Matthias, vielen Dank!
It works now. Your questions were mostly about unrelated code that somehow survived as I stripped things down to make the example. Removing CRTSCTS did the trick. I see that you are using non-canonical reads. Do you know if canonical works on Cygwin? In my finished program I will indeed be reading input from the UART. But "res = read(fd,inbuf,255);" returns on several occations when it contents are not terminated by \n, \r or 0. As you probably see from my code, I have copied the Serial HOWTO code. Børge On Thu, Oct 29, 2009 at 10:59, Matthias Andree <matthias.and...@gmx.de> wrote: > Børge Strand-Bergesen schrieb: > >> I'm writing some C code to control an external MCU over UART. >> Everything works like a charm using TeraTerm or cat >>/dev/ttyS0. gcc >> is 3.4.4. In a different program (not inserted), I am able to use >> read() to get information from the MCU. Cygwin is "CYGWIN_NT-5.1 >> 1.5.25(0.156/4/2) 2008-06-12 19:34". >> >> However, it seems like no information is sent when I call write(). Are >> there any known bugs with Cygwin when it comes to this? > > "Works for me", albeit with MSP430 behind a FTDI USB/serial converter and > without CRTSCTS and lower bit rate (57600). > >> I have inserted my code below. Thanks for any help! >> >> "f" is a valid command to the MCU. The MCU will disregard any \r or >> \n. I have tried hitting the enter button, not just 'a' on the >> keyboard. >> >> >> Borge >> >> >> #include <sys/types.h> >> #include <sys/stat.h> >> #include <fcntl.h> >> #include <termios.h> >> #include <stdio.h> >> #include <string.h> >> >> #define BAUDRATE B115200 >> #define MODEMDEVICE "/dev/ttyS0" >> #define _POSIX_SOURCE 1 /* POSIX compliant source */ > > This must be before the first #include. > >> #define FALSE 0 >> #define TRUE 1 >> >> >> FILE *keyboard; >> int status; >> >> main() >> { >> int fd,c, res; >> struct termios oldtio,newtio; >> >> keyboard = fopen("/dev/tty", "r"); //open the terminal keyboard > > What's that good for? You're not using that. > >> if (!keyboard) >> { >> fprintf(stderr, "Unable to open /dev/tty\n"); >> exit(1); >> } >> >> fd = open(MODEMDEVICE, O_RDWR | O_NOCTTY ); >> if (fd <0) {perror(MODEMDEVICE); exit(-1); } >> >> fcntl(fd, F_SETFL, 0); // Needed??? > > Not needed. > >> >> tcgetattr(fd,&oldtio); // Save >> current port settings >> >> // Non-canonical init. >> bzero(&newtio, sizeof(newtio)); > > bzero() isn't standard. Use memset(), sample below. > >> newtio.c_cflag = BAUDRATE | CRTSCTS | CS8 | CLOCAL | CREAD; > > Does the µC support CRTSCTS? If not, that's why it fails. > > Also, BAUDRATE may not fit into speed_t according to > /usr/include/sys/termios.h, > so you're losing the "extended baud rate" flag and are actually programming 75 > Baud instead of 115200. Use cfsetXspeed (X is i or o) to manipulate newtio > instead, example (in C++): > > struct termios newtio; > /* configure serial interface to 57600 8N1 no-canonical */ > memset(&newtio, 0, sizeof(newtio)); > newtio.c_cflag = CS8 | CLOCAL | CREAD; > newtio.c_iflag = 0; > newtio.c_oflag = 0; > newtio.c_lflag = 0; > newtio.c_cc[VTIME] = 0; > newtio.c_cc[VMIN] = 1; /* at least 1 characters */ > if (cfsetispeed(&newtio, B57600)) throw("cfsetispeed"); > if (cfsetospeed(&newtio, B57600)) throw("cfsetospeed"); > if (tcflush(fd, TCIFLUSH)) throw("tcflush"); > if (tcsetattr(fd, TCSANOW, &newtio)) throw("tcsetattr"); > > >> newtio.c_iflag = IGNPAR; >> newtio.c_oflag = 0; >> newtio.c_lflag = 0; >> newtio.c_cc[VTIME] = 0; // >> inter-character timer unused >> newtio.c_cc[VMIN] = 5; // blocking >> read until 5 chars received >> >> tcflush(fd, TCIFLUSH); >> tcsetattr(fd,TCSANOW,&newtio); >> >> while (1) >> { >> status = getc(stdin); >> if (status == 'a') { >> char outbuf[] = "f"; >> printf("%s", outbuf); // This >> printout is ok >> write(fd, outbuf, 1); // This >> doesn't seem to get sent down the uart! >> } >> >> } > > You're apparently not reading from the serial line. Is that intentional? > >> tcsetattr(fd,TCSANOW,&oldtio); // Restore port >> settings > > This is unreached (dead) code. > >> } > > HTH > > -- > Problem reports: http://cygwin.com/problems.html > FAQ: http://cygwin.com/faq/ > Documentation: http://cygwin.com/docs.html > Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple > > -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple