Provide Serial Monitor data interface via virtual port for use by external tools

[bixbyru]

Describe the request

Provide a means to route traffic from the USB serial connection to an external virtual port which would be accessible via an external terminal.

Since this routing mechanism is already in place, it seems that it would not be that difficult to implement.

🙂 Users who prefer to use an external terminal would benefit from the same convenient serial port juggling capability Arduino IDE provides to Serial Monitor users.

🙂 This would reduce user pressure for addition of advanced capabilities to the Arduino IDE Serial Monitor.

Describe the current behavior

Access to the board's port may be required by the sketch upload tool in addition to by Serial Monitor. In order to allow sketch uploads to be performed while Serial Monitor is open, Arduino IDE automatically disconnects Serial Monitor from the port at the start of the upload process, then reconnects Serial Monitor after it finishes.

Serial Monitor intentionally has a very simple design, which may lack functionality some users require. They may thus use a more capable standalone terminal (e.g., PuTTY, xterm).

🙁 Use of an external terminal is inconvenient because the user must manually close the port in the standalone terminal before performing each sketch upload via Arduino IDE (otherwise the upload will fail due to the terminal blocking access to the port).

Arduino IDE version

155f0ae

Operating system

All

Operating system version

Any

Additional context

Additional requests

• https://forum.arduino.cc/t/ive-seen-a-few-posts-about-the-serial-monitor/1411877/8
• https://forum.arduino.cc/t/ive-seen-a-few-posts-about-the-serial-monitor/1411877/10

Related

• Add a "line wrap" switch to the serial monitor #257
• Tear off serial monitor window (and maybe others) #289
• Serial Monitor plugin system to be able to add protocols like VT100, VTX, VTnnn, etc. #406
• Add a save output to file option to serial monitor #549
• Add search capability in serial monitor #1553
• Clear Serial Monitor output field on receipt of control character #1726
• Add HEX mode to Serial Monitor #1727
• Serial monitor character encoding option #1728
• Add support for pasting multi-line strings in Serial Monitor #2164
• detect clickable links in serial monitor terminal with offset color? #2390

Issue checklist

• I searched for previous requests in the issue tracker
• I verified the feature was still missing when using the latest nightly build
• My request contains all necessary details

[dankeboy36]

hello, I like the idea and I am mainly commenting because I am interested in implementing something similar around the Arduino CLI, and the Arduino IDE could also use this, instead of using the gRPC API of the CLI directly.

From my side, the main challenge is port arbitration during upload. A virtual port (pty on Linux/macOS, RFC2217/TCP on all OSes) is easy to expose, but the uploader still needs exclusive access to the real device. If an external terminal is attached to the virtual port while the IDE starts an upload, you typically end up with a busy port error unless there is a coordinator. This is something the Arduino IDE can do because it has full control over the monitor widget and performs the upload command.

One workable approach is to have a small bridge process that owns the real serial port and exposes a virtual endpoint to external tools. Before upload, the IDE/CLI would tell the bridge to suspend: it closes the hardware port, keeps the virtual endpoint open, and either buffers or drops I/O (optionally toggling carrier so terminals pause). After upload, the bridge resumes and the external terminal continues without needing to reconnect.

Notes:

• On Linux/macOS we can provide a PTY that looks like a normal tty and also an RFC2217/TCP endpoint.
• On Windows, creating a true virtual COM port requires a driver (e.g., com0com), so RFC2217/TCP is the practical default; tools like PuTTY/Tera Term/pySerial can connect over TCP.
• Without a suspend/resume hook from the IDE/CLI (or the uploader using the same bridge), uploads will remain racy with external tools.

If there is interest, I can prototype this with the Arduino CLI: a bridge service with a suspend()/resume() API that the IDE calls around uploads. (Related: dankeboy36/vscode-arduino-api#8 (comment))

If anyone knows of existing implementations in PlatformIO or other toolchains that coordinate uploads with a virtual port, I would be happy to investigate.

[ritesh006]

@bixbyru is this you problem solved with solution provided by @dankeboy36

[ritesh006]

@bixbyru I hope your problem is solved