It's funny, that you can set your Main oscillator to 88..108MHz (using FRC and PLL), route it to REFOCLK output pin, then sample analog input @22KHz (to say) and use the ADC output to change OSCTUN and... voilà, an FM transmitter is done!
(of course, the output is not exactly a sine wave but... )
It does work and... well, just a simple idea. Try it!
