linux serial port help

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Try this code instead to see if it makes any difference. Incidentally, compile this with a command that has at least these options:

gcc -O2 -Wall -W foo.c

You could also add -ansi to the options, and then the code would need "#define GNUSOURCE 1" added at the very top.

int portopen(char *); int portcnfg(int);

#define TESTSTRING "LCD TEST-n" #define DEVICEPORT "-dev-ttyS2" #define BAUD B9600

int main(void) { int fd, bytes;

if (-1 == (fd = portopen(DEVICEPORT))) { fprintf(stderr, "Unable to open port device %s.-n", DEVICEPORT); exit(EXITFAILURE); }

if (-1 == (fd = portcnfg(fd))) { fprintf(stderr, "Unable to configure port device %s.-n", device); exit(EXITFAILURE); }

bytes = write(fd, TESTSTRING, strlen(TESTSTRING));

if (bytes == (int) strlen(TESTSTRING)) { fprintf(stderr, "String written.-n"); } else { switch (bytes) { case -1: fprintf(stderr, "A write error occurred.-n"); break; case 0: fprintf(stderr, "No data was written.-n"); break; default: fprintf(stderr, "Complete string not written.-n"); break; } }

return EXITSUCCESS; }

int portopen(char *device) { int fd;

if (-1 != (fd = open(device, ORDWR ONOCTTY ONONBLOCK))) { if (-1 == (fcntl(fd, FSETFL, 0))) { return -1; } if (-1 == tcflush(fd, TCIOFLUSH)) { close(fd); return -1; } } return fd; }

int portcnfg(int fd) { struct termios tty;

memset(&tty, 0, sizeof tty); * avoids setting each flag. *

tty.ciflag = IGNBRK IGNPAR; * input flags * tty.ccflag = CS8 CREAD CLOCAL;* control flags *

* always set bit rate just before calling tcsetattr() * cfsetispeed(&tty, BAUD); cfsetospeed(&tty, BAUD);

if (-1 == (tcsetattr(fd, TCSAFLUSH, &tty)) { return -1; }

return fd; }

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