[Soekris] COM2 Problem with OpenBSD4.3 on NET4501

[grice]

OpenBSD 4.3 installed smoothly, but I’ve been wrestling with serial 
communication over COM2 for days now.  At the moment I have a simple C program 
designed to echo any data sent to the serial port to stdout.  I’ve tested the 
program on other OpenBSD 4.3 PCs without issue, but when I move the code to 
the Soekris board, I see data being received, but it’s entirely corrupted.  At 
this point I have tried sending the data at multiple baud rates, both with and 
without CTS/RTS.  The results are always the same.  I receive data as it’s 
being sent, but it’s not the data I expect.

The code for the echo program is listed below.  Must CTS/RTS be connected?  I 
noticed in another message thread, 19200 is the recommended baud rate for 
COM2.  Is this true?  If so, why?  Must I use 19200?  Any other 
recommendations?

Strangely enough, I actually always receive data back from the COM2 connection 
as well, whether the echo program is running or not.  For example, sending the 
character ‘t’, I get back 0x0000.  If I send “test”, I receive 
0x000246000000.  Again, this occurs whether or not the program is running 
(note that the program doesn’t actually return anything via the serial port at 
all).   I suspect this is a configuration issue, but quite honestly I’m a 
loss.  Any suggestions would be greatly welcomed.

Have a great weekend - Greg

Echo Program:

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
        
#define BAUDRATE B9600
#define MODEMDEVICE "/dev/cua01"
#define _POSIX_SOURCE 1 /* POSIX compliant source */ #define FALSE 0 #define 
TRUE 1

int main(int argc, char **argv)
{
      unsigned char serialbuf[512];
      int fd, resume;
      struct termios oldtio, newtio;

      int n = 0;

      // Open serial port for communications
      fd = open(MODEMDEVICE, O_RDWR | O_NOCTTY); 
      if (fd < 0) 
      {
            perror(MODEMDEVICE); 
            exit(-1); 
      }
      else
      {
            printf("\nSerial Port Initializing...\n\n");
      }
    
      // Save existing port settings
      tcgetattr(fd, &oldtio);     
      bzero(&newtio, sizeof(newtio)); 
    
      /* 
             CRTSCTS : flow control 
             CS8     : 8N1 
             CLOCAL  : local connection, no modem contol
             CREAD   : enable receiving characters
      */
      newtio.c_cflag = BAUDRATE | CS8 | CLOCAL | CREAD | CRTSCTS;

      newtio.c_iflag = IGNPAR;
      newtio.c_oflag = 0;
      newtio.c_lflag = 0;

      newtio.c_cc[VTIME]    = 0;  
      newtio.c_cc[VMIN]     = 1;     
    
      // Activate settings
      tcflush(fd, TCIFLUSH); 
      tcsetattr(fd,TCSANOW,&newtio);
    
      // Begin Receiving serial data communication
      printf("\nReceiving on Serial Port...\n");
      while(1)
      {
            resume = read(fd,serialbuf,512); 
            if (resume > 0)
            {   
              printf("Size: %d\n", resume);
              for (n=0; n<resume; n++)
                  printf("%c\n",serialbuf[n]);
            }
            
      }
      tcsetattr(fd, TCSANOW, &oldtio);
      return 0;
}






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