The methods duty_u16() and duty_ns() are implemented to match the existing
docs. The duty will remain the same when the frequency is changed.
Standard ESP32 as well as S2, S3 and C3 are supported.
Thanks to @kdschlosser for the fix for rounding in resolution calculation.
Documentation is updated and examples expanded for esp32, including the
quickref and tutorial. Additional notes are added to the machine.PWM docs
regarding limitations of hardware PWM.
This adds an initial specification of the machine.PWM class, to provide a
way to generate PWM output that is portable across the different ports.
Such functionality may already be available in one way or another (eg
through a Timer object), but because configuring PWM via a Timer is very
port-specific, and because it's a common thing to do, it's beneficial to
have a top-level construct for it.
The specification in this commit aims to provide core functionality in a
minimal way. It also somewhat matches most existing ad-hoc implementations
of machine.PWM.
See discussion in #2283 and #4237.
Signed-off-by: Damien George <damien@micropython.org>
