定时器输出双脉冲

huige · 发表于 2018-3-6 15:25:38

各位好！请指教如下问题：需要输出如下图的波形脉冲，

我用STM32C8的定时器3去尝试实现该波形，定时器初始化如下（原子哥的库）：

void TIM3_Int_Init(u16 arr,u16 psc)
{
TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
NVIC_InitTypeDef NVIC_InitStructure;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); //ê±Öóê1Äü

TIM_TimeBaseStructure.TIM_Period = arr;
TIM_TimeBaseStructure.TIM_Prescaler =psc;
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

TIM_ITConfig(TIM3,TIM_IT_Update,ENABLE );

NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

TIM_Cmd(TIM3, ENABLE);
}

输出管脚PB5（LED0）初始化为：
void LED_Init(void)
{
GPIO_InitTypeDef  GPIO_InitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB|RCC_APB2Periph_GPIOE, ENABLE);//ê1ÄüPB,PE¶Ë¿úê±Öó

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;    //LED0-->PB.5
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOB, &GPIO_InitStructure);
GPIO_SetBits(GPIOB,GPIO_Pin_5);

}
中断函数如下:
void TIM3_IRQHandler(void)
{
static unsigned char flag=0;

if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET)
{
TIM_ClearITPendingBit(TIM3, TIM_IT_Update );
}

switch(flag)
{
   case 0:TIM3_Int_Init(19875,719);//198.75ms
         flag++;
         LED0=0;
         break;

case 1:TIM3_Int_Init(10,7199);//1ms
         flag++;
         LED0=1;
         break;
case 2:TIM3_Int_Init(25,71);//25us
         flag++;
         LED0=0;
         break;
case 3:TIM3_Int_Init(225,71);//225us
         flag++;
         LED0=1;
         break;
case 4:TIM3_Int_Init(19875,719);//198.75ms
         flag=1;
         LED0=0;
         break;

}

}

另外主函数里只运行了一个死循环，循环里面没有其他语句。按照如上程序编译，用示波器观察PB5管脚的
输出波形，却只能得到一个占空比为50%，周期为14us的矩形波。请问按照上面思路不能输出目标波形的问题出在哪？
是否还需要考虑将Timer3部分重映射到PB5？