Needed LPTIMER valid reinitialize sequence

[npatil15]

Hello,

I have problem statement, in which I have to re-Initialize lptimer for different timer value, as per current scenario, I have

Clock: 32Khz (LSI)

Divisor = 128

Period: Any time as per dynamic input.

So I want information about how I can safely reset the lptimer and then again re-init for different timer. Here is the reference lptimer code. where

/* uint32_t effectiveFreq = 32000/ 128; // 250 Hz
 uint32_t tickTimeInMS = 1000 / effectiveFreq; // 4 ms*/
#define TICK_TIME_IN_MS 4
void ReInit_LPTIM1(uint32_t timerInMS)
{
  /*lptimer reset block start*/
    HAL_LPTIM_IC_Stop_IT(&hlptim1, LPTIM_CHANNEL_1);

    __HAL_LPTIM_DISABLE(&hlptim1);

    if (HAL_LPTIM_DeInit(&hlptim1) != HAL_OK)
    {
      Error_Handler();
    }

    __HAL_RCC_LPTIM1_FORCE_RESET();
    __HAL_RCC_LPTIM1_RELEASE_RESET();
  /*lptimer reset block end*/
  LPTIM_OC_ConfigTypeDef sConfig1 = {0};

  hlptim1.Instance = LPTIM1;
  hlptim1.Init.Clock.Source = LPTIM_CLOCKSOURCE_APBCLOCK_LPOSC;
  hlptim1.Init.Clock.Prescaler = LPTIM_PRESCALER_DIV128;
  hlptim1.Init.Trigger.Source = LPTIM_TRIGSOURCE_SOFTWARE;
  hlptim1.Init.UpdateMode = LPTIM_UPDATE_IMMEDIATE;
  hlptim1.Init.CounterSource = LPTIM_COUNTERSOURCE_INTERNAL;
  hlptim1.Init.Input1Source = LPTIM_INPUT1SOURCE_GPIO;
  hlptim1.Init.Input2Source = LPTIM_INPUT2SOURCE_GPIO;
  hlptim1.Init.RepetitionCounter = 0;

  hlptim1.Init.Period = timerInMS/TICK_TIME_IN_MS - 1 ;

  if (HAL_LPTIM_Init(&hlptim1) != HAL_OK)
  {
    Error_Handler();
  }
  sConfig1.Pulse = hlptim1.Init.Period;
  sConfig1.OCPolarity = LPTIM_OCPOLARITY_HIGH;
  if (HAL_LPTIM_OC_ConfigChannel(&hlptim1, &sConfig1, LPTIM_CHANNEL_1) != HAL_OK)
  {
    Error_Handler();
  }

  __HAL_LPTIM_ENABLE_IT(&hlptim1, LPTIM_IT_CC1);
  HAL_LPTIM_IC_Start_IT(&hlptim1, LPTIM_CHANNEL_1);
}

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Here, adding reset block is not working correctly, and if we remove this reset block then it works fine. But I want it should be clear/reset before re-initialize for safe working for longer run.

Thanks

Nitin 

[ahsrabrifat · Accepted solution]

Here’s a modified ReInit_LPTIM1() approach that should work more reliably and be safe for long-term use without hard-resetting the peripheral at the RCC level:

void ReInit_LPTIM1(uint32_t timerInMS)
{
    // Step 1: Disable LPTIM and stop channel
    __HAL_LPTIM_DISABLE(&hlptim1);
    HAL_LPTIM_IC_Stop_IT(&hlptim1, LPTIM_CHANNEL_1);
    
    // Step 2: Disable interrupt
    __HAL_LPTIM_DISABLE_IT(&hlptim1, LPTIM_IT_CC1);
    
    // Step 3: DeInit peripheral
    if (HAL_LPTIM_DeInit(&hlptim1) != HAL_OK)
    {
        Error_Handler();
    }

    // Step 4: Reconfigure peripheral without RCC force-reset
    LPTIM_OC_ConfigTypeDef sConfig1 = {0};

    hlptim1.Instance = LPTIM1;
    hlptim1.Init.Clock.Source = LPTIM_CLOCKSOURCE_APBCLOCK_LPOSC;
    hlptim1.Init.Clock.Prescaler = LPTIM_PRESCALER_DIV128;
    hlptim1.Init.Trigger.Source = LPTIM_TRIGSOURCE_SOFTWARE;
    hlptim1.Init.UpdateMode = LPTIM_UPDATE_IMMEDIATE;
    hlptim1.Init.CounterSource = LPTIM_COUNTERSOURCE_INTERNAL;
    hlptim1.Init.Input1Source = LPTIM_INPUT1SOURCE_GPIO;
    hlptim1.Init.Input2Source = LPTIM_INPUT2SOURCE_GPIO;
    hlptim1.Init.RepetitionCounter = 0;

    // Step 5: Calculate and set new period
    hlptim1.Init.Period = timerInMS / TICK_TIME_IN_MS - 1;

    if (HAL_LPTIM_Init(&hlptim1) != HAL_OK)
    {
        Error_Handler();
    }

    sConfig1.Pulse = hlptim1.Init.Period;
    sConfig1.OCPolarity = LPTIM_OCPOLARITY_HIGH;

    if (HAL_LPTIM_OC_ConfigChannel(&hlptim1, &sConfig1, LPTIM_CHANNEL_1) != HAL_OK)
    {
        Error_Handler();
    }

    // Step 6: Re-enable interrupt and start again
    __HAL_LPTIM_ENABLE_IT(&hlptim1, LPTIM_IT_CC1);
    HAL_LPTIM_IC_Start_IT(&hlptim1, LPTIM_CHANNEL_1);
}

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