migrating to v4.1 event handlers

[mzimmers]

Hi all -

I'm assessing the work required to move from v4.0 to v4.1. One area of concern is event handlers. In v4.0, I registered my handler:

Code: Select all

esp_err_t event_handler(void *ctx, system_event_t *event)
{
    Tasks *tasks = reinterpret_cast<Tasks *> (event);

    // disconnect reason code stuff.
    char ssid[32];
    uint8_t ssid_len;
    uint8_t reason;

    switch(event_id)
    {
    case SYSTEM_EVENT_STA_DISCONNECTED:
        reason = event->event_info.disconnected.reason;
        ssid_len = event->event_info.disconnected.ssid_len;
        strncpy(ssid, (char *) event->event_info.disconnected.ssid, ssid_len);
        ...
}
ESP_ERROR_CHECK(esp_event_loop_init((system_event_cb_t) event_handler, m_tasks)); // v4.0 and below.

In v4.1, the event handling doesn't seem to make use of the system_event_t struct. What do I do in order to retrieve information like this?

Thanks...

[ESP_igrr]

With the new event handlers based on esp_event, you obtain the extra info by casting the event_data pointer. You need to cast it to the structure corresponding to the event type. For instance, see https://github.com/espressif/esp-idf/bl ... main.c#L40

For the WIFI_EVENT_STA_DISCONNECTED event, corresponding event structure is wifi_event_sta_disconnected_t, defined here: https://github.com/espressif/esp-idf/bl ... pes.h#L551

[mzimmers]

Ahh...thanks, Igrr.

On a related subject, my app isn't progressing out of the Wifi connected state. I'm still using the old SYSTEM_EVENT_STA_* symbols, and it looks like the Wifi state machine might have changed in v4.1. The example you provided doesn't really cover this; is there a doc that explains the new state machine?

EDIT: oh, I get it -- it's not enough to merely check the event ID; you have to check the event base as well, right? OK, let me work with this a little; I'll report back.

Thanks again.

[mzimmers]

I've changed my handler to match my understanding of the v4.1 Wifi/IP events. Here's a snippet:

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static void event_handler(void *ctx,
                          esp_event_base_t event_base,
                          int32_t event_id,
                          void *event_data)
{
    std::string currentTime;
    Tasks *tasks = reinterpret_cast<Tasks *> (ctx);
    time_t now;
    union
    {
        wifi_event_sta_disconnected_t *disc;
        wifi_event_sta_scan_done_t *scan;
        void *pVoid;
    } eventData;

    // get the data pointer from the argument.
    eventData.pVoid = event_data;

    time(&now);
    currentTime.assign(tasks->wifi->getTimeString(now));

    if (event_base == WIFI_EVENT)
    {
        switch(event_id)
        {
        case WIFI_EVENT_STA_CONNECTED:
            ESP_LOGI(TAG, "event_handler(): Wifi connected at %s.", currentTime.c_str());
            tasks->wifi->setCommsState(WIFI_STATE_CONNECTED_TO_AP);
            tasks->wifi->setDisconnectReason(INVALID_DISCONNECT_REASON);
            // reset the connection delay.
            tasks->wifi->setConnectDelay(WIFI_CONNECT_DELAY_DEFAULT);
            break;
		...
	}
    }
    else if (event_base == IP_EVENT)
    {
        switch(event_id)
        {
        //      case SYSTEM_EVENT_STA_GOT_IP:
        case IP_EVENT_STA_GOT_IP:
            ESP_LOGI(TAG, "event_handler(): device received IP address from wifi server at %s.", currentTime.c_str());
            tasks->wifi->setCommsState(WIFI_STATE_IP_ADDRESS_ASSIGNED);
            tasks->wifi->storeIPinfo();
            break;
		...
	}
    }
}

ESP_ERROR_CHECK(esp_event_handler_register(ESP_EVENT_ANY_BASE,
										   ESP_EVENT_ANY_ID,
										   &event_handler,
										   m_tasks)); // v4.1

It all works...I get the WIFI_EVENT_STA_CONNECTED event, but not the IP_EVENT_STA_GOT_IP. Can someone see what I'm missing? Thanks.

[ESP_igrr]

Please try enabling verbose log output — there should be logs of all events being delivered to the callbacks.

Also please check that you aren't calling both the legacy event loop functions (esp_event_loop_init) and the new ones. Either the old ones, OR the new ones, should work.

[mzimmers]

Hi Igrr --

Confirmed that I'm not calling esp_event_loop_init().

When I select verbose output, I can't build:

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C:/esp-idf/components/log/include/esp_log.h:281:13: error: 'len' may be used uninitialized in this function [-Werror=maybe-uninitialized]
             ets_printf(LOG_FORMAT(log_tag_letter, format), esp_log_timestamp(), tag, ##__VA_ARGS__); \
             ^~~~~~~~~~
C:/esp-idf/components/soc/src/hal/sdio_slave_hal.c:375:14: note: 'len' was declared here
     uint32_t len;
              ^~~

When I select debug output, I get a panic early in startup (not enough stack displayed to trace).

Thanks...

[mzimmers]

BTT: anyone have a suggestion here? I'd really like to get this functional.

By the way, I think this document https://docs.espressif.com/projects/esp ... /wifi.html is out of date:

s1.2: The main task calls esp_event_loop_init() to create a system Event task and initialize an application event’s callback function. In the scenario above, the application event’s callback function does nothing but relaying the event to the application task.

Thanks.