static void Main()
    {
        Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
        IPEndPoint localEP = new IPEndPoint(IPAddress.Any, 0);
        socket.Bind(localEP);
        while( my_condition){
             Receive();}
    }

    private bool Receive()
    {
        received = false;

        if (socket != null)
        {
            SocketAsyncEventArgs ae = new SocketAsyncEventArgs();
            ae.SetBuffer(recvBuffer, 0, recvBuffer.Length);

            // callback
            EventHandler<SocketAsyncEventArgs> rcb = new EventHandler<SocketAsyncEventArgs>(ReceiveCallback);
            ae.Completed += rcb;

            socket.ReceiveAsync(ae);

            int counter = 0;
            int recv_timeout = 500;

            // create a delay waiting for data
            while (!received && counter <= recv_timeout)
            {
                double nanosecs = recv_timeout * 1000;
                long nanosperTick = (1000L * 1000L * 1000L) / Stopwatch.Frequency;

                int ticks = (int)(nanosecs / nanosperTick);

                Stopwatch sw = Stopwatch.StartNew();

                while (sw.ElapsedTicks < ticks) { }

                sw.Stop();

                counter++;
            }

            ae.Completed -= rcb;
            ae.Dispose();
        }

        return received;
    }

    private void ReceiveCallback(object sender, SocketAsyncEventArgs e)
    {
        switch (e.LastOperation)
        {
            case SocketAsyncOperation.Receive:
                if (e.BytesTransferred == Number_of_bytes_I_wait_for)
                {
                    //get e.Buffer !
                }
                else
                    Console.WriteLine("??? number_of_bytes received: " + e.BytesTransferred);
                break;
        }
    }