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operation of MCASP1 on AM335X with exernal ACLKX but not AHCLKX ?

Hi,

our application needs to create SPDIF signal using MCASP1. Due to pinmux restrictions we are only able to inject an external reference clock to MCASP1_ACLKX but not at MCASP1_AHCLKX.

Please let me know if the serial port can operate without AHCLKX input but with a reference clock input via ACLKX to get a correct XCLK.

Since the internal PLL of AM335X cannot create a valid AUXCLK for standard audio sampling frequencies deriving AUXCLK from CPU clock is not an option.

thanks and regards,

Christoph

  • Hi Christoph,

    Yes, the McASP can operate with only an ACLKX input.   To select the bit clock to be externally sourced from the ACLKX pin, CLKXM should be set to 0.

    See section 22.3.5 (Clock and Frame Sync Generators) of the TRM for more details.

    Regards,

    Melissa