Ethernet and DMA

Hi everyone,

I'm working with a LwIP Stack (only using UDP) and make some timing measurements to find the nottlenecks of the stack.

So I saw that the data transfer to the SMSC chip needs quiet some time. To reduce this time I added a DMA controller via SOPC builder.

The problem is that when I start the DMA controller it will never end. The busy flag is set for ever.

Does somebody use a DMA controller to get the data in the SMSC?

Thx for your help

revolt

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SOPC Connections

SDRAM

-- DMA -- Tristate-Bridge -- SMSC

int.SRAM /

Code:

int doDMAEthernet(volatile unsigned int* puiReadAddr,volatile unsigned int* puiWriteAddr,unsigned int uiLen)

{

while ((IORD_ALTERA_AVALON_DMA_STATUS(DMA_ETHERNET_BASE) & ALTERA_AVALON_DMA_STATUS_BUSY_MSK));

IOWR_ALTERA_AVALON_DMA_CONTROL(DMA_ETHERNET_BASE,0);

IOWR_ALTERA_AVALON_DMA_STATUS(DMA_ETHERNET_BASE, 0);

IOWR_ALTERA_AVALON_DMA_LENGTH(DMA_ETHERNET_BASE, uiLen);

IOWR_ALTERA_AVALON_DMA_RADDRESS(DMA_ETHERNET_BASE, puiReadAddr);

IOWR_ALTERA_AVALON_DMA_WADDRESS(DMA_ETHERNET_BASE, puiWriteAddr);

// Start DMA

// WORD (32 BIT) transfer

// LEEN = Ends transaction when length reg reaches zero, write to constant address

// WCON = write to fix address

IOWR_ALTERA_AVALON_DMA_CONTROL(DMA_ETHERNET_BASE,ALTERA_AVALON_DMA_CONTROL_GO_MS

K |

ALTERA_AVALON_DMA_CONTROL_WORD_MSK|

ALTERA_AVALON_DMA_CONTROL_WCON_MSK|

ALTERA_AVALON_DMA_CONTROL_LEEN_MSK);

while ((IORD_ALTERA_AVALON_DMA_STATUS(DMA_ETHERNET_BASE) & ALTERA_AVALON_DMA_STATUS_BUSY_MSK));

return 0;

}