【自学嵌入式：stm32单片机】PWMI模式测频率和占空比

目录

PWMI模式测频率和占空比

接线图

image

配置图

image
目前我们给的标准频率是1MHz，计数器自大只能计到65535，所以所测量的最低频率是1M/65535，这个值大概是15Hz，如果信号频率再低，计数器就要溢出了，如果想再价降低一些最低频率限制，我们可以把预分频Prescaler再加大点，这样标准频率就更低，所支持测量的最低频率也更低
对于测量频率的上限，最大频率没有明显的界限，因为随着待测频率的增大，误差也会逐渐增大，非要找上限，是标准频率1MHz，信号频率比标准频率还高，肯定测不了，最大频率要看对误差的要求，要求误差等于千分之一，频率为上限，这个上限就是1M/1000 = 1KHz，如果要求误差可以到百分之一，那频率上限就是1M/100 = 10KHz，提高频率上限，把PSC降低一些，提高标准频率，上限就会提高，如果频率还要更高，考虑使用测频法，这里是测周法，除了测量误差外，还会有晶振误差。

代码实现

标准库实现

已开源到：https://gitee.com/qin-ruiqian/jiangkeda-stm32
PWM.c和上一个文章一样

IC.h

#ifndef __IC_H
#define __IC_H

void IC_Init(void);
uint32_t IC_GetFreq(void);
uint32_t IC_GetDuty(void);

#endif

IC.c

#include "stm32f10x.h"                  // Device header

//初始化捕获输入
void IC_Init(void)
{
	//IC初始化是每个通道共用一个初始化函数
	//初始化PA0
	//打开APB2总线的GPIOA外设并开启时钟
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
	GPIO_InitTypeDef GPIO_InitStructure;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU; //上拉输入
	//普通推挽/开漏输出，引脚控制权是来自于输出数据寄存器的
	//如果想用定时器来控制引脚，就需要使用复用开漏/推挽输出的模式
	//在这里输出数据寄存器将被断开，输出控制权将转移给片上外设
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6; //TIM3的CHI1
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_Init(GPIOA, &GPIO_InitStructure);
	//开启时钟，TIM3，因为TIM2用于发射PWM信号了
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
	//选择时基单元的时钟，选择内部时钟
	TIM_InternalClockConfig(TIM3); //TIM3的时钟单元由内部时钟来驱动
	// 初始化时基单元用的结构体
	TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
	TIM_TimeBaseInitStructure.TIM_ClockDivision = TIM_CKD_DIV1; //选择滤波器1分频
	TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up; //向上计数
	//定时频率=72MHz/(PSC+1)/(ARR+1)
	//定时1s，也就是定时频率为1Hz
	TIM_TimeBaseInitStructure.TIM_Period = 65536 - 1; //ARR，16位计数器满量程计数
	//如果想要更高分辨率，ARR调成1000-1，频率72M/预分频/1000
	//占空比就是CCR/1000
	TIM_TimeBaseInitStructure.TIM_Prescaler = 72 - 1; //PSC，测周法的标准频率fc
	//72M/预分频，就是计数器自增的频率，就是计数标准频率，根据信号频率的分布范围来调整
	TIM_TimeBaseInitStructure.TIM_RepetitionCounter = 0; //重复计数器，高级计数器才有的，置0就行，TIM2-TIM4是通用计数器
	TIM_TimeBaseInit(TIM3, &TIM_TimeBaseInitStructure);
	
	//初始化输入捕获单元
	TIM_ICInitTypeDef TIM_ICInitStructure;
	TIM_ICInitStructure.TIM_Channel = TIM_Channel_1; //TIM3的通道1
	TIM_ICInitStructure.TIM_ICFilter = 0xF; //滤波器滤波强度
	TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising; //上升沿触发
	TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1; //每次触发都有效，不分频
	TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI; //直连输入，测频率
	TIM_ICInit(TIM3, &TIM_ICInitStructure);
	//通道2的初始化，可以复制一份初始化
	//st公司做了TIM_PWMIConfig更方便配置，这个函数只支持通道1和通道2的配置
//	TIM_ICInitStructure.TIM_Channel = TIM_Channel_2; //TIM3的通道2
//	TIM_ICInitStructure.TIM_ICFilter = 0xF; //滤波器滤波强度
//	TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Falling; //下降沿触发
//	TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1; //每次触发都有效，不分频
//	TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_IndirectTI; //交叉输入，测占空比
//	TIM_ICInit(TIM3, &TIM_ICInitStructure);
	TIM_PWMIConfig(TIM3, &TIM_ICInitStructure); //这个函数会自动把另一个通道初始化成相反的配置
	
