Hi everybody,
I?ve been trying to use the serial port of a FADS 823 board to control
an external hardware and I had some problems.
I?ve implemented and tested some functions using the serial port of my
PC (running Red Hat 6.2) to make this hardware control and everything
worked fine.
But, when I tried to use the same functions (with the same serial port
configuration) in my FADS board running the 2.4.4 Linux kernel version
(from denx.de), I couldn?t read the messages that I received at my
serial port (read returns -1).
I?ve made another test using the non canonical example mentioned in
Peter Baumann?s howto (Serial Programming Howto) to receive, at my
board, messages that I sent from my PC using miniterm (I?ve used the non
canonical example because the configuration that I use for receiving the
messages at the serial port is similar).
When I tried this, the board?s serial port driver didn?t buffer any
message (well, I think so, cause I coudn?t read nothing) before I sent a
Carriage Return or a Line Feed.
For each message I send, I must to send a CR ou LF before. For example:
PC FADS BOARD
1234 No response
<CR>1234 1234
<LF>1234 1234
This fact doesn?t happen when I use the PC?s serial port to receive
messages (using the same program).
Does anyone know what could be the problem?
Thanks,
Sakai
PS:
The program that I have used for reading the serial port:
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <stdio.h>
#define BAUDRATE B9600
#ifdef PPC
#define MODEMDEVICE "/dev/ttyS0"
#else
#define MODEMDEVICE "/dev/ttyS1"
#endif
#define _POSIX_SOURCE 1 /* POSIX compliant source */
#define FALSE 0
#define TRUE 1
volatile int STOP=FALSE;
main()
{
int fd,c, res;
struct termios oldtio,newtio;
char buf[255];
fd = open(MODEMDEVICE, O_RDWR | O_NOCTTY );
if (fd <0) {perror(MODEMDEVICE); exit(-1); }
tcgetattr(fd,&oldtio); /* save current port settings */
bzero(&newtio, sizeof(newtio));
newtio.c_cflag = BAUDRATE | CRTSCTS | CS8 | CLOCAL | CREAD;
newtio.c_iflag = IGNPAR;
newtio.c_oflag = 0;
/* set input mode (non-canonical, no echo,...) */
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 (STOP==FALSE) { /* loop for input */
res = read(fd,buf,5); /* returns after 5 chars have been input */
//buf[res]=0; /* so we can printf... */
for (c=0;c<res;c++)
printf("%02x ",buf[c]);
printf(":%d\n",res);
//printf(":%s:%d\n", buf, res);
if (buf[0]=='z') STOP=TRUE;
}
tcsetattr(fd,TCSANOW,&oldtio);
}
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