嵌入式蓝桥杯PWM程序编写

其他 2021-01-25 04:15:15 阅读次数: 0

首先我们确认好的输出PWM引脚是
在这里插入图片描述
PA6 TIM3 CH1 作为输出1
PA7 TIM3 CH2 作为输出2
还是打开32固件库关于PWM输出的文件
路径如下
\STM32固件库v3.5\STM32F10x_StdPeriph_Lib_V3.5.0\Project\STM32F10x_StdPeriph_Examples\TIM\PWM_Output
找到主函数 把里面内容全部复制到我们创建的函数
void TIM3_PWM_Init（void）里面

void TIM3_PWM_Init（void）{
    
    }

因为代码量太大影响读阅读所以就不贴出来了

接着我们复制解构体名称

TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
TIM_OCInitTypeDef  TIM_OCInitStructure;

然后我们把预分屏值写入

uint16_t PrescalerValue = 0;

然后是CCR1的值写入

uint16_t CCR1_Val = 333;

然后我们把其余CCR配置的函数删除
被其余CCR的函数如下

  /* PWM1 Mode configuration: Channel2 */
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = CCR2_Val;
  TIM_OC2Init(TIM3, &TIM_OCInitStructure);
  TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);
  /* PWM1 Mode configuration: Channel3 */
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = CCR3_Val;
  TIM_OC3Init(TIM3, &TIM_OCInitStructure);
  TIM_OC3PreloadConfig(TIM3, TIM_OCPreload_Enable);
  /* PWM1 Mode configuration: Channel4 */
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = CCR4_Val;
    TIM_OC4Init(TIM3, &TIM_OCInitStructure);
  TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Enable);

接着针对我们报错的两个函数进行配置
其实固件库是利用函数引用
我们只需要把其相应的函数模块替换名称就可以了

首先是RCC的 文件

void RCC_Configuration(void)
{
    
    
  /* TIM3 clock enable */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

  /* GPIOA and GPIOB clock enable */
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOB |
                         RCC_APB2Periph_GPIOC | RCC_APB2Periph_AFIO, ENABLE);
}

我们用到的PWM输出是
TIM3 CCR2 对应的就是PA7引脚
TIM2 CCR2 对应的就是PA1引脚
在这里插入图片描述

在这里插入图片描述

所以我们只保留 TIM3 和PA口 和 复用的时钟

  /* TIM3 clock enable */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

  /* GPIOA and GPIOB clock enable */
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);

接着是我们的GPIO的引脚IO口
和之前配置过程一样
找到这一段代码

  /*GPIOB Configuration: TIM3 channel1, 2, 3 and 4 */
  GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_6 | GPIO_Pin_7 | GPIO_Pin_8 | GPIO_Pin_9;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOC, &GPIO_InitStructure);
  GPIO_PinRemapConfig(GPIO_FullRemap_TIM3, ENABLE);

然后只保留PA7就可以了

  GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_7;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

  GPIO_Init(GPIOA, &GPIO_InitStructure);

接下来我们就已经配置好了一个IO口的输入输出了
接下来我们来计算输出PWM频率
我们来看看这段注释

  /* -----------------------------------------------------------------------
    TIM3 Configuration: generate 4 PWM signals with 4 different duty cycles:
    The TIM3CLK frequency is set to SystemCoreClock (Hz), to get TIM3 counter
    clock at 24 MHz the Prescaler is computed as following:
     - Prescaler = (TIM3CLK / TIM3 counter clock) - 1
    SystemCoreClock is set to 72 MHz for Low-density, Medium-density, High-density
    and Connectivity line devices and to 24 MHz for Low-Density Value line and
    Medium-Density Value line devices

    The TIM3 is running at 36 KHz: TIM3 Frequency = TIM3 counter clock/(ARR + 1)
                                                  = 24 MHz / 666 = 36 KHz
    TIM3 Channel1 duty cycle = (TIM3_CCR1/ TIM3_ARR)* 100 = 50%
    TIM3 Channel2 duty cycle = (TIM3_CCR2/ TIM3_ARR)* 100 = 37.5%
    TIM3 Channel3 duty cycle = (TIM3_CCR3/ TIM3_ARR)* 100 = 25%
    TIM3 Channel4 duty cycle = (TIM3_CCR4/ TIM3_ARR)* 100 = 12.5%
  ----------------------------------------------------------------------- */

