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ADAU1701 as I2S slave

Question asked by peterjv on Jun 11, 2018
Latest reply on Jun 14, 2018 by DaveThib

Hello,

 

I am trying to transfer 48 kHz digital stereo audio from a slave ADAU1701 to an external master through the I2S interface. I can however only get a partial data transmittal between the two devices. The master can be configured for either 16 or 24 bit audio, which results in one of the following two signal sets:

 

16 bit stereo:

  • MCLK: 12.288 MHz (fs * 256)
  • LRCLK: 48 kHz (fs)
  • BCLK: 1.536 MHz (fs * 32)
  • SDATA: Slave ADAU transmits data for the left channel, but nothing for the right channel

 

24 bit stereo:

  • MCLK: 12.288 MHz (fs * 256)
  • LRCLK: 48 kHz (fs)
  • BCLK: 2.304 MHz (fs * 48)
  • SDATA: Slave ADAU transmits data for the left channel, but only partial data for the right channel

 

I think my problem is that the master does not add “empty” BCLK cycles to achieve BCLK = 64*fs. This leads to my questions:

 

  1. Does the ADAU1701 require 64 BCLK cycles per LRCLK cycle in slave I2S mode to operate correctly?
  2. Can the digital slave interface of the ADAU1701 be configured to accept either 32 or 48 BCLK cycles per LRCLK cycle?

 

Thanks,

Peter

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