STM32H7的低功耗定时器LPTIM，时钟源采用外部脉冲或者其它低功耗时钟

eric2013

说明：

这里所谓的采用外部脉冲就是这里的说明：


官方例子LPTIM_PulseCounter

使用LPTIM的好处是系统处于睡眠，停机状态可以正常工作（除了待机模式）。

这个例子实现PD12做时钟源的脉冲输入，PD13做输出的。每采集100个输入，输出1次。

并且设了一个用户按键唤醒停机模式，唤醒后停止PWM输出。


测试代码：

此功能重点还是函数HAL_LPTIM_Init的参数配置学习。

1. /* Private typedef -----------------------------------------------------------*/
   
2. /* Private define ------------------------------------------------------------*/
   
3. /* Set the Maximum value of the counter (Auto-Reload) that defines the Period */
   
4. #define PeriodValue             (uint32_t) (100 -1)
   
5. 
   
6. /* Set the Compare value that defines the duty cycle */
   
7. #define PulseValue              (uint32_t) (50 -1)
   
8. 
   
9. /* Private macro -------------------------------------------------------------*/
   
10. /* Private variables ---------------------------------------------------------*/
    
11. /* LPTIM handle declaration */
    
12. LPTIM_HandleTypeDef             LptimHandle;
    
13. 
    
14. /* Clocks structure declaration */
    
15. RCC_PeriphCLKInitTypeDef        RCC_PeriphCLKInitStruct;
    
16. 
    
17. /* Private function prototypes -----------------------------------------------*/
    
18. static void SystemClock_Config(void);
    
19. static void Error_Handler(void);
    
20. static void CPU_CACHE_Enable(void);
    
21. /* Private functions ---------------------------------------------------------*/
    
22. 
    
23. /**
    
24.   * @brief  Main program
    
25.   * @param  None
    
26.   * @retval None
    
27.   */
    
28. int main(void)
    
29. {
    
30. /* This sample code shows how to use STM32H7xx LPTIM HAL API to generate a
    
31.     PWM at the lowest power consumption, using an external counter clock, in
    
32.     Low Power mode (STOP mode).*/
    
33. 
    
34.         /* Enable the CPU Cache */
    
35.   CPU_CACHE_Enable();
    
36.   
    
37.   /* STM32H7xx HAL library initialization:
    
38.        - Systick timer is configured by default as source of time base, but user
    
39.          can eventually implement his proper time base source (a general purpose
    
40.          timer for example or other time source), keeping in mind that Time base
    
41.          duration should be kept 1ms since PPP_TIMEOUT_VALUEs are defined and
    
42.          handled in milliseconds basis.
    
43.        - Set NVIC Group Priority to 4
    
44.        - Low Level Initialization
    
45.      */
    
46.   HAL_Init();
    
47. 
    
48.   /* Configure the system clock to 400 MHz */
    
49.   SystemClock_Config();
    
50. 
    
51.   /* Configure LED2 */
    
52.   BSP_LED_Init(LED2);
    
53.   
    
54.   /* User push-button (EXTI_Line15_10) will be used to wakeup the system from STOP mode */
    
55.   BSP_PB_Init(BUTTON_USER, BUTTON_MODE_EXTI);
    
56. 
    
57.   /* ### - 1 - Initialize LPTIM peripheral ################################## */
    
58.   /*
    
59.    *  Instance        = LPTIM1
    
60.    *  Clock Source    = Ultra Low Power source (external input 1)
    
61.    *  Clock prescaler = 1 (No division)
    
62.    *  Counter Trigger = Software trigger
    
63.    *  Output Polarity = High
    
64.    *  Update mode     = Immediate (Registers are immediately updated after any
    
65.    *                    write access)
    
66.    */
    
67. 
    
68.   LptimHandle.Instance = LPTIM1;
    
69.   
    
70.   LptimHandle.Init.Clock.Source    = LPTIM_CLOCKSOURCE_ULPTIM;
    
71.   LptimHandle.Init.Clock.Prescaler = LPTIM_PRESCALER_DIV1;
    
72.   LptimHandle.Init.CounterSource   = LPTIM_COUNTERSOURCE_EXTERNAL;
    
73.   LptimHandle.Init.Trigger.Source  = LPTIM_TRIGSOURCE_SOFTWARE;
    
74.   LptimHandle.Init.OutputPolarity  = LPTIM_OUTPUTPOLARITY_HIGH;
    
75.   LptimHandle.Init.UpdateMode      = LPTIM_UPDATE_IMMEDIATE;
    
76.   
    
77.   /* Initialize LPTIM peripheral according to the passed parameters */
    
78.   if (HAL_LPTIM_Init(&LptimHandle) != HAL_OK)
    
79.   {
    
80.     Error_Handler();
    
81.   }
    
82. 
    
83.   /* ### - 2 - Start generating the PWM signal ############################## */
    
84.   /*
    
85.    *  Period = 99
    
86.    *  Pulse  = 49
    
87.    *  According to this configuration, the duty cycle will be equal to 50% and
    
88.    *  the output frequency will be equal to the input frequency divided by 100
    
89.    *  since the LPTIM have to count 100 external clock edges each period.
    
90.    */
    
91.   if (HAL_LPTIM_PWM_Start(&LptimHandle, PeriodValue, PulseValue) != HAL_OK)
    
92.   {
    
93.     Error_Handler();
    
94.   }
    
95.   
    
96.   /* ### - 3 - Enter in Stop mode ########################################### */
    
97.   HAL_PWR_EnterSTOPMode(PWR_LOWPOWERREGULATOR_ON, PWR_STOPENTRY_WFI);
    
98. 
    
99.   /* ### - 4 - Stop counting when leaving Stop mode ########################## */
    
100.   if (HAL_LPTIM_PWM_Stop(&LptimHandle) != HAL_OK)
     
101.   {
     
102.     Error_Handler();
     
103.   }
     
104. 
     
105.   /* Infinite Loop */
     
106.   while (1)
     
107.   {        
     
108.   }
     
109. }

复制代码

eric2013

测试这个超时功能，软件触发或者外部触发都没有问题。