fix zpwm generator bug

chip/zpwm_generator.cpp

@@ -50,15 +50,12 @@ void ZPWMGenerator::startPWM(float freq, float duty) {
     Error_Handler();
   }
   HAL_TIM_PWM_Stop(m_htim, m_channel);
+  __HAL_TIM_SET_COUNTER(m_htim, 0);
   if (HAL_TIM_PWM_Start(m_htim, m_channel) != HAL_OK) {
     Error_Handler();
   }
 }
 void ZPWMGenerator::stopPWM() {
   float duty = 0;
-  if (!m_polarity) {
-    duty = 100.0 - duty;
-  }
-  //  HAL_TIM_PWM_Stop(m_htim, m_channel);
   startPWM(duty);
 }