Add ESP-NOW Support

[microdev1]

ESP-NOW is a proprietary wireless communication protocol which supports direct communication between espressif devices.
This would be of particular interest for low-power wireless communication requirements.

This PR is based on the previous work by @nickzoic, @shawwwn, @glenn20 and contributions from @zoland, including:

• Issue ESP-Now Protocol micropython/micropython-esp32#197
• Initial branch from @nickzoic: https://github.com/nickzoic/micropython-esp32/tree/esp32-espnow
• Updates from @shawwwn: esp32/esp8266: add support for ESP-NOW micropython/micropython#4115
• More progress from @nickzoic: https://github.com/nickzoic/micropython/tree/espnow-4115
• Changes from @glenn20: esp32: ESP-NOW support for ESP32 and ESP8266 micropython/micropython#6515

Closes #3999.
Closes glenn20#4.

[dhalbert]

@microdev1 Thank you for taking this on! We certainly have gotten a lot of call for it.

I realize this is a draft, and you know there are things left to do, so many of my comments are more just to make a TODO list that can be checked off.

Targeting this for 9.0.0 might make sense, since then we can use ESP-IDF v5.0 from the start. I will set it to that milestone for now.

[glenn20]

@microdev1 Thanks also for taking this on. I confess I couldn't work out where to get started porting this to circuitpython. If there is anything I can do to help, let me know.

[microdev1]

...If there is anything I can do to help, let me know.

@glenn20 (and others) Sure, will let you know and thanks for all the work you have done already. 🙂

Targeting this for 9.0.0 might make sense...

I am hoping this can be in CP8. The ESP-NOW API doesn't seem to have changed in [email protected].

[dhalbert]

I am hoping this can be in CP8. The ESP-NOW API doesn't seem to have changed in [email protected].

We could do for 8.x.x. We are trying to close out 8.0.0 really soon, but we have a bunch of things for 8.x.x.

[tannewt]

Thank you for porting this over!

Do you want to keep it MP compatible?

[glenn20]

Do you want to keep it MP compatible?

While I'm not the port-er, I'd be interested in maintaining compatibility with the original module on MP. I'm happy to adopt agreed changes to the api into the MP module if required.

[tannewt]

@glenn20 Sounds good. I'd love your feedback on my inline comments then.

[microdev1]

I have reworked the API. There are still some changes to be made in the underneath implementation and a few checks to be run but the API will largely remain the same and I'd like to get your opinion on it.

[nickzoic]

Hey this is cool, thanks @microdev1 and @glenn20 for picking it up and running with it!
(also g'day to @tannewt and @dhalbert !)

[tannewt]

Thank you for the updates! @glenn20 and @nickzoic please let me know what you think of my API suggestions.

[microdev1]

In the ESP-NOW packet the message comes after a wifi_promiscuous_pkt_t and a espnow_frame_format_t.
Currently only the rssi is parsed from wifi_promiscuous_pkt_t, thoughts on exposing it entirely as a wifi.Monitor packet?

[tannewt]

One minor doc fix, otherwise the API looks good. Thank you!

[tannewt]

Looks good to me!

[dhalbert]

Thanks, looks good to me too!