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Using a Digital Input for an Additional Control Potentiometer

I'm using an ADAU1701 and I essentially need 5 AUX ADC controls (5 different control pots) I'm using the 4 AUX ADCs already, so I just need one more (I'm already using both audio ADC inputs) I assume this is simple enough by using one of the serial data inputs and using the output master clocks to clock the external ADC, but I'm not quite sure how to approach it. Does anyone have a suggestion of a specific ADC part number to use? Serial data confuses me somewhat so I never know what specifications I need. The more instructions you can give me, the better.

Thanks a lot.

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  • Austin wrote:

    Actually in looking at the AD7910 a little more it seems like you can use CS essentually the same as the LRCLK since the date is triggered out on the edge of CS.

    That was my initial thought, yes. However, the problem is that the number of bits actually differs. It looks like the AD7910 will be spitting out 16 bits of data, but the ADAU1701 will be expecting 32 bits. I'm not sure how that will work.

    The question to the ADC team is really this: If we pull CS low and start toggling the CLK line, the AD7910 expects 16 periods before the CS line goes high. If we were to keep toggling the CS line an additional 16 times, would the AD7910 output only zeros?

    If so, then there's a chance this could work. Still, I've never tried anything like this so I think it would require verification on actual hardware in order to be sure it will actually work.

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  • Austin wrote:

    Actually in looking at the AD7910 a little more it seems like you can use CS essentually the same as the LRCLK since the date is triggered out on the edge of CS.

    That was my initial thought, yes. However, the problem is that the number of bits actually differs. It looks like the AD7910 will be spitting out 16 bits of data, but the ADAU1701 will be expecting 32 bits. I'm not sure how that will work.

    The question to the ADC team is really this: If we pull CS low and start toggling the CLK line, the AD7910 expects 16 periods before the CS line goes high. If we were to keep toggling the CS line an additional 16 times, would the AD7910 output only zeros?

    If so, then there's a chance this could work. Still, I've never tried anything like this so I think it would require verification on actual hardware in order to be sure it will actually work.

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