AnsweredAssumed Answered

Stm32F207 Ethernet Multicast RX

Question asked by Sebastian Fett on Jun 23, 2017
Latest reply on May 22, 2018 by Kamil Alkhouri


Currently I'm using lwip + tinymDNS on a stm32f207.

The mDNS needs multicast packets. I activated IGMP in the lwip stack and it works.

mDNS messages were sent as mutlicast packets.

But the one thing that did not work was the reception of multicast packets. 


After some digging I found the ETH configuration in the STM HAL drivers. 

There the multicast frame filtering is set to "PERFECT". But no filter MACs are set up.


When I wrote the right MAC into the ETH_MACA1 register manually and activated it by setting the AE bit everything worked. 


I would have expected that when I join a igmp group that the according MAC is set as a filter. Or that at least the multicast frame filtering would be disabled alltogether. But I could not find anything related to that in the code. 


Is that functionality not implemented or am I just blind?


My stm32f2xx_hal_eth.c is v1.1.3 from June 2016. And lwip 1.4.1.


Thanks for any hints and best regards,