Increase I2S Audio output from 48Khz to 192Khz

Feb 15, 2019 - 3:52 AM

  • How do I change the clock to increase the I2S audio output from 48Khz to 192Khz for the XMOS chip/I2S audio ?

  • The XMOS oscillator is Y6. It's a 24 MHz clock. It's used only for the XMOS processor.
    The audio sampling oscillator is Y9. It's 24.576 MHz. Located on the top of the board, very close to the heatsink and next to the Class-D amp- not far from the USB connector. I would think to sample at 192 KHz you will need to reprogram the XMOS itself. Or possibly there's a command that can be sent to it to change a clock rate divisor, but I don't see that in the docs. Y9 drives the audio clock input to the XMOS and the audio amplifier chip and determines
    the sample rates. Note that the Class-D audio amplifier does not support sample rates above 48 KHz so to use 192 KHz the XMOS will give you digital out. The stream could then be programmed to GPIO pins.

  • Is there a way (via soldering) to access a digital out on the atomic pi? Would this be the raw i2s stream or spdif? Is there any additional interpretation of this stream needed or can it be routed directly to a DAC or i2s->spdif converter?

    Likewise for the i2s audio inputs available on the 10 pin headers -- can they talk to any generic i2s microphone, e.g. or are special drivers or programming needed (in linux).