LPTIM2 Pulse Counter

[mccabehm]

On NUCLEO-H563ZI board I put 3KHz square wave on LPTIM2_ETR (PC4). I want LPTIM2 to continuously count. However the count never increases. LPTIM2 setup...

And

Clock looks like

MX_LPTIM2_Init() looks like

static void MX_LPTIM2_Init(void)
{
  /* USER CODE BEGIN LPTIM2_Init 0 */
  /* USER CODE END LPTIM2_Init 0 */
  /* USER CODE BEGIN LPTIM2_Init 1 */
  /* USER CODE END LPTIM2_Init 1 */
  hlptim2.Instance = LPTIM2;
  hlptim2.Init.Clock.Source = LPTIM_CLOCKSOURCE_ULPTIM;
  hlptim2.Init.Clock.Prescaler = LPTIM_PRESCALER_DIV1;
  hlptim2.Init.UltraLowPowerClock.Polarity = LPTIM_CLOCKPOLARITY_RISING;
  hlptim2.Init.UltraLowPowerClock.SampleTime = LPTIM_CLOCKSAMPLETIME_DIRECTTRANSITION;
  hlptim2.Init.Trigger.Source = LPTIM_TRIGSOURCE_SOFTWARE;
  hlptim2.Init.Period = 65535;
  hlptim2.Init.UpdateMode = LPTIM_UPDATE_IMMEDIATE;
  hlptim2.Init.CounterSource = LPTIM_COUNTERSOURCE_EXTERNAL;
  hlptim2.Init.Input1Source = LPTIM_INPUT1SOURCE_GPIO;
  hlptim2.Init.Input2Source = LPTIM_INPUT2SOURCE_GPIO;
  hlptim2.Init.RepetitionCounter = 0;
  if (HAL_LPTIM_Init(&hlptim2) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN LPTIM2_Init 2 */
  /* USER CODE END LPTIM2_Init 2 */
}

Startup looks like

...  
MX_LPTIM2_Init();
/* USER CODE BEGIN 2 */
...
HAL_LPTIM_Counter_Start(&hlptim2);
...

 Following HAL_LPTIM_Counter_Start() CR = 0x5 and and CFGR = 0x800001. But CNT is zero. Same result if I use alternate ETR PE0.

What is missing?

[Sarra.S]

Hello @mccabehm, 

The input source is set to LPTIM_INPUT1SOURCE_GPIO, which means that the LPTIM2 is expecting the input signal to come from a GPIO pin, however, your input signal is coming from an external trigger pin (PE0 or PC4).

Try changing the input source to LPTIM_INPUT1SOURCE_EXTERNAL

Hope that helps!

[mccabehm]

No, not a solution yet! Any way undo the accept?

The initialization already sets clock source to LPTIM_COUNTERSOURCE_EXTERNAL. Not clear to me why I need input sources at all. At one time LPTIM1, LPTIM2, and LPTIM6 worked fine. Then something unknown changed and none of the LPTIMs count.

[waclawek.jan]

Read out and check/post content of LPTIM and relevant GPIO registers.

JW

[mccabehm · Accepted solution]

Sarra,

Thank you! Using LPTIM_INPUT1SOURCE_GPIO works. LPTIM2 configured with STM32CubeIDE as follows...