Hi Guys,
I'm working on an application that connects to a remote server, for the
sake of testing lets say the remote server port is 80.
The FPGA is a XUPV2P board , that has been tested with the inbuilt
utilities and the tcp/ip port works and will support a demo webserver.
The cables are good, the led's are on , and flash when the board is pinged
(though a reply is nver returned)
The version of LWIP is 3.00a in RAW API mode.
We have a function that initialises the tcp/ip, along the lines of:
init_tcpip(){
........
lwip_init();
......
if (!xemac_add(&default_netif, &ipaddr, &netmask, &gw, mac_ethernet_address,
EMAC_BASEADDR)) {
printf("Error adding N/W interface\n\r");
return; // -1;
}
netif_set_default(&default_netif);
netif_set_up(&default_netif);
}
then we call this to trigger a connection
int connect_server(void)
{
struct ip_addr server;
IP4_ADDR(&server, 192, 168, 5, 52); //our server (mac)
printf(" * Image server at %u.%u.%u.%u\n",
ip4_addr1(&server), ip4_addr2(&server), ip4_addr3(&server),
ip4_addr4(&server));
struct tcp_pcb *tpcb = tcp_new();
if (!tpcb)
{
printf("FATAL: tcp_new() failed\n");
return -1;
}
tcp_err(tpcb, error);
tcp_sent(tpcb, data_sent);
tcp_poll(tpcb, data_poll, 4);
//printf(" * connecting...\n");
//just queue a SYN, it does not actually wait for connection!!
//port 7683
if (tcp_connect(tpcb, &server, 80, connected))
{
printf("tcp connect failed!\n");
return 1;
} else{
printf("tcp SYN Queued!\n");
return 0;
}
}
What we see next is interesting:
using wire shark, the board sends out a single ARP packet to the
destination server, and a reply is sent back from the server to the FPGA
board.
in about 0.2ms.
However LWIP has the debug code turned on, and it clearly shows 4 ARP
packets being triggered , and nothing being recived to the FPGA, in response
to the ARP.
the connection then failes due to the ARP time out.
The LWIP never even makes it as far as the callback "connected" routine,
from the tcp_connect.
it is as if there is some sort of error occuring inside of LWIP, that
causes the connection to fail.
I would assume that if the first ARP packet is making it to the wire, then
surely , i'm fairly close to a solution.
where do i start looking, and how would i debug this?
Steve
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