DMA address bus problem [F28377D]

Sh.Sasaki

Guru 13625 points

Hi,

Please let me know about DMA address bus.

I found a description of the following. (Datasheet : SPRS880A)

Therefore, I think DMA is able to access the EMIF1_CS0.

But, DMA address bus is 22-bit(0x3FFFFF).

SDRAM address is 0x80000000. DMA(0x3FFFFF) is not accessible in SDRAM.

As follows.(TRM : SPRUHM8A)

Now, I have connected to SDRAM to EMIF_CS0.

How to access the SDRAM(0x80000000) using the DMA ?

Regards,

FSSer

over 9 years ago

0 Vivek Singh over 9 years ago

TI__Guru** 109105 points

Hi FSSer,

Address bus of DMA has been extended to 32bit on this device. This info has not updated in TRM. We'll correct the same in next revision of TRM.

Please use the SDRAM address (0x8000_0000) as destination address for DMA and it should work fine.

Regards,

Vivek Singh

0 Sh.Sasaki over 9 years ago in reply to Vivek Singh

Guru 13625 points

Hi Vivek Singh,

Thank you for reply !

I will contact my customer.

Best, Regards

FSSer

0 King Kong over 9 years ago in reply to Vivek Singh

Intellectual 540 points

Hi Vivek Singh,

I am going to try to use the DMA to read the EMIF.

Here my question is, can I directly read the EMIF with CPU? If yes, how to read it? 22bit-address(address bus) vs 32bit-address(EMIF address).

Bests,

King

0 Vivek Singh over 9 years ago in reply to King Kong

TI__Guru** 109105 points

Hi King,

Yes, you can do the same using following intrinsics.

For 16-bit read:

unsigned int variable = __addr32_read_uint16(unsigned long address);

For 32-bit read:

unsigned long variable = __addr32_read_uint32(unsigned long address);

Regards,

Vivek Singh

0 King Kong over 9 years ago in reply to Vivek Singh

Intellectual 540 points

Hi Vivek Singh

Thanks for your help :)

Bests,

King

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DMA address bus problem [F28377D]