I have the I2C working fine for the ADAU1372. It responds with the appropriate values at the expected address (0x3D); I can read and write the initial registers and read them back. I can read the default reset values just fine.
And then I enable my oscillator on the MCLKIN pin, and my I2C goes AWOL. I can't get it back until I cause the PD pin to go low *AND* I disable the oscillator again. If I leave an oscillating signal on MCLKIN, I can reset the part until the end of time and my I2C won't come back. Once I disable the oscillator on the MCLKIN pin, then resetting the part gets my I2C back.
This feels like the part is switching to SPI mode somehow. I'm a bit stumped, though, as I have Pin 4 (SS_/ADDR0) hardwired to Vdd to explicitly prevent this from happening.
Has anybody else seen this? Is this something that would happen if a ground pin isn't soldered right? I'm very confused.
Thanks for any help.