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Using AUDIO_PLL as McASP2_AHCLKX_SOURCE on Mistral DM8148 EVM

Stephan
Prodigy 110 points

I'm trying to configure McASP2 to create all I2S clocks including MCLK from the internal AUDIO_PLL running at 24.576MHz. In the McASP2_AHCLKX_SOURCE mux, I can select between XREF_CLK0-2, OSC1 and ATCLK0-3. I cannot select AUDIO_PLL as source. If I select OSC1, I do get a valid 1.411MHz BCLK on the ACLKX pin.  

Is there a way to (internally) route AUDIO_PLL_OUT to ATCLKn? I can't find any reference to ATCLK other than as mux input. What exactly is ATCLK?

And what is the relation/difference of the clock selected in CM_AUDIOCLK_MCASP2_CLKSEL to the one selected in McASP2_AHCLKX_SOURCE?

 

Thanks,

Stephan

  • 0
    TI__Genius 15310 points

    Stephan,

    According to the Table 7-26, PLL_AUDIO is available for only for McASP3/4/5.

     

    Regards,

    Viet

  • 0 in reply to Viet Dinh
    Prodigy 110 points

    Thanks for the reply. What exactly is the function of the CM_AUDIOCLK_MCASP2_CLKSEL?

    If I alternatively want to route AUDIO_PLL to an IO pin (and route it back to the McASP2 external in), what would be the best way to do this? I tried setting CLKOUT_MUX to PRCM_SYSCLK_OUT and CM_CLKOUT_CTRL.CLKOUT2SOURCE to AUDIO_PLL_CLK but then I only get a 32 kHz signal on clkout1 pin. If I set  CM_CLKOUT_CTRL.CLKOUT2SOURCE to VIDEO_PLL_CLK instead, I do get the correct PLL clock from the Video PLL...

    Confused,

    Stephan