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Altera_Forum's avatar
Altera_Forum
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15 years ago

questions about DMA transmition

hi:

I want to transmit data from FIFO to sdram by DMA in SOPC builder.

in NIOSII eclipse,

if((tx=alt_avalon_dma_send(txchan,(void*)tx_data,0x1000,NULL,NULL))<0)

{

printf("failed to send data from fifo \n");

)

always printf: failed to send data from fifo

I add "while(1)" to contain this code:

while(1)

{

//the number of translated data at one time

for(j=0;j<=100;j++)

{

if((tx=alt_avalon_dma_send(txchan,(void*)tx_data,0x1000,NULL,NULL))<0)

{

printf("failed to send data from fifo \n");

//

}

if( j==90)

exit(1);

}

but it always failed ...

is there somebody can give me any hints? thanks~

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    hi,gurus

    I have try lots of times ,but always failed,so I hope someone can give me help~

    the self-made SOPC component is connected to read master port of DMA, SDRAM is connected to write master port of DMA.

    the setl-made component is connected to avalon bus as a slave interface.when I use "IORD"to read the component,it is right,but when I connect is to DMA,DMA transmits failed~

    if((rx= alt_avalon_dma_prepare(rxchan,rx_buffer,1024,done_t,NULL))<0)

    {

    printf("rxchan receive failed.reason: %d",rx);

    exit(1);

    }

    dma_prepare always failed, if the self-made component has some problems (the component consist of a FIFO which connected to avalon through slave port )??

    The NiosII software code is attached

    the pogrammme is very urge,and there is nobody around me can give me advise,so I hope you gurus can give me some hints~

    thanks very much~~
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    /* begin receive data*/

    if((rx= alt_avalon_dma_prepare(rxchan,rx_buffer,1024,done_t,NULL))<0)

    {

    printf("rxchan receive failed.reason: %d",rx);

    exit(1);

    }

    after running,niosII console:

    rx=-28;

    I check the meaning of "28" in altera_avalon_dma.h:

    start = priv->tx_start;

    end = priv->tx_end;

    slot = &priv->tx_buf[end];

    next = (end + 1) & ALT_AVALON_DMA_NSLOTS_MSK;

    if (next == start)

    {

    return -ENOSPC;

    }

    so I guess that there is no room in memory,but I am not sure which memory has no room and why it has no room,so I delete my signaltapII file so as to let more room off,but the error is still there.

    I will keep trying~
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    15 years ago

    hi,

    I have solved the above problem,that is ,the data writen into the FIFO can be transfered to the SDRAM by the DMA .

    here I have some feelings which be shared with yours.

    1: DMA transmition ,FIFO (slave port attached into Avalon bus) to SDRAM,because of reading the same address(FIFO base address),so you only need to open received channel(rxchan),and set iocl(mode,RX_only),then ,prepare .

    2:there seems the SOPC can do lots for you,so you need not care about the details too much:)

    best regards