Jim: You didn't say what your end goal is, so I have to guess what you are trying to do.
The CLK in question is the SPI CLK, not a sampling clock. So, should you want to use this ADC, (and there are reasons you might not want to) You will probably be better off using one of the two SPI interfaces, and not just any four GPIO lines. This is not an audio ADC. This is an instrumentation ADC. The differences are that audio codecs are usually twos-complement output, and use a sampling clock to get very regular sampling intervals, and include the necessary input Nyquist filter as a built-in as part of the chip. This ADC only does one conversion when you access it and ask it with the SPI bus. You could do some software calisthenics to call for the samples very regularly, but will get a lot of jitter in the sampling because of the nature of (most) BBB Operating systems. This will show up in the audio as distortion. You could do the one-sided data to two's complement conversion in software. You could add a Nyquist filter in hardware between the microphone and the input to this ADC. So, it all depends what you are trying to do. If you want a minimum quality audio input and an educational experience in the topics I listed above, keep going. If you are trying to get a quality audio input for something, look at one of the audio capes for the BBB. Or pick a real audio ADC for your hardware design. --- Graham == -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
