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About AD1955 SPI setting and I2S signal frequency.

Question asked by homeway on Mar 12, 2018
Latest reply on Mar 15, 2018 by homeway

Hi ADI,

 

I have many questions about AD1955.

 

-----------------SPI control setting---------------

I want to use 24.576 MHz as MCLK, and  play sample rate 192 kHz or 96 kHz PCM audio.

According to https://ez.analog.com/thread/18961#90158

I think SPI register should be set as below:

 

[Register  0]

15--0 Operation

14--0 Not Muted

13:12--00 PCM

11:10--00 Stereo

9:8--10 (for 192KHz) / 01 (for 96kHz)

7:6--00 None

5:4--00 I2S

3:2--00 24bits

1:0--00 Register 0

 

[Register 1]

10:9-- 01 512 x fs (48 kHz*512= 24.576 MHz)

1:0-- 01 Register 1

 

Q1. Does [Register 0 9:8] set the interpolation mode?  

If yes, when I setting [Register 0 10:9] 192 kHz, why don't I need to change MCLK Mode [Register 1 10:9] setting for different fs?  

PCM mode

Q2. What value should I setting for residual bits of register 1?

 

---------------I2S signal frequency-----------------

 

If I want to play 192 kHz / 24 bits audio, 

 

MCLK= sample rate * bits * channel# = 192k * (24+8) * 2 = 12.288 MHz

LRCK= 192 kHz

BCLK= 12.288 MHz.

 

Q3. The MCLK frequency which I used for AD1955 should be multiplier for 12.288MHz, is it right?

 

Q4.  What is the meaning for 8 bits?

 

Q5. If I use 24.576 MHz as MCLK, can I use 24.576 MHz for BCLK?

 

Please help me to figure out these questions, thanks a lot.

 

B.R.

Homeway 

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