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ADAU1701 I2C unresponsive

Question asked by jakej on Mar 18, 2016
Latest reply on Apr 19, 2016 by jakej

I have an ADAU1701 set up on a breakout board like so, following the typical application schematic:

Screen Shot 2016-03-18 at 3.43.57 PM.png

 

I'm not seeing any response on I2C writing at 107 khz:

 

adau1701-nack.PNG

 

 

Here's MCLKI, using this crystal ABLS-12.288MHZ-B4-T Abracon LLC | Crystals and Oscillators | DigiKey:

 

adau1701-clock-periodicity.PNG

Why is it periodic? I tried reducing the crystal resistor to 50ohm instead of 100ohm without significant change. The swing at the highest point here is .5v to 1.5v, and at worst from 0.9v to 1.1v.

 

Using external 3.3v and 1.8v switching regulators with a TekPower source running at 3.8v.

 

I've tried using a two crystals - the one above, and http://www.ndk.com/images/products/catalog/c_NX3225GA-STD-CRG-2_e.pdf with similar results

 

Screen Shot 2016-03-18 at 3.58.30 PM.pngScreen Shot 2016-03-18 at 3.58.40 PM.pngScreen Shot 2016-03-18 at 3.58.48 PM.png

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