	
	
	//配置TRGI的触发源位TI1FP1
	TIM_SelectInputTrigger(TIM3, TIM_TS_TI1FP1);
	//配置从模式为Reset，自动CNT清零
	TIM_SelectSlaveMode(TIM3, TIM_SlaveMode_Reset);
	// CNT不断自增，即使信号不过来也会自增
	// 这没关系，因为有信号来的时候，它就会在从模式的作用下自动清零
	TIM_Cmd(TIM3, ENABLE);
}

//获取频率，单位Hz
uint32_t IC_GetFreq(void)
{
	//PSC 72 - 1,fc =1MHz
	return 1000000 / (TIM_GetCapture1(TIM3) + 1); //+1补误差
}

//获取占空比
uint32_t IC_GetDuty(void)
{
	//高电平计数值存在CCR2里
	//整个周期存在CCR1里
	//CC2 / CCR1就是占空比
	//为了能显示整数，乘100放大
	return ((TIM_GetCapture2(TIM3)+1) * 100 / TIM_GetCapture1(TIM3)); //+1补误差
}

main.c

#include "stm32f10x.h"                  // Device header
#include "Delay.h"
#include "MYOLED.h"
#include "PWM.h"
#include "IC.h"

int main(void)
{
	PWM_Init();
	MYOLED_Init();
	IC_Init();
	PWM_SetPrescaler(720-1); //Freq = 72M / (PSC +1) / (ARR + 1)
	PWM_SetCompare1(50); //占空比
	MYOLED_ShowString(0,0,"Freq:00000Hz");
	MYOLED_ShowString(0,1,"Duty:00%");
	while(1)
	{
		MYOLED_ShowNum(5, 0, IC_GetFreq(), 5);
		MYOLED_ShowNum(5, 1, IC_GetDuty(), 2);
	}
}

HAL库实现

已开源到：https://gitee.com/qin-ruiqian/jiangkeda-stm32-hal
比上一个文章多了设置TIM3的通道2：
image
PWM.c和上一篇文章一样

IC.h

/*
 * IC.h
 *
 *  Created on: Aug 14, 2025
 *      Author: Administrator
 */

#ifndef HARDWARE_IC_H_
#define HARDWARE_IC_H_


typedef struct IC{
	TIM_HandleTypeDef htim; //当前用的是哪个定时器
	uint32_t ch; //当前用的是定时器的哪个通道
	uint32_t ch2; //第二个通道
}IC;

void IC_Init(IC* ic, TIM_HandleTypeDef tim, uint32_t Channel, uint32_t Channel2); //初始化IC
uint32_t IC_GetFreq(IC* ic); //获取频率，单位Hz
uint32_t IC_GetDuty(IC* ic); //获取占空比

#endif /* HARDWARE_IC_H_ */

IC.c

/*
 * IC.c
 *
 *  Created on: Aug 14, 2025
 *      Author: Administrator
 */


#include "stm32f1xx_hal.h"
#include "IC.h"

//把初始化定时器TIM3的过程放到IC里面
TIM_HandleTypeDef htim; //当前用的是哪个定时器

//初始化IC
void IC_Init(IC* ic, TIM_HandleTypeDef tim, uint32_t Channel, uint32_t Channel2)
{
	//开启对应定时器
	ic->htim = tim;
	ic->ch = Channel;
	ic->ch2 = Channel2;
	//打开输入捕获
	HAL_TIM_IC_Start(&(ic->htim), ic->ch);
	//打开输入占空比捕获
	HAL_TIM_IC_Start(&(ic->htim), ic->ch2);
}

