Warning

This document is not updated for ESP32C5 yet, so some of the content may not be correct.

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Sleep Modes

Overview

ESP32-C5 supports two major power saving modes: Light-sleep and Deep-sleep. According to the features used by an application, there are some sub sleep modes. See Sleep Modes for these sleep modes and sub sleep modes. Additionally, there are some power-down options that can be configured to further reduce the power consumption. See Power-down Options for more details.

There are several wakeup sources in the sleep modes. These sources can also be combined so that the chip will wake up when any of the sources are triggered. Wakeup Sources describes these wakeup sources and configuration APIs in detail.

The configuration of power-down options and wakeup sources are optional. They can be configured at any moment before entering the sleep modes.

Then the application can call sleep start APIs to enter one of the sleep modes. See Entering Sleep for more details. When the wakeup condition is met, the application is awoken from sleep. See Checking Sleep Wakeup Cause on how to get the wakeup cause, and Disable Sleep Wakeup Source on how to handle the wakeup sources after wakeup.

Sleep Modes

In Light-sleep mode, the digital peripherals, most of the RAM, and CPUs are clock-gated and their supply voltage is reduced. Upon exit from Light-sleep, the digital peripherals, RAM, and CPUs resume operation and their internal states are preserved.

In Deep-sleep mode, the CPUs, most of the RAM, and all digital peripherals that are clocked from APB_CLK are powered off. The only parts of the chip that remain powered on are:

RTC controller

RTC FAST memory

Wakeup Sources

Wakeup sources can be enabled using esp_sleep_enable_X_wakeup APIs. Wakeup sources are not disabled after wakeup, you can disable them using esp_sleep_disable_wakeup_source() API if you do not need them any more. See Disable Sleep Wakeup Source.

Following are the wakeup sources supported on ESP32-C5.

Timer

The RTC controller has a built-in timer which can be used to wake up the chip after a predefined amount of time. Time is specified at microsecond precision, but the actual resolution depends on the clock source selected for RTC_SLOW_CLK.

RTC peripherals or RTC memories do not need to be powered on during sleep in this wakeup mode.

esp_sleep_enable_timer_wakeup() function can be used to enable sleep wakeup using a timer.

GPIO Wakeup

Any IO can be used as the external input to wake up the chip from Light-sleep. Each pin can be individually configured to trigger wakeup on high or low level using the gpio_wakeup_enable() function. Then the esp_sleep_enable_gpio_wakeup() function should be called to enable this wakeup source.

Additionally, IOs that are powered by the VDD3P3_RTC power domain can be used to wake up the chip from Deep-sleep. The wakeup pin and wakeup trigger level can be configured by calling esp_deep_sleep_enable_gpio_wakeup(). The function will enable the Deep-sleep wakeup for the selected pin.

Note

UART Wakeup (Light-sleep Only)

When ESP32-C5 receives UART input from external devices, it is often necessary to wake up the chip when input data is available. The UART peripheral contains a feature which allows waking up the chip from Light-sleep when a certain number of positive edges on RX pin are seen. This number of positive edges can be set using uart_set_wakeup_threshold() function. Note that the character which triggers wakeup (and any characters before it) will not be received by the UART after wakeup. This means that the external device typically needs to send an extra character to the ESP32-C5 to trigger wakeup before sending the data.

esp_sleep_enable_uart_wakeup() function can be used to enable this wakeup source.

After waking-up from UART, you should send some extra data through the UART port in Active mode, so that the internal wakeup indication signal can be cleared. Otherwises, the next UART wake-up would trigger with two less rising edges than the configured threshold value.

Disable Sleep Wakeup Source

Previously configured wakeup sources can be disabled later using esp_sleep_disable_wakeup_source() API. This function deactivates trigger for the given wakeup source. Additionally, it can disable all triggers if the argument is ESP_SLEEP_WAKEUP_ALL.

Power-down Options

The application can force specific powerdown modes for RTC peripherals and RTC memories. In Deep-sleep mode, we can also isolate some IOs to further reduce current consumption.

Power-down of RTC Peripherals and Memories

By default, esp_deep_sleep_start() and esp_light_sleep_start() functions power down all RTC power domains which are not needed by the enabled wakeup sources. To override this behaviour, esp_sleep_pd_config() function is provided.

