ultrasonic-poc VS HID

That's why I don't use them for anything fancy

Heh, ultrasonic phase offset can be done with an Arduino's analog comparator (NOT the ADC which is too slow) - here's one I prepared earlier

hackaday.com has a zillion links to examples; here's one two three four of mine and I've also got a laundry list of companies I've helped but whose technical details I can't legally publish (note that I've assisted many but not all of the companies in that link)

HC-SR04 can't, but the transducers on it can - here's a proof-of-concept I threw together a while ago to play with them, although you may want a capacitor in series with R6 if you want it to work over longer distances than ~10cm or so

PS: https://github.com/triffid/ultrasonic-poc may interest you ;)

If you're curious here's a couple of my AVR projects (not using Arduino libraries at all), and here's an NRF52 one

ChatGPT often gets stuff wrong and likely can't handle more advanced programming techniques (eg this sort of thing), so it's only going to be useful for basic stuff and shouldn't be used beyond your ability to critically analyze or debug code.

Does this proof of concept where I get absurd precision (at short range) from a couple ultrasonic transducers salvaged from a HC-SR04 and a few resistors count?

Here's a random proof-of-concept I threw together a while ago for super precise ultrasonic wind speed measurement (or very short distances) - it uses the analog comparator plugged into timer input compare for phase analysis, which is where the precision comes from.

I don't think the built-in keyboard library identifies itself as "boot capable" in the HID descriptor, which is necessary for simpler keyboard devices. Try using NicoHood's HID library with the "BootKeyboard" object.

Looks great! How did you handle the programming? Did you follow a guide, or did you implement the Arduino HID Project library?

Skip the esp then and pick up any dev board supported by the HID project.

You can make it act like a HID - which is what I assume many people have done - with custom drivers like this one. https://github.com/NicoHood/HID

You can use Arduino HID Project which allows to reprogram atmega16u2 which performs USB communications on Uno. Then you can upload HID sketch on 16u2 and "normal" code on atmega328 which would do everything and send desired wheel state via serial. On 16u2 side you will parse that serial command from 328 and translate it into HID message

I'm trying to grab the "microphone muted" LED status from the HID library, but it seems like the library only supports a select few statuses out of the box: https://github.com/NicoHood/HID/issues/151

https://github.com/NicoHood/HID for a real UNO

Nano (atmega328) doesnt have native USB support (just a USB to UART converter). UNO also doesnt have native USB support, but has a atmega16U2 on board. You can flash this chip and build a USB HID bridge -> https://github.com/NicoHood/HID/

Try using NicoHood's HID project and the system key page: https://github.com/NicoHood/HID/blob/master/examples/System/System.ino