Yrurtj

I am using stty configured serial ports on an embedded ubuntu 15.10 system to communicate between a machine vision process on the ubuntu system and a flight controller. The ports are used only between the embedded system and the flight controller. This works fine for com between these 2 systems

I log into the embedded system using ssh over wifi. This also works fine.

UNTIL, the machine vision process tries to get console input. Just good old scanf(). Or fgets(). Or cin.

If I turn off the embedded system to flight controller communications, scanf() and similar work fine. But if that underlying code is running, input from stdin no longer works. scan() doesn't wait for any input, and the buffer has garbage in it. Similar results using fgets(), etc.

Reading suggests that stty sets stdin to the port being configured. If so, the open() and close() calls in the communications code are likely closing stdin, and could be the source of my issue. Is there a way to use stty without changing stdin to stop this? I have tried lots of combinations but haven't found one that fixes things.

Here are the current stty config statements:

stty -F /dev/ttyS1 115200

stty -F /dev/ttyS2 115200

Here is the abbreviated com code that uses them - argument dev is cstring of dev name:

    while(keepTryingCount) {



        // open dev

        // if fd invalid, and open() fails; report and exit

        if(fd==-1 && (fd=open(dev, O_RDONLY | O_NOCTTY)==-1)) {

            msg("cannot open port from fc %s: errno error: %s. exiting nown", dev, strerror(errno));

            exit(0);

        }

        // check for bytes to read, if here fd is valid

        // if ioctl() fails

        //  report, close and mark fd, dec keepTryingCount: close/open dev seems to fix ioctl() issues

        bytesToRead = 0;

        if(ioctl(fd, FIONREAD, &bytesToRead)==-1) {

            msg("readFCmsg() ioctl error %d %sn", errno, strerror(errno));

            close(fd); fd=-1; --keepTryingCount;

        }



        // if here, fd open, and ioctl() successful, so test for #bytes to read

        else if(bytesToRead>0) {



            // lots of code doing reading and buffer mgm't omitted





        else {

            close(fd); fd=-1; keepTryingCount=0;

        }

    } // end while(keepTryingCount)

I have also tried configuring the ports using setserial. This appears to never work. setserial -a reports the change, but the ports don't work, and stty reports they remain set at 9600 baud. Here are the setserial commands I tried:

setserial /dev/ttyS1 spd_cust baud_base 115200 divisor 1

setserial /dev/ttyS2 spd_cust baud_base 115200 divisor 1

I did try altering the boot time config file - in this case /var/lib/setserial/autoserial.conf. There is no /etc/serial.conf, or /var/run/setserial.conf, that I can find. This also does not seem to work.

So, having experimented a few days away - I thought I'd ask for some help.

Any and all constructive comments welcome!

thanks