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STM32 Timer - I can only get OCx to pulse one time. How do I trigger another pulse?

Louis1
Associate II

STM32WB55xx

I am using TIM1 CH1N and CH2N to create a pulse on each pin that lasts 1000 counts.

The MX_TIM1_Init() is shown below. After this is set up (along with the clock configuration), I run HAL_TIMEx_OCN_Start_IT() on each channel and I see that each pin pulses for 1000 counts. However, if I wanted to pulse the pins again, I try running HAL_TIMEx_OCN_Start_IT() again but I'm not seeing the pulse anymore.

I've also tried calling HAL_TIMEx_OCN_Stop_IT() before calling Start() again but nothing happens. I know the counter is running and every time that CNT == ARR, I get a compare interrupt. The problem is that the output pin is already high when the interrupt is called (Active on matched doesn't end up doing anything).

I would like to be able to set the output pin to its idle state and reset the counter so that I can control exactly when I trigger the pulse.

static void MX_TIM1_Init(void)
{
 
  /* USER CODE BEGIN TIM1_Init 0 */
 
  /* USER CODE END TIM1_Init 0 */
 
  TIM_ClockConfigTypeDef sClockSourceConfig = {0};
  TIM_MasterConfigTypeDef sMasterConfig = {0};
  TIM_OC_InitTypeDef sConfigOC = {0};
  TIM_IC_InitTypeDef sConfigIC = {0};
  TIM_BreakDeadTimeConfigTypeDef sBreakDeadTimeConfig = {0};
 
  /* USER CODE BEGIN TIM1_Init 1 */
 
  /* USER CODE END TIM1_Init 1 */
  htim1.Instance = TIM1;
  htim1.Init.Prescaler = 63;
  htim1.Init.CounterMode = TIM_COUNTERMODE_UP;
  htim1.Init.Period = 10000;
  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();
  }
  sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
  if (HAL_TIM_ConfigClockSource(&htim1, &sClockSourceConfig) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_TIM_OC_Init(&htim1) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_TIM_IC_Init(&htim1) != HAL_OK)
  {
    Error_Handler();
  }
  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();
  }
  sConfigOC.OCMode = TIM_OCMODE_ACTIVE;
  sConfigOC.Pulse = 1000;
  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_OC_ConfigChannel(&htim1, &sConfigOC, TIM_CHANNEL_1) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_TIM_OC_ConfigChannel(&htim1, &sConfigOC, TIM_CHANNEL_2) != HAL_OK)
  {
    Error_Handler();
  }
  sConfigIC.ICPolarity = TIM_INPUTCHANNELPOLARITY_RISING;
  sConfigIC.ICSelection = TIM_ICSELECTION_DIRECTTI;
  sConfigIC.ICPrescaler = TIM_ICPSC_DIV1;
  sConfigIC.ICFilter = 0;
  if (HAL_TIM_IC_ConfigChannel(&htim1, &sConfigIC, TIM_CHANNEL_3) != 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.BreakAFMode = TIM_BREAK_AFMODE_INPUT;
  sBreakDeadTimeConfig.Break2State = TIM_BREAK2_DISABLE;
  sBreakDeadTimeConfig.Break2Polarity = TIM_BREAK2POLARITY_HIGH;
  sBreakDeadTimeConfig.Break2Filter = 0;
  sBreakDeadTimeConfig.Break2AFMode = TIM_BREAK_AFMODE_INPUT;
  sBreakDeadTimeConfig.AutomaticOutput = TIM_AUTOMATICOUTPUT_DISABLE;
  if (HAL_TIMEx_ConfigBreakDeadTime(&htim1, &sBreakDeadTimeConfig) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN TIM1_Init 2 */
 
  /* USER CODE END TIM1_Init 2 */
  HAL_TIM_MspPostInit(&htim1);
 
}

4 REPLIES 4

I don't get it - why, instead of wildly clicking in CubeMX and staring at undocumented gibberish, you don't read the RM and write a normal program?

It does exactly what you told it to do:

#defineTIM_OCMODE_ACTIVE TIM_CCMR1_OC1M_0 /*!< Set channel to active level on match */

i.e. it sets output, and then sets it again and again, regardless of it being already set.

What you are looking for is probably

#defineTIM_OCMODE_PWM1 (TIM_CCMR1_OC1M_2 | TIM_CCMR1_OC1M_1) /*!< PWM mode 1 */

JW

Louis1
Associate II

This is the first time I've ever used STM products so I'm very lost.

So by using the PWM mode, is there a way to only pulse it once? I need a way to trigger a single pulse but to trigger it multiple times whenever I would like.

This is the first time I've ever used STM products so I'm very lost.

So by using the PWM mode, is there a way to only pulse it once? I need a way to trigger a single pulse but to trigger it multiple times whenever I would like.

> This is the first time I've ever used STM products so I'm very lost.

That's OK. By the time you've used STM32 for the thousandth time, you'll be less lost. But how less, depends on how will you approach those remaining 998 cases. Clicking will hardly do.

> So by using the PWM mode, is there a way to only pulse it once?

Use, for example, the aptly named One-Pulse Mode, by setting TIMx_CR1.OPM. I don't know what's the Cube/HAL incantation for that.

JW