[En-Nut-Discussion] Problems with TCP-Sendbuffer size(?)

Ole Reinhardt ole.reinhardt at embedded-it.de
Thu Oct 13 12:40:40 CEST 2011

Hi Klaus,

> Ive got a running project (Sam7ek) connected directly by ethernet.
> Now a wiz610 WLAN<>LAN bridge comes in between and Ive got a problem when sending more than ca. 512 Bytes using an telnet-connection and fputs() from the ethernut side. 
> NutSleep() and NutYield() do not help. The sleeping-time is spend before sending the first signs other the net.
> If I send smaller pieces everything seems fine. After ethernut has crashed I can see 512 send bytes on my PC side of the telnet connection.

Are you sure your Board crashed? You might have got a stack problem.
Have you allocated your send buffer from the stack (as local variable)
or have you used malloc / NutHeapAlloc?

Never use such large local variables :)

btw: to make sure all data is written out you should add a fflush() at
the point where you want to make sure that all data is send.

> How can I tell the TCP-Stack to send all the data he has to deliver and wait for the completion?

As above: First check that you did not allocate the whole send buffer as
local variabel. Next add a fflush() after your fputs().

> Im using NutOS 4.8.9 up to now, because using 4.10rc1 ive got a problem with getting the IP-adress with or without DHCP using the tcps demo.
> This has been changed, but I was not able to find out the problem with my board. Even when I used this part from my working 4.8.9 project the 4.10 version does not get an IP-adress. 

Sounds strange. Nut/OS 4.10 is definately working fine on our eNet-sam7X

If you like, you might contact me by private mail to solve your problem.




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