I'm trying to write a program to talk to a serial port (eventually to=20
talk to an embedded device but for now i'm using a null modem cable=20
hooked up to a windows PC running putty). The program was initially=20
written in pascal but I translated it to C both to check if the problem=20
was a bug in the fpc run time library and to make it easier to get=20
assistance with it.

The word test is sent sucessfully to the machine running putty but=20
nothing is received. This issue happens with both the pascal and C=20
versions of the code. Anyone familiar with termios able to tell me where=20
i'm going wrong?

i'm pretty sure the hardware is ok because I have tested it using minicom.

pascal version

program gateway;
uses
  baseunix,
  unix,
  unixutil,
  termio; // despite the name the fpc termio unit seems to be an=20
interface to termios
var
  device: string;
  fd : longint;
  config : termios;
  count : longint;
  buf : array[0..1023] of byte;
begin
  device :=3D paramstr(1);
  fd :=3D fpopen(device,O_RDWR or O_NOCTTY);
  writeln(fd);
  if isatty(fd)=3D0 then begin
    writeln('not a tty');
    halt(1);
  end;
  if tcgetattr(fd,config) <0 then begin
    writeln('could not get termios attributes');
    halt(2);
  end;
  config.c_iflag :=3D 0;
  config.c_oflag :=3D 0;
  config.c_cflag :=3D 0;
  config.c_lflag :=3D 0;
  cfmakeraw(config);
  cfsetispeed(config,B19200);
  cfsetospeed(config,B19200);
  config.c_cc[VMIN]  :=3D 1;
  config.c_cc[VTIME] :=3D 0;
  if   tcsetattr(fd,TCSAFLUSH,config) <0 then begin
    writeln('could not set termios attributes');
    halt(3);
  end;
  fpwrite(fd,'test'#13#10,6);
  while true do begin
    writeln(fd);
    count :=3D fpread(fd,buf,sizeof(buf));
    writeln(count);
    fpwrite(fd,buf,count);
//    writeln(count);
  end;
  fpclose(fd);
end.


C version

#include <termios.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>


int main(int argc, char *argv[])

{
  struct termios config;
  char * device;
  int fd;
  char buf[1024];
  int count;
  device =3D argv[1];
  fd =3D open(device,O_RDWR | O_NOCTTY);
  printf("%i\n",fd);
  if (!isatty(fd)) {
    printf("not a tty\n");
    return 1;
  }
  if (tcgetattr(fd,&config) <0) {
    printf("could not get termios attributes\n");
    return 2;
  }
  config.c_iflag =3D 0;
  config.c_oflag =3D 0;
  config.c_cflag =3D 0;
  config.c_lflag =3D 0;
  cfmakeraw(&config);
  cfsetispeed(&config,B19200);
  cfsetospeed(&config,B19200);
  config.c_cc[VMIN]  =3D 1;
  config.c_cc[VTIME] =3D 0;
  if (tcsetattr(fd,TCSAFLUSH,&config) <0) {
    printf("could not set termios attributes\n");
    return 3;
  }
  write(fd,"test\r\n",6);
  while (1) {
    printf("%i\n",fd);
    count =3D read(fd,&buf,sizeof(buf));
    printf("%i\n",count);
    write(fd,&buf,count);
//    writeln(count);
  }
  close(fd);
  return 0;
}
--=20
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