嵌入式蓝桥杯PWM程序编写

程序员文章站 2022-03-07 18:22:25

首先还是打开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_TimeBaseInitType...

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
嵌入式蓝桥杯PWM程序编写

嵌入式蓝桥杯PWM程序编写

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;                //ÖØ¸´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);

}

本文地址：https://blog.csdn.net/m0_46179894/article/details/108170788

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