Handle unexpected events on serial ports

[facchinm]

While working with low power, the serial port can disappear/reappear very often (see arduino-libraries/ArduinoLowPower#7).

This makes using the serial monitor very frustrating (especially on Linux) since the port will acquire another name if reconnected while the monitor is open. Changing port will close the monitor for good, so it must be reopened manually.

This patch tries to add a couple of "helpers" to make the situation less terrible.

• Automatically reopens the serial monitor when changing port.
• Suspend the serial monitor when the board disappears, and try resuming when it reappears.

[grezco]

I tried this IDE version, but with MKR WiFi1010, on Windows 10, it's the same problem.
The serial.print is not working anymore after it is waking up

[PaulStoffregen]

Could this be done without the timer?

If you look at the work on PluggableDiscovery and try running SerialDiscovery_JSON on Linux, the future may look like near real-time response to USB add & remove events.

One second delay isn't very long for humans, but a device can reset and reappear withing 1 second on most Linux & Mac systems. Even Windows 10 is better about delays with detecting devices. And that's just USB.

[facchinm]

1 second delay is just an example; we could be much more tight since calling discovery() does only recover the cached port list (which are polled once per second or by the event in your implementation).
Anyway, I'm still waiting for libusb/libusb#86 to be finished so we can have a cross platform way to perform hotplug detection

[ArduinoBot]

✅ Build completed.

Please test this code using one of the following:

⬇️ http://downloads.arduino.cc/javaide/pull_requests/arduino-PR-8046-BUILD-791-linux32.tar.xz
⬇️ http://downloads.arduino.cc/javaide/pull_requests/arduino-PR-8046-BUILD-791-linux64.tar.xz
⬇️ http://downloads.arduino.cc/javaide/pull_requests/arduino-PR-8046-BUILD-791-windows.zip
⬇️ http://downloads.arduino.cc/javaide/pull_requests/arduino-PR-8046-BUILD-791-macosx.zip
⬇️ http://downloads.arduino.cc/javaide/pull_requests/arduino-PR-8046-BUILD-791-linuxarm.tar.xz

ℹ️ The linuxarm build is still experimental and may not be always available.

[ArduinoBot]

✅ Build completed.

Please test this code using one of the following:

⬇️ http://downloads.arduino.cc/javaide/pull_requests/arduino-PR-8046-BUILD-884-linux32.tar.xz
⬇️ http://downloads.arduino.cc/javaide/pull_requests/arduino-PR-8046-BUILD-884-linux64.tar.xz
⬇️ http://downloads.arduino.cc/javaide/pull_requests/arduino-PR-8046-BUILD-884-windows.zip
⬇️ http://downloads.arduino.cc/javaide/pull_requests/arduino-PR-8046-BUILD-884-macosx.zip
⬇️ http://downloads.arduino.cc/javaide/pull_requests/arduino-PR-8046-BUILD-884-linuxarm.tar.xz

ℹ️ The linuxarm build is still experimental and may not be always available.

[per1234]

@facchinm build 884 fixes the upload failure reported in #8851 for me. I still get the double ports entry reported there, but I think that part of the issue is already fixed by a different commit since it doesn't occur in the beta build of the IDE, so that's no problem. Thanks!