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
