Posted on August 31, 2015 at 22:01No, the 48-pin package is restrictive in this regard. You don't even can output the I2S PLL onto MCO2, nor you have the I2S_CLK input available (which btw. would be the same pin as MCO2).
You could generate the whole I2S clock stack using chained timers and feed it back to the I2S module (used as slave) externally, but that's hardly practical. I wouldn't attempt to generate MCLK from the main PLL, which even if set in the same way as the I2S PLL, might be not synchronous sufficiently to the I2S clocks.
There are codecs out there which are capable of reconstructing MCLK from other clocks using an internal PLL, some can generate also the whole clock stack so that the mcu is then the slave.
JW