//获取频率，单位Hz
uint32_t IC_GetFreq(IC* ic)
{
	//PSC 72 - 1,fc =1MHz
	uint32_t capture = (HAL_TIM_ReadCapturedValue(&(ic->htim), ic->ch) + 1);
	return 1000000 / capture; //+1补误差
}

//获取占空比
uint32_t IC_GetDuty(IC* ic)
{
	//高电平计数值存在CCR2里
	//整个周期存在CCR1里
	//CC2 / CCR1就是占空比
	//为了能显示整数，乘100放大
	uint32_t ccr1 = HAL_TIM_ReadCapturedValue(&(ic->htim), ic->ch);
	uint32_t ccr2 = HAL_TIM_ReadCapturedValue(&(ic->htim), ic->ch2);
	return (ccr2+1) * 100 / ccr1; //+1补误差
}

main.c

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2025 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "MYOLED.h"
#include "PWM.h"
#include "IC.h"
/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */

/* USER CODE END PTD */

/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */

/* USER CODE END PD */

/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */

/* USER CODE END PM */

/* Private variables ---------------------------------------------------------*/
TIM_HandleTypeDef htim2;
TIM_HandleTypeDef htim3;

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_TIM2_Init(void);
static void MX_TIM3_Init(void);
/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */

/* USER CODE END 0 */

/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{

  /* USER CODE BEGIN 1 */

  /* USER CODE END 1 */

  /* MCU Configuration--------------------------------------------------------*/

  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();

  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

  /* Configure the system clock */
  SystemClock_Config();

  /* USER CODE BEGIN SysInit */

  /* USER CODE END SysInit */

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_TIM2_Init();
  MX_TIM3_Init();
  /* USER CODE BEGIN 2 */
  MYOLED_Init();
  PWM pwm;
  PWM_Init(&pwm, htim2, TIM_CHANNEL_1);
  IC ic;
  IC_Init(&ic, htim3, TIM_CHANNEL_1, TIM_CHANNEL_2);
  PWM_SetCompare(&pwm, 50);
  PWM_SetPrescaler(&pwm, 720-1);
  MYOLED_ShowString(0,0,"Freq:00000Hz");
  MYOLED_ShowString(0,1,"Duty:00%");
  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
	  MYOLED_ShowNum(5, 0, IC_GetFreq(&ic), 5);
	  MYOLED_ShowNum(5, 1, IC_GetDuty(&ic), 2);
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}

/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
  RCC_OscInitStruct.HSEState = RCC_HSE_ON;
  RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
  RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
  {
    Error_Handler();
  }
}

/**
  * @brief TIM2 Initialization Function
  * @param None
  * @retval None
  */
static void MX_TIM2_Init(void)
{

  /* USER CODE BEGIN TIM2_Init 0 */

  /* USER CODE END TIM2_Init 0 */

  TIM_ClockConfigTypeDef sClockSourceConfig = {0};
  TIM_MasterConfigTypeDef sMasterConfig = {0};
  TIM_OC_InitTypeDef sConfigOC = {0};

  /* USER CODE BEGIN TIM2_Init 1 */

  /* USER CODE END TIM2_Init 1 */
  htim2.Instance = TIM2;
  htim2.Init.Prescaler = 720-1;
  htim2.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim2.Init.Period = 100-1;
  htim2.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  htim2.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_ENABLE;
  if (HAL_TIM_Base_Init(&htim2) != HAL_OK)
  {
    Error_Handler();
  }
  sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
  if (HAL_TIM_ConfigClockSource(&htim2, &sClockSourceConfig) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_TIM_PWM_Init(&htim2) != HAL_OK)
  {
    Error_Handler();
  }
  sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
  sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
  if (HAL_TIMEx_MasterConfigSynchronization(&htim2, &sMasterConfig) != HAL_OK)
  {
    Error_Handler();
  }
  sConfigOC.OCMode = TIM_OCMODE_PWM1;
  sConfigOC.Pulse = 0;
  sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
  sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
  if (HAL_TIM_PWM_ConfigChannel(&htim2, &sConfigOC, TIM_CHANNEL_1) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN TIM2_Init 2 */

