Just a quick note. For people (late to) upgrading their Ubuntu installation to Ubuntu 18.04.2 LTS (or near version) the helpful /etc/udev rules that have been successfully separating us from nasty ModemManager issues are no longer being processed.
It was a nasty shock returning to my beloved TinyFPGA after a month with Icarus to find that the board would no longer program.
The remedy (once again) is to disable the ModemManager.
Here’s an Arduino person talking to someone from ModemManager team
Mr ModemManager seems mystified as to why we should be saying we’re a AT device… Perhaps if we find where that happens all this ModemManager horror will go away.
sudo systemctl stop ModemManager.service
Will stop the service. And the following will disable it.
sudo systemctl disable ModemManager.service