DMA Transfer Issue

Hi BadOmen,

I am using NIOS s version of CPU, i think it does not have data cache.

The address range for SDRAM is 00000000h to 01FFFFFFh before SDRAM there is an clock crossing bridge it's address range is 02000000h to 03FFFFFFh.

My program code size is 40Kbytes. I write a data pattern of 64 words starting at address 00100000.

My on-chip RAM is at address 05000000h.

After DMA when i check at 00100000h address i see the data pattern. but when i see at 05000000h i see some garbage value, before DMA value at 05000000h was 0h.

Any idea why is going wrong?

thanks,

bhupesh

If your sdram has an adress range from 00000000h to 01FFFFFFh and your clock crossing bridge starts at 02000000h assuming only the sdram is behind that bridge, then it is correct that this bridge has an adress range from 02000000h to 03FFFFFFh as you just have to add both adress values.

your problem is that you write to 00100000 but there is no sdram, as you must take the bridge into account, you have no memory between 00000000h to 01FFFFFFh

i bet it will work if you change 00100000 to 02100000

Hi MSchmitt,

Yes my SDRAM is behind clock crossing bridge.

I tried with 02100000 insted of 00100000 but no sucess.

I will try to tap some signal n see...

thanks

now i am a bit confused.

if your sdram is behind the bridge and that bridge is between nios and dma the nios and dma must have the same adress to gain access.

so i wonder why you see your pattern at 00100000 instead of 02100000

could you post a screenshot of the sopc to see the connection between nios, dma bridge and sdram ?

i see my pattern at both the address 00100000 & 02100000.

i have attached the screenshot of the sopc system.

MSchmitt

pls. also find the c code attached.

bhupesh

i see no mistake in sopc.

your ddr memory must be at 02000000 and i do not see any memory at 00100000

you programm uses values from system.h

DDR_SDRAM_BASE is this value 00000000 or is it 02000000 ?

if you modify your application a bit

case 'B': // DDR write operation

DDR_write_ADDRESS = to_hex(&packet[1]);

data = to_hex(&packet[9]);

for(i=1;i<=32;i++)

{

IOWR(DDR_write_ADDRESS,0,data);

iprintf("Written %08x to address %08x \n", data, DDR_write_ADDRESS);

DDR_write_ADDRESS += 1;

data += 1;

}

break;

now could enter any real adress without system.h

now try again 02100000