Cannot get PWM to output on STM32L496AG Discovery Board

TomC · ‎2022-02-08

When I view the CNT register of the TIM8 structure during debug it does count up to 1000 before resetting. I am using PI6 of the discovery board (Discovery Board Manual). The pin does not output a pulse however I confirmed that the circuit works electrically just by using the pin as a GPIO to control an LED.

Please see clock, Timer 8 config as well as Timer 8 start.

/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
 
  /** Configure the main internal regulator output voltage
  */
  if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1) != HAL_OK)
  {
    Error_Handler();
  }
  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_MSI;
  RCC_OscInitStruct.MSIState = RCC_MSI_ON;
  RCC_OscInitStruct.MSICalibrationValue = 0;
  RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_6;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  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_MSI;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
 
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
  {
    Error_Handler();
  }
}

/**
  * @brief TIM8 Initialization Function
  * @param None
  * @retval None
  */
static void MX_TIM8_Init(void)
{
 
  /* USER CODE BEGIN TIM8_Init 0 */
 
  /* USER CODE END TIM8_Init 0 */
 
  TIM_ClockConfigTypeDef sClockSourceConfig = {0};
  TIM_MasterConfigTypeDef sMasterConfig = {0};
  TIM_OC_InitTypeDef sConfigOC = {0};
  TIM_BreakDeadTimeConfigTypeDef sBreakDeadTimeConfig = {0};
 
  /* USER CODE BEGIN TIM8_Init 1 */
 
  /* USER CODE END TIM8_Init 1 */
  htim8.Instance = TIM8;
  htim8.Init.Prescaler = 4000-1;
  htim8.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim8.Init.Period = 1000-1;
  htim8.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
  htim8.Init.RepetitionCounter = 0;
  htim8.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
  if (HAL_TIM_Base_Init(&htim8) != HAL_OK)
  {
    Error_Handler();
  }
  sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
  if (HAL_TIM_ConfigClockSource(&htim8, &sClockSourceConfig) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_TIM_PWM_Init(&htim8) != HAL_OK)
  {
    Error_Handler();
  }
  sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
  sMasterConfig.MasterOutputTrigger2 = TIM_TRGO2_RESET;
  sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
  if (HAL_TIMEx_MasterConfigSynchronization(&htim8, &sMasterConfig) != HAL_OK)
  {
    Error_Handler();
  }
  sConfigOC.OCMode = TIM_OCMODE_PWM1;
  sConfigOC.Pulse = 500;
  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(&htim8, &sConfigOC, TIM_CHANNEL_2) != HAL_OK)
  {
    Error_Handler();
  }
  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(&htim8, &sBreakDeadTimeConfig) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN TIM8_Init 2 */
 
  /* USER CODE END TIM8_Init 2 */
  HAL_TIM_MspPostInit(&htim8);
 
}

/**
  * @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_TIM8_Init();
  MX_TIM4_Init();
  /* USER CODE BEGIN 2 */
  HAL_TIM_PWM_Start(&htim8, HAL_TIM_ACTIVE_CHANNEL_2);
  HAL_TIM_PWM_Start(&htim4, HAL_TIM_ACTIVE_CHANNEL_4);
  /* USER CODE END 2 */
 
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */
 
    /* USER CODE BEGIN 3 */
	  __NOP();
//	  __HAL_TIM_SET_COMPARE(&htim8, TIM_CHANNEL_2, 500);
  }
  /* USER CODE END 3 */
}

Muhammed Güler · ‎2022-02-08

You used HAL_TIM_ACTIVE_CHANNEL_X instead of TIM_CHANNEL_X

as you can see they have completely different values

#define TIM_CHANNEL_1 0x00000000U /*!< Capture/compare channel 1 identifier */

#define TIM_CHANNEL_2 0x00000004U /*!< Capture/compare channel 2 identifier */

#define TIM_CHANNEL_3 0x00000008U /*!< Capture/compare channel 3 identifier */

#define TIM_CHANNEL_4 0x0000000CU /*!< Capture/compare channel 4 identifier */

#define TIM_CHANNEL_ALL 0x0000003CU /*!< Global Capture/compare channel identifier */

HAL_TIM_ACTIVE_CHANNEL_1 = 0x01U, /*!< The active channel is 1 */

HAL_TIM_ACTIVE_CHANNEL_2 = 0x02U, /*!< The active channel is 2 */

HAL_TIM_ACTIVE_CHANNEL_3 = 0x04U, /*!< The active channel is 3 */

HAL_TIM_ACTIVE_CHANNEL_4 = 0x08U, /*!< The active channel is 4 */

HAL_TIM_ACTIVE_CHANNEL_CLEARED = 0x00U /*!< All active channels cleared */

View solution in original post

Tesla DeLorean · ‎2022-02-08

Check pin AF mux setting vs data sheet.

Check MOE bit Master Output Enable for TIM1 TIM1 Advanced Timers

Tips, Buy me a coffee, or three.. PayPal Venmo
Up vote any posts that you find helpful, it shows what's working..

waclawek.jan · ‎2022-02-08

TIM8 needs to have TIM8_BDTR.MOE set to enable outputs.

I don't know what's Cube/HAL incantation for this, but you should be able to find it easily in Cube sources.

JW

Muhammed Güler · ‎2022-02-08