Question

我使用STM32Cube初始化代码生成器生成初始化的Timer函数。为了产生固定占空比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功能，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pulse_width中的sConfigOC.Pulse = pulse_width值时，这足以在上述注释中指定的固定占空比下运行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，在初始化所有函数之后。我无休止地称这三个功能

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

我试过并在示波器上获得了奇怪的波形，但这可能是因为ADC引脚悬空，导致浮动测量干扰算法的占空比。同时调用定时器的初始化将中断PWM信号。有没有更好的方法在不使用全局变量的情况下运行代码时更改占空比，或者每次我想更新占空比时都不会初始化定时器。任何链接将不胜感激。

Answer 1

当您想要更改设置时，不要重新启动计时器，HAL有一个专门用于此目的的宏：

Button b

对于定时器1 - 通道1和定时器1 - 通道2，它应如下所示：

/**
  * @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__))

Answer 2

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

ARR寄存器是您在根据所需占空比计算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.*/ 
}

使用STM32 HAL定时器并调整PWM信号的占空比

2 个答案: