使用TIM2在PA0口控制发光二极管的亮度，用接在PA3和PA8脚的按键控制PWM宽度

在网上找了一些例程，对我的帮助很大，弄了一上午，当看到发光二极管的亮度随着按键改变时，这种喜悦感是做其他事情感受不到的，这就是我玩单片机的乐趣所在！

不说废话了，先初始化I/O

void GPIO_Configuration(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;

  GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_0 ;                          //PWM输出
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOA, &GPIO_InitStructure);

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3 | GPIO_Pin_8 ;   //两个按键
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_10MHz;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
}


配置TIM2 :

void TIM_Configuration(void)
{
  TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
  TIM_OCInitTypeDef  TIM_OCInitStructure;
  TIM_TimeBaseStructure.TIM_Period = 999;
  TIM_TimeBaseStructure.TIM_Prescaler = 0;
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

  TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

  
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = 500;   //改变这里的值就能改变PWM宽度
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

  TIM_OC1Init(TIM2, &TIM_OCInitStructure);

  TIM_OC1PreloadConfig(TIM2, TIM_OCPreload_Enable);

  TIM_ARRPreloadConfig(TIM2, ENABLE);

  
  TIM_Cmd(TIM2, ENABLE);
}

要想在程序执行中改变PWM宽度  就要使用
TIM_SetCompare1(TIM2, TIMCompare1);
我个人理解  TIMCompare1相当于TIM2初始化里的TIM_OCInitStructure.TIM_Pulse，只要改变这个值就能改变PWM的宽度
while(1){
    scan_bit1 = GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_3);
      scan_bit2 = GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_8);
      if(scan_bit1==0) TIMCompare1+=1;
      if(scan_bit2==0) TIMCompare1-=1;
      if(TIMCompare1>999) TIMCompare1=999;
      if(TIMCompare1<1) TIMCompare1=1;   
      TIM_SetCompare1(TIM2, TIMCompare1);
}

按键程序没有加延时去抖动，所以按一下亮度会改变很多

我实际用的时候把TIMCompare1得值显示到液晶屏上了，按住按键 屏幕上的数值会飞快的增加（减少），亮度也会改变，很有意思！！