It seems that at_usb2 is the same as ttyGS0
on the Ubuntu host /dev/ttyUSB3 receives from WP7702 /dev/at_usb2
echo -e “HELLO” > /dev/at_usb2
That is fine by me to use /dev/at_usb2 instead of /dev/ttyGS0,
but is there any documentation describing how all this relates?