336 rx:540 fe:6 pe:60 DTR
2: uart:unknown port:000003E8 irq:4
3: uart:unknown port:000002E8 irq:3
I suppose that parity error or frame error isn't the problem because I don't use software and hardware flow control, but now I am not sure.
any advice??
Best reagards. |
