1| Supported Targets | ESP32 | ESP32-S2 | ESP32-C3 | 2| ----------------- | ----- | -------- | -------- | 3 4# Deep Sleep Example 5 6(See the README.md file in the upper level 'examples' directory for more information about examples.) 7 8The [deep sleep mode](https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/system/sleep_modes.html#sleep-modes) of the ESP32 is a power saving mode that causes the CPU, majority of RAM, and digital peripherals that are clocked from APB_CLK to be powered off. Deep sleep mode can be exited using one of multiple [wake up sources](https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/system/sleep_modes.html#wakeup-sources). This example demonstrates how to use the [`esp_sleep.h`](https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/system/sleep_modes.html#api-reference) API to enter deep sleep mode, then wake up form different sources. 9 10The following wake up sources are demonstrated in this example (refer to the [Wakeup Sources documentation](https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/system/sleep_modes.html#wakeup-sources) for more details regarding wake up sources): 11 121. **Timer:** An RTC timer that can be programmed to trigger a wake up after a preset time. This example will trigger a wake up every 20 seconds. 132. **EXT1:** External wake up 1 which is tied to multiple RTC GPIOs. This example use GPIO2 and GPIO4 to trigger a wake up with any one of the two pins are HIGH. 143. **Touch:** Touch pad sensor interrupt. This example uses touch pads connected to GPIO32, GPIO33 in ESP32 or GPIO9 in ESP32-S2 to trigger a wake up when any of the pads are pressed. 154. **ULP:** Ultra Low Power Coprocessor which can continue to run during deep sleep. This example utilizes the ULP and constantly sample the chip's temperature and trigger a wake up if the chips temperature exceeds ~5 degrees Celsius. 16 17Note: Some wake up sources can be disabled via configuration (see section on [project configuration](#Configure-the-project)) 18 19In this example, the `CONFIG_BOOTLOADER_SKIP_VALIDATE_IN_DEEP_SLEEP` Kconfig option is used, which allows you to reduce the boot time of the bootloader during waking up from deep sleep. The bootloader stores in rtc memory the address of a running partition and uses it when it wakes up. This example allows you to skip all image checks and speed up the boot. 20 21## How to use example 22 23### Hardware Required 24 25This example should be able to run on any commonly available ESP32 development board without any extra hardware if only **Timer** and **ULP** wake up sources are used. However, the following extra connections will be required for the remaining wake up sources. 26 27- **EXT1:** GPIO2 and GPIO4 should be connected to LOW to avoid floating pins. When triggering a wake up, connect one or both of the pins to HIGH. Note that floating pins may trigger a wake up. 28 29- **Touch:** GPIO32, GPIO33 in ESP32 or GPIO9 in ESP32-S2 should be connected to touch sensors (see [Touch Sensor Application Note](https://github.com/espressif/esp-iot-solution/blob/release/v1.0/documents/touch_pad_solution/touch_sensor_design_en.md)). 30 31### Configure the project 32 33``` 34idf.py menuconfig 35``` 36 37* **Touch wake up** can be enabled/disabled via `Example configuration > Enable touch wake up` 38* **ULT wake up** can be enabled/disabled via `Example configuration > Enable temperature monitoring by ULP` 39 40Wake up sources that are unused or unconnected should be disabled in configuration to prevent inadvertent triggering of wake up as a result of floating pins. 41 42### Build and Flash 43 44Build the project and flash it to the board, then run monitor tool to view serial output: 45 46``` 47idf.py -p PORT flash monitor 48``` 49 50(Replace PORT with the name of the serial port to use.) 51 52(To exit the serial monitor, type ``Ctrl-]``.) 53 54See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects. 55 56## Example Output 57 58On initial startup, this example will detect that this is the first boot and output the following low: 59 60``` 61... 62I (304) cpu_start: Starting scheduler on PRO CPU. 63I (0) cpu_start: Starting scheduler on APP CPU. 64Not a deep sleep reset 65Enabling timer wakeup, 20s 66Enabling EXT1 wakeup on pins GPIO2, GPIO4 67Touch pad #8 average: 2148, wakeup threshold set to 2048. 68Touch pad #9 average: 2148, wakeup threshold set to 2048. 69Enabling touch pad wakeup 70Enabling ULP wakeup 71Entering deep sleep 72``` 73 74The ESP32 will then enter deep sleep. When a wake up occurs, the ESP32 must undergo the entire boot process again. However the example will detect that this boot is due to a wake up and indicate the wake up source in the output log such as the following: 75 76``` 77... 78I (304) cpu_start: Starting scheduler on PRO CPU. 79I (0) cpu_start: Starting scheduler on APP CPU. 80Wake up from timer. Time spent in deep sleep: 20313ms 81ULP did 110 temperature measurements in 20313 ms 82Initial T=87, latest T=87 83Enabling timer wakeup, 20s 84Enabling EXT1 wakeup on pins GPIO2, GPIO4 85Touch pad #8 average: 2149, wakeup threshold set to 2049. 86Touch pad #9 average: 2146, wakeup threshold set to 2046. 87Enabling touch pad wakeup 88Enabling ULP wakeup 89Entering deep sleep 90``` 91
