我配置TIM2的通道输出PWM波形，用寄存器操作的，但是怎么输出一直是个高电平，求高手指点，谢谢！配置程序如下：
void PWM_Timer2_Init(void)
{
GPIO_Pin_Init(PORTA，GPIO_Pin_3，GPIO_MODE_AF_PP，GPIO_PULLUP, GPIO_SPEED_HIGH,AF1);

TIM_TypeDef *Timer = TIM2;
/* Enable the Low Speed APB (APB1) peripheral clock  */
RCC->APB1ENR1 |= RCC_APB1ENR1_TIM2EN;            //__TIM2_CLK_ENABLE()
/* Timer2 control register 1 (TIMx_CR1) */
Timer->CR1 &= ~(TIM_CR1_DIR | TIM_CR1_CMS);    // Clear direcion and center aligned mode bits
Timer->CR1 |= TIM_COUNTERMODE_CENTERALIGNED1;
Timer->CR1 &= ~TIM_CR1_CKD;                             // clesr clock division bits
     Timer->CR1 |= TIM_CLOCKDIVISION_DIV1;          // division = 1
// Timer2 prescaler (TIMx_PSC)
Timer->PSC = TIM2_PRESCALER_VALUE;                 // initialize Timer2 prescale value = 1
   
// TIM2 capture/compare mode register 4  (TIMx_CCMR2)
Timer->CCMR2 &= ~TIM_CCMR2_CC4S;                // Capture/Compare Channel4 is configured as output
// Timer->CCMR2 &= ~TIM_CCMR2_OC4PE;           // Output Compare Channel4 Preload disabled, TIMx_CCR1 can be written at anytime
Timer->CCMR2 |=  TIM_CCMR2_OC4PE;                // Output Compare 4 preload enable
Timer->CCMR2 &= ~TIM_CCMR2_OC4M;               // clear Output compare 4 mode
Timer->CCMR2 |=  TIM_CCMR2_OC4M_1;              // OC1M: Output compare 4 mode = 6, PWM mode 1
Timer->CCMR2 |=  TIM_CCMR2_OC4M_2;

Timer->CCER  |=  TIM_CCER_CC4P;
Timer->CCMR2 &=  ~TIM_CCMR2_OC4FE;
Timer->CR2  &=  ~TIM_CR2_OIS1;

Timer->CCMR2 |=  TIM_CCMR2_OC4CE;               // Output Compare Ch4 Clear Enable
     
     // TIM2 auto-reload register (TIM2_ARR)           // initialize PWM frequency
     Timer->ARR = 699;                                        // initialize Timer2 Auto Reload Register
// TIM2 capture/compare register 4 (TIM2_CCR4)          // initialize duty cycle
     Timer->CCR4 = 200;                                       // initialize Timer2 Capture/Compare Register 4
     
// TIM2 control register 1 (TIMx_CR1)   
     Timer->CR1 |= TIM_CR1_CEN;         // Timer2 enable
     // TIM2 capture/compare enable register (TIMx_CCER)
Timer->CCER = Timer->CCER |=  TIM_CCER_CC4E;
}

调好了，问题已经解决，配置程序没问题，程序里面的标志位没有使能导致的！谢谢各位关注！