使用 TCP 套接字接收数据
FreeRTOS-Plus-TCP 网络教程节选

#define BUFFER_SIZE 512

static void prvEchoClientRxTask( void *pvParameters )

{

Socket_t xSocket;

static char cRxedData[ BUFFER_SIZE ];

BaseType_t lBytesReceived;



    /* It is assumed the socket has already been created and connected before

    being passed into this RTOS task using the RTOS task's parameter. */

    xSocket = ( Socket_t ) pvParameters;



    for( ;; )

    {

        /* Receive another block of data into the cRxedData buffer. */

        lBytesReceived = FreeRTOS_recv( xSocket, &cRxedData, BUFFER_SIZE, 0 );



        if( lBytesReceived > 0 )

        {

            /* Data was received, process it here. */

            prvProcessData( cRxedData, lBytesReceived );

        }

        else if( lBytesReceived == 0 )

        {

            /* No data was received, but FreeRTOS_recv() did not return an error.

            Timeout? */

        }

        else

        {

            /* Error (maybe the connected socket already shut down the socket?).

            Attempt graceful shutdown. */

            FreeRTOS_shutdown( xSocket, FREERTOS_SHUT_RDWR );

            break;

        }

    }



    /* The RTOS task will get here if an error is received on a read.  Ensure the

    socket has shut down (indicated by FreeRTOS_recv() returning a -pdFREERTOS_ERRNO_EINVAL

    error before closing the socket). */



    while( FreeRTOS_recv( xSocket, pcBufferToTransmit, xTotalLengthToSend, 0 ) >= 0 )

    {

        /* Wait for shutdown to complete.  If a receive block time is used then

        this delay will not be necessary as FreeRTOS_recv() will place the RTOS task

        into the Blocked state anyway. */

        vTaskDelay( pdTICKS_TO_MS( 250 ) );



        /* Note - real applications should implement a timeout here, not just

        loop forever. */

    }



    /* Shutdown is complete and the socket can be safely closed. */

    FreeRTOS_closesocket( xSocket );



    /* Must not drop off the end of the RTOS task - delete the RTOS task. */

    xTaskDelete( NULL );

}



Example using FreeRTOS_recv()