Using the G55 Xplained Pro, I have an audio player working quite well. Now, I would like to get actual 48Khz/12,288 Mhz clocking for the I2S. Without changing the system clock I am not seeing a way to accomplish this, beyond extra hardware outside of the G55 and running the I2S as a slave. Because of the codec I am using, I don't think that is possible.
I have been wondering if the G55 would still run if I used a 12.288 Mhz XTAL OSC instead of the 12Mhz. ? Otherwise, I am not seeing another method I can use to cleanly do this.
[update] On the G55 Xplained Pro the XIN pin can accept a crystal oscillator. The MAIN_CLOCK in the G55 isn't being used to the 12.288 can be used by the MAIN_CLOCK. Then, set the PCKx (PCK4 for I2SC0) to use MAIN_CLOCK
God I wish the documentation was up to 2015 standards for Atmel parts. It really is a complete mess.