TDM / I2S conversion using ADAU1761

In an application with 2 RX, 3 TX digital channels, I am struggling to find an economical solution to convert the TDM inputs and outputs to I2S to interface with external components which do not support TDM. Effectively, I need to:

- Convert L, R I2S to TDM -> DSP

- Convert DSP L', R', Mic TDM to 2 separate I2S

The power consumption of the ADAU1761 make it the best (if not the only) choice for this application which must remain under 165mw in total, but the lack of multiple I2S channels is limiting. Does anyone have a recommendation?

Thanks,

Jake Jennings

  • 0
    •  Analog Employees 
    on May 17, 2016 6:41 PM over 4 years ago

    Hello Jake,

    Can you clarify your needs a bit more? I am reading that you have two channels in TDM that you need to convert to I2S. Well, it is two channels so no conversion required. So this is why I must be missing something.

    So you have a DSP of some sort that only has TDM output and you need to extract pairs of channels and create several I2S outputs.

    Then you have several I2S sources that you need to assemble into a TDM stream to feed to the DSP.

    So outline both of these in detail and we may have some solutions for you.

    Dave T

  • We have a similar need; to convert TDM8 out of the Aurora DSP (kickstarter) to 8x i2S. We are hoping it has been done already, but any leads to a solution will be appreciated. Thanks!

  • 0
    •  Analog Employees 
    on Apr 9, 2020 8:53 PM 7 months ago in reply to chj

    Hello chj,

    If you are thinking of using the ADAU1761 for this it will not work. Because the input and output serial ports share the same LRCLK and BCLK. So if you set it up for TDM8 input then you get TDM8 output. 

    What you would need to use is the ADAU1452. I do want to clarify something. You do not need 8xI2S, you need 4xI2S because I2S is stereo. So the 8 channels of  one TDM 8 stream would map to four streams of I2S with two channels each.  The ADAU1452 can do this. Then you have a very powerful DSP to do processing of the audio. 

    When I searched the web I did find that someone already designed this board. It is on the kickstarter web site. 

    I just wished they used the Analog Devices ADC and DACs. 

    Dave T

  • Thanks for your response. I was entering the "thinking box" last time due to this obstacle with TDM8. So sorry for late reply. You are probably pointing to the Aurora Kickstarter project which is the reason for my investigation, That is the card we plan (ned) to use. But, this card is desgned with ANALOG multiple outs, not Digital. It is a pitty because the rest of it is great. One can fetch the TDM8 and create the digital multichannel, but then we have DACs that are SPDIF and/or I2s compliant, but not TDM8 compliant. So I need an adapter from tdm8 to 4x  I2s. Thanks for the correction, but that was what I meant; a total of 8 channels on i2s. Any further comments?

  • 0
    •  Analog Employees 
    on Oct 26, 2020 3:46 PM 1 month ago in reply to chj

    Hello chj,

    The ADAU1452 will take in TDM8 and three other sources and you can convert them into 4x I2S outputs. 

    Dave T