In ESP32-C5, there is only RTC FAST memory, so if some variables in the program are marked by RTC_DATA_ATTR, RTC_SLOW_ATTR or RTC_FAST_ATTR attributes, all of them go to RTC FAST memory. It will be kept powered on by default. This can be overridden using esp_sleep_pd_config() function, if desired.

Power-down of Flash

By default, to avoid potential issues, esp_light_sleep_start() function does not power down flash. To be more specific, it takes time to power down the flash and during this period the system may be woken up, which then actually powers up the flash before this flash could be powered down completely. As a result, there is a chance that the flash may not work properly.

So, in theory, it is ok if you only wake up the system after the flash is completely powered down. However, in reality, the flash power-down period can be hard to predict (for example, this period can be much longer when you add filter capacitors to the flash's power supply circuit) and uncontrollable (for example, the asynchronous wake-up signals make the actual sleep time uncontrollable).

Warning

If a filter capacitor is added to your flash power supply circuit, please do everything possible to avoid powering down flash.

Therefore, it is recommended not to power down flash when using ESP-IDF. For power-sensitive applications, it is recommended to use Kconfig option CONFIG_ESP_SLEEP_FLASH_LEAKAGE_WORKAROUND to reduce the power consumption of the flash during Light-sleep, instead of powering down the flash.

However, for those who have fully understood the risk and are still willing to power down the flash to further reduce the power consumption, please check the following mechanisms:

Setting Kconfig option CONFIG_ESP_SLEEP_POWER_DOWN_FLASH only powers down the flash when the RTC timer is the only wake-up source and the sleep time is longer than the flash power-down period.

Calling esp_sleep_pd_config(ESP_PD_DOMAIN_VDDSDIO, ESP_PD_OPTION_OFF) powers down flash when the RTC timer is not enabled as a wakeup source or the sleep time is longer than the flash power-down period.

Note

ESP-IDF does not provide any mechanism that can power down the flash in all conditions when Light-sleep.
esp_deep_sleep_start() function forces power down flash regardless of user configuration.

Configuring IOs (Deep-sleep Only)

Some ESP32-C5 IOs have internal pullups or pulldowns, which are enabled by default. If an external circuit drives this pin in Deep-sleep mode, current consumption may increase due to current flowing through these pullups and pulldowns.

Entering Sleep

esp_light_sleep_start() or esp_deep_sleep_start() functions can be used to enter Light-sleep or Deep-sleep modes correspondingly. After that, the system configures the parameters of RTC controller according to the requested wakeup sources and power-down options.

It is also possible to enter sleep modes with no wakeup sources configured. In this case, the chip will be in sleep modes indefinitely until external reset is applied.

UART Output Handling

Before entering sleep mode, esp_deep_sleep_start() will flush the contents of UART FIFOs.

When entering Light-sleep mode using esp_light_sleep_start(), UART FIFOs will not be flushed. Instead, UART output will be suspended, and remaining characters in the FIFO will be sent out after wakeup from Light-sleep.

Checking Sleep Wakeup Cause

esp_sleep_get_wakeup_cause() function can be used to check which wakeup source has triggered wakeup from sleep mode.

Application Example

protocols/sntp demonstrates the implementation of basic functionality of Deep-sleep, where ESP module is periodically waken up to retrieve time from NTP server.
system/deep_sleep demonstrates the usage of Deep-sleep wakeup triggered by various sources, such as the RTC timer, GPIOs, EXT0, EXT1, the touch sensor, supported by ESP32-C5.
system/light_sleep demonstrates the usage of Light-sleep wakeup triggered by various sources, such as the timer, GPIOs, the touch sensor, supported by ESP32-C5.

API Reference

Header File

components/esp_hw_support/include/esp_sleep.h
This header file can be included with:
#include "esp_sleep.h"

Functions

esp_err_t esp_sleep_disable_wakeup_source(esp_sleep_source_t source)

Disable wakeup source.

This function is used to deactivate wake up trigger for source defined as parameter of the function.

See docs/sleep-modes.rst for details.

Note

This function does not modify wake up configuration in RTC. It will be performed in esp_deep_sleep_start/esp_light_sleep_start function.

