async input()

[kamocat]

One of the many uses of async coroutines is waiting for user input while completing background tasks.
There are examples for buttons, but digitalIO.value wasn't a blocking function anyway so polling it is trivial.

My issue is that I am trying to use the serial console to interact with the device, and input() is most definitely a blocking function.
The implementations I've found seem to be platform-dependent, communicating with a separate UI thread or relying on non-standard libraries. Even the aioconsole library seems to do this.

It seems there should be a non-blocking way to read from sys.stdio, as it's a stream. There is some discussion of this in the circuitpython docs, but no methods given. The asyncio streams appear to be TCP-only.

[kamocat]

I tried using sys.stdin.read() but apparently that's a blocking function too.

async def ainput():
    while(True):
        x = sys.stdin.read(100)
        if(len(x) > 0):
            return x
        await asyncio.sleep(0.1)

[dhalbert]

you can use supervisor.runtime.serial_bytes_available to see if there's any input to read. Read the characters one at a time with sys.stdin.read(1) until .serial_bytes_available is false.

Right now this is a boolean. In 9.1.0 it will change to an int telling you how many characters are available. See #9141

You can also use usb_cdc.console to read the console stream as bytes. Also note that on many boards you can enable a second CDC input stream that does not have the REPL on it, which you can use solely for data. See https://learn.adafruit.com/customizing-usb-devices-in-circuitpython/circuitpy-midi-serial#usb-serial-console-repl-and-data-3096590. On Espressif there aren't enough USB endpoints available to enable it without disabling other things, but it's fine on most other chips.

[dhalbert]

There are some impressively complicated ways to do this in CPython (desktop Python): https://stackoverflow.com/questions/35223896/listen-to-keypress-with-asyncio

[kamocat]

Interesting. So if I only have single-byte characters, I can use the count from usb_cdc like so:

async def ainput():
    usb_cdc.console.timeout = 0
    x = ""
    while(True):
        n = usb_cdc.console.in_waiting
        x += sys.stdin.read(n)
        if('\n' in x):
            return x
        await asyncio.sleep(0.1)

But then it breaks if I press a "delete" character. Also interesting is that the input isn't echoed back this way.
It will do for now, thank you!