中断控制pwm的呼吸灯实验，运行后无效果

ID:366743 · 发表于 2018-7-20 15:37

stm32f103c8t6练习pwm（脉冲宽度调制）实验，从网上找到一串代码，稍作修改后运行，不能实现呼吸灯效果，仅仅是PB5,PB6 led灯初始化成功发光，初学stm32,新手上路诸多问题难解，还望大神赐教

代码如下：

#include "stm32f10x.h"
#include "my.h"

void RCC_cfg(void);
void GPIO_cfg(void);
void TIMER_cfg(void);
void PWM_cfg(void);

int led_fx=1;
int led_dt=0;


   void LED_Init(void)
{

GPIO_InitTypeDef  GPIO_InitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB|RCC_APB2Periph_GPIOE, ENABLE);    //使能PB,PE端口时钟

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5 | GPIO_Pin_6;    //LED0-->PB.5 端口配置
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;    //推挽输出
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;    //IO口速度为50MHz
GPIO_Init(GPIOB, &GPIO_InitStructure);    //根据设定参数初始化GPIOB.5
GPIO_SetBits(GPIOB,GPIO_Pin_5 | GPIO_Pin_6  );    //PB.5 输出高
   //PE.5 输出高
}

int main(void)
{

RCC_cfg();
GPIO_cfg();
TIMER_cfg();
PWM_cfg();
//使能TIM2计时器，开始输出PWM
TIM_Cmd(TIM2, ENABLE);
   LED_Init();
while(1)
   {
      delay_ms(5);
      if(led_fx==1)
      {
               led_dt++;
      }
      else
      {
         led_dt--;
      }
      if(led_dt>500) led_fx=0;
      if(led_dt==0) led_fx=1;
      TIM_SetCompare4(TIM2,led_dt);
}
}

void RCC_cfg(void)
{
   //定义错误状态变量
   ErrorStatus HSEStartUpStatus;
   //将RCC寄存器重新设置为默认值
   RCC_DeInit();
   //打开外部高速时钟晶振
   RCC_HSEConfig(RCC_HSE_ON);
   //等待外部高速时钟晶振工作
   HSEStartUpStatus = RCC_WaitForHSEStartUp();
   if(HSEStartUpStatus == SUCCESS)
   {
            //设置AHB时钟(HCLK)为系统时钟
            RCC_HCLKConfig(RCC_SYSCLK_Div1);
            //设置高速AHB时钟(APB2)为HCLK时钟
            RCC_PCLK2Config(RCC_HCLK_Div1);
            //设置低速AHB时钟(APB1)为HCLK的2分频
            RCC_PCLK1Config(RCC_HCLK_Div2);
            //设置FLASH代码延时
            FLASH_SetLatency(FLASH_Latency_2);
            //使能预取指缓存
            FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);
            //设置PLL时钟，为HSE的9倍频 8MHz * 9 = 72MHz
            RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);
            //使能PLL
            RCC_PLLCmd(ENABLE);
            //等待PLL准备就绪
            while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET);
            //设置PLL为系统时钟源
            RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
            //判断PLL是否是系统时钟
            while(RCC_GetSYSCLKSource() != 0x08);
   }
   //开启TIM2的时钟
   RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2,ENABLE);
   //开启GPIOB的时钟和复用功能
   RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO,ENABLE);
}

void GPIO_cfg(void)
{
   GPIO_InitTypeDef GPIO_InitStructure;
// GPIO_PinRemapConfig(GPIO_PartialRemap1_TIM2, ENABLE);    //映射引脚，默认PA3 ->TIM2_CH4因此不用映射
   //选择引脚3
   GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
   //输出频率最大50MHz
   GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
   //复用推挽输出
   GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
      //PA
   GPIO_Init(GPIOA,&GPIO_InitStructure);
}

void TIMER_cfg(void)
{
   TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
   //重新将Timer设置为缺省值
   TIM_DeInit(TIM2);
   //采用内部时钟给TIM2提供时钟源
   TIM_InternalClockConfig(TIM2);
   //预分频系数为0
   TIM_TimeBaseStructure.TIM_Prescaler = 0;
   //设置计数溢出大小
   TIM_TimeBaseStructure.TIM_Period = 500;
   //设置计数器模式为向上计数模式(+1)
   TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
   //设置时钟分割
   TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
   //将配置应用到TIM2中
   TIM_TimeBaseInit(TIM2,&TIM_TimeBaseStructure);
}

void PWM_cfg(void)
{
   TIM_OCInitTypeDef TimOCInitStructure;
   //设置缺省值
   TIM_OCStructInit(&TimOCInitStructure);
   //PWM模式1输出
   TimOCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
   //设置占空比 (Led亮度)
   TimOCInitStructure.TIM_Pulse = 0;
   //TIM输出比较极性高
   TimOCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
   //使能输出状态
   TimOCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
   //TIM2的CH4输出
   TIM_OC4Init(TIM2, &TimOCInitStructure);
   //设置TIM2的PWM输出为使能
   TIM_CtrlPWMOutputs(TIM2,ENABLE);
}

ID:366743 · 发表于 2018-7-21 16:49

TimOCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;将这一句的pwm高极性改成低极性，即TimOCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;

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