to add two cents to the both prior messages:
If you’re using the STM Libraries, especially the CubeMX generated software, be aware that the Ethernet implementation prior to ST Firmware Library 1.4 has some major bugs. 1.4 seems to be better, but still has no zero-copy driver. Although, that won’t be your problem. I would point to some design issues as well. You should not have a direct interaction between the LwIP and Modbus parts (use queues or task notifications for that) and so on.
Michał Karczewski <address@hidden> , 28.02.2015 6:59:
I'm working on project that needs some web functionality. Using STM32F429 + PHY LAN8720 with FreeRTOS and LwIP 1.4.1 raw API. I'm running webserver from SDCard, which is showing numbers generate by microcontroller firmware, and Modbus communication protocol over TCP. As far as I'm testing only one of these functionality, everything works fine - problems starts when I'm trying to run both at once. To be precise:
As I said before, everything works fine until I run both function at once. Then modbus starts losing connection every few (random) seconds, and website overwrite values with much bigger interval than one second. Everything is very unstable.
My question is - is there possibility to increase LwIP performance, and if is, what I should trying to modify to get better results. I'm using also external SRAM memory, but I'm entirely sure how I should apply it to cooperate with LwIP.