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

[Mike Fleetwood]

Hi Simon,

Thanks for this - looks like getting closer!  I thought the problem must 
be happening at a low level, otherwise why should it stop all LWIP function?

I'm using F427, initial code generated by CubeMX, including ethernet.c.  
I hadn't got around to looking at what ethernet.c did (really didn't 
want to wade through all the "HAL" nonsense!).

I'm sending data packet every 4mS.  Packet transmission time is, I 
think, about 80uS for the test snippet.  It was about 300uS for a decent 
audio packet.  At the moment, it's running on a fairly slow (10Mbit) 
network segment, so obviously the packet times would be faster at 
100Mbit.  There's not much other traffic on the network, so I don't see 
that this should tax the DMA too much.

I wrote a previous version of this application a couple of years ago, 
running on F107 (I think), but all raw-api, no RTOS.  That worked fine 
with a similar packet size and rate (although I can't remember the exact 
details).

1, I'll have a look at ethernet.c and see what's going on.  I'll report 
the bug to ST, but I know from experience they don't exactly respond 
quickly!

2, I'll have a play with different packet sizes and rates to explore 
where the limits are!

Many thanks,

Mike.


On 28/07/2016 12:02, Simon Goldschmidt wrote:
> Mike Fleetwood wrote:
> > If, by "low level netif driver" you mean the ethernet adaptor interface driver
> That's it.
>
> > - that was provided by ST, and is the latest version they offer - I'm not aware 
> > of any reported problems with it.
> I've had a quick look at the ethernetif.c file generated by CubeMX: at least 
> for the F439, it returns
> ERR_USE when no more TX DMA descriptors are available. This is clearly a bug as ERR_USE 
> means "Address in use"
> (and it has been like that since the beginning of the universe). ERR_MEM would 
> be a better return value.
>
> [You might want to report that bug back to STM]
>
> In any case, you try to send faster than the chip or the cable can...
>
> Simon
>
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