TIM_CCER_CCxNP
wfhw->ccer |= TIM_CCER_CCxNP(ch + 1);
mask = TIM_CCER_CCxP(ch + 1) | TIM_CCER_CCxNP(ch + 1);
#define TIM_CCER_CC1NP TIM_CCER_CCxNP(1) /* Capt/Comp 1N Polarity */
#define TIM_CCER_CC2NP TIM_CCER_CCxNP(2) /* Capt/Comp 2N Polarity */
#define TIM_CCER_CC3NP TIM_CCER_CCxNP(3) /* Capt/Comp 3N Polarity */
#define TIM_CCER_CC4NP TIM_CCER_CCxNP(4) /* Capt/Comp 4N Polarity */