Hi,
I am trying use the DMA example code as it is given in the nios 2 s/w handbook,
the code is as given below,
#include <stdio.h># include <stdlib.h># include "sys/alt_dma.h"# include "system.h"
static volatile int rx_done = 0;
/*
* Callback function that obtains notification that the data
* is received.
*/
static void done (void* handle, void* data)
{
rx_done++;
}
/*
*
*/
int main (int argc, char* argv[], char* envp[])
{
int rc;
alt_dma_txchan txchan;
alt_dma_rxchan rxchan;
void* tx_data = (void*) 0x901000; /* pointer to data to send */
void* rx_buffer = (void*) 0x902000; /* pointer to rx buffer */
/* Create the transmit channel */
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, 128, 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,
128,
done,
NULL)) < 0)
{
printf ("Failed to post read request, reason = %i\n", rc);
exit (1);
}
/* Post the receive request */
if ((rc = alt_dma_rxchan_prepare (rxchan,
rx_buffer,
128,
done,
NULL)) < 0)
{
printf ("Failed to post read request, reason = %i\n", rc);
exit (1);
}
/* wait for transfer to complete */
while (!rx_done);
printf ("Transfer successful!\n");
return 0;
}
But code is exiting, with an error ( Failed to open transmit channel ).
I want to understand, where am I doing worng.
