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Ethernet speed with STM32F407VG and LAN8720A

Question asked by tereniev.oleg on Feb 10, 2016
 Hi.
 I need transmit some data readed from FSMC (SRAM-like external interface) with speed about 3072000 Mbit/sec. So, I don't need handshacking, and choise UDP. Minimal data packet has size 192 bytes, usually MTU ~1504 bytes, it means I can send 7 parts in one packet. Next: 3072000/8=384000 => 384000/(192*7) => 286 packets per second.
 I have SK-STM32F407 board and example with minimal changing between ST's example.
But! 'Standalone' LwIP example without any delays can send only ~20 packets! It isn't enought, of course. I measured some moments with oscilloscope + bitbang and programming metod, its show that one loop need more 1 millisec, usually 2..4! What CPU doing on 168MHz?! And 1/50 times loop spend about 1 sec. No comments.
 
 Qu: Did anybody use this MCU with equel or more ethernet speed?

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