发送 UDP 数据（标准接口）
FreeRTOS-Plus-TCP 网络教程节选

static void vUDPSendUsingStandardInterface( void *pvParameters )

{

Socket_t xSocket;

struct freertos_sockaddr xDestinationAddress;

uint8_t cString[ 50 ];

uint32_t ulCount = 0UL;

const TickType_t x1000ms = 1000UL / portTICK_PERIOD_MS;



   /* Send strings to port 10000 on IP address 192.168.0.50. */

   xDestinationAddress.sin_addr = FreeRTOS_inet_addr( "192.168.0.50" );

   xDestinationAddress.sin_port = FreeRTOS_htons( 10000 );



   /* Create the socket. */

   xSocket = FreeRTOS_socket( FREERTOS_AF_INET4, /* Used for IPv4 UDP socket. */


                                 /* FREERTOS_AF_INET6 can be used for IPv6 UDP socket. */

                              FREERTOS_SOCK_DGRAM, /*FREERTOS_SOCK_DGRAM for UDP.*/

                              FREERTOS_IPPROTO_UDP );



   /* Check the socket was created. */

   configASSERT( xSocket != FREERTOS_INVALID_SOCKET );



   /* NOTE: FreeRTOS_bind() is not called.  This will only work if

   ipconfigALLOW_SOCKET_SEND_WITHOUT_BIND is set to 1 in FreeRTOSIPConfig.h. */



   for( ;; )

   {

       /* Create the string that is sent. */

       sprintf( cString,

                "Standard send message number %lurn",

                ulCount );



       /* Send the string to the UDP socket.  ulFlags is set to 0, so the standard

       semantics are used.  That means the data from cString[] is copied

       into a network buffer inside FreeRTOS_sendto(), and cString[] can be

       reused as soon as FreeRTOS_sendto() has returned. */

       FreeRTOS_sendto( xSocket,

                        cString,

                        strlen( cString ),

                        0,

                        &xDestinationAddress,

                        sizeof( xDestinationAddress ) );



       ulCount++;



       /* Wait until it is time to send again. */

       vTaskDelay( x1000ms );

   }

}



Example using FreeRTOS_sendto() with the standard (as opposed to zero copy) calling semantics