For the Nucleo-575ZI-Q, while in stop mode 2, I have the capture module enabled, I set CH1 IO Usage as input.
A square wave generator connected to PC1->LPTIM_CH1.
While the Micro is in stop mode 2 an indeterminate number of pulses trigger successive captures.
If the pulses on PC1 were odd CCR1 has the correct data.
If the pulses on PC1 were even CCR1 value doesn't updated at all.
Please note that all pulses arrive while STM32U575 is on stop mode.
I made a very short project isolating the problem, the RTC is used to exit stop mode 2 every second, when waking up only CRR1 is read and returns to stop mode 2.
void FM_MAIN_Main()
{
uint16_t capture = 0;
HAL_LPTIM_IC_Start(&hlptim1, LPTIM_CHANNEL_1);
__HAL_RCC_LPTIM1_CLKAM_ENABLE();
for (;;)
{
HAL_GPIO_WritePin(LED_GPIO_Port, LED_Pin, GPIO_PIN_SET);
capture = LPTIM1->CCR1;
FM_DEBUG_UartUint16(capture);
HAL_GPIO_WritePin(LED_GPIO_Port, LED_Pin, GPIO_PIN_RESET);
HAL_SuspendTick();
HAL_PWREx_EnterSTOP2Mode(PWR_STOPENTRY_WFI);
HAL_ResumeTick();
}
}
/**
* @brief LPTIM1 Initialization Function
* None
* @retval None
*/
static void MX_LPTIM1_Init(void)
{
/* USER CODE BEGIN LPTIM1_Init 0 */
/* USER CODE END LPTIM1_Init 0 */
LPTIM_IC_ConfigTypeDef sConfig = {0};
/* USER CODE BEGIN LPTIM1_Init 1 */
/* USER CODE END LPTIM1_Init 1 */
hlptim1.Instance = LPTIM1;
hlptim1.Init.Clock.Source = LPTIM_CLOCKSOURCE_APBCLOCK_LPOSC;
hlptim1.Init.Clock.Prescaler = LPTIM_PRESCALER_DIV1;
hlptim1.Init.Trigger.Source = LPTIM_TRIGSOURCE_SOFTWARE;
hlptim1.Init.Period = 65535;
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;
if (HAL_LPTIM_Init(&hlptim1) != HAL_OK)
{
Error_Handler();
}
sConfig.ICInputSource = LPTIM_IC1SOURCE_GPIO;
sConfig.ICPrescaler = LPTIM_ICPSC_DIV1;
sConfig.ICPolarity = LPTIM_ICPOLARITY_RISING;
sConfig.ICFilter = LPTIM_ICFLT_CLOCK_DIV1;
if (HAL_LPTIM_IC_ConfigChannel(&hlptim1, &sConfig, LPTIM_CHANNEL_1) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN LPTIM1_Init 2 */
/* USER CODE END LPTIM1_Init 2 */
}
/**
* @brief RTC Initialization Function
* None
* @retval None
*/
static void MX_RTC_Init(void)
{
/* USER CODE BEGIN RTC_Init 0 */
/* USER CODE END RTC_Init 0 */
RTC_PrivilegeStateTypeDef privilegeState = {0};
/* USER CODE BEGIN RTC_Init 1 */
/* USER CODE END RTC_Init 1 */
/** Initialize RTC Only
*/
hrtc.Instance = RTC;
hrtc.Init.HourFormat = RTC_HOURFORMAT_24;
hrtc.Init.AsynchPrediv = 127;
hrtc.Init.SynchPrediv = 255;
hrtc.Init.OutPut = RTC_OUTPUT_DISABLE;
hrtc.Init.OutPutRemap = RTC_OUTPUT_REMAP_NONE;
hrtc.Init.OutPutPolarity = RTC_OUTPUT_POLARITY_HIGH;
hrtc.Init.OutPutType = RTC_OUTPUT_TYPE_OPENDRAIN;
hrtc.Init.OutPutPullUp = RTC_OUTPUT_PULLUP_NONE;
hrtc.Init.BinMode = RTC_BINARY_NONE;
if (HAL_RTC_Init(&hrtc) != HAL_OK)
{
Error_Handler();
}
privilegeState.rtcPrivilegeFull = RTC_PRIVILEGE_FULL_NO;
privilegeState.backupRegisterPrivZone = RTC_PRIVILEGE_BKUP_ZONE_NONE;
privilegeState.backupRegisterStartZone2 = RTC_BKP_DR0;
privilegeState.backupRegisterStartZone3 = RTC_BKP_DR0;
if (HAL_RTCEx_PrivilegeModeSet(&hrtc, &privilegeState) != HAL_OK)
{
Error_Handler();
}
/** Enable the WakeUp
*/
if (HAL_RTCEx_SetWakeUpTimer_IT(&hrtc, 0, RTC_WAKEUPCLOCK_CK_SPRE_16BITS, 0) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN RTC_Init 2 */
/* USER CODE END RTC_Init 2 */
}
