使用STM32 HAL定时器和调整PWM信号的占空比

Question

我使用STM32Cube初始化代码生成器生成了一个初始化的Timer函数。为了生成固定占空比 PWM 信号，我将 HAL_TIM_Base_Start(&htim1); //Starts the TIM Base generation 和 HAL_TIM_PWM_Start(&htim1, TIM_CHANNEL_1)//Starts the PWM signal generation 添加到定时器初始化函数中，如下所示。

/* Private variables ---------------------------------------------------------*/
int pulse_width=0;

/* TIM1 init function */
static void MX_TIM1_Init(void)
{

  TIM_ClockConfigTypeDef sClockSourceConfig;
  TIM_MasterConfigTypeDef sMasterConfig;
  TIM_OC_InitTypeDef sConfigOC;
  TIM_BreakDeadTimeConfigTypeDef sBreakDeadTimeConfig;

  htim1.Instance = TIM1;
  htim1.Init.Prescaler = 0;//we want a max frequency for timer, so we set prescaller to 0         
  //And our timer will have tick frequency
  htim1.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim1.Init.Period = 1066;//max value for timer is 16bit = 65535, TIM_Period = timer_tick_frequency / PWM_frequency - 1  
  //In our case, for 15Khz PWM_frequency, set Period to TIM_Period = 16MHz / 15KHz - 1 = 1066
  htim1.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  htim1.Init.RepetitionCounter = 0;
  if (HAL_TIM_Base_Init(&htim1) != HAL_OK)/* to use the Timer to generate a simple time base for TIM1 */
  {
    Error_Handler();
  }

  sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;//the default clock is the internal clock from the APBx, using this function
  if (HAL_TIM_ConfigClockSource(&htim1, &sClockSourceConfig) != HAL_OK)//Initializes the TIM PWM Time Base according to the specified
//parameters in the TIM_HandleTypeDef and create the associated handle.
  {
    Error_Handler();
  }

  if (HAL_TIM_PWM_Init(&htim1) != HAL_OK)
  {
    Error_Handler();
  }

  sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
  sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
  if (HAL_TIMEx_MasterConfigSynchronization(&htim1, &sMasterConfig) != HAL_OK)
  {
    Error_Handler();
  }

  //sConfig: TIM PWM configuration structure
  //set duty cycle: pulse_length = ((1066 + 1) * duty_cycle) / (100 - 1)
    sConfigOC.OCMode = TIM_OCMODE_PWM1;
  sConfigOC.Pulse = pulse_width;/* 50% duty cycle is 538, set to 0 initially*///
  sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
  sConfigOC.OCNPolarity = TIM_OCNPOLARITY_HIGH;
  sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
  sConfigOC.OCIdleState = TIM_OCIDLESTATE_RESET;
  sConfigOC.OCNIdleState = TIM_OCNIDLESTATE_RESET;
  if (HAL_TIM_PWM_ConfigChannel(&htim1, &sConfigOC, TIM_CHANNEL_1) != HAL_OK)
  {
    Error_Handler();
  }

  if (HAL_TIM_PWM_ConfigChannel(&htim1, &sConfigOC, TIM_CHANNEL_2) != HAL_OK)
  {
    Error_Handler();
  }

  sBreakDeadTimeConfig.OffStateRunMode = TIM_OSSR_ENABLE;
  sBreakDeadTimeConfig.OffStateIDLEMode = TIM_OSSI_ENABLE;
  sBreakDeadTimeConfig.LockLevel = TIM_LOCKLEVEL_1;
  sBreakDeadTimeConfig.DeadTime = 0;
  sBreakDeadTimeConfig.BreakState = TIM_BREAK_ENABLE;
  sBreakDeadTimeConfig.BreakPolarity = TIM_BREAKPOLARITY_HIGH;
  sBreakDeadTimeConfig.AutomaticOutput = TIM_AUTOMATICOUTPUT_ENABLE;
  if (HAL_TIMEx_ConfigBreakDeadTime(&htim1, &sBreakDeadTimeConfig) != HAL_OK)
  {
    Error_Handler();
  }