里面说了他已经将72Mhz 分解成了 24Mhz
我猜测是这一句

  PrescalerValue = (uint16_t) (SystemCoreClock / 24000000) - 1;

预分配值等于时钟除以24000000 - 1
然后时钟再除以预分频值
这样写的好处是 不管你时钟频率是多少 除以这个PrescalerValue
得到都是24Mhz

接着看到24Mhz分解成了36KHz
我猜是这一句吧

  TIM_TimeBaseStructure.TIM_Period = 665;

设置周期是665 就完成一次周期频率变成了 36KHz
而我们要得到40KHz
就要来反向计算一下 240 000 K/40K=600
于是我们改成

  TIM_TimeBaseStructure.TIM_Period = 599;

于是应该就可以实现40KHz方波输出供给超声波使用了
以下是PWM配置的完整代码


#include "timer.h"
_Bool TIM2_led_flag =0; 
u8 Tim2_conter =0;

void TIM2_Config(void)
{
    
    
  TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStrure;
  NVIC_InitTypeDef NVIC_InitStrure;
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2,ENABLE);
	
	TIM_TimeBaseInitStrure.TIM_CounterMode=TIM_CounterMode_Up;
	TIM_TimeBaseInitStrure.TIM_Period=1000;//¼ÆÊýµ½1000 µÈÓÚ³ËÒÔÁË1000
	TIM_TimeBaseInitStrure.TIM_Prescaler=  71 ; //72HMz/72=1Mhz = 1 000 000
	TIM_TimeBaseInitStrure.TIM_RepetitionCounter= 0;                //Öظ´ÇëÇó¼ÆÊýÆ÷
	TIM_TimeBaseInit(TIM2,&TIM_TimeBaseInitStrure);
	
  TIM_ITConfig(TIM2,TIM_IT_Update,ENABLE);
	TIM_Cmd(TIM2,ENABLE);
	
	
	NVIC_InitStrure.NVIC_IRQChannel=TIM2_IRQn;
	NVIC_InitStrure.NVIC_IRQChannelCmd=ENABLE;
	NVIC_InitStrure.NVIC_IRQChannelPreemptionPriority=0;
	NVIC_InitStrure.NVIC_IRQChannelSubPriority=1;
	NVIC_Init(&NVIC_InitStrure);
	
}
void TIM2_IRQHandler()
{
    
    
	if(TIM_GetITStatus(TIM2,TIM_IT_Update)!=RESET)
	{
    
    
		Tim2_conter++;
		
		TIM_ClearITPendingBit(TIM2,TIM_IT_Update);
		if(Tim2_conter > 250)
		{
    
    
		Tim2_conter=0;
		TIM2_led_flag = !TIM2_led_flag;
		}
	}
}

void TIM3_PWM_Init(void)
{
    
    
 uint16_t PrescalerValue = 0;
 uint16_t CCR1_Val = 333;
 TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
 TIM_OCInitTypeDef  TIM_OCInitStructure;
 GPIO_InitTypeDef GPIO_InitStructure;   
  /* System Clocks Configuration */
  /* TIM3 clock enable */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

  /* GPIOA and GPIOB clock enable */
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);

  /* GPIO Configuration */
    /*GPIOB Configuration: TIM3 channel1, 2, 3 and 4 */
  GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_7;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

  GPIO_Init(GPIOA, &GPIO_InitStructure);

  GPIO_PinRemapConfig(GPIO_FullRemap_TIM3, ENABLE);	


  /* -----------------------------------------------------------------------
    TIM3 Configuration: generate 4 PWM signals with 4 different duty cycles:
    The TIM3CLK frequency is set to SystemCoreClock (Hz), to get TIM3 counter
    clock at 24 MHz the Prescaler is computed as following:
     - Prescaler = (TIM3CLK / TIM3 counter clock) - 1
    SystemCoreClock is set to 72 MHz for Low-density, Medium-density, High-density
    and Connectivity line devices and to 24 MHz for Low-Density Value line and
    Medium-Density Value line devices

