STM32U5的LPTIM3在STOP2模式下无法唤醒问题解析

static void MX_LPTIM3_Init(void)

{

 /* USER CODE BEGIN LPTIM3_Init 0 */

 /* USER CODE END LPTIM3_Init 0 */

 /* USER CODE BEGIN LPTIM3_Init 1 */

 /* USER CODE END LPTIM3_Init 1 */

 hlptim3.Instance = LPTIM3;

 hlptim3.Init.Clock.Source = LPTIM_CLOCKSOURCE_APBCLOCK_LPOSC;

 hlptim3.Init.Clock.Prescaler = LPTIM_PRESCALER_DIV1;

 hlptim3.Init.Trigger.Source = LPTIM_TRIGSOURCE_SOFTWARE;

 hlptim3.Init.Period = 99;

 hlptim3.Init.UpdateMode = LPTIM_UPDATE_IMMEDIATE;

 hlptim3.Init.CounterSource = LPTIM_COUNTERSOURCE_INTERNAL;

 hlptim3.Init.Input1Source = LPTIM_INPUT1SOURCE_GPIO;

 hlptim3.Init.Input2Source = LPTIM_INPUT2SOURCE_GPIO;

 hlptim3.Init.RepetitionCounter = 0;

 if (HAL_LPTIM_Init(&hlptim3) != HAL_OK)

 {

 Error_Handler();

 }

 /* USER CODE BEGIN LPTIM3_Init 2 */

 /* USER CODE END LPTIM3_Init 2 */

}

启动 LPTIM3 :



if (HAL_LPTIM_TimeOut_Start_IT(&hlptim3, TIMEOUT) != HAL_OK)

 {

 Error_Handler();

 }

在主循环中重复进入 STOP2 模式，由 LPTIM3 周期唤醒，这里需要注意一点的是在进入之前需 要先把滴答定时器关掉，否则有可能无法进入 STOP2 模式。

/* Suspend Tick */

HAL_SuspendTick();



/* Enter in Stop mode */

HAL_PWREx_EnterSTOP2Mode(PWR_STOPENTRY_WFI);

3.1.2. 配置电源模式输出引脚 



为了方便低功耗调试，STM32U5 提供了电源模式输出 pin 脚用于指示 MCU 所处的低功耗模式，具体引脚分别是 PA5/PA6/PA7。

 /*Configure GPIO pin : PA5 */

 GPIO_InitStruct.Pin = GPIO_PIN_5;

 GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;

 GPIO_InitStruct.Pull = GPIO_NOPULL;

 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;

 GPIO_InitStruct.Alternate = GPIO_AF0_CSLEEP;

 HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);



 /*Configure GPIO pin : PA6 */

 GPIO_InitStruct.Pin = GPIO_PIN_6;

 GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;

 GPIO_InitStruct.Pull = GPIO_NOPULL;

 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;

 GPIO_InitStruct.Alternate = GPIO_AF0_CSTOP;

 HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);



 /*Configure GPIO pin : PA7 */

 GPIO_InitStruct.Pin = GPIO_PIN_7;

 GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;

 GPIO_InitStruct.Pull = GPIO_NOPULL;

 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;

 GPIO_InitStruct.Alternate = GPIO_AF0_SRDSTOP;

 HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);