STM32L010C6Tx Sleep Mode

ZKURT.1 · ‎2022-02-02

Hi. I am using STM32L010C6Tx. I want my microprocessor to sleep for 10 seconds after processing. I want to use Sleep Mode. I don't have any interrupt pins. I want it to wake up after 10 seconds. How can I do?

Jaroslav BECKA · ‎2022-02-04

Hi,

find attached my code for STM32L010x.

It utilizes an RTC wake-up timer to wake-up the CPU from the SLEEP mode every 10 sec.

RTC is clocked by the LSE (accurate external low-speed oscillator).

I set asynchronous RTC divider to 127 and synchronous RTC divider to 255 to get 1 Hz (take a look into the reference manual RM0451, this clock on the output of the synchronous prescaler is marked as ck_spre)

The ck_spre clock is then used to feed the RTC wake-up timer (so 1 clock cycle takes 1 second).

The RTC wake-up timer is set to 0x0009 to fire an interrupt every 10 seconds.

You may want to change the RTC clock source from LSE to LSI, if there is no 32.768k quartz for LSE available on your board.

The wake-up period would then be far less accurate.

Before entering the SLEEP mode you need to disable the SysTick timer, otherwise its interrupt would wake-up the CPU within 1 ms (the SysTick is typically set to raise an interrupt every 1 ms).

HAL code generated by STM32CubeMX configures the SysTick at the beginning of the main function.

To disable the SysTick you can call:

HAL_SuspendTick();

After wake-up I toggle with PA5 before entering the SLEEP again to verify the proper wake-up period with my Saleae digital analyzer (see the picture below).

This part can be easily removed by removing the associated GPIO code.

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2022 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
 
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
 
/* USER CODE END Includes */
 
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
 
/* USER CODE END PTD */
 
/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
/* USER CODE END PD */
 
/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
 
/* USER CODE END PM */
 
/* Private variables ---------------------------------------------------------*/
RTC_HandleTypeDef hrtc;
 
/* USER CODE BEGIN PV */
 
/* USER CODE END PV */
 
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_RTC_Init(void);
/* USER CODE BEGIN PFP */
 
/* USER CODE END PFP */
 
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
 
/* USER CODE END 0 */
 
/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{
  /* USER CODE BEGIN 1 */
 
  /* USER CODE END 1 */
 
  /* MCU Configuration--------------------------------------------------------*/
 
  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();
 
  /* USER CODE BEGIN Init */
 
  /* USER CODE END Init */
 
  /* Configure the system clock */
  SystemClock_Config();
 
  /* USER CODE BEGIN SysInit */
 
  /* USER CODE END SysInit */
 
  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_RTC_Init();
  /* USER CODE BEGIN 2 */
  HAL_RTCEx_DeactivateWakeUpTimer(&hrtc);
  __HAL_RTC_WAKEUPTIMER_CLEAR_FLAG(&hrtc, RTC_FLAG_WUTF);
  __HAL_RTC_WAKEUPTIMER_EXTI_CLEAR_FLAG();
  HAL_RTCEx_SetWakeUpTimer_IT(&hrtc, 0x0009, RTC_WAKEUPCLOCK_CK_SPRE_16BITS); //ck_spre ~1 Hz (40 kHz div127 div 315) used as clock for the RTC wake-up timer
  /* USER CODE END 2 */
 
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */
 
    /* USER CODE BEGIN 3 */
	  HAL_SuspendTick(); // Disable SysTick, otherwise it would wake-up the CPU within 1 ms
	  HAL_PWR_EnterSLEEPMode(PWR_MAINREGULATOR_ON, PWR_SLEEPENTRY_WFI);
	  HAL_ResumeTick(); // Enable SysTick after wake-up
	  HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_5); // Toggle with a pin to check the wake-up period
  }
  /* USER CODE END 3 */
}
 
/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
  RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
 
