STM32F303ZE：PWM只有一半的频率

Question

我目前正在为一个项目从事 STM32 编程。对于这个项目，我需要产生一个 20kHz (=f_pwm) 中心对齐的 PWM。使用 CubeMX，我通过使用 PLLCLK*2 将 TIM1 clk 设置为 144 MHz (=f_tim)。然后我将 ARR 寄存器设置为 period=f_tim/(2*f_pwm)。 *2 来自中心对齐模式，因为它向上和向下计数。使用这些参数对 STM32 进行编程后，我只能得到 10 kHz（在示波器上测量）。我的计算和时钟设置似乎是正确的（也通过生成的代码和写入的寄存器进行了检查），所以我现在没有想法了。有没有人已经遇到过这样的问题或知道原因可能是什么？抓到我的CubeMX时钟配置和相应的代码部分。

感谢大家的关注！

CubeMX clock config

系统时钟配置：

    void SystemClock_Config(void)
{

  RCC_OscInitTypeDef RCC_OscInitStruct;
  RCC_ClkInitTypeDef RCC_ClkInitStruct;
  RCC_PeriphCLKInitTypeDef PeriphClkInit;

    /**Initializes the CPU, AHB and APB busses clocks 
    */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = 16;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
  RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
  RCC_OscInitStruct.PLL.PREDIV = RCC_PREDIV_DIV1;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    _Error_Handler(__FILE__, __LINE__);
  }

    /**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(__FILE__, __LINE__);
  }

  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USART3|RCC_PERIPHCLK_TIM1
                              |RCC_PERIPHCLK_ADC12|RCC_PERIPHCLK_ADC34
                              |RCC_PERIPHCLK_TIM20;
  PeriphClkInit.Usart3ClockSelection = RCC_USART3CLKSOURCE_PCLK1;
  PeriphClkInit.Adc12ClockSelection = RCC_ADC12PLLCLK_DIV64;
  PeriphClkInit.Adc34ClockSelection = RCC_ADC34PLLCLK_DIV64;
  PeriphClkInit.Tim1ClockSelection = RCC_TIM1CLK_PLLCLK;
  PeriphClkInit.Tim20ClockSelection = RCC_TIM20CLK_PLLCLK;
  if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
  {
    _Error_Handler(__FILE__, __LINE__);
  }

    /**Configure the Systick interrupt time 
    */
  HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);

    /**Configure the Systick 
    */
  HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);

  /* SysTick_IRQn interrupt configuration */
  HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);
}

TIM1 初始化：

void MX_TIM1_Init(void)
{
  TIM_ClockConfigTypeDef sClockSourceConfig;
  TIM_MasterConfigTypeDef sMasterConfig;
  TIM_OC_InitTypeDef sConfigOC;
  TIM_BreakDeadTimeConfigTypeDef sBreakDeadTimeConfig;

  htim1.Instance = TIM1;
  htim1.Init.Prescaler = 1;
  htim1.Init.CounterMode = TIM_COUNTERMODE_CENTERALIGNED3;
  htim1.Init.Period = 3600;
  htim1.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  htim1.Init.RepetitionCounter = 0;
  htim1.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
  if (HAL_TIM_Base_Init(&htim1) != HAL_OK)
  {
    _Error_Handler(__FILE__, __LINE__);
  }

  sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
  if (HAL_TIM_ConfigClockSource(&htim1, &sClockSourceConfig) != HAL_OK)
  {
    _Error_Handler(__FILE__, __LINE__);
  }

  if (HAL_TIM_PWM_Init(&htim1) != HAL_OK)
  {
    _Error_Handler(__FILE__, __LINE__);
  }

  sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
  sMasterConfig.MasterOutputTrigger2 = TIM_TRGO2_RESET;
  sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
  if (HAL_TIMEx_MasterConfigSynchronization(&htim1, &sMasterConfig) != HAL_OK)
  {
    _Error_Handler(__FILE__, __LINE__);
  }

  sConfigOC.OCMode = TIM_OCMODE_PWM1;
  sConfigOC.Pulse = 0;
  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_3) != HAL_OK)
  {
    _Error_Handler(__FILE__, __LINE__);
  }

  sBreakDeadTimeConfig.OffStateRunMode = TIM_OSSR_DISABLE;
  sBreakDeadTimeConfig.OffStateIDLEMode = TIM_OSSI_DISABLE;
  sBreakDeadTimeConfig.LockLevel = TIM_LOCKLEVEL_OFF;
  sBreakDeadTimeConfig.DeadTime = 0;
  sBreakDeadTimeConfig.BreakState = TIM_BREAK_DISABLE;
  sBreakDeadTimeConfig.BreakPolarity = TIM_BREAKPOLARITY_HIGH;
  sBreakDeadTimeConfig.BreakFilter = 0;
  sBreakDeadTimeConfig.Break2State = TIM_BREAK2_DISABLE;
  sBreakDeadTimeConfig.Break2Polarity = TIM_BREAK2POLARITY_HIGH;
  sBreakDeadTimeConfig.Break2Filter = 0;
  sBreakDeadTimeConfig.AutomaticOutput = TIM_AUTOMATICOUTPUT_DISABLE;
  if (HAL_TIMEx_ConfigBreakDeadTime(&htim1, &sBreakDeadTimeConfig) != HAL_OK)
  {
    _Error_Handler(__FILE__, __LINE__);
  }

  HAL_TIM_MspPostInit(&htim1);

}

设置CCR并启动PWM：

//Sets TIM_CCR (Compares to counter value), From _hal_tim_ex.h:921
  __HAL_TIM_SET_COMPARE(&htim1,TIM_CHANNEL_3,1800);
  //Start PWM
  HAL_TIM_PWM_Start_IT(&htim1,TIM_CHANNEL_3);

Answer 1

自己解决了：我把Prescaler（Register TIMx_PSC）设置为1（按理说，f_tim/1 = f_tim，对吧？）。将其设置为 0 后，我得到了所需的 f_pwm。然后我深入研究了我的 STM 数据 sheet，发现 f_tim 的计算方式如下：f_tim = f_clk / (PSC+1)。因此：Prescale 设置为 0 给出 prescale 1，设置为 1 给出 2 等

STM32F303ZE：PWM只有一半的频率

STM32F303ZE: PWM has only half the frequency

frequency

clock

stm32

pwm