Streaming DMA UART

Update:

Fixed the issue with the addressing, specified 8 bit transfers, and changed it around to use external memory. I also specified within the SOPC to only allow 8 bit transfers for the DMA. I'm not sure why I had to specify it in both the C code and the SOPC. It now seems to work. I haven't tested it with onchip memory yet.

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

alt_u8 buffer[16] __attribute__ ((section (".ext_ram")));

static volatile int dma_complete = 0;

void dma_done (void* handle)

{

dma_complete = 1;

}

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

{

int rc;

buffer[0] = 0x30;

buffer[1] = 0x31;

buffer[2] = 0x32;

buffer[3] = 0x33;

void* tx_data = (void*) &buffer[0];

printf("Hello from Nios II!\n");

alt_dma_txchan tx;

if ((tx = alt_dma_txchan_open("/dev/dma")) == NULL)

{

printf("Failed to open device!\n");

exit(1);

}

alt_dma_txchan_ioctl(tx, ALT_DMA_SET_MODE_8, NULL);

alt_dma_txchan_ioctl(tx, ALT_DMA_RX_STREAM_ON, (void*) UART1_BASE+1);

dma_complete = 0;

if ((rc = alt_dma_txchan_send (tx, tx_data, 4, dma_done, NULL)) < 0 )

{

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

exit(1);

}

while (!dma_complete);

alt_dma_txchan_close (tx);

printf("Transaction Complete!\n");

return 0;

}