Re: [lwip-users] Fail on too much data?

[Tomáš Švec]

Right, makes sense :) Thanks for the quick explanation.

I have one more question, however - if I decide to send huge chunks of data (like some hi-res pictures stored in an external flash via SPI or something), does that mean I need to set TCP_SND_BUF to the greatest size of the file I will be sending?

Tomas

2012/9/10 Simon Goldschmidt <address@hidden>

Tomáš Švec wrote:

> When I step through the code, it stops in tcp_out.c on these lines:
>
>   /* fail on too much data */
>   if (len > pcb->snd_buf)...
>
> I am sending 1150 bytes, while there is only a 256 bytes sending buffer. I get that, but how is it supposed to be sent correctly? Should my code handle the fragmentation itself?

Yes, it should.

> That doesn't make sense, does it?

Regarding TCP it doesn't make sense. Regarding embedded systems, it does: You have configured lwIP in a way to limit its internal buffer memory lower than your code expects it to. In other words it's a configuration problem: TCP_SND_BUF is not big enough to send your data in one chunk. This is not a problem but your application must be able to handle this or you can incise the send buffer if your available memory allows it.

Simon
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