Hi,
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?
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 */
#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
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???
tcgetattr(fd,&oldtio); // Save current
port settings
// Non-canonical init.
bzero(&newtio, sizeof(newtio));
newtio.c_cflag = BAUDRATE | CRTSCTS | CS8 | CLOCAL | CREAD;
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!
}
}
tcsetattr(fd,TCSANOW,&oldtio); // Restore port settings
}
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