How to simulate UART device

[iBobik]

Describe your core improvement

I use SDL/host platform to simulate embedded project for rapid development, especially LVGL UI.

ESP32 target have UART device which I does not have on the desktop. There I need:

• at least dummy device what will do nothing, just sit in the esphome project so the will think it is there
• better some monitor to show incomming messages on the virtual device from the esphome project
• best have some UI (web or interactive cli) to also send some messages from the virtual device to the esphome project

Is there at least some example how to do simple script in macOS what will create such virtual device I can hook to the esphome project?

Ideally I would like to have option in UART component what will expose websocket where I can send and receive messages by my simple script. Or option what will execute such script and utilize stdio for this.

uart:
  stdio: cat # Simple monitor
  stdio: ./device-simulator.sh
  websocket_port: 8123 # Web app can connect to http://localhost:8123 and offer custom UI simulating the device

Current limitations

Currently port option is practical only for use-cases where I connect real device to the computer

Technical benefits

Improve developer experience where desktop simulator is helpful for complex projects.

Additional context

No response

[ssieb]

You can setup a socket or pty to connect to.

[iBobik]

Yes, this seems like a way, but I was not able to make it working. Some working examples would be helpful.

[ssieb]

This was on Linux, but I think it's the same on mac. It depends on what exactly you're trying to do.
Option 1, maybe one way:
mknod /tmp/pipe p
Use /tmp/pipe for the port: and then you can write to /tmp/pipe from something else and esphome will read it.

Option 2, better:
Install socat using brew or ports.
Run socat PTY,link=/tmp/client PTY,link=/tmp/esphome
Use /tmp/esphome for the port: and then you can read and write to /tmp/client.
There are options to echo the traffic as well.
socat can do TCP and many other things as well, so you could connect a TCP port to the esphome PTY for example.

If you need more help with this, come ask on the esphome discord server.