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C6713DSK Codec question

Bendous
Intellectual 340 points

Hello all,

 

I am using the AIC23 codec on the C6713DSK to output an analogue signal. The codec is working but the ADC does not seem to hold the value for long. Is it supposed to do that or is something wrong with my code?

 

  • 0
    Intellectual 340 points

     

    A colleague of mine suggested it is because of the high-pass filter, which blocks the DC component. So as long as the frequency is within the audio range, it passes and if it is too low or too high it is attenuated.

     

    If this is the case, can the filter be disabled in order to output an unfiltered analogue signal???

     

    Thanks for the help in advance.

  • 0 in reply to Bendous
    Expert 1545 points

    I assume that in your previous post you mean the DAC doesn't hold its output value. Your colleague is right. The codec is ac-coupled. Check out the circuit diagram for the DSK. Line in and line out sockets are connected to the codec via first order high-pass RC filters. You could disable them using a soldering iron. From memory - I haven't got the circuit diagram to hand - the headphone out connection may NOT be ac-coupled. Try connecting your 'scope to that. I think that output signals are routed to both headphone AND line out.