Parameters

source -- - number of source to disable of type esp_sleep_source_t

Returns

ESP_OK on success
ESP_ERR_INVALID_STATE if trigger was not active

esp_err_t esp_sleep_enable_timer_wakeup(uint64_t time_in_us)

Enable wakeup by timer.

Parameters

time_in_us -- time before wakeup, in microseconds

Returns

ESP_OK on success
ESP_ERR_INVALID_ARG if value is out of range (TBD)

bool esp_sleep_is_valid_wakeup_gpio(gpio_num_t gpio_num)

Returns true if a GPIO number is valid for use as wakeup source.

Note

For SoCs with RTC IO capability, this can be any valid RTC IO input pin.

Parameters: gpio_num -- Number of the GPIO to test for wakeup source capability
Returns: True if this GPIO number will be accepted as a sleep wakeup source.

esp_err_t esp_sleep_enable_gpio_wakeup(void)

Enable wakeup from light sleep using GPIOs.

Each GPIO supports wakeup function, which can be triggered on either low level or high level. Unlike EXT0 and EXT1 wakeup sources, this method can be used both for all IOs: RTC IOs and digital IOs. It can only be used to wakeup from light sleep though.

To enable wakeup, first call gpio_wakeup_enable, specifying gpio number and wakeup level, for each GPIO which is used for wakeup. Then call this function to enable wakeup feature.

Note

On ESP32, GPIO wakeup source can not be used together with touch or ULP wakeup sources.

Returns

ESP_OK on success
ESP_ERR_INVALID_STATE if wakeup triggers conflict

esp_err_t esp_sleep_enable_uart_wakeup(int uart_num)

Enable wakeup from light sleep using UART.

Use uart_set_wakeup_threshold function to configure UART wakeup threshold.

Wakeup from light sleep takes some time, so not every character sent to the UART can be received by the application.

Note

ESP32 does not support wakeup from UART2.

Parameters

uart_num -- UART port to wake up from

Returns

ESP_OK on success
ESP_ERR_INVALID_ARG if wakeup from given UART is not supported

esp_err_t esp_sleep_enable_bt_wakeup(void)

Enable wakeup by bluetooth.

Returns

ESP_OK on success
ESP_ERR_NOT_SUPPORTED if wakeup from bluetooth is not supported

esp_err_t esp_sleep_disable_bt_wakeup(void)

Disable wakeup by bluetooth.

Returns

ESP_OK on success
ESP_ERR_NOT_SUPPORTED if wakeup from bluetooth is not supported

esp_err_t esp_sleep_enable_wifi_wakeup(void)

Enable wakeup by WiFi MAC.

Returns

ESP_OK on success

esp_err_t esp_sleep_disable_wifi_wakeup(void)

Disable wakeup by WiFi MAC.

Returns

ESP_OK on success

esp_err_t esp_sleep_enable_wifi_beacon_wakeup(void)

Enable beacon wakeup by WiFi MAC, it will wake up the system into modem state.

Returns

ESP_OK on success

esp_err_t esp_sleep_disable_wifi_beacon_wakeup(void)

Disable beacon wakeup by WiFi MAC.

Returns

ESP_OK on success

uint64_t esp_sleep_get_ext1_wakeup_status(void)

Get the bit mask of GPIOs which caused wakeup (ext1)

If wakeup was caused by another source, this function will return 0.

Returns: bit mask, if GPIOn caused wakeup, BIT(n) will be set

esp_err_t esp_sleep_pd_config(esp_sleep_pd_domain_t domain, esp_sleep_pd_option_t option)

Set power down mode for an RTC power domain in sleep mode.

If not set set using this API, all power domains default to ESP_PD_OPTION_AUTO.

Parameters

domain -- power domain to configure
option -- power down option (ESP_PD_OPTION_OFF, ESP_PD_OPTION_ON, or ESP_PD_OPTION_AUTO)

Returns

ESP_OK on success
ESP_ERR_INVALID_ARG if either of the arguments is out of range

esp_err_t esp_deep_sleep_try_to_start(void)

Enter deep sleep with the configured wakeup options.

The reason for the rejection can be such as a short sleep time.

Note

In general, the function does not return, but if the sleep is rejected, then it returns from it.

Returns

No return - If the sleep is not rejected.
ESP_ERR_SLEEP_REJECT sleep request is rejected(wakeup source set before the sleep request)

void esp_deep_sleep_start(void): Enter deep sleep with the configured wakeup options.

