Deep sleep

Deep sleep is how you get a sketch to run for months on a battery. E-paper needs no power to hold its image, so between refreshes the board can idle almost indefinitely.

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With all peripherals asleep, Inkplate 6COLOR draws about 18 µA in deep sleep.

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Simple deep sleep

Check how deep sleep works with the example below:

#define uS_TO_S_FACTOR 1000000ULL // Conversion factor for micro seconds to seconds
#define TIME_TO_SLEEP  20 // How long ESP32 will be in deep sleep (in seconds)
void setup(){
    // your code
    ///...
    esp_sleep_enable_timer_wakeup(TIME_TO_SLEEP * uS_TO_S_FACTOR); // Activate wake-up timer -- wake up after 20s here
    esp_deep_sleep_start(); // Put ESP32 into deep sleep. Program stops here.
}

esp_sleep_enable_timer_wakeup()

This function enables wakeup by timer.

Returns type: int

Returns value: Returns ESP error code

Function parameters:

Type	Name	Description
uint64_t	time_in_us	Wakeup time in microseconds.

esp_deep_sleep_start()

This function enters deep sleep with the configured wakeup options.

Returns type: none

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Wake on button press

To wake up using the Wake button, call the ESP32 function esp_sleep_enable_ext0_wakeup() before putting it to sleep.

// Go to sleep for TIME_TO_SLEEP seconds
esp_sleep_enable_timer_wakeup(TIME_TO_SLEEP * uS_TO_S_FACTOR);

// Enable wakeup from deep sleep on GPIO 36 (wake button)
esp_sleep_enable_ext0_wakeup(GPIO_NUM_36, LOW);

// Go to sleep
esp_deep_sleep_start();

esp_sleep_enable_ext0_wakeup()

This function uses the external wakeup feature of the RTC_IO peripheral.

Returns type: int

Returns value: Returns ESP error constant

Function parameters:

Type	Name	Description
gpio_num_t	gpio_num	GPIO number used as wakeup source. Only GPIOs with RTC functionality can be used.
int	level	Input level which will trigger wakeup.

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Full examples

Check out the full examples from this page, along with many more usage options below:

Inkplate6COLOR_Simple_Deep_Sleep.ino

This example will show you how to use the low-power functionality of the Inkplate board.

Inkplate6COLOR_Wake_Up_Button.ino

Full example on how to implement the WAKE UP button with deep sleep on Inkplate 6COLOR.

Inkplate6COLOR_RTC_Alarm_With_Deep_Sleep.ino

This example will show you how to use the RTC alarm interrupt with deep sleep.