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Interfacing two AD1939 codecs through daisy chaining

Question asked by @444 on Jan 16, 2018
Latest reply on Jan 16, 2018 by DaveThib

DaveThib Hi,

I would like to daisy chain two AD1939 Codecs with DSP. My intention is to have 8 inputs and 8 outputs and I plan to use 4 DAC channels on each Codec. But I have the luxury of only 1 TDM DOUT and bitclock limited at 256Fs (Fs=48KHz) at the DSP side.

My doubt is regarding the DAC interfacing. The example shown in the datasheet is matching my requirements, however, with some modifications. I plan to leave DSDATA3 of second codec (DSP is interfaced with) to be left unused (I will be using only 4 DAC channels in each Codec), though the codec will be configured to run as Dual line TDM. This is to limit the bit clock at 256Fs and want to speak to DACs Also running at 48KHz instead of 96 Mentioned in the diagram. 

 

Can sombody please confirm if this works out for me?
Also could someone please elaborate how the data will be visible at DSDATA2(out)  from DSDATA1(in) ? Is it a shift register kind of thing? 

  • Will the empty slot be there on DSDATAout at the start of each frame or will the data from the past frame would still be pushed out at  DSDATA when second sync starts (continuous stream of data sent at DSDATAin)?

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