Hello,
I'm using an SBC1788 board with an LPC1788 micro controller and successfully implemented a web server based on lwIP v1.4.1 with FreeRTOS v7.4.2.
I am using zero copy TX buffers located in the external SDRAM, the performance is quite good (the webpage of 600KB (also buffered in the external SDRAM) gets loaded up in less than 1sec), and was working flawlessly, until I added emWin to the project. Using the embedded LCD controller from the LPC1788 and the video buffers also located in the external SDRAM I got also the LCD and touchscreen working, however I notice that the web-server was no longer working.
After some debugging I found the following:
- the problem with the web-server is that some TX packets are not sent out at all, although the frame transmission gets correctly called, so from 100 packets only around 70-80 are sent out
- the only thing that will cause this problem is the LCD power control. When I enable power to the LCD controller the problem is there, if I disable power to the LCD controller it's gone.
I'm guessing it could be a conflict between the Ethernet chip and LCD controller both accessing the external SDRAM through DMA, but I have no idea on how to proceed.
I tried different AHB matrix priority settings, without any success.
Any thoughts on this?