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By Misha Green
#94975 I have an application built with ESP_RTOS_SDK version 3.4.
It mainly runs in light sleep and wakes up every few seconds to take a reading. After collecting a set of readings, it turns on wifi and sends it to a server, then turns off wifi and starts collecting another set of data.

Unfortunately, Wifi does not always start after a light sleep:

    reboot, start wifi ... works
    reboot, light sleep, start wifi ... works
    reboot, start wifi, stop wifi, light sleep, start wifi ... does not work

I would appreciate suggestions about how to make it start.

I am using the following code to enter light sleep:

Code: Select allvoid light_sleep (void) {

  gpio_wakeup_enable(GPIO_WAKE_PIN, GPIO_INTR_LOW_LEVEL);
  esp_sleep_enable_gpio_wakeup();
  esp_sleep_enable_timer_wakeup (10000000L);

  ESP_LOGI (TAG, "Entering light sleep");
  esp_light_sleep_start ();
  vTaskDelay (1);
  // Wake up here
  esp_sleep_disable_wakeup_source (ESP_SLEEP_WAKEUP_GPIO);
  esp_sleep_disable_wakeup_source (ESP_SLEEP_WAKEUP_TIMER);
  ESP_LOGI (TAG, "Awake again");

}


This works, but when I try to start Wifi after a light sleep, nothing happens. I stop wifi before light sleep and restart if afterwards using these two routines, which work correctly before a light sleep:

Code: Select allstatic void app_wifi_start (wifi_mode_t mode, int retries) {

    max_retries = retries;

    ESP_ERROR_CHECK(esp_event_handler_register(WIFI_EVENT, ESP_EVENT_ANY_ID, &wifi_event_handler, NULL));
    ESP_ERROR_CHECK(esp_event_handler_register(IP_EVENT, IP_EVENT_STA_GOT_IP, &ip_event_handler, NULL));

    ESP_ERROR_CHECK(esp_wifi_set_mode(mode));
    current_mode = mode;

    switch (mode) {
        case WIFI_MODE_STA:
            sta_prepare ();
            break;

        case WIFI_MODE_AP:
            ap_prepare ();
            break;

        case WIFI_MODE_APSTA:
            ap_prepare ();
            sta_prepare ();
            break;

        default:
            break;   

    }

    ESP_ERROR_CHECK(esp_wifi_start());

}


// -----------------------------------------------------------------------------------------------
static void app_wifi_stop (void) {

    ESP_ERROR_CHECK(esp_event_handler_unregister(IP_EVENT, IP_EVENT_STA_GOT_IP, &ip_event_handler));
    ESP_ERROR_CHECK(esp_event_handler_unregister(WIFI_EVENT, ESP_EVENT_ANY_ID, &wifi_event_handler));

    switch (current_mode) {
        case WIFI_MODE_STA:
            sta_cancel ();
            break;

        case WIFI_MODE_AP:
            ap_cancel ();
            break;

        case WIFI_MODE_APSTA:
            ap_cancel ();
            sta_cancel ();
            break;

        default:
            break;   
    }

    ESP_ERROR_CHECK(esp_wifi_stop ());
    vTaskDelay (1000 / portTICK_RATE_MS);
    ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_NULL));

    current_mode = WIFI_MODE_NULL;
    sta_connected = false;

}