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DS90UB940-Q1: When should I use the I2S slave mode/master mode

Sherry Liang
Genius 10255 points
Part Number: DS90UB940-Q1

Dear team,

There is not too much description about I2S slave mode and master mode in the datasheet. I don't  know the difference between these two modes, then I don't know when should I use the slave mode? When should I use the master mode? Are they used in different scenarios？

Could you please help answer this question?

Thanks & Best Regards,

Sherry

  • 0
    TI__Guru** 103215 points

    Hello Sherry,

    We will respond back to you shortly today - sorry for the delay. 

    Thank you,

    Casey 

  • 0
    TI__Intellectual 2930 points

    Sherry

       i2S master or slave is really determined by where the Audio controller is placed. In most of our applications, this is on the Head unit, on the serializer side, so that generates i2S serial clock and word selects are generated. On the Deserializer side, 948 or 940 will be a master and will drive the audio receiver and audio amp.

    There could be some application s where the controller is on the Deserializer side, in which case, 940 will need to be programmed as slave and we take clock (SCL) and WS as input signals and generate data synchronous to that clock

    Thanks

    Vijay

  • 0 in reply to Vijaya Ceekala
    TI__Genius 10255 points

    Dear Vijay,

    Ok, got it! But the clock is also output when setting slave mode, you can refer below picture,

    Thanks & Best REgards,

    Sherry

  • 0 in reply to Sherry Liang
    TI__Intellectual 2930 points

    Hello Sherry

           Sorry for not being very clear. Thank you very much for pointing out something in our Datasheet that could be mis-leading and needs more explanation. 

    What we refer to slave mode is applicable for 8-channel audio. In this case Audio source is on the Serializer side and uses I2S_DA/DB/DC/ etc pins to drive Audio into the serializer which show up on the Deserializer I2S_DA/DB/DC..etc outputs. 

    What we refer to as Master mode is ONLY relevant when 948 or 940 is paired with 949 Serializer and Audio is send through AUX input of 949.,SDIN as Audio Input. Shown below:

    So slave terminology represents standard 8-channel audio and master terminology refers to use of AUX channel Audio. Once again than you very much for pointing out that the description is not very clear. We will include a more explicit explanation of this in our next datasheet release

    Thanks

    Vijay

  • 0 in reply to Vijaya Ceekala
    TI__Genius 10255 points

    Hi Vijay,

    Got it! Very clear, thank you very much!

    Thanks & Best Regards,

    Sherry