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BCLK Settings, Sampling Point or Format Selection

Category: Software
Product Number: ADAU1467

Hello together, 

we have a question regarding the selection of the BCLK settings in SigmaDSPs. The best would be to share an example. 

SigmaDSP Serial In Settings:

When we assume that we configured the Serial-Input as I2S-Slave. What would be the correct setting for the SigmaDSP, when our I2S-Master applys the signal transition on the falling BCLK edge?

When we have to select which format is used by the I2S-Master, then we would have to set option 1, I guess. But if we have to select at which BCLK edge the data should be sampled (Sampling Point), we would have to select Option 2. Can you confirm which one is right? 

SigmaDSP Serial Out Settings: 
Here we have the same question. We are pretty sure that on the serial output is selects the format and not the sampling point. As long as the DSP is the I2S-Master we also can verify this by our self. But when the Serial-Out is I2S-Slave we have the same quesion. Is there any difference between the meaning of the settings for Input/Output? 

Best regards,



  • Hello Eric,

    I know this is always confusing and the GUI as good as it is still could be better. What does not help in some ways is that the part internally "helps" you with this. 

    If you set it up for the I2S standard which is LRCLK edge falling for the start of the frame and the left channel. Then setup the BCLK falling to be the "data-change" edge then it will work. The data will change on the falling edge if it is an output port and it will expect the sender to change the data on the falling edge if it is an input port. Setting the port to be a clock master or slave does not matter. So you should set it for negative polarity. 

    So there is no difference in the meaning for serial input and output. A negative polarity signal means that is the data change edge. 

    Dave T

  • Hello Dave, 

    as always, thanks a lot. This makes it clear. We always have to match the formats of I2S sender/receiver and not setup the sampling point. 

    Best regards,