    The TIM3 is running at 36 KHz: TIM3 Frequency = TIM3 counter clock/(ARR + 1)
                                                  = 24 MHz / 666 = 36 KHz
    TIM3 Channel1 duty cycle = (TIM3_CCR1/ TIM3_ARR)* 100 = 50%
    TIM3 Channel2 duty cycle = (TIM3_CCR2/ TIM3_ARR)* 100 = 37.5%
    TIM3 Channel3 duty cycle = (TIM3_CCR3/ TIM3_ARR)* 100 = 25%
    TIM3 Channel4 duty cycle = (TIM3_CCR4/ TIM3_ARR)* 100 = 12.5%
  ----------------------------------------------------------------------- */
  /* Compute the prescaler value */
  PrescalerValue = (uint16_t) (SystemCoreClock / 24000000) - 1;
  /* Time base configuration */
  TIM_TimeBaseStructure.TIM_Period = 599;
  TIM_TimeBaseStructure.TIM_Prescaler = PrescalerValue;
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

  TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

  /* PWM1 Mode configuration: Channel1 */
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = CCR1_Val;
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

  TIM_OC2Init(TIM3, &TIM_OCInitStructure);

  TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);

  TIM_ARRPreloadConfig(TIM3, ENABLE);

  /* TIM3 enable counter */
  TIM_Cmd(TIM3, ENABLE);

}




void TIM2_PWM_Init(void)
{
    
    
 uint16_t PrescalerValue = 0;
 uint16_t CCR1_Val = 300;
 TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
 TIM_OCInitTypeDef  TIM_OCInitStructure;
 GPIO_InitTypeDef GPIO_InitStructure;   
  /* System Clocks Configuration */
  /* TIM2 clock enable */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

  /* GPIOA and GPIOB clock enable */
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);

  /* GPIO Configuration */
    /*GPIOB Configuration: TIM2 channel1, 2, 3 and 4 */
  GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_1;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

  GPIO_Init(GPIOA, &GPIO_InitStructure);

  GPIO_PinRemapConfig(GPIO_FullRemap_TIM2, ENABLE);	


  /* -----------------------------------------------------------------------
    TIM3 Configuration: generate 4 PWM signals with 4 different duty cycles:
    The TIM3CLK frequency is set to SystemCoreClock (Hz), to get TIM3 counter
    clock at 24 MHz the Prescaler is computed as following:
     - Prescaler = (TIM3CLK / TIM3 counter clock) - 1
    SystemCoreClock is set to 72 MHz for Low-density, Medium-density, High-density
    and Connectivity line devices and to 24 MHz for Low-Density Value line and
    Medium-Density Value line devices

    The TIM3 is running at 36 KHz: TIM3 Frequency = TIM3 counter clock/(ARR + 1)
                                                  = 24 MHz / 666 = 36 KHz
    TIM3 Channel1 duty cycle = (TIM3_CCR1/ TIM3_ARR)* 100 = 50%
    TIM3 Channel2 duty cycle = (TIM3_CCR2/ TIM3_ARR)* 100 = 37.5%
    TIM3 Channel3 duty cycle = (TIM3_CCR3/ TIM3_ARR)* 100 = 25%
    TIM3 Channel4 duty cycle = (TIM3_CCR4/ TIM3_ARR)* 100 = 12.5%
  ----------------------------------------------------------------------- */
  /* Compute the prescaler value */
  PrescalerValue = (uint16_t) (SystemCoreClock / 24000000) - 1;
  /* Time base configuration */
  TIM_TimeBaseStructure.TIM_Period = 599;
  TIM_TimeBaseStructure.TIM_Prescaler = PrescalerValue;
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

  TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

  /* PWM1 Mode configuration: Channel1 */
  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = CCR1_Val;
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

  TIM_OC2Init(TIM2, &TIM_OCInitStructure);

  TIM_OC2PreloadConfig(TIM2, TIM_OCPreload_Enable);

  TIM_ARRPreloadConfig(TIM2, ENABLE);

  /* TIM3 enable counter */
  TIM_Cmd(TIM2, ENABLE);

}

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