  HAL_TIM_MspPostInit(&htim1);//output pin assignment
    HAL_TIM_Base_Start(&htim1); //Starts the TIM Base generation
  if (HAL_TIM_PWM_Start(&htim1, TIM_CHANNEL_1) != HAL_OK)//Starts the PWM signal generation
  {
    /* PWM Generation Error */
    Error_Handler();
  }

  /* Start channel 2 */
  if (HAL_TIM_PWM_Start(&htim1, TIM_CHANNEL_2) != HAL_OK)
  {
    /* PWM Generation Error */
    Error_Handler();
  }

}

当我硬编码正确的值以替换 sConfigOC.Pulse = pulse_width 中的 pulse_width 值时，这足以运行上面评论中指定的固定占空比的 PWM。在另一个函数中，我有一个算法可以更新 pulse_width 全局变量。该函数称为：adjust_PWM();。该算法计算从 ADC 测量的值并存储为全局变量。该函数称为：Data_Update();。在main()中，所有函数初始化完成后。我没完没了地调用这三个函数

Data_Update();
adjust_PWM();   
MX_TIM1_Init();

我试过了并在示波器上获得了奇怪的波形，但这可能是因为 ADC 引脚浮动，导致浮动测量干扰算法的占空比。此外，连续调用定时器的初始化会中断 PWM 信号。有没有更好的方法来更改占空比运行在不使用全局变量的情况下更改代码，或者每次我想更新占空比时都不需要初始化计时器。任何 link 将不胜感激。

Answer 1

编写您自己的函数来更新控制占空比的寄存器。您将必须手动更新相应的 CCRx 寄存器（x 是您正在使用的 PWM 通道，在您的情况下是 CCR1）。

ARR 寄存器是您在根据所需的占空比计算 CCR 寄存器的新值时将参考的寄存器。

void adjust_PWM_DC(TIM_HandleTypeDef* const pwmHandle, const float DC)
{
    assert(pwmHandle != NULL);
    assert((DC >= 0.0F) && (DC <= 100.0F));

    /* The duty cycle value is a percentage of the reload register value (ARR). Rounding is used.*/
    uint32_t newRegVal = (uint32_t)roundf((float32_t)(pwmHandle->Instance->ARR) * (DC * 0.01F));

    /*In case of the DC being calculated as higher than the reload register, cap it to the reload register*/
    if(newRegVal > pwmHandle->Instance->ARR){
        newRegVal = pwmHandle->Instance->ARR);
    }

    /*Assign the new DC count to the capture compare register.*/
    pwmHandle->Instance->CCR1 = (uint32_t)(roundf(newRegVal));  /*Change CCR1 to appropriate channel, or pass it in with function.*/ 
}

Answer 2

当您想要更改设置时不要重新初始化计时器，HAL 有一个专门用于此目的的宏，称为：

/**
  * @brief  Sets the TIM Capture Compare Register value on runtime without
  *         calling another time ConfigChannel function.
  * @param  __HANDLE__: TIM handle.
  * @param  __CHANNEL__ : TIM Channels to be configured.
  *          This parameter can be one of the following values:
  *            @arg TIM_CHANNEL_1: TIM Channel 1 selected
  *            @arg TIM_CHANNEL_2: TIM Channel 2 selected
  *            @arg TIM_CHANNEL_3: TIM Channel 3 selected
  *            @arg TIM_CHANNEL_4: TIM Channel 4 selected
  * @param  __COMPARE__: specifies the Capture Compare register new value.
  * @retval None
  */
#define __HAL_TIM_SET_COMPARE(__HANDLE__, __CHANNEL__, __COMPARE__) \
(*(__IO uint32_t *)(&((__HANDLE__)->Instance->CCR1) + ((__CHANNEL__) >> 2)) = (__COMPARE__))

对于定时器 1 - 通道 1 和定时器 1 - 通道 2，它应该如下所示：

Data_Update();
adjust_PWM();

__HAL_TIM_SET_COMPARE(&htim1, TIM_CHANNEL_1, pulse_width);
__HAL_TIM_SET_COMPARE(&htim1, TIM_CHANNEL_2, pulse_width);

使用STM32 HAL定时器和调整PWM信号的占空比

Using STM32 HAL Timer and Adjusting the Duty Cycle of a PWM signal

c

embedded

microcontroller

timer

stm32