DMA transfer

I copied an example from the Altera Nios II Software Developer’s Handbook, chapter "Using DMA Devices" using memory to memory data transfer. I modified the code a bit .....

The good thing is that there are no error messages, but the dma-transfer does not complete by setting the rx_done flag.

Perhaps a beginners fault? Can somebody help me?

Freeck

# include <stdio.h># include "system.h"# include "sys/alt_dma.h"# include "alt_types.h"

/* Create the transmit channel */

static volatile int rx_done = 0;

/* ready handler*/

static void done (void* handle, void* data)

{

rx_done++;

}

int main (int argc, char* argv[], char* envp[])

{

int rc;

alt_u8 Inbuf[1024], Outbuf[1024];

alt_dma_txchan txchan;

alt_dma_rxchan rxchan;

void* tx_data = (void*) &Inbuf[0]; /* pointer to data to send */

void* rx_buffer = (void*) &Outbuf[0]; /* pointer to rx buffer */

if ((txchan = alt_dma_txchan_open("/dev/dma_0")) == NULL)

{

printf ("Failed to open transmit channel\n");

exit (1);

}

/* Create the receive channel */

if ((rxchan = alt_dma_rxchan_open("/dev/dma_0")) == NULL)

{

printf ("Failed to open receive channel\n");

exit (1);

}

/* Post the transmit request */

if ((rc = alt_dma_txchan_send (txchan,tx_data,1024,NULL,NULL)) < 0)

{

printf ("Failed to post transmit request, reason = %i\n", rc);

exit (1);

}

/* Post the receive request */

if ((rc = alt_dma_rxchan_prepare (rxchan,rx_buffer,1024,done,NULL)) < 0)

{

printf ("Failed to post read request, reason = %i\n", rc);

exit (1);

}

/* wait for transfer to complete */

printf ("wait for transfer to complete\n");

while (!rx_done);

printf("Transfer successful!\n");

return 0;

}