Create new SerialPort object when System.OperationException occurs

[doingnz]

Recreate SerialPort object when Meadow is reset and the SerialPort connection is lost.

This change feels like a hack, however simple testing shows it works. With this change, I can do meadow listen and then reset the Meadow by pressing the physical Reset button or I can Publish a new app from the cloud and listen reconnects when the Meadow restarts after outputting a message.

Meadow StdOut: Updater State -> UpdateInProgress
Meadow StdOut: Applying update from '/meadow0/update-store/42c6dcf2bdf243b389fca94303792b2d/42c6dcf2bdf243b389fca94303792b2d.zip'
Meadow StdOut: Extracting update to '/meadow0/update'...
Meadow StdOut: Extracting took 2.595 seconds.
Meadow StdOut: Contents of Update
Meadow StdOut: ------------------
Meadow StdOut: + update
Meadow StdOut: + update
Meadow StdOut: + app
Meadow StdOut: - App.dll
Meadow StdOut: + alt-min
Meadow StdOut: Stopping application to allow update
Meadow StdOut: Requesting a device reset to apply the Update
Meadow StdOut: Resetting device...
-----------------------------------------------------
An error occurred while listening to the serial port.
Open new MeadowSerialDevice.OpenSerialPort("COM6")
-----------------------------------------------------
Meadow StdInfo: Meadow successfully started MONO
Meadow StdOut: Log level: Trace
Meadow StdOut: LoadSettings took 5110
Meadow StdOut: Looking for app assembly...
Meadow StdOut: Found '/meadow0/App.dll'
Meadow StdOut: Looking for IApp...
Meadow StdOut: App is type MeadowApp
Meadow StdOut: Finding 'MeadowApp' took 0ms
Meadow StdOut: Creating 'F7FeatherV2' instance took 1635ms
Meadow StdOut: Device Initialize starting...
Meadow StdOut: Device is configured to use WiFi for the network interface```

Long term might be better to pass in a SerialPortFactory rather than a SerialPort given SerialPort.Close() or SerialPort.Dispose() amount to the same thing forcing one to do a new SerialPort(...)

Testing was only done on Windows, need to test on other supported platforms.

Testing Steps - Local Hardware Reset.

1. deploy application to meadow.
2. Run meadow listen and confirm trace output displayed from running application
3. Press Reset button on Meadow to restart the hardware.
4. Meadow CLI should display a banner warning connection to Meadow lost
5. When Meadow reboots, the trace output should be displayed after the banner without needing to close CLI and re-run meadow listen

OTA publish

1. Deploy OTA enabled application to meadow
2. Run meadow listen and confirm trace output displayed from running application
3. Publish OTA update
4. Meadow should reboot once OTA update has been applied.
5. Meadow listen should automatically reconnect and continue to display the trace output without re-running meadow listen

[CartBlanche]

@doingnz thanks for sending the PR. I'll be playing with it this weekend and will reply back on Monday.

[CartBlanche]

I did some initial testing on Mac and I'm not seeing the reconnect, so think I may be doing something wrong.

@doingnz could you outline, in the PR description, the detailed steps required to test the change.

[doingnz]

I have added testing steps to description. Note only tested on Windows.

You may want to enable VS2022 to break on System.OperationCanceledException to confirm this exception is raised on a MAC or other supported platforms. When you press Reset button on Meadow, then the lower driver layers for the SerialPort should raise an exception as the USB connection was lost.

[doingnz]

There may be other unintended consequences of this change on the CLI when using the meadow flash os command. I am currently seeing different behaviour in my CLI build with this change compared to the regular 1.2.0 CLI where my version fails to progress past the step after verifying Mono runtime successfully flashed. Just repeatedly outputs Connecting to Meadow on COMx

Meadow StdInfo: Verifying 80% complete
Meadow StdInfo: Verifying 90% complete
Meadow StdInfo: Mono runtime successfully flashed.

Transfer Complete, wrote 3145728 bytes to Meadow

-----------------------------------------------------
An error occurred while listening to the serial port.
Open new MeadowSerialDevice.OpenSerialPort("COM3")
-----------------------------------------------------

Connecting to Meadow on COM3


Connecting to Meadow on COM3


Connecting to Meadow on COM3

[doingnz]

If I comment out the exception handler, then meadow flash os works correctly. Appears a higher layer of code is expecting the exception and uses it to advance the state of the CLI when flashing the OS.

Someone more familiar with the CLI would need to give some thought on where is the best place to create a new SerialPort object after the connection is lost when the USB disconnects on Meadow restart.

[CartBlanche]

@doingnz thanks again for the PR, but just wanted to let you know that we've been working on v2 of the CLI (https://github.com/WildernessLabs/Meadow.CLI/tree/develop/Source/v2 ) so the team's focus is in getting that ready and stable for public consumption. If you have the time/cycles please grab the v2-alpha from the latest CI off develop branch (the zip file is named *..1.3.5.0.zip) , but once unzipped you'll see if it 2.0.0.0) and let me know if you are still seeing the System.OperationException.

After downloading the zip file and extracting it, be sure to uninstall the current CLI 1st, then:
dotnet tool install WildernessLabs.Meadow.CLI --global --version '2.0.0.0-alpha' --add-source .
where "." is the path to the download location of extracted *nupkg.

The commands will change for that release. So for flashing use:
firmware write -v 1.x.x.x
and before calling device info use:
port select Select a port from a list of available local serial ports

then the usual device info.

D.