PWM timer2 period and update method configuration register.
| TIMER2_PRESCALE | period of PT0_clk = Period of PWM_clk * (PWM_timer2_PRESCALE + 1) |
| TIMER2_PERIOD | period shadow register of PWM timer2 |
| TIMER2_PERIOD_UPMETHOD | Update method for active register of PWM timer2 period, 0: immediate, 1: TEZ, 2: sync, 3: TEZ | sync. TEZ here and below means timer equal zero event |