X-Recipient: archive-cygwin AT delorie DOT com X-SWARE-Spam-Status: No, hits=-2.1 required=5.0 tests=AWL,BAYES_00,SPF_PASS X-Spam-Check-By: sourceware.org Message-ID: <4AE96795.4080705@gmx.de> Date: Thu, 29 Oct 2009 10:59:49 +0100 From: Matthias Andree User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.8.1.23) Gecko/20090812 Thunderbird/2.0.0.23 Mnenhy/0.7.6.666 MIME-Version: 1.0 To: cygwin AT cygwin DOT com Subject: Re: write() to /dev/ttyS0 has no effect References: <187469a20910290204n67867327w7b8759e1aae85b3e AT mail DOT gmail DOT com> In-Reply-To: <187469a20910290204n67867327w7b8759e1aae85b3e@mail.gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-IsSubscribed: yes Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner AT cygwin DOT com Mail-Followup-To: cygwin AT cygwin DOT com Delivered-To: mailing list cygwin AT cygwin DOT com 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 > #include > #include > #include > #include > #include > > #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