[ts-7000] Re: Disabling TS-UARTs on TS-7800

["malcolmnixon" <>]

> At the lowest level, a TS-UART is enabled when its speed is set to a 
> non-zero baud rate.  When the baud rate is 0 the port is disabled. 
>  From the software perspective under Linux, the port is disabled when 
> the corresponding device node(s) are closed, and enabled when a 
> corresponding device node is open.  (I put "(s)" because many TS-UARTs 
> have a separate device node for 9-bit mode.)
> 
> If you never open the device and never write a different value to the 
> STAT register of that port you are effectively keeping it disabled.

Still no luck. I produced a test application (source included at the end of 
this message) in order to test both hypotheses:
  1) Never opening /dev/ttts5.
  2) Opening /dev/ttts5 and configuring a baud rate of 0.

To test only accessing /dev/ttts4 run:
    'sertest -rts=/dev/ttts4'

To test accessing /dev/ttts4 with /dev/ttts5 set to 0 baud run:
    'sertest -rts=/dev/ttts4 -dis=/dev/ttts5'

In either case (when executed from a cold reboot) the scope shows the RTS line 
held low at ~ -6V without toggling. Conversely if the application is compiled 
for Linux or Cygwin the scope shows a nice 1Hz toggle (executed with 'sertest 
-rts=/dev/ttyS0')

Many thanks for the assistance,
 - Malcolm

/************ sertest.c follows *************/

#include <sys/termios.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>

int main(int argc, const char **argv)
{
    const char *rts_dev = "/dev/ttts4";
    const char *dis_dev = NULL;
    int rts_fh;
    int dis_fh;
    int i;
    
    /* Process Command-line Arguments */
    for (i = 1; i < argc; ++i)
    {
        if (strcmp(argv[i], "-?") == 0 || strcmp(argv[i], "--help") == 0)
        {
            printf("sertest [-rts=devname] [-dis=devname]\n");
            printf("    -rts : RTS-Toggling device (e.g /dev/ttts4)\n");
            printf("    -dis : Optional Port to Disable (e.g /dev/ttts5)\n");
            return 1;
        }
        else if (strncmp(argv[i], "-rts=", 5) == 0)
        {
            rts_dev = argv[i] + 5;
        }
        else if (strncmp(argv[i], "-dis=", 5) == 0)
        {
            dis_dev = argv[i] + 5;
        }
    }

    /* Test for disable port */
    if (dis_dev != NULL)
    {
        struct termios options;
        
        /* Open disable port */
        printf("Opening Port %s to Disable\n", dis_dev);
        dis_fh = open(dis_dev, O_RDWR | O_NOCTTY | O_NONBLOCK);
        if (dis_fh < 0)
        {
            perror("open");
            return 1;
        }
        
        /* Initialize options */
        memset(&options, 0, sizeof(options));
        options.c_cflag = IGNBRK;
        options.c_oflag = 0;
        options.c_cflag = CREAD | CLOCAL | CS8;
        options.c_lflag = 0;
        cfsetispeed(&options, B0);
        cfsetospeed(&options, B0);
        
        /* Set options */
        if (tcsetattr(dis_fh, TCSANOW, &options) != 0)
        {
            perror("tcsetattr");
            return 1;
        }
    }

    /* Open ttts4 */
    printf("Opening Port %s to Toggle RTS\n", rts_dev);
    rts_fh = open(rts_dev, O_RDWR | O_NOCTTY | O_NONBLOCK);
    if (rts_fh < 0)
    {
        perror("open");
        return 1;
    }
    
    /* Loop Forever */
    for (;;)
    {
        int rts_flg = TIOCM_RTS;
        int nr;
        
        /* Clear the RTS Line */
        nr = ioctl(rts_fh, TIOCMBIC, &rts_flg);
        if (nr != 0)
            perror("ioctl(TIOCMBIC)");
        
        /* Sleep 1 second */
        sleep(1);

        /* Set the RTS Line */
        nr = ioctl(rts_fh, TIOCMBIS, &rts_flg);
        if (nr != 0)
            perror("ioctl(TIOCMBIS)");
        
        /* Sleep 1 second */
        sleep(1);
    }
}





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