I think the STM32F7 Ethernet MAC does not work well in RMII mode.

[Asantos]

Posted on March 22, 2017 at 02:12

Using the STM32CubeMx v4.20, I did a webserver with a custom page that show two pictures of about 27KB each. I tested the webserver with the STM32F746G-DISCO , NUCLEO-F746ZG and  NUCLEO-F767ZI.

What happens is that when I press F5 to reload the page in the web-browser, most times it takes a long time to reload the pictures. See Wireshark captures in anexo.

When I tested the same page with the same LwIP configuration in the FRDM-K64F board (RMII using KSZ8081RNA), it works ok, I can press F5 very fast and the page always reloads very fast. I also teste in a STM32F407-EVAL board (MII mode) and also worked fine.

  I  put an external SPI ethernet controller in the NUCLEO-F746ZG and I only changed the ethernetif.c to redirect the packets to the external controller. And the webserver also worked fine, always with fast reloads.  

   

  So the problem should be the hardware MAC/PHY of the STM32F7 boards or the CubeMx Ethernet driver.

   

  Did someone also experience this problem on some STM32F7 RMII boards?

[Amel NASRI]

Posted on March 22, 2017 at 10:42

Hi

Mendes.Ari

‌,

There is a known RMII related issue already documented on the

http://www.st.com/content/ccc/resource/technical/document/errata_sheet/group0/23/a6/11/0b/30/24/46/a5/DM00257543/files/DM002575pdf/jcr:content/translations/en.DM002575pdf

(Ethernet erroneous data received in RMII configuration).

This limitation is fixed on devices having revision 'Z'.

-Amel

[Asantos]

Posted on March 22, 2017 at 11:25

Amel, 

I know that.

 My NUCLEO-F767ZI uses a revision Z chip, and I verify the problem using the STM32F746 from DISCO and NUCLEO boards.

Ari.

[Asantos]

Posted on May 09, 2017 at 01:57

  Hi,  

I've mounted and tested  a custom board using the STM32F767ZI and the KSZ8081RNA Phy, and the webserver still slow because of missing packets. The problem problably should be the STM32F7 MAC hardware or the STM32F7cubeMx ethernet driver.

Can someone send me an example of webserver using the LwIp for the STM32F746-Discovery or for the NUCLEO-L767ZI or for the NUCLEO-L476ZG that I can reload the page very fast without crashes?

 Ari.