Specifications

PWM Waveform Generation With Compare Units and PWM Circuits
6-59 Event Manager (EV)
There are usually two compare matches in a PWM period in symmetric PWM
waveform generation, one during the upward counting before period match,
and another during downward counting after period match. A new compare
value becomes effective after the period match (reload on period) because it-
makes it possible to advance or delay the second edge of a PWM pulse. An
application of this feature is when a PWM waveform modification compen-
sates for current errors caused by the dead-band in AC motor control.
Because the compare registers are shadowed, a new value can be written to
them at any time during a period. For the same reason, new values can be writ-
ten to the action and period registers at any time during a period to change the
PWM period or to force changes in the PWM output definition.