ESP32 Forum

Posted: **Fri Jun 15, 2018 1:18 pm**

Hello,
I would like to use the netconn api in lwIP to use multicast.

There is the function "netconn_join_leave_group" which has the parameter "netif_addr" which is described as "the IP address of the network interface on which to send the imgp message".

Is there a macro I can use for this parameter?
As my ESP32 gets an IP via DHCP the IP might change.
So how can I make sure that always the correct IP is used?

Thank you very much.

Posted: **Fri Jun 15, 2018 1:35 pm**

https://github.com/espressif/esp-idf/bl ... ple_main.c

Posted: **Tue Jun 19, 2018 2:13 pm**

Thanks!

Sadly I could not get it to work.
Your example uses BSD sockets which I would like to avoid.

It would be really great if someone could help me to get it work.

Please see my example.

Thank you very much!

Code: Select all

static void udp_send_multicast(void *pvParameters) {

	char tag[] = "udp_multicast_send_task";
	ESP_LOGI(tag,"udp_multicast_send task started \n");

	struct netconn *conn;
		struct netbuf *buf;
		char* data;

		struct ip_addr_t multicastip; //Says size of multicastip is unknown
		IP4_ADDR(&multicastip,239,255,255,250);

		char msg [100];
	    sprintf(msg, "multicast test message");

		conn = netconn_new(NETCONN_UDP);
		netconn_bind(conn,IP_ADDR_ANY,4990);
		netconn_join_leave_group(conn,multicastip,0,NETCONN_JOIN); //What do I have to use here as second and third argument?
		while(1) {
			buf = netbuf_new();
			data = netbuf_alloc(buf, sizeof(msg));
			memcpy(data,msg,sizeof(msg));
			netconn_send(conn,buf);
			netbuf_delete(buf);
			vTaskDelay(10000 / portTICK_PERIOD_MS);
		}
}

ESP32 Forum

lwIP netconn: netif_addr, what is the correct variable

lwIP netconn: netif_addr, what is the correct variable

Re: lwIP netconn: netif_addr, what is the correct variable

Re: lwIP netconn: netif_addr, what is the correct variable