我用的定时器中断输出固定个数PWM为什么不准确呢

bridgym · 发表于 2017-8-29 15:48:06

我用的定时器4输出固定个数的PWM，但是仿真输出的个数和我程序设定的不一样，我程序设置5个PWM，仿真中它输出9个，无语，求大神解答
void PWM_Init(u16 arr,u16 psc)
{
u16 val1=arr/5;

GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4 ,ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB|RCC_APB2Periph_AFIO ,ENABLE);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6|GPIO_Pin_7|GPIO_Pin_8|GPIO_Pin_9;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOB, &GPIO_InitStructure);

TIM_TimeBaseInitStructure.TIM_Period=arr;
TIM_TimeBaseInitStructure.TIM_Prescaler=psc;
TIM_TimeBaseInitStructure.TIM_ClockDivision=0;
TIM_TimeBaseInitStructure.TIM_CounterMode=TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM4,&TIM_TimeBaseInitStructure);

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_Pulse = val1;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
TIM_OC1Init(TIM4, &TIM_OCInitStructure);
TIM_OC1PreloadConfig(TIM4, TIM_OCPreload_Enable);

TIM_ARRPreloadConfig(TIM4, ENABLE);

TIM_ClearITPendingBit(TIM4, TIM_IT_CC1);
TIM_ITConfig(TIM4,TIM_IT_CC1,ENABLE);

}
void NVIC_Config(void)
{
NVIC_InitTypeDef NVIC_InitStructure;
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn  ;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

}

主函数
u32 step=0;
int main()
{
delay_init();
uart_init(9600);
NVIC_Config();
PWM_Init(99,719);
LED_Init();
TIM_Cmd(TIM4,ENABLE);
while(1)
{

delay_ms(100);
   LED1=!LED1;
   delay_ms(100);

}

}
void TIM4_IRQHandler(void)
{
if(TIM_GetITStatus(TIM4,TIM_IT_CC1)!=RESET)
{
TIM_ClearITPendingBit(TIM4,TIM_IT_CC1);
step++;
printf("%d\n",step);
if(step==5)
{
TIM_Cmd(TIM4,DISABLE);
}
}

}