pcnt: rotary encoder wake up system from light sleep example

examples/peripherals/pcnt/rotary_encoder/README.md

@@ -53,6 +53,8 @@ The GPIO used by the example can be changed according to your board by `EXAMPLE_
 
 ### Build and Flash
 
+By configuring one of the EC11 GPIO (e.g. `EXAMPLE_EC11_GPIO_A`) as a wake up source, we can make the rotary encoder wake the system from light sleep. This example can illustrate this feature if you enable the `EXAMPLE_WAKE_UP_LIGHT_SLEEP` from the menuconfig.
+
 Run `idf.py -p PORT flash monitor` to build, flash and monitor the project.
 
 (To exit the serial monitor, type ``Ctrl-]``.)

examples/peripherals/pcnt/rotary_encoder/main/Kconfig.projbuild

@@ -0,0 +1,8 @@
+menu "Example Configuration"
+    config EXAMPLE_WAKE_UP_LIGHT_SLEEP
+        bool "Configure the EC11 to wake up light sleep"
+        default "n"
+        help
+            Whether to use one of the EC11 channel to wake up the chip from light sleep.
+            The wake up is not triggered by PCNT peripheral, but by the digital GPIO.
+endmenu

examples/peripherals/pcnt/rotary_encoder/main/rotary_encoder_example_main.c

@@ -4,11 +4,14 @@
  * SPDX-License-Identifier: CC0-1.0
  */
 
+#include "sdkconfig.h"
 #include "freertos/FreeRTOS.h"
 #include "freertos/task.h"
 #include "freertos/queue.h"
 #include "esp_log.h"
 #include "driver/pulse_cnt.h"
+#include "driver/gpio.h"
+#include "esp_sleep.h"
 
 static const char *TAG = "example";
 
@@ -81,6 +84,13 @@ void app_main(void)
     ESP_LOGI(TAG, "start pcnt unit");
     ESP_ERROR_CHECK(pcnt_unit_start(pcnt_unit));
 
+#if CONFIG_EXAMPLE_WAKE_UP_LIGHT_SLEEP
+    // EC11 channel output high level in normal state, so we set "low level" to wake up the chip
+    ESP_ERROR_CHECK(gpio_wakeup_enable(EXAMPLE_EC11_GPIO_A, GPIO_INTR_LOW_LEVEL));
+    ESP_ERROR_CHECK(esp_sleep_enable_gpio_wakeup());
+    ESP_ERROR_CHECK(esp_light_sleep_start());
+#endif
+
     // Report counter value
     int pulse_count = 0;
     int event_count = 0;