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BF548 Audio signal processing (AD1980 Callback)


I'm currently trying to extract audio input data, perform some signal processing, and output something at the end. (Much like the talkthrough on the 533 boards).

I have been using the audio loopback project to attempt this, and for starters, I've tried something very simple: Set all left audio out to zero. (Just to make sure I am actually able to manipulate the data somehow).

In regards to the code, this is what I've done:

            /* copy the source (ADC) data to DAC channels */
            for (i = 0;i < (BUFFER_SIZE_PER_CHANNEL * NUM_ADC_CHANNELS); i++)
                /* copy ADC left channel data to PCM out Left */
                *(pDest+(NUM_DAC_CHANNELS*i))    = 0;
                /* copy ADC right channel data to PCM out right */
                *(pDest+1+(NUM_DAC_CHANNELS*i)) = *(pSrc+1+(NUM_ADC_CHANNELS*i));

However, this does not silence the left output at all.  I am very confused, am I doing something wrong? Or have I modified the whole thing incorrectly?

I've also noticed that after I press PB4 (to terminate the program), it says "Done!", but audio is still coming in and going out.

Other than what I've written above, I have not changed the program.

I realise it is only a basic operation I am trying to achieve at the moment, but I want to take it one step at a time.  It will get much more difficult in the future (planning to write functions which will process a 2 second audio input, and analyse the data, to detect speech), so if you guys could help me get over this hurdle, that'd be great.



Additional information: Using VisualDSP+++ V5 (with update 6 applied).

File edited is Audio_Loopback.c

Codec: ad1980

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