71 lines
2.4 KiB
ReStructuredText
71 lines
2.4 KiB
ReStructuredText
.. _esp32-light-sleep-sample:
|
|
|
|
ESP32 Light Sleep demo
|
|
######################
|
|
|
|
Overview
|
|
********
|
|
|
|
This example illustrates usage of light sleep mode. Unlike deep sleep mode,
|
|
light sleep preserves the state of the memory, CPU, and peripherals. Execution
|
|
of code on both CPUs is stopped when esp_light_sleep_start() function is called.
|
|
When the chip exits light sleep mode, execution continues at the point where it
|
|
was stopped, and esp_light_sleep_start() function returns.
|
|
|
|
The example enables the following wakeup sources:
|
|
|
|
* ``Timer``: wake up the chip in 2 seconds.
|
|
* ``EXT0``: wake up the chip if a button attached to GPIO0 is pressed (i.e. if
|
|
GPIO0 goes low).
|
|
|
|
Requirements
|
|
************
|
|
|
|
This example can be used with any ESP32 development board. Most boards have a
|
|
button attached to GPIO0, often labelled BOOT. If the board does not have such
|
|
button, an external button can be connected, along with a 10k pull-up resistor,
|
|
and a 100nF capacitor to ground for debouncing.
|
|
|
|
Building, Flashing and Running
|
|
******************************
|
|
|
|
.. zephyr-app-commands::
|
|
:zephyr-app: samples/boards/esp32/light_sleep
|
|
:board: esp32_devkitc_wroom/esp32/procpu
|
|
:goals: build flash
|
|
:compact:
|
|
|
|
Sample Output
|
|
=================
|
|
ESP32 core output
|
|
-----------------
|
|
|
|
In the scenario below, the button attached to GPIO0 was pressed and held for
|
|
about 500 ms, after the second wakeup from light sleep. The program has
|
|
indicated the wakeup reason after each sleep iteration.
|
|
|
|
.. code-block:: console
|
|
|
|
*** Booting Zephyr OS build zephyr-v3.1.0-3667-gb42e2b225ecf ***
|
|
|
|
Entering light sleep
|
|
Returned from light sleep, reason: timer, t=3344 ms, slept for 2001 ms
|
|
Entering light sleep
|
|
Returned from light sleep, reason: timer, t=5354 ms, slept for 2000 ms
|
|
Entering light sleep
|
|
Returned from light sleep, reason: pin, t=5885 ms, slept for 521 ms
|
|
Waiting for GPIO0 to go high...
|
|
Entering light sleep
|
|
Returned from light sleep, reason: timer, t=8765 ms, slept for 2000 ms
|
|
Entering light sleep
|
|
Returned from light sleep, reason: timer, t=10776 ms, slept for 2001 ms
|
|
Entering light sleep
|
|
|
|
Troubleshooting
|
|
***************
|
|
|
|
If pressing the button attached to GPIO0 does not affect program behavior,
|
|
check DTR/RTS configuration in the serial monitor. This is not necessary for
|
|
IDF monitor, but for other tools it might be necessary to set DTR and RTS line
|
|
state to "disabled" or "de-asserted".
|