DMA transfer (Reception) not proper when implemented with ethernet communication

arunnmishra · ‎2014-11-23

Posted on November 24, 2014 at 07:54

Hello there,

I am using Lwip library for Ethernet implementation. I poll for the Ethernet packet in main loop. Then the packet is passed to further libraries to process it.

Meanwhile I have also to receive 8 bit data on Port GPIOH with clock on Timer 8 capture. Using DMA2, channel 7.

Receiving 220 bytes of parallel data @20 Mhz. DMA transfers it from GPIO port H to internal RAM

If I run the DMA without ethernet, it runs perfectly fine. but when ethernet is switched on, some of the DMA packets are lost.

Did a test and found 400 packets out of 100000. (0.4%)

Do not have sufficient window to retransmit the packet.

But cannot afford to loose the packet.

Hardware issues like noise etc are ruled out. Please Help.

Thanks in advance

#stm32f4 #dma

waclawek.jan · ‎2014-11-24

Posted on November 24, 2014 at 15:24

You didn't say which chip, but try to place the ethernet buffers and the DMA target into different SRAM.

JW