C6748 Edma3 with McASP in Ping Pong Mode

HI:

    holle ,I am a china user; I need a example for omap-l138 interrupt;In my project need time interrupt to drive ads8566;

can you help me;   my email is huxiangwu@163.com

   Thank's in advance for Your Help

  huxiangwu 

Please reference the EDMA3 user guide.  Section 3.4.4 has a good overview on how to implement ping-pong buffering. 

- Christina

Christina,

I have read the Section 3.4.4 of the EDMA3 user guide and have a fairly good understanding of how the DMA controller works. However, I don't have any idea where to start writing code. I found an excellent example of ping-pong buffer code over in the C5515 product group (http://code.google.com/p/c5505-ezdsp/) which gave tremendous insight how to the code should be written. I have successfully gotten it to run on my C5515 EZDDP USB stick.

Now I am looking for similar example code for my OMAP-L138 eXperiementer kit  that will allow me to input audio from the C3106 audio codec, process the audio in the C6748DSP, then output the processed audio back to the C3106 codec. Where can I find this type of example code?

thx

MikeH

Mike,

I don't think that there is a ready example for McASP that you can reference outside of BIOS, but the BIOS PSP driver package does include register layer CSL (rCSL) and example programs in C that you can use as a starting point: http://software-dl.ti.com/dsps/dsps_public_sw/psp/BIOSPSP/index.html

-Tommy

Tommy,

First of all, thanks for the response.

Secondly, this is very disappointing, and somewhat surprising, that there is not a readily available example for what must be a *very* common application (interrupt driven DMA from audio codec to/from C6748 in ping-pong mode).

I have downloaded and installed the psp BIOS/DSP package that you reference. I cannot find the example programs that you are referring to. Can you point them out to me? This is a very large set of code and a bit overwhelming.

MikeH

Hi Mike,

Please see:

http://processors.wiki.ti.com/index.php/Getting_Started_Guide_for_C6748

See using example section that points to the audio example:

http://processors.wiki.ti.com/index.php/GSG_C6748:_Using_Example_Software

C:\Program Files\Texas Instruments\pspdrivers_01_30_00\packages\ti\pspiom\examples\evm6748\audio\build

in the audioSample_io.c file that is part of this program, you can see the "ping pong" buffering at the function "Audio_echo_Task". You can replace the mem copy:

memcpy(xmt,rcv,BUFSIZE * RX_NUM_SERIALIZER);

by your algorithm

Mike,

CSL examples here: .....\pspdrivers_01_30_01\packages\ti\pspiom\cslr\evm6748\examples

-Tommy

Mariana, Tommy,

Thanks for the pointers. Will give it a try.

MikeH