Ethernet speed with STM32F407VG and LAN8720A

[t2399]

Posted on February 10, 2016 at 04:42

 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

http://starterkit.ru/html/doc/SK-STM32F407_V1A.pdf

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?

#stm32f4 #ethernet