Lwip的UDP例程

if(flag) //your own flag to trigger event
{
               pudp_buf = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
               if(pudp_buf)
               {
                   IP4_ADDR(&dest_ip, alarm_ip[0],alarm_ip[1],
                                      alarm_ip[2],alarm_ip[3]);                 

                    memcpy(pudp_buf->payload,temp_out_buf,len);
                    err=udp_sendto(udp_comm_pcb,pudp_buf,&dest_ip,TCP_COMM_PORT);//Port to send        

                    pbuf_free(pudp_buf);
                    if(err)
                         printf("udp_sendto err!\n");
               }
  }