开发环境介绍：

MCU：STM32F407ZET6

网卡：LAN8720A

LWIP版本：V1.1.0

FreeRTOS 版本：V10.2.1

LAN8720A硬件原理图：

硬件连接说明：

MII_RX_CLK/RMII_REF_CLK ------>PA1                   MII_TXD0 ------>PB12

MII_MDIO  ------>PA2                                                 MII_TXD1 ------>PB13

MII_RESET ------>PA3                                               MII_MDC ------>PC1

MII_RX_DV/RMII_CRSDV ------>PA7                        MII_RXD0 ------>PC4

MII_RX_ER  ------>PB10                                            MII_RXD1 ------>PC5

MII_TX_EN  ------>PB11

Lwip组播配置：

上图中创建了一个10ms的循环定时器，定时器回调函数为： LwipTimCallBack

void LwipTimCallBack(TimerHandle_t xTimer)
{
    uint32_t LocaTime = xTaskGetTickCount();
    LwIP_Periodic_Handle(LocaTime);
}

 netconf.c--->void LwIP_Periodic_Handle(volatile uint32_t localtime)内添加igmp计时器调用算法

ethernetif.c--->static void low_level_init(struct netif *netif)添加

 netif->flags = NETIF_FLAG_BROADCAST | NETIF_FLAG_ETHARP | NETIF_FLAG_IGMP;

 在stm32f429_phy.c---->static void ETH_MACDMA_Config(void)方法中进行以下设置：

组播接收消息设置：

接收消息使用的是8081端口，发送消息使用的是8080端口。组播地址239.0.0.1。客户端设置可参考另一篇文章：QT学习笔记_UDP组播通信（加入组播）_qt 实现udp通信工程文件添加什么-CSDN博客

static void MulticastRxTask(void *pcParameter)
{
	uint32_t NotifyValue = 0;
	UBaseType_t uxHighWaterMark;
	struct netconn *udpconn;
	udpconn = netconn_new(NETCONN_UDP);
	ip_addr_t destipaddr;
	IP4_ADDR(&destipaddr,239,0,0,1);
	netconn_bind(udpconn,IP_ADDR_ANY,8081);
	netconn_join_leave_group(udpconn,&destipaddr,IP_ADDR_ANY,NETCONN_JOIN);
    uxHighWaterMark = uxTaskGetStackHighWaterMark(NULL);
	while(1)
	{
		struct netbuf *recebuf;
		
		if(netconn_recv(udpconn,&recebuf) == ERR_OK)//会自己阻塞
		{
			uint16_t ReceByteCount = recebuf->p->len;
			uint8_t *pData = recebuf->p->payload;
			if((pData[0] == 0xAA &&pData[1] == 0xBB))memcpy((void *)MulticastBuf,(void *)pData,ReceByteCount);
			netbuf_delete(recebuf);
		}
		uxHighWaterMark = uxTaskGetStackHighWaterMark( NULL );
	}
}

组播发送消息：

void MulticastTxTask(void *pvParameter)
{
  struct netconn *udpconn;
  udpconn = netconn_new(NETCONN_UDP);
  netconn_bind(udpconn, IP_ADDR_ANY, 8080);
  ip_addr_t ipMultiCast;
  IP4_ADDR(&ipMultiCast, 239, 0, 0, 1);
  netconn_connect(udpconn,&ipMultiCast,8080);
  for(;;)
  {
    uint32_t NotifyValue = 0;
    struct netbuf *sendbuf = netbuf_new();
    xTaskNotifyWait(ULONG_MAX,ULONG_MAX,&NotifyValue,portMAX_DELAY);
    switch(NotifyValue)
    {//组桢
      MulticastRxStruct.ReceLen =MakeUpInfoBack(0x3031,MulticastRxStruct.Data);break;
    default:break;
    }
    netbuf_alloc(sendbuf,MulticastRxStruct.ReceLen);
    netbuf_ref(sendbuf,MulticastRxStruct.Data,MulticastRxStruct.ReceLen);//发送指定长度字符串
    netconn_send(udpconn,sendbuf);//发送报文
    netbuf_delete(sendbuf);
  }
}