To start a PWM waveform, the CPU configures or updates parameters PWMPER (period desired) and PWMHI (high time desired), then issues an HSR 0b10 for initialization. After CPU initialization (refer to Figure 1), the TPU generates a low-to-high transition and calculates the pulse timing (next fall time, next rise time). The time of the most recent rising edge is moved from parameter PWMRIS to parameter OLDRIS, where it can be read at any time by the CPU. Calculation of the fall time is made by adding OLDRIS to PWMHI. The next rise time is calculated by adding the period desired from PWMPER to the rise time, now in OLDRIS, and then placing the projected new rise time into PWMRIS.