Very, very, very good indeed! Thanks for the effort!
I've a question for you, one that I did not bother to search yet. Can we program arduino PWM outputs to be non-synchronous, ie, not based on same frequency and phase shift (latter is more important) ?
I am to try (all I can do is try) to do a sigma-delta modulated output. It's fairly easy on an FPGA, but not that easy with a micro unless I have a hard-realtime system. For sigma-delta I need quite a lot of "oversampling", and any significant non hard-RT change will be a disaster.
So I once thought: if I could have all those PWM out-of-phase and with different frequencies, maybe I can be able to have, using some CPLD or discrete logic, a nice sigma-delta output, with a combinatorial circuit.
Still, your page is excellent !!! Let me congratulate you again, and in hopes other electronic tutorials will follow.
Álvaro