`esp32` / `esp32c3` Serial object.

[bill88t]

Currently on boards without usb_cdc it's impossible to get a console object for the main uart/serial peripheral interface.

It's needed to read in_waiting, reset_input_buffer, reset_output_buffer and have access to raw read/write.

[tannewt]

For the ESP32 I think a board.SOMETHING for the UART object should be sufficient.

On C3 we will need to make an object for the USB to Serial/JTAG interface.

[bill88t]

Perhaps, due to how few use console objects, it would be wise to just make a python module for now, to wrap the old serial functions.

It would only need to:

• Wrap the regular serial i/o.
• While serial bytes available is True, read them in a temporary buffer and return the count in in_waiting.

connected and out_waiting do not have to be implemented/wrapped, since they are not applicable.

I will make it and name it virtUART. Perhaps as a 9.0 api change, it should be considered doubling down on the nice console objects, replacing runtime.serial* stuff and instead provide a runtime.serial console object.

The main benefit of such an approach is that console objects can be swapped on-the-fly (replaced in a class), to redirect the io.

I have already implemented the code for it in jcurses, and it works beautifully.
Such switching code could be used with bluetooth uart and perhaps even wifi.

I could in the future even imagine the circuitpython core logs being passed around via wifi just by setting a console object in supervisor.

[berkut0]

I recently discovered that I can't communicate with the ESP32-C3 based controller via serial port bypassing REPL. It's not the most convenient thing in the world! I think I'll have to swap out the ESP32-C3 for another board.