Radio and Connection Sleep/Reopen

[calittle]

This is an enhancement request to provide for dropping a connection and shutting off the radio after a specified time period of no use or after a fixed time period. Upon request e.g. post(), WifiManager will turn on the radio and reestablish the connection and reset the timer. This could be useful for battery-powered projects where always-on radio and connections will drain the battery quickly.

[siddacious]

@brentru Does the NINA firmware have a shutdown feature?

[mscosti]

I'm not sure exactly what 'low power mode' does, but NINA does support putting it into a low power mode: https://github.com/adafruit/nina-fw/blob/master/main/CommandHandler.cpp#L148-L162

[ladyada]

thats as good as yr gonna get. anyone want to implement that function as a PR? :)

[anecdata]

The two pull requests above summarize the current state of power control of the ESP32 NINA co-processor:

• NINA sets a nominal lower power mode by default that reduces power usage to about half when not communicating with the AP. This is the normal level of opereation already. There is a higher power saving mode that would require NINA and ESP32SPI changes, but also may introduce operational differences.
• A disconnect() function is now available in ESP_SPIcontrol, reducing average power usage to about half in common use cases. This function can now be used directly in user code, or could be incorporated into higher-level libraries like WiFiManager.

[brentru]

A disconnect() function is now available in ESP_SPIcontrol, reducing average power usage to about half in common use cases. This function can now be used directly in user code, or could be incorporated into higher-level libraries like WiFiManager.

Exciting - I want to incorporate this into MiniMQTT.

[anecdata]

Just a note that ESP32SPI NTP using esp.get_time() doesn't play well with staying disconnected until needed since the ESP32 needs some interval (~15 seconds I believe) after connection before it will return valid seconds. HTTP/TCP/UDP/etc at the circuitpython level has no such limitation.