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ADAU1701 GPIO synced to sample rate

Question asked by wygonski on May 12, 2015
Latest reply on May 14, 2015 by wygonski

I'm working with a ADAU1701 with an interface to a microcontroller and numerous other system components.    The uC needs to do some processing with data generated by the SigmaDSP, and the processing should be done at a 1 kHz rate synchronized to the 48k DSP sample rate.   So far, I can successfully interrupt the uC with a GP output from the SigmaDSP and read the data I need with a DSP Readback cell.   The GP output from the DSP is generated by a stopwatch, however I am finding that it doesn't seem to be synchronized to the analog output. I observed this by triggering a scope on this pulse train while displaying the analog sine output (the analog out jitters/drifts with respect to the pulses).

 

Here's the graph.   I was expecting that the GPIO_1 output pulse would be in sync with the DAC0 output signal.

DSP Readback.png

 

Is there something I'm not understanding about this, or is there a better way to sync the GPIO with the sample rate?

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