  /* USER CODE END TIM2_Init 2 */
  HAL_TIM_MspPostInit(&htim2);

}

/**
  * @brief TIM3 Initialization Function
  * @param None
  * @retval None
  */
static void MX_TIM3_Init(void)
{

  /* USER CODE BEGIN TIM3_Init 0 */

  /* USER CODE END TIM3_Init 0 */

  TIM_ClockConfigTypeDef sClockSourceConfig = {0};
  TIM_SlaveConfigTypeDef sSlaveConfig = {0};
  TIM_MasterConfigTypeDef sMasterConfig = {0};
  TIM_IC_InitTypeDef sConfigIC = {0};

  /* USER CODE BEGIN TIM3_Init 1 */

  /* USER CODE END TIM3_Init 1 */
  htim3.Instance = TIM3;
  htim3.Init.Prescaler = 72-1;
  htim3.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim3.Init.Period = 65535;
  htim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  htim3.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_ENABLE;
  if (HAL_TIM_Base_Init(&htim3) != HAL_OK)
  {
    Error_Handler();
  }
  sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
  if (HAL_TIM_ConfigClockSource(&htim3, &sClockSourceConfig) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_TIM_IC_Init(&htim3) != HAL_OK)
  {
    Error_Handler();
  }
  sSlaveConfig.SlaveMode = TIM_SLAVEMODE_RESET;
  sSlaveConfig.InputTrigger = TIM_TS_TI1FP1;
  sSlaveConfig.TriggerPolarity = TIM_INPUTCHANNELPOLARITY_RISING;
  sSlaveConfig.TriggerFilter = 0;
  if (HAL_TIM_SlaveConfigSynchro(&htim3, &sSlaveConfig) != HAL_OK)
  {
    Error_Handler();
  }
  sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
  sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
  if (HAL_TIMEx_MasterConfigSynchronization(&htim3, &sMasterConfig) != HAL_OK)
  {
    Error_Handler();
  }
  sConfigIC.ICPolarity = TIM_INPUTCHANNELPOLARITY_RISING;
  sConfigIC.ICSelection = TIM_ICSELECTION_DIRECTTI;
  sConfigIC.ICPrescaler = TIM_ICPSC_DIV1;
  sConfigIC.ICFilter = 0;
  if (HAL_TIM_IC_ConfigChannel(&htim3, &sConfigIC, TIM_CHANNEL_1) != HAL_OK)
  {
    Error_Handler();
  }
  sConfigIC.ICPolarity = TIM_INPUTCHANNELPOLARITY_FALLING;
  sConfigIC.ICSelection = TIM_ICSELECTION_INDIRECTTI;
  if (HAL_TIM_IC_ConfigChannel(&htim3, &sConfigIC, TIM_CHANNEL_2) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN TIM3_Init 2 */

  /* USER CODE END TIM3_Init 2 */

}

/**
  * @brief GPIO Initialization Function
  * @param None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};
  /* USER CODE BEGIN MX_GPIO_Init_1 */

  /* USER CODE END MX_GPIO_Init_1 */

  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOD_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_GPIOB_CLK_ENABLE();

  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(GPIOB, GPIO_PIN_8|GPIO_PIN_9, GPIO_PIN_SET);

  /*Configure GPIO pins : PB8 PB9 */
  GPIO_InitStruct.Pin = GPIO_PIN_8|GPIO_PIN_9;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_OD;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

  /* USER CODE BEGIN MX_GPIO_Init_2 */

  /* USER CODE END MX_GPIO_Init_2 */
}

/* USER CODE BEGIN 4 */

/* USER CODE END 4 */

/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler_Debug */
  /* User can add his own implementation to report the HAL error return state */
  __disable_irq();
  while (1)
  {
  }
  /* USER CODE END Error_Handler_Debug */
}

#ifdef  USE_FULL_ASSERT
/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  * @param  file: pointer to the source file name
  * @param  line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t *file, uint32_t line)
{
  /* USER CODE BEGIN 6 */
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */

实现效果

内部PA0发射PWM信号
image
信号发射器发射PWM信号
image

posted @ 2025-08-14 16:04  秦瑞迁  阅读(84)  评论(0)    收藏  举报