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TMS320C6713: Audio Application, distortion problems

Started by jakobashtar March 16, 2005


Hello

Hope you all had a beautiful day and have a little bit of energy
left to
help a newbie like me. I got a DSP-board for the first time some
weeks ago
and I have been playing with it since then. It's a TMS320C6713 DSK.

I have made a small audio application that reads a sample from "line
in" and
sends it to "line out" ...so I guess I have some sort of loopback-
thing
going on...The source code is _very_ basic because that is the way I
want to
start out to begin with to get a better understanding of what's
going
on.....and I also wanna keep it as simple as possible...

However, when I try to put some code between the reading and the
writing of
a sample the sound gets distorted and I don't really know what I
should do
about that...so I was hoping that maybe some of you clever folks
could give
me a hint or two? :o)

The for-loop in the source code below is just to check what effect
_any_
code between the reading and writing of a sample will have on the
quality of
the playback....it was my intention to replace the loop with some
signal
processing stuff later on...

Thanks...and have a great day...

Here is the simple source code that is in my main program: #include "dsk6713.h"
#include "dsk6713_aic23.h"
DSK6713_AIC23_Config config =
{0x0017,0x0017,0x01f9,0x01f9,0x0011,0x0000,0x0000,0x0043,0x001d,0x000
1};
DSK6713_AIC23_CodecHandle hCodec;
unsigned int mySample;

void main()
{
DSK6713_init();
hCodec=DSK6713_AIC23_openCodec(0,&config);
while(1)
{
DSK6713_AIC23_read(hCodec, &mySample);
for (i=0;i<1000;i++);
while(!DSK6713_AIC23_write(hCodec , mySample));
}
}


Hi,

I don't know anything about the codec. But I asume it works like this:
The code has a trigger signal for write data and read data. Your code
doesn't seam to take care of these signals.

I would do it thisway:
- read the codec data via EDMA to an input buffer
- write the code data via EDMA from an output buffer
- after each read trigger an IRQ which processes the data
(copies it forn input to output buffer)

HTH Gustl jakobashtar wrote:
>
>
> Hello
>
> Hope you all had a beautiful day and have a little bit of energy
> left to
> help a newbie like me. I got a DSP-board for the first time some
> weeks ago
> and I have been playing with it since then. It's a TMS320C6713 DSK.
>
> I have made a small audio application that reads a sample from "line
> in" and
> sends it to "line out" ...so I guess I have some sort of loopback-
> thing
> going on...The source code is _very_ basic because that is the way I
> want to
> start out to begin with to get a better understanding of what's
> going
> on.....and I also wanna keep it as simple as possible...
>
> However, when I try to put some code between the reading and the
> writing of
> a sample the sound gets distorted and I don't really know what I
> should do
> about that...so I was hoping that maybe some of you clever folks
> could give
> me a hint or two? :o)
>
> The for-loop in the source code below is just to check what effect
> _any_
> code between the reading and writing of a sample will have on the
> quality of
> the playback....it was my intention to replace the loop with some
> signal
> processing stuff later on...
>
> Thanks...and have a great day...
>
> Here is the simple source code that is in my main program: > #include "dsk6713.h"
> #include "dsk6713_aic23.h"
> DSK6713_AIC23_Config config =
> {0x0017,0x0017,0x01f9,0x01f9,0x0011,0x0000,0x0000,0x0043,0x001d,0x000
> 1};
> DSK6713_AIC23_CodecHandle hCodec;
> unsigned int mySample;
>
> void main()
> {
> DSK6713_init();
> hCodec=DSK6713_AIC23_openCodec(0,&config);
> while(1)
> {
> DSK6713_AIC23_read(hCodec, &mySample);
> for (i=0;i<1000;i++);
> while(!DSK6713_AIC23_write(hCodec , mySample));
> }
> }