Note

The function does not do a return (no rejection). Even if wakeup source set before the sleep request it goes to deep sleep anyway.

esp_err_t esp_light_sleep_start(void)

Enter light sleep with the configured wakeup options.

Returns

ESP_OK on success (returned after wakeup)
ESP_ERR_SLEEP_REJECT sleep request is rejected(wakeup source set before the sleep request)
ESP_ERR_SLEEP_TOO_SHORT_SLEEP_DURATION after deducting the sleep flow overhead, the final sleep duration is too short to cover the minimum sleep duration of the chip, when rtc timer wakeup source enabled

esp_err_t esp_deep_sleep_try(uint64_t time_in_us)

Enter deep-sleep mode.

The device will automatically wake up after the deep-sleep time Upon waking up, the device calls deep sleep wake stub, and then proceeds to load application.

Call to this function is equivalent to a call to esp_deep_sleep_enable_timer_wakeup followed by a call to esp_deep_sleep_start.

The reason for the rejection can be such as a short sleep time.

Note

In general, the function does not return, but if the sleep is rejected, then it returns from it.

Parameters

time_in_us -- deep-sleep time, unit: microsecond

Returns

No return - If the sleep is not rejected.
ESP_ERR_SLEEP_REJECT sleep request is rejected(wakeup source set before the sleep request)

void esp_deep_sleep(uint64_t time_in_us)

Enter deep-sleep mode.

The device will automatically wake up after the deep-sleep time Upon waking up, the device calls deep sleep wake stub, and then proceeds to load application.

Call to this function is equivalent to a call to esp_deep_sleep_enable_timer_wakeup followed by a call to esp_deep_sleep_start.

Note

The function does not do a return (no rejection).. Even if wakeup source set before the sleep request it goes to deep sleep anyway.

Parameters: time_in_us -- deep-sleep time, unit: microsecond

esp_err_t esp_deep_sleep_register_hook(esp_deep_sleep_cb_t new_dslp_cb)

Register a callback to be called from the deep sleep prepare.

Warning

deepsleep callbacks should without parameters, and MUST NOT, UNDER ANY CIRCUMSTANCES, CALL A FUNCTION THAT MIGHT BLOCK.

Parameters

new_dslp_cb -- Callback to be called

Returns

ESP_OK: Callback registered to the deepsleep misc_modules_sleep_prepare
ESP_ERR_NO_MEM: No more hook space for register the callback

void esp_deep_sleep_deregister_hook(esp_deep_sleep_cb_t old_dslp_cb)

Unregister an deepsleep callback.

Parameters: old_dslp_cb -- Callback to be unregistered

esp_sleep_wakeup_cause_t esp_sleep_get_wakeup_cause(void)

Get the wakeup source which caused wakeup from sleep.

Returns: cause of wake up from last sleep (deep sleep or light sleep)

void esp_wake_deep_sleep(void)

Default stub to run on wake from deep sleep.

Allows for executing code immediately on wake from sleep, before the software bootloader or ESP-IDF app has started up.

This function is weak-linked, so you can implement your own version to run code immediately when the chip wakes from sleep.

See docs/deep-sleep-stub.rst for details.

void esp_set_deep_sleep_wake_stub(esp_deep_sleep_wake_stub_fn_t new_stub)

Install a new stub at runtime to run on wake from deep sleep.

If implementing esp_wake_deep_sleep() then it is not necessary to call this function.

However, it is possible to call this function to substitute a different deep sleep stub. Any function used as a deep sleep stub must be marked RTC_IRAM_ATTR, and must obey the same rules given for esp_wake_deep_sleep().

void esp_set_deep_sleep_wake_stub_default_entry(void): Set wake stub entry to default esp_wake_stub_entry

esp_deep_sleep_wake_stub_fn_t esp_get_deep_sleep_wake_stub(void)

Get current wake from deep sleep stub.

Returns: Return current wake from deep sleep stub, or NULL if no stub is installed.

void esp_default_wake_deep_sleep(void)

The default esp-idf-provided esp_wake_deep_sleep() stub.

See docs/deep-sleep-stub.rst for details.

void esp_deep_sleep_disable_rom_logging(void)

Disable logging from the ROM code after deep sleep.

