[Dspforum] EDMA Questions

[Alan Ding]

- ping and pong buffers are of size COMPLEX*FFTLEN. Does that mean that they
are automatically filled with complex zeros or do we have to do that?

I think we have to do that... I'm still trying to figure out how this
element index offset thing work.   Since we are DMA'ing 32-bit ints that are
L and R channels into a float buffer, how do we extract just the left
channel?


- i have issues finding/understanding RLD register. What is it used for?

>From spru234.pdf:

"EDMA Channel Count Reload/Link Address Parameter (RLD)
The EDMA channel count reload/link address parameter (RLD) in the EDMA
parameter entries specifies the value used to reload the element count field
and the link address. The RLD is shown in Figure 2-18 and described in
Table 2-25.
The 16-bit unsigned element count reload (ELERLD) value reloads the
element count (ELECNT) field in the EDMA channel transfer count parameter
(CNT), once the last element in a frame is transferred. ELERLD is used only
for a 1D element sync (FS = 0) transfer, since the EDMA has to keep track of
the next element address using the element count. This is necessary for
multiframe
EDMA transfers, where frame count value is greater than 0. See
section 1.7 for more details.
The EDMA controller provides a mechanism to link EDMA transfers. This is
analogous to the autoinitialization feature in the DMA. When LINK = 1 in the
EDMA channel options parameter (OPT), the 16-bit link address (LINK)
specifies the lower 16-bit address in the parameter RAM where the EDMA
loads/reloads the parameters of the next event in the chain. Since the
entire
EDMA parameter RAM is located in the 01A0 xxxxh area, only the lower 16-bit
address is required.
The reload parameters are specified in the address range 01A0 0180h to
01A0 07F7h. You must ensure that the link address is on a 24-byte boundary,
and that the operation is undefined if this rule is violated (see section
1.9). In
addition to the reload parameter space, the entry of any unused EDMA
channel can also be used for linking. The EDMA can always have up to 85
programmed entries, regardless of the number of channels actually used."

On Mon, Nov 2, 2009 at 11:07 PM, Nenad Uzunovic
<nenad at roboticresearch.com>wrote:

> Hi there,
>
> I have a few questions about the EDMA lab.
>
> - ping and pong buffers are of size COMPLEX*FFTLEN. Does that mean that
> they are automatically filled with complex zeros or do we have to do that?
>
> - i have issues finding/understanding RLD register. What is it used for?
>
> Thanks,
> Nenad
>
>
>
>
>
>
>
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> Dspforum mailing list
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>



-- 
-------------------------------------------------------
Alan Ding
Master of Sci, Electrical Engineering
Johns Hopkins University

Email: alan33d at gmail.com
Contact #: 4844593290
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