I've written a little keyboard to UART script as a first step to something more complex. The following code will let me send data from a PuTTY terminal over the serial connection, display it (STDOUT), and send a period back over the UART. In other words, the UART connection is working.

However, if I uncomment the "my $outchar=<>;" line, everything stops working. I suspect this is because it's blocking. I've also tried replacing the line with a "my $outchar=getc();" line. This works a little better in that the characters coming in over the serial port eventually print, but only if a couple characters are typed on STDIN. This despite the `stty cbreak` instruction.

use warnings;
use strict;

use IO::Termios ();

$| = 1;

my $fh = IO::Termios->open('/dev/ttyAPP4', '115200,8,n,1')
    or die "IO::Termios->open: $!";

`stty cbreak`;
print $fh "Begin\n\r";

while(1){
    my $inchar=<$fh>;
#    my $outchar=<>;
    if($inchar){
        print $inchar;
        print $fh ".";
    }
#    if($outchar){
#       print $fh $outchar;
#    }
}

[download]

Is there a non-blocking approach to doing what I'm after? I managed to get the IO:Termios module installed, though it was a little nightmarish. I dread having to add another module. :p

Thanks in advance for any advice!

Calvin

In reply to problem with simple STDIN to UART script by CSTJr

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