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McBSP as I2S Slave

Sean Lyons
Prodigy 80 points
Other Parts Discussed in Thread: TMS320F28335, TLV320DAC3101

Hello,

I am trying to interface the TMS320F28335 McBSPA with the TLV320DAC3101 using I2S. The DAC is the I2S master, providing both the bit and word clocks (connected to MCLKXA and MFSXA) and the DSP is providing the data (16 bit stereo). I am basing my code off the F28335/AIC23 app note, but I do not want to use the DMA. I have verified that the FSXA pulse is at 44.1kHz (my sample rate) and the BCLK (MCLKXA) is at 1.4MHz on a scope.

The data I am attempting to send is very noisy and erratic, can anyone help to remedy this problem?

I can provide sample code, schematics and o-scope screenshots if need be.

  • 0
    TI__Guru* 95315 points
    Sean,
    I am trying to understand if we are looking at a hardware issue (circuit design/Board layout) or a software issue here. I presume it is the former, since you mention the data is "noisy". The reason I mentioned software is because you also mention that it is "erratic" . Did you mean to say "erroneous", as in incorrect data is received? Please do clarify the precise nature of issue we are debugging here and we will take it from that point on. In the interim, scope captures will indeed be useful.
  • 0 in reply to Hareesh Janakiraman
    Prodigy 80 points
    Hareesh,

    Thank you for your response. I was able to get the problem resolved using a McBSP tutorial.

    The heart of my problem was a firmware bug. I was attempting to send both channels of audio data in one XRDY interrupt. Instead, I changed my code to alternate between channel buffers and only write one 16 bit value to DXR1 each time. I believe this is why my data was not making sense while probing on the scope.