serial port

$ stty -F /dev/ttyACM0 cs8 9600 ignbrk -brkint -imaxbel -opost -onlcr -isig\
-icanon -iexten -echo -echoe -echok -echoctl -echoke noflsh -ixon -crtscts

$ screen /dev/ttyACM0 9600

<?php


$fp =fopen("/dev/ttyACM0", "w+");
if( !$fp) {
        echo "error";d
        die();
}

fwrite($fp, “Hello!”);
fclose($fp);