Pico CODECS needing MCLK

[palmerr23]

Developing an I2S project on a Pi Pico that requires MCLK at 256Fs, I discovered that the sysclk neds to be set at a different value than that recommended in Arduino Pico for Fs = 44.1kHz.

When I had sysclk set at the recommended value there were regular gaps in the 44.1kHz waveforms.

Values that work for me are:

static const int I2SSYSCLK_44_1 = 158400; // 22.05, 44.1 kHz sample rates
static const int I2SSYSCLK_8 = 153600;      // 24, 48, 96 kHz sample rates

They are set using the standard ArduinoPico way using the following code, at the beginning of setup( ):

set_sys_clock_khz(DESIRED_SYSCLK, false);

While the revised 44.1kHz sysclk produces a continuous signal, it does raise Fs to 44.2kHz

I will continue to seek a better compromise and will report better sysclk frequencies here.

I hope this is helpful to others in the same situation.