菜鸡求教，stm32f103的板子，做两路pwm输出，结果有一路没反应。

本菜鸡想用stm32103的板子控制两路舵机，就干脆直接在pwm程序上改了。我查了一下TIM3通道2的复用口的PB5，我就加一个通道1的复用口的PB4。

但结果是原来的PB5口好用得很，但新加的PB4口毛用没有。求大神帮我解答，万分感谢！

void TIM3_PWM_Init(u16 arr,u16 psc)
{  
    //定义变量
    GPIO_InitTypeDef GPIO_InitStructure;
    TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
    TIM_OCInitTypeDef  TIM_OCInitStructure;
    //IO口配置
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);    
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB  | RCC_APB2Periph_AFIO, ENABLE);  

    GPIO_PinRemapConfig(GPIO_PartialRemap_TIM3, ENABLE); 
    //使能PA4、PA5
    GPIO_InitStructure.GPIO_Pin =GPIO_Pin_4|GPIO_Pin_5; 
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; 
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

    //定时器通用配置
    TIM_TimeBaseStructure.TIM_Period = arr; 
    TIM_TimeBaseStructure.TIM_Prescaler =psc;
    TIM_TimeBaseStructure.TIM_ClockDivision = 0;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  
    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

    //通道1配置
    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2; 
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; 
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; 
    TIM_OC2Init(TIM3, &TIM_OCInitStructure);  
    TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);  

    //通道2配置
    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2; 
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; 
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; 
    TIM_OC1Init(TIM3, &TIM_OCInitStructure);  
    TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);  

    TIM_Cmd(TIM3, ENABLE);  

}

 int main(void)
 {      
    u16 led0pwmval=0;
    u8 dir=1;   
    delay_init();            
    NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2); 

    LED_Init();             
    TIM3_PWM_Init(20000-1,72-1);    
  while(1)
    {
        TIM_SetCompare2(TIM3,20000-500);
        TIM_SetCompare1(TIM3,20000-500);
        delay_ms(1000); 
        TIM_SetCompare2(TIM3,20000-550);
        TIM_SetCompare1(TIM3,20000-550);
        delay_ms(1000);         
    }    
 }

IO口配置应该没有问题的，主要看下：
1.你可以只开PB4一路试下，看行不行。
2.你的PWM输出频率周期是多少？可以先把while(1)里面的内容去掉，将
TIM_SetCompare2(TIM3,20000-500);
TIM_SetCompare1(TIM3,20000-500);
两行放到 TIM3_PWM_Init(20000-1,72-1); 下面试下，看看两路有没有波形
3.如果还是都不行，可以参考我在stm32f105的板子上的4路PWM的代码，如下面所示

u16 CCR1_Val = 500;
u16 CCR2_Val = 375;
u16 CCR3_Val = 250;
u16 CCR4_Val = 125;
ErrorStatus HSEStartUpStatus;

/* Private function prototypes -----------------------------------------------*/
void RCC_Configuration(void);
void GPIO_Configuration(void);
void NVIC_Configuration(void);

/* Private functions ---------------------------------------------------------*/

/*******************************************************************************
* Function Name  : main
* Description    : Main program
* Input          : None
* Output         : None
* Return         : None
*******************************************************************************/
int main(void)
{
#ifdef DEBUG
  debug();
#endif

  /* System Clocks Configuration */
  RCC_Configuration();

  /* NVIC Configuration */
  NVIC_Configuration();

  /* GPIO Configuration */
  GPIO_Configuration();

  /* -----------------------------------------------------------------------
    TIM3 Configuration: generate 4 PWM signals with 4 different duty cycles:
    TIM3CLK = 36 MHz, Prescaler = 0x0, TIM3 counter clock = 36 MHz
    TIM3 ARR Register = 999 => TIM3 Frequency = TIM3 counter clock/(ARR + 1)
    TIM3 Frequency = 36 KHz.
    TIM3 Channel1 duty cycle = (TIM3_CCR1/ TIM3_ARR)* 100 = 50%
    TIM3 Channel2 duty cycle = (TIM3_CCR2/ TIM3_ARR)* 100 = 37.5%
    TIM3 Channel3 duty cycle = (TIM3_CCR3/ TIM3_ARR)* 100 = 25%
    TIM3 Channel4 duty cycle = (TIM3_CCR4/ TIM3_ARR)* 100 = 12.5%
  ----------------------------------------------------------------------- */

  /* Time base configuration */
  TIM_TimeBaseStructure.TIM_Period = 999;
  TIM_TimeBaseStructure.TIM_Prescaler = 0;
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

  TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

  /* PWM1 Mode configuration: Channel1 */
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = CCR1_Val;
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

  TIM_OC1Init(TIM3, &TIM_OCInitStructure);

  TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);

  /* PWM1 Mode configuration: Channel2 */
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = CCR2_Val;

  TIM_OC2Init(TIM3, &TIM_OCInitStructure);

  TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);

  /* PWM1 Mode configuration: Channel3 */
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = CCR3_Val;

  TIM_OC3Init(TIM3, &TIM_OCInitStructure);

  TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Enable);

  /* PWM1 Mode configuration: Channel4 */
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = CCR4_Val;

  TIM_OC4Init(TIM3, &TIM_OCInitStructure);

  TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Enable);

  TIM_ARRPreloadConfig(TIM3, ENABLE);

  /* TIM3 enable counter */
  TIM_Cmd(TIM3, ENABLE);

  while (1)
  {}
}