Re: [lwip-users] Problems with sending UDP packets in FreeRTOS

[Mike Fleetwood]

Hi Simon,

That is exactly what I was trying to identify.

I put the "borrowed" code in to prove/check that fault wasn't in what I 
had written - succeeded there, I think.

After that, it has to be at some lower level - that it, either in LWIP 
or in ST's driver interface.  So, now we know the low level driver 
returns ERR_USE (when maybe it would be more useful to return something 
like ERR_DMA?).  I was kind of hoping that someone might be able to 
suggest a reason why?

It has been suggested that the data rate is too high.  An overall packet 
size of 67 bytes sent every 4mS is not exactly "SuperFast".  I have a 
180MHz CPU and a 10MHz ethernet segment.  I know the whole packet send 
gets processed, from creation to end of wire transmission in a maximum 
of about 200uS - long before I start creating the next one - so what 
possible reason is there for the DMA to run out of buffers?  There is 
virtually no other traffic on this network segment that could cause 
collision and no ARP to wait for (which would have happened at a higher 
level anyway).

I have reduced the send rate to one every 100mS, and the packet data is 
25 bytes - so far (since last compile) it has successfuly sent about 20k 
packets.  This is with all the other threads enabled and regular access 
to the HTTP status page to see how it's getting on (no warning 
messages).  I'm using my original udp_test function - that checks for 
errors and reports them (not the "borrowed" one!).

I'm going to try bigger or faster packets in a minute.

Many thanks,

Mike.


On 28/07/2016 16:27, goldsimon wrote:
> Sylvain Rochet wrote:
> > The fact that it is your code and not your code doesn't change anything
> > about the fact that it is completely wrong.
>
> Indeed. Not completely wrong maybe, but at least bad quality. However, 
> it changes everything about suspecting something about Mike driver's 
> code quality:
>
> > I assume your whole software quality is between
> > poor to critically wrong. Given that, the bug is
> > probably in your low level netif driver.
>
> And I guess that could have been what Mike was complaining about... ;-)
>
> Simon
>
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