Ticks in SWI period

Alexandra-

> Aswering all the questions:
> 1. In fact, I did not check if I used codec settings for stereo.
> However, I added some variables to find the number of samlpes in
> one frame and it's OK (180 samples). Well... maybe codec really
> reads more data, I have to check it, but the size of processed
> frame is proper.

If you get 180 samples, but the time period represents 45 msec instead of 22.5, you
might have the AD535 sample rate set to 4 kHz, or you might have the serial port
configured such that every other frame is being received. Suggest to look for things
like that.

One way to tell for sure if your A/D interface is correct is use a mic + amplifier
(or sound card input) and loopback to a speaker and listen. Anything that sounds
weird then you know you're not sampling correctly.

> 2. Duration of interruption processing is small enough. If the
> processing is not finished when the next SWI occurs, some synch
> errors appear and the whole program crashes... so I know
> immediately that something is wrong. It doesn't matter if the
> processing time is 5ms or 20ms, as long as it is not longer
> than interruption period, SWIs appear when the input frame is
> filled and ready, so the period is fixed.

What do you mean by "SWI"? NOrmally that's a software interrupt, but you shouldn't
be using SWI. Your interrupts should be hardware driven, either by McBSP0 (sample
basis) or DMA event (buffer/frame basis).

> 3. It is c6711 DSK board and I use built-in AD535.

Ok. That's very important info, you should include that in your first post.

-Jeff Start a New Thread

The problem is that the theoretical frame duration and the interruption period don't fit each other. Period is fixed and I checked it's 45ms, but the frame should generate SWI every 22,5ms (as being filled). What can be the reason of it? Start a New Thread