esp-idf/examples/wifi/power_save/main/power_save.c

/* Power save Example

   This example code is in the Public Domain (or CC0 licensed, at your option.)

   Unless required by applicable law or agreed to in writing, this
   software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
   CONDITIONS OF ANY KIND, either express or implied.
*/

/*
   this example shows how to use power save mode
   set a router or a AP using the same SSID&PASSWORD as configuration of this example.
   start esp32 and when it connected to AP it will enter power save mode
*/
#include "freertos/FreeRTOS.h"
#include "freertos/event_groups.h"
#include "esp_wifi.h"
#include "esp_log.h"
#include "esp_event_loop.h"
#include "esp_pm.h"
#include "nvs_flash.h"

/*set the ssid and password via "make menuconfig"*/
#define DEFAULT_SSID CONFIG_WIFI_SSID
#define DEFAULT_PWD CONFIG_WIFI_PASSWORD

#define DEFAULT_LISTEN_INTERVAL CONFIG_WIFI_LISTEN_INTERVAL

#if CONFIG_POWER_SAVE_MIN_MODEM
#define DEFAULT_PS_MODE WIFI_PS_MIN_MODEM
#elif CONFIG_POWER_SAVE_MAX_MODEM
#define DEFAULT_PS_MODE WIFI_PS_MAX_MODEM
#elif CONFIG_POWER_SAVE_NONE
#define DEFAULT_PS_MODE WIFI_PS_NONE
#else
#define DEFAULT_PS_MODE WIFI_PS_NONE
#endif /*CONFIG_POWER_SAVE_MODEM*/


static const char *TAG = "power_save";


static esp_err_t event_handler(void *ctx, system_event_t *event)
{
    switch(event->event_id) {
    case SYSTEM_EVENT_STA_START:
	ESP_LOGI(TAG, "SYSTEM_EVENT_STA_START");
	ESP_ERROR_CHECK(esp_wifi_connect());
	break;
    case SYSTEM_EVENT_STA_GOT_IP:
	ESP_LOGI(TAG, "SYSTEM_EVENT_STA_GOT_IP");
	ESP_LOGI(TAG, "got ip:%s\n",
		ip4addr_ntoa(&event->event_info.got_ip.ip_info.ip));
        break;
    case SYSTEM_EVENT_STA_DISCONNECTED:
	ESP_LOGI(TAG, "SYSTEM_EVENT_STA_DISCONNECTED");
	ESP_ERROR_CHECK(esp_wifi_connect());
	break;
    default:
        break;
    }
    return ESP_OK;
}

/*init wifi as sta and set power save mode*/
static void wifi_power_save(void)
{
    tcpip_adapter_init();
    ESP_ERROR_CHECK(esp_event_loop_init(event_handler, NULL));
    
    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
    ESP_ERROR_CHECK(esp_wifi_init(&cfg));
    wifi_config_t wifi_config = {
	.sta = {
	    .ssid = DEFAULT_SSID,
	    .password = DEFAULT_PWD,
	    .listen_interval = DEFAULT_LISTEN_INTERVAL,
	},
    };
    ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA));
    ESP_ERROR_CHECK(esp_wifi_set_config(ESP_IF_WIFI_STA, &wifi_config));
    ESP_ERROR_CHECK(esp_wifi_start());

    ESP_LOGI(TAG, "esp_wifi_set_ps().");
    esp_wifi_set_ps(DEFAULT_PS_MODE);
}

void app_main()
{
    // Initialize NVS
    esp_err_t ret = nvs_flash_init();
    if (ret == ESP_ERR_NVS_NO_FREE_PAGES) {
        ESP_ERROR_CHECK(nvs_flash_erase());
        ret = nvs_flash_init();
    }
    ESP_ERROR_CHECK( ret );

#if CONFIG_PM_ENABLE
    // Configure dynamic frequency scaling: maximum frequency is set in sdkconfig,
    // minimum frequency is XTAL.
    rtc_cpu_freq_t max_freq;
    rtc_clk_cpu_freq_from_mhz(CONFIG_ESP32_DEFAULT_CPU_FREQ_MHZ, &max_freq);
    esp_pm_config_esp32_t pm_config = {
            .max_cpu_freq = max_freq,
            .min_cpu_freq = RTC_CPU_FREQ_XTAL,
#if CONFIG_FREERTOS_USE_TICKLESS_IDLE
            .light_sleep_enable = true
#endif
    };
    ESP_ERROR_CHECK( esp_pm_configure(&pm_config) );
#endif // CONFIG_PM_ENABLE

    wifi_power_save();
}