Using LSB of RTC_STORE4.

void esp_sleep_config_gpio_isolate(void): Configure to isolate all GPIO pins in sleep state.

void esp_sleep_enable_gpio_switch(bool enable)

Enable or disable GPIO pins status switching between slept status and waked status.

Parameters: enable -- decide whether to switch status or not

Macros

ESP_PD_DOMAIN_RTC8M

ESP_SLEEP_POWER_DOWN_CPU

Type Definitions

typedef void (*esp_deep_sleep_cb_t)(void)

typedef esp_sleep_source_t esp_sleep_wakeup_cause_t

typedef void (*esp_deep_sleep_wake_stub_fn_t)(void): Function type for stub to run on wake from sleep.

Enumerations

enum esp_sleep_pd_domain_t

Logic function used for EXT1 wakeup mode.

Power domains which can be powered down in sleep mode

Values:

enumerator ESP_PD_DOMAIN_RTC_PERIPH: RTC IO, sensors and ULP co-processor.

enumerator ESP_PD_DOMAIN_XTAL: XTAL oscillator.

enumerator ESP_PD_DOMAIN_XTAL32K: External 32 kHz XTAL oscillator.

enumerator ESP_PD_DOMAIN_RC32K: Internal 32 kHz RC oscillator.

enumerator ESP_PD_DOMAIN_RC_FAST: Internal Fast oscillator.

enumerator ESP_PD_DOMAIN_VDDSDIO: VDD_SDIO.

enumerator ESP_PD_DOMAIN_MODEM: MODEM, includes WiFi, Bluetooth and IEEE802.15.4.

enumerator ESP_PD_DOMAIN_TOP: SoC TOP.

enumerator ESP_PD_DOMAIN_MAX: Number of domains.

enum esp_sleep_pd_option_t

Power down options.

Values:

enumerator ESP_PD_OPTION_OFF: Power down the power domain in sleep mode.

enumerator ESP_PD_OPTION_ON: Keep power domain enabled during sleep mode.

enumerator ESP_PD_OPTION_AUTO: Keep power domain enabled in sleep mode, if it is needed by one of the wakeup options. Otherwise power it down.

enum esp_sleep_source_t

Sleep wakeup cause.

Values:

enumerator ESP_SLEEP_WAKEUP_UNDEFINED: In case of deep sleep, reset was not caused by exit from deep sleep.

enumerator ESP_SLEEP_WAKEUP_ALL: Not a wakeup cause, used to disable all wakeup sources with esp_sleep_disable_wakeup_source.

enumerator ESP_SLEEP_WAKEUP_EXT0: Wakeup caused by external signal using RTC_IO.

enumerator ESP_SLEEP_WAKEUP_EXT1: Wakeup caused by external signal using RTC_CNTL.

enumerator ESP_SLEEP_WAKEUP_TIMER: Wakeup caused by timer.

enumerator ESP_SLEEP_WAKEUP_TOUCHPAD: Wakeup caused by touchpad.

enumerator ESP_SLEEP_WAKEUP_ULP: Wakeup caused by ULP program.

enumerator ESP_SLEEP_WAKEUP_GPIO: Wakeup caused by GPIO (light sleep only on ESP32, S2 and S3)

enumerator ESP_SLEEP_WAKEUP_UART: Wakeup caused by UART (light sleep only)

enumerator ESP_SLEEP_WAKEUP_WIFI: Wakeup caused by WIFI (light sleep only)

enumerator ESP_SLEEP_WAKEUP_COCPU: Wakeup caused by COCPU int.

enumerator ESP_SLEEP_WAKEUP_COCPU_TRAP_TRIG: Wakeup caused by COCPU crash.

enumerator ESP_SLEEP_WAKEUP_BT: Wakeup caused by BT (light sleep only)

enum esp_sleep_mode_t

Sleep mode.

Values:

enumerator ESP_SLEEP_MODE_LIGHT_SLEEP: light sleep mode

enumerator ESP_SLEEP_MODE_DEEP_SLEEP: deep sleep mode

enum [anonymous]

Values:

enumerator ESP_ERR_SLEEP_REJECT

enumerator ESP_ERR_SLEEP_TOO_SHORT_SLEEP_DURATION

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