STM32F4的PWM脉冲数量精确输出

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void TIM2_Config(u32 cycle)
{
	GPIO_InitTypeDef GPIO_InitStructure;
	TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
	TIM_OCInitTypeDef TIM_OCInitStructure;
	
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2,ENABLE);//使能定时器时钟
	
	RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);//使能IO口时钟
	
	GPIO_PinAFConfig(GPIOA,GPIO_PinSource0,GPIO_AF_TIM2);//PA0复用为定时器2
	
	
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;           
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;        //复用功能
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;	//速度100MHz
	GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;      //推挽复用输出
	GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;        //上拉
	GPIO_Init(GPIOA,&GPIO_InitStructure);               //初始化PA0
	
	
	TIM_TimeBaseStructure.TIM_Prescaler=8400-1;                  //定时器分频
	TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up;//向上计数模式
	TIM_TimeBaseStructure.TIM_Period=cycle;                  //自动重装载值
	TIM_TimeBaseStructure.TIM_ClockDivision=TIM_CKD_DIV1; 	
	TIM_TimeBaseInit(TIM2,&TIM_TimeBaseStructure);           //初始化定时器

	
	TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;            //选择PWM模式
	TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;//比较输出使能
	TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;    //输出极性低
	TIM_OC1Init(TIM2, &TIM_OCInitStructure);                     //初始化定时器通道
	
	/*定时器主模式设置*/
	TIM_SelectMasterSlaveMode(TIM2, TIM_MasterSlaveMode_Enable);
    TIM_SelectOutputTrigger(TIM2, TIM_TRGOSource_OC1Ref);
	
	TIM_Cmd(TIM2, ENABLE);

	TIM_OC1PreloadConfig(TIM2, TIM_OCPreload_Enable);//使能定时器在ccr上的预装载寄存器
	
	TIM_ARRPreloadConfig(TIM2,ENABLE);//ARPE使能
	TIM_SetCompare1(TIM2,1000);
}

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void TIM3_Config(u32 PulseNum)
{
	GPIO_InitTypeDef GPIO_InitStructure;
	TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
	TIM_OCInitTypeDef TIM_OCInitStructure;
	
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3,ENABLE);//使能定时器时钟
	
	RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);//使能IO口时钟
	
	GPIO_PinAFConfig(GPIOC,GPIO_PinSource6,GPIO_AF_TIM3);//PC6复用为定时器3
	
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;           
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;        //复用功能
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;	//速度100MHz
	GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;      //推挽复用输出
	GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;        //上拉
	GPIO_Init(GPIOC,&GPIO_InitStructure);               //初始化PC6
	
	TIM_TimeBaseStructure.TIM_Prescaler=8400-1;                  //定时器分频
	TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up;//向上计数模式
	TIM_TimeBaseStructure.TIM_Period=PulseNum;               //自动重装载值
	TIM_TimeBaseStructure.TIM_ClockDivision=TIM_CKD_DIV1; 	
	TIM_TimeBaseInit(TIM3,&TIM_TimeBaseStructure);           //初始化定时器
	
	TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;            //选择PWM模式
	TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;//比较输出使能
	TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;    //输出极性低
	TIM_OC1Init(TIM3, &TIM_OCInitStructure);                     //初始化定时器通道
	
	/*定时器从模式设置*/
	TIM_SelectInputTrigger(TIM3, TIM_TS_ITR1);
    TIM_SelectSlaveMode(TIM3,TIM_SlaveMode_Gated );

	TIM_Cmd(TIM3, ENABLE);
	
	TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);//使能定时器在ccr上的预装载寄存器
	
	TIM_ARRPreloadConfig(TIM3,ENABLE);//ARPE使能
	
	TIM_SetCompare1(TIM3,20);
}

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void Pulse_output(u32 cycle,u32 PulseNum)
{
	TIM2_Config(cycle);
	TIM_Cmd(TIM2, ENABLE);
	TIM3_Config(PulseNum);
	TIM_Cmd(TIM3, ENABLE);
}

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int main(void)
{ 
	u16 led0pwmval=0;    
	u8 dir=1;
	NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);//设置系统中断优先级分组2
	delay_init(168);  //初始化延时函数
	uart_init(115200);//初始化串口波特率为115200
	//LED_Init();
	Pulse_output(2000-1,40-1);
    while(1);
}