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[lwip-users] Re: ARP not working

From: Bernard Mentink
Subject: [lwip-users] Re: ARP not working
Date: Fri, 18 Feb 2011 18:56:56 +1300


I have fixed my debugger issue, and am now able to debug through the driver.

I have found that by putting a breakpoint in the etharp_input function, that the PC will get an ARP reply, so it looks like some weid
timing of buffering issue maybe ..

I have also noticed that once the ARP has been replied to, that it takes 5..10 seconds for the receive callback to be called.

Any idea's


On Fri, Feb 18, 2011 at 8:33 AM, Bernard Mentink <address@hidden> wrote:
Hi All,

I have just ported the lwIP stack to the NXP LPC17xx family combined with QP OS and have it mostly working except for ARP.

What works is:

1. udp_send(), udp_sendto() etc .. I han't tried tcp yet ..
2. I can ping the stack fine.
3. Receive sort of works .. explain shortly ..

To test, I created a test program on the PC that just sends x UDP packets and expects x packets from the device.
However, what I am seeing with Wireshark is that the ARP request goes out, but MOST of the time is ignored, I see no reply back from lwIP.
Occasionally the ARP is accepted and I see the packet exchange, however, I see the packet from the PC, then approx 10 seconds later (a timeout perhaps?) I see the packet from lwIP (testing with one packet).
The packets are formed correctly with IP address and port numbers ..

The only part of lwIP I have ported is the driver, so expect a problem there .... what would be best way to debug this? Anyone have some idea's?
I see you can turn on debugging in   lwipopts.h, but I don't have a UARTprintf() function implemented ....

On an aside, I am using GCC tools coupled with eclipse and openocd for development, however if I compile in debug symbols for my lwIP library the elf file created causes a GDB crash, so I can only debug through my application code
but not through the lwIP stack .... havn't found a solution to that, so am stuck.

Many thanks,

You always have believers and scepticts.. A True inventor is always a believer..

You always have believers and scepticts.. A True inventor is always a believer..

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