Enabling hibernate mode on ESP32-S2

[mzakharo]

Hello,

I wanted to document the journey here on enabling hibernation mode (ultra-low power deep sleep) on ESP32-S2 (UM-FeatherS2) board.
It takes a couple of changes to get this message on the UART0 console when entering deepsleep mode:

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D (5225) sleep: RTC_PERIPH: OFF
D (5225) sleep: RTC_SLOW_MEM: OFF
D (5225) sleep: RTC_FAST_MEM: OFF

First of all, in order to see the debug prints on the UART console from ESP-IDF, you have to change micropython/ports/esp32/boards/sdkconfig.base

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CONFIG_LOG_DEFAULT_LEVEL_DEBUG=y
CONFIG_LOG_DEFAULT_LEVEL=4

Then, to be able to turn off RTC_FAST_MEM on ESP32-S2 , add the following to sdconfig.base

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CONFIG_ESP32S2_ALLOW_RTC_FAST_MEM_AS_HEAP=n

Finally, add this to machine_sleep_helper() function inside modmachine.c

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 esp_sleep_pd_config(ESP_PD_DOMAIN_RTC_PERIPH,   ESP_PD_OPTION_OFF);
 esp_sleep_pd_config(ESP_PD_DOMAIN_RTC_SLOW_MEM, ESP_PD_OPTION_OFF);
 esp_sleep_pd_config(ESP_PD_DOMAIN_RTC_FAST_MEM, ESP_PD_OPTION_OFF);
 esp_sleep_pd_config(ESP_PD_DOMAIN_XTAL,         ESP_PD_OPTION_OFF);

Profit.

[tepalia02]

Thanks a lot for sharing all these details with us.

[pythoncoder]

@mzakharo Interesting. I tested a UM Feather S2 just issuing machine.deepsleep(time) with standard firmware. The current draw of my sample was 65μA which I thought was very impressive. What figure do you achieve with your additional changes?

[mzakharo]

@mzakharo Interesting. I tested a UM Feather S2 just issuing machine.deepsleep(time) with standard firmware. The current draw of my sample was 65μA which I thought was very impressive. What figure do you achieve with your additional changes?

Sorry for the late reply. I am using nRF Profiler Kit II to measure current, and my UM Feather S2 deep sleep is 34 uA @ 3.3V. I am applying power through the JST connector, not USB. This should give lower current. Also, be mindful of the on-board Ambient sensor. You will get lowest reading when the room is dark . I just soldered it off the board to get consistent current measurement.

[mzakharo]

My nRF Profiler kit II measures 34uA @ 3.3V. Ensure you measure through JST connector, not USB. Also Ambient light sensor will throw off your reading. Measure when room is dark, or just solder it off for consistent measurement.