Another issue I had, just FYI:
I had alot of trouble uploading code to tinyscreen+ on Linux. Half the time it would fail or tell me the port was busy. This is due to ModemManager scoping out any serial ports to see if they are GSM modems. You can fix this by putting a udev rule something like this in /etc/udev/rules.d/77-arduino.rules
# stop modemmanager from checking every serial port for a modem.. it locks up the port
# for a few seconds and interferes with uploading.
#
# arduino
ATTRS{idVendor}=="2a03", ENV{ID_MM_DEVICE_IGNORE}="1"
# tinyscreen / atmel
ATTRS{idVendor}=="03eb", ENV{ID_MM_DEVICE_IGNORE}="1"
...as described here:
http://starter-kit.nettigo.eu/2015/serial-port-busy-for-avrdude-on-ubuntu-with-arduino-leonardo-eth/