Added ESP32 compatible methods for setting/getting sleep mode

[drzony]

As discussed with @d-a-v

[d-a-v]

Thanks

[d-a-v]

getSleepMode() != WIFI_NONE_SLEEP
(so LIGHT and MODEM are treated as sleep mode enabled)

[drzony]

I thought about that, but see my comment above. To maintain ESP32 compatibility I did it the same way that it's on ESP32:
https://github.com/espressif/arduino-esp32/blob/3fe7c2e8cdcc34af0f5d3c55f8b4cb79ef5318cf/libraries/WiFi/src/WiFiGeneric.cpp#L669

[drzony]

One other option would be to drop the bool version

[d-a-v]

Indeed, the comment there is:

// @return true if modem sleep is enabled
bool WiFiGenericClass::getSleep()

The naming is confusing, because "light sleep" is also an enabled sleep mode while "none sleep" has sleep mode disabled.
What about replicating the comment in esp8266 .h file, insisting on that it reflects the esp32 API ?

One other option would be to drop the bool version

That would defeat the goal of this PR. We just need to not add it in esp8266 documentation.
esp32 libraries will compile, esp8266 .h readers will see the comment, esp8266 api is unchanged.

[mcspr]

Is this right though? MODEM is default, hence it should be MIN? LIGHT is 'sleepier' mode afaik

[drzony]

See this comment:
#7901 (comment)

[mcspr]

From the docs on ESP8266 it seems that WIFI_PS_MIN_MODEM == WIFI_LIGHT_SLEEP and WIFI_PS_NONE == WIFI_NONE_SLEEP

https://www.espressif.com/sites/default/files/documentation/2c-esp8266_non_os_sdk_api_reference_en.pdf ?
(still applies to the 2.2.x branch)

3.5.54. wifi_set_sleep_type

• Default mode: Modem-sleep.
• In order to lower the power comsumption, ESP8266 changes the TCP timer
  tick from 250ms to 3s in light-sleep mode, which leads to increased timeout for
  TCP timer. Therefore, the modem-sleep or deep-sleep mode should be used
  where there is a requirement for the accurancy of the TCP timer.

Plus:
https://github.com/espressif/arduino-esp32/blob/15bae92a72c102331e7eaf7dcb439e8ad6920184/tools/sdk/include/esp32/esp_wifi_types.h#L192-L196

Meaning, NONE - power-save features are disabled, MIN - minimum amount of power-saving features, but some are enabled, MAX - maximum power-save mode

[drzony]

Then I don't understand the number 3 in @d-a-v comment. Why WIFI_MODEM_SLEEP is on enabled and WIFI_LIGHT_SLEEP is on disabled?

[mcspr]

🤷
Following esp32 api, 1st choice is used there. ::setSleep(enum) is used to select the MAX sleep mode
(ref. espressif/arduino-esp32#3896 and espressif/arduino-esp32#3900)

[d-a-v]

I was wrong, sorry! I swapped MODEM and LIGHT sleep modes.
MODEM is indeed the default and is between NONE and LIGHT.