stm32f103的PWM输出疑问

hijkstra · 发表于 2018-1-23 13:49:59

大家好！现在使用stm32f103调试一个小程序，注意到stm32F103的pwm输出好像不能低于1Hz,这是怎么回事呢？麻烦帮助一下啊，多谢啦！！！
下面是pwm的代码。

void TIM3_GPIO_Config(void)
{
GPIO_InitTypeDef GPIO_InitStructure;

/*GPIOA Configuration: TIM3 channel 4 as alternate function push-pull*/

GPIO_StructInit(&GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_0;//| GPIO_Pin_1
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;       // 复用推挽输出
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOB, &GPIO_InitStructure);
}

void TIM3_Configuration(void)
{
TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
TIM_OCInitTypeDef  TIM_OCInitStructure;
  /* Time base configuration */
  /*定义TIM3工作在1KHz，TIM3预分频到36MHz，在预装载到1KHz*/
  TIM_TimeBaseStructure.TIM_Period = 10000-1;//0xea5f;    //当定时器从0计数到999，即为1000次，为一个定时周期
  TIM_TimeBaseStructure.TIM_Prescaler = 72-1;//2;//TIM3Prescaler;       //设置预分频：不预分频，即为36MHz
  TIM_TimeBaseStructure.TIM_ClockDivision = 0; //设置时钟分频系数：不分频
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //向上计数模式
  TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;       //配置为PWM模式1
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = 5000; //设置通道3的电平跳变值，输出另外一个占空比的PWM
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;//TIM_OCNPolarity_High
  TIM_OC3Init(TIM3, &TIM_OCInitStructure);    //使能通道4
  TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Enable);
  TIM_ARRPreloadConfig(TIM3, ENABLE);    // 使能TIM3重载寄存器ARR
  /* TIM3 enable counter */
  TIM_Cmd(TIM3, ENABLE);                //使能定时器3

//TIM_ITConfig(TIM3, TIM_IT_CC4, ENABLE);
//TIM_SetAutoreload(TIM2, 0xFFFF); //设置溢出中断比较值
//TIM_ITConfig(TIM3, TIM_IT_Update,  ENABLE ); //设置溢出中断
}

void NVIC_TIME3_Configuration(void)
{
NVIC_InitTypeDef NVIC_InitStructure;
//打开TIM2的全局中断，在中断中判断是更新中断还是捕捉中断
/* Enable the TIM2 global Interrupt */
// NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);

NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}

void TIM3_Init(void)
{
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3 , ENABLE);
TIM3_GPIO_Config();
TIM3_Configuration();
NVIC_TIME3_Configuration();

TIM3_HzOut.hzOut = 100;
TIM3_HzOut.hzOut_decimal = 0;
TIM3_HzOut.ratio = 50;
//tim3_ratio = 50;//默认的占空比是50%
//tim3_hzOut = 100;//默认输出100Hz的脉冲波;
//tim3_hzOut_decimal = 0;//默认小数是0.0hz；

// TIM3_HzOut.duty_ratio = 50;//默认的占空比是50%;

}