[应用程序问题] 请高手指点下，stm32 pwm无输出问题。 下一步, 直流电机

用ＰＡ8的ＰＷＭ控制直流电机。但是ＰＷＭ无输出。请指点下。
void RCC_Configuration(void)
{   
    ErrorStatus HSEStartUpStatus;
    //使能外部晶振
    RCC_HSEConfig(RCC_HSE_ON);
    //等待外部晶振稳定
    HSEStartUpStatus = RCC_WaitForHSEStartUp();
    //如果外部晶振启动成功，则进行下一步操作
    if(HSEStartUpStatus==SUCCESS)
    {
        //设置HCLK（AHB时钟）=SYSCLK
        RCC_HCLKConfig(RCC_SYSCLK_Div1);
        //PCLK1(APB1) = HCLK/2
        RCC_PCLK1Config(RCC_HCLK_Div2);
        //PCLK2(APB2) = HCLK
        RCC_PCLK2Config(RCC_HCLK_Div1);
        
        //设置ADC时钟频率
        RCC_ADCCLKConfig(RCC_PCLK2_Div2);
        //FLASH时序控制
        //推荐值：SYSCLK = 0~24MHz   Latency=0
        //        SYSCLK = 24~48MHz  Latency=1
        //        SYSCLK = 48~72MHz  Latency=2
        FLASH_SetLatency(FLASH_Latency_2);
        //开启FLASH预取指功能
        FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
        //PLL设置 SYSCLK/1 * 6 = 12*1*6 = 72MHz
        RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_6);
        //启动PLL
        RCC_PLLCmd(ENABLE);
        //等待PLL稳定
        while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET);
        //系统时钟SYSCLK来自PLL输出
        RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
        //切换时钟后等待系统时钟稳定
        while(RCC_GetSYSCLKSource()!=0x08);
    }
    //启动GPIO
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB | RCC_APB2Periph_GPIOC | RCC_APB2Periph_GPIOD | RCC_APB2Periph_GPIOE , ENABLE);
    //启动AFIO
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);
    //启动USART1
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
//启动TIM1
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);
/* SPI1 Periph clock enable */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);
/* SPI2 Periph clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI2, ENABLE);
//FSMC
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_FSMC, ENABLE);
        
}
void GPIO_Configuration(void)
{
..........
// Configure SPI1 pins: SCK, MISO and MOSI and PA8WM
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5| GPIO_Pin_6 | GPIO_Pin_7 | GPIO_Pin_8;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOA, &GPIO_InitStructure);
........
}

void PWM1_configuration(void)
{
TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
TIM_OCInitTypeDef  TIM_OCInitStructure;

/* Time base configuration */
TIM_TimeBaseStructure.TIM_Period =999;   //4=10k
TIM_TimeBaseStructure.TIM_Prescaler = 0x1C1F;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;
TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);
TIM_ARRPreloadConfig(TIM1, ENABLE);

/* PWM1 Mode configuration: Channel1 */
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Disable;
TIM_OCInitStructure.TIM_Pulse =999;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
TIM_OC1Init(TIM1, &TIM_OCInitStructure);
TIM_OC1PreloadConfig(TIM1, TIM_OCPreload_Enable);
/* TIM1 enable counter */
TIM_Cmd(TIM1, ENABLE);
    TIM_CtrlPWMOutputs(TIM1, ENABLE);
}
void PWM1_set(unsigned short v)
{
TIM_OCInitTypeDef  TIM_OCInitStructure;

/* PWM1 Mode configuration: Channel1 */
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Disable;
TIM_OCInitStructure.TIM_Pulse =10*(100-v);
if (v<2) TIM_OCInitStructure.TIM_Pulse =10;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
TIM_OC1Init(TIM1, &TIM_OCInitStructure);
TIM_OC1PreloadConfig(TIM1, TIM_OCPreload_Enable);
}
...............

Ｖ值为0到100之间的数。网上看例程，查资料，不知道问题出在哪。

官网例程 试过吗