Re: [lwip-users] ERR_MEM when sending large data, LWIP stats show no error

[Nathan Hartman]

On Sep 14, 2017, at 5:09 AM, Adrian Figueroa <address@hidden> wrote:
> 
> I did some more testing and it does not seem to be systematic. As lwIP is not 
> showing errors in any of the stats, it is likely not its fault.
> 
> Do you have any suggestions on how to find the reason for dropped packets? 
> Maybe someone has experience with the HAL drivers of the STM32F7.
> 
> I can see some errors in low_level_output() in ethernetif.c.
> 
> This fails:
> 
>      if((DmaTxDesc->Status & ETH_DMATXDESC_OWN) != (uint32_t)RESET)
>      {
>        errval = ERR_USE;
>        goto error;
>      }
> 
> When DmaTxDesc->Status  equals 818937856. What does this mean? Is the DMA 
> used by something else?

I am not familiar with this part but one potential pitfall with many micro 
controllers is that not all of memory is accessible to the DMA. Is the entire 
message in an area of memory accessible to the DMA?