mqtt_settings settings = {
    .host = "iot.eclipse.org",
    .port = 1883, // unencrypted
    .client_id = "some_client_id",
    .username = "",
    .password = "",
    .clean_session = 0,
    .keepalive = 120,
    .lwt_topic = "/lwt",
    .lwt_msg = "offline",
    .lwt_qos = 0,
    .lwt_retain = 0,
    .connected_cb = connected_cb,
    .disconnected_cb = disconnected_cb,
    .subscribe_cb = subscribe_cb,
    .publish_cb = publish_cb,
    .data_cb = data_cb
};