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ADAU1452: using LRCLK_IN0 pin for both I2S input clock and Clock Generator 3 external FREF for I2S output clock

Question asked by alfred1520 on Jan 8, 2016
Latest reply on Jan 13, 2016 by DaveThib

I searched for "ADAU1452 clock generator 3 input reference" and found no relavent discussion, hence this question.

 

I am using ADAU1452. My design has two inputs:

 

1) ADC, which drives LRCLK_IN2 that is derived from ADAU1452 CLKOUT so there is no problem.

2) External I2S, which drives LRCLK_IN0 and is asynchronous to the ADAU1452 clock.

 

The DAC is clocked by LRCLK_OUT0.

 

My application needs to switch between these input sources under MCU control. So it looks like for maintaining clock sync I should source LRCLK_OUT0 from Clock Generator 3 and switch CLK_GEN3_SRC and the N/M registers on the fly to maintain the correct clock domain.

 

Am I on the right path?

 

I discovered that I have to set the MP10 pin function in the MP10 MODE register to 'Multipurpose function MP10' in order for the Clock Generator 3 to produce clock. But this causes LRCLK_IN0 to lose its I2S function! Will I have to use a separate pin for this purpose? I found no mention of this topic in the datasheet, ADAU1452.pdf dated '1/14—Rev. 0 to Rev. A'.

 

Thanks for any help.

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