Posted on May 17, 2011 at 13:30Make sure that you do DMA directly in and out of lwIP pbufs, not copying data to intermedeate buffers. Also use checksum offloading to increase throughput. To do this you need to change lwIP ICMP code so that it will not generate checksums, other parts of lwIP can be made to ignore checksums by using #defines.
With correct use of DMA and checksum offloading stm32f107 can achieve pretty good ETH throughput. At least in my experiences with adequate number of input descriptors mcu can correctly input all udp data that modern windows workstation can output without dropping a packet.
I think that if you can provide good ports of FreeRTOS and lwIP to stm32 you will increase the appeal of stm32 to developpers, not to mention lower the threshold of starting app development. Both FreeRTOS and lwIP have already been ported to stm32 but at least the ports I've seen have poorly implemented ETH interfacing.
And btw, if you choose the FreeRTOS approach, make sure to be extra carefull with those bit-field variables in USB OTG library code as FreeRTOS will usually (you can change this through #defines though) init stack to some magic value
🙂
