# External Period Resets

The period timer can be reset and held at zero by a logic level from one of various sources. The Reset event also resets the postscaler counter. The resetting source is selected with the ERS bits.

The Reset can be configured with the ERSNOW bit to occur on either the next PWM clock or the next PWM period Reset event. When the ERSNOW bit is set, then the Reset will occur on the next PWM clock. When the ERSNOW bit is cleared, then the Reset will be held off until the timer resets at the end of the period. The difference between a normal period Reset and an ERS Reset is that once the timer is reset, it is held at zero until the ERS signal goes false. The following timing diagrams illustrate the two types of external Reset.

Figure 1. Right Aligned Mode with ERSNOW = 1
Figure 2. Left Aligned Mode with ERSNOW = 0