电机专题3：舵机 stm32

舵机原理

舵机的外形如下：

舵机的结构：

舵机的接线方式：

示意图：

舵机工作原理：

我们使用的舵机型号为 MG996R，由上面的舵机原理可知，只需要生成一个周期为20ms的PWM脉冲，通过调整PWM脉宽就可以对应的改变舵机的角度。以下是舵机参数：

 

舵机控制

接下来，我们通过stm32来生成PWM，控制电机，stm32cubeMX的配置如下：

这里，预分频PSC = 720，则定时器每10us计数一次，重装载值为2000，则PWM周期为2000 * 10(us) = 20ms，正好是舵机控制所需要的周期。脉宽为150*10/1000 = 1.5ms，对应初始角度为0的位置。

接下来是控制代码：

/**
  * @brief 调整舵机角度
  * @param angle 输入角度范围：-90 ~ 90
  */
void MG996R_Set_Angle(int16_t angle)
{
	uint16_t CCR_value = 0;
	
	if ((-90 <= angle) && (angle <= 90))
	{
		CCR_value = (10. / 9) * angle + 150;		// 角度 to CCR值
	}
	else
	{
		CCR_value = 150;
	}
	
	__HAL_TIM_SET_COMPARE(&htim3, TIM_CHANNEL_1, CCR_value);
}

这个函数，用来将输入的角度值，转换成对应的定时器PWM的比较值CCR寄存器。angle = -90时，脉宽为0.5ms，对应的CCR为50，angle = 90时，脉宽为2.5ms，对应的CCR为250。由此可以得到这个关系式：

CCR_value = (10. / 9) * angle + 150;		// 角度 to CCR值

接下来，开启定时器，然后在主函数中进行测试：

完整的工程代码如下：

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * 
© Copyright (c) 2019 STMicroelectronics.
  * All rights reserved.
  *
  * This software component is licensed by ST under BSD 3-Clause license,
  * the "License"; You may not use this file except in compliance with the
  * License. You may obtain a copy of the License at:
  *                        opensource.org/licenses/BSD-3-Clause
  *
  ******************************************************************************
  */
/* USER CODE END Header */

/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "tim.h"
#include "gpio.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */

/* 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 ---------------------------------------------------------*/

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
/* USER CODE BEGIN PFP */
void MG996R_Set_Angle(int16_t angle);

/* 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 */
	int16_t angle = 0;
	
  /* 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_TIM3_Init();
  /* USER CODE BEGIN 2 */
	
	HAL_TIM_PWM_Start(&htim3, TIM_CHANNEL_1);
	
	MG996R_Set_Angle(0);

  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */

		for (angle = -90; angle <= 90; angle += 10)
		{
			MG996R_Set_Angle(angle);
			HAL_Delay(100);
		}
		
		for (angle = 90; angle >= -90; angle -= 10)
		{
			MG996R_Set_Angle(angle);
			HAL_Delay(100);
		}

  }
  /* 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 CPU, AHB and APB busses clocks 
  */
  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 busses 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();
  }
}

/* USER CODE BEGIN 4 */

/**
	* @brief 调整舵机角度
	* @param angle 输入角度范围：-90 ~ 90
	*/
void MG996R_Set_Angle(int16_t angle)
{
	uint16_t CCR_value = 0;
	
	if ((-90 <= angle) && (angle <= 90))
	{
		CCR_value = (10. / 9) * angle + 150;		// 角度 to CCR值
	}
	else
	{
		CCR_value = 150;
	}
	
	__HAL_TIM_SET_COMPARE(&htim3, TIM_CHANNEL_1, CCR_value);
}

/* 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 */

  /* 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,
     tex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */

/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/