NiosII DMA Tutorial

Thanks Cris. I will try that.

You understood correctly. That sequence is correct.

Thanks a lot Cris!! Last question, how can i connect the RD signal that the DMA gives before reading to the FIFO that is outsite my system? I probably have to read it from somewhere. I looked into the embbeded periphals guide from ALTERA but found nothing regarding this RD signal to synchronize with the fifo.

This piece of code sets the bit manually.

Cool, how can i set it in the software? I see is the 8th bit that i must set to 1. Where can i find examples of that? Thanks

Thanks a lot for this posts, Cris i can tranfer from my onchip memory to my sdram memory without any problems. But now i want to do something differnt. Really simmilar to what fightingdreamer did.

@ Aprado

Hi aprado,

# include "sys/alt_dma.h"# include "altera_avalon_dma.h"
# define DMA_LENGTH  512
volatile int dma_complete;
short rx_buffer; // pointer to rx buffer
short tx_buffer; // pointer to tx buffer
void dma_done (void* handle, void* data)
{
    int rc;
    // turn the LED off (for DEBUG)
    rc = IORD_ALTERA_AVALON_PIO_DATA(LED_PIO_BASE);
    IOWR_ALTERA_AVALON_PIO_DATA(LED_PIO_BASE, rc & ~0x10);
    
    dma_complete = 1;
}
int test_dma(void)
{
    int rc;
    alt_dma_txchan txchan;
    alt_dma_rxchan rxchan;
    void* tx_data =   (void*) tx_buffer; // pointer to data to send
  
    dma_complete = 0;
    // Create the transmit channel
    if ((txchan = alt_dma_txchan_open("/dev/ts_dma")) == NULL)   {
        printf ("Failed to open transmit channel\n");
        return -1;
        }
    // Create the receive channel
    if ((rxchan = alt_dma_rxchan_open("/dev/ts_dma")) == NULL)   {
        printf ("Failed to open receive channel\n");
        return -2;
        }
    if(alt_dma_txchan_ioctl(txchan, ALT_DMA_SET_MODE_16, NULL)<0)   {
        return -3;
        }
    if(alt_dma_rxchan_ioctl(rxchan,ALT_DMA_SET_MODE_16,NULL)<0)   {
        return -4;
        }
    if(alt_dma_txchan_ioctl(txchan,ALT_DMA_TX_ONLY_OFF,NULL)<0)  {
        return -5;
        }
    if(alt_dma_rxchan_ioctl(rxchan,ALT_DMA_RX_ONLY_OFF,NULL)<0) {
        return -6;
        }
    printf ("Test DMA transfer...\n");
    // turn a LED on (for DEBUG)
    rc = IORD_ALTERA_AVALON_PIO_DATA(LED_PIO_BASE);
    IOWR_ALTERA_AVALON_PIO_DATA(LED_PIO_BASE, rc | 0x10);
    // Post the transmit request
    if ((rc = alt_dma_txchan_send (txchan,tx_data,DMA_LENGTH-16,NULL,NULL)) < 0)    {
        printf ("Failed to post transmit request, reason = %i\n", rc);
        return -7;
        }
    // Post the receive request
    if ((rc = alt_dma_rxchan_prepare (rxchan,rx_buffer,DMA_LENGTH-16, dma_done,NULL)) < 0)   {
        printf ("Failed to post read request, reason = %i\n", rc);
        return -8;
        }
    // wait for transfer to complete
    while (!dma_complete)
        TK_SLEEP(10);
    printf ("Transfer successful!\n");
    
    return 0;
}