  /** Configure the main internal regulator output voltage
  */
  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
  /** Configure LSE Drive Capability
  */
  HAL_PWR_EnableBkUpAccess();
  __HAL_RCC_LSEDRIVE_CONFIG(RCC_LSEDRIVE_LOW);
  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI|RCC_OSCILLATORTYPE_LSE;
  RCC_OscInitStruct.LSEState = RCC_LSE_ON;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
 
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
  {
    Error_Handler();
  }
  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_RTC;
  PeriphClkInit.RTCClockSelection = RCC_RTCCLKSOURCE_LSE;
  if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
  {
    Error_Handler();
  }
}
 
/**
  * @brief RTC Initialization Function
  * @param None
  * @retval None
  */
static void MX_RTC_Init(void)
{
 
  /* USER CODE BEGIN RTC_Init 0 */
 
  /* USER CODE END RTC_Init 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;
  if (HAL_RTC_Init(&hrtc) != HAL_OK)
  {
    Error_Handler();
  }
 
  /* USER CODE BEGIN RTC_Init 2 */
 
  /* USER CODE END RTC_Init 2 */
 
}
 
/**
  * @brief GPIO Initialization Function
  * @param None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};
 
  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOC_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();
 
  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_5, GPIO_PIN_RESET);
 
  /*Configure GPIO pin : PA5 */
  GPIO_InitStruct.Pin = GPIO_PIN_5;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
 
}
 
/* USER CODE BEGIN 4 */
void HAL_RTCEx_WakeUpTimerEventCallback(RTC_HandleTypeDef *hrtc)
{
	// Callback called from the RTC interrupt service routine
}
/* USER CODE END 4 */
 
/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler_Debug */
  /* User can add his own implementation to report the HAL error return state */
  __disable_irq();
  while (1)
  {
  }
  /* USER CODE END Error_Handler_Debug */
}
 
#ifdef  USE_FULL_ASSERT
/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  * @param  file: pointer to the source file name
  * @param  line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t *file, uint32_t line)
{
  /* USER CODE BEGIN 6 */
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */

View solution in original post

KnarfB · ‎2022-02-02

Set an RTC alarm, see https://community.st.com/s/question/0D50X00009ZETli/can-i-configure-stm32l0-to-wake-up-from-standy-mode-every-15-minutes-with-rtc or the internet.

hth

KnarfB

ZKURT.1 · ‎2022-02-02

thank you. The link you posted doesn't say how to do it. The examples I've found have always been made with an interrupt pin. I have very little time. I don't know what to do. Can you help me?

TDK · ‎2022-02-02

> The examples I've found have always been made with an interrupt pin.

How hard did you look?

First hit for "stm32 rtc wakeup example"

https://community.st.com/s/question/0D50X0000AFoZdXSQV/how-to-wakeup-on-time-in-time-with-rtc-

Took me all of 5 seconds to type that into Google. If for some reason you don't like that result there are many other relevant results that follow it.

If you feel a post has answered your question, please click "Accept as Solution".

ZKURT.1 · ‎2022-02-02

Of course there are examples I found, but I couldn't get it to work. For example, in your example, the program works once and does not work again. It works with the Standby reset logic I know. After 10 seconds it should work again but it doesn't. Why do you think it might?

#include <string.h>
#include <stdio.h>
#define printf(...)  HAL_UART_Transmit((UART_HandleTypeDef *)&hlpuart1, (uint8_t *)u_buf,\
		                                sprintf((char*)u_buf,__VA_ARGS__), 0xFFFF);
uint8_t u_buf[256];
int main(void)
{
  /* USER CODE BEGIN 1 */
 
  /* USER CODE END 1 */
 
  /* MCU Configuration--------------------------------------------------------*/
 
  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();
 
  /* USER CODE BEGIN Init */
 
  /* USER CODE END Init */
 
  /* Configure the system clock */
  SystemClock_Config();
 
  /* USER CODE BEGIN SysInit */
 
  /* USER CODE END SysInit */
 
  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_LPUART1_UART_Init();
  MX_RTC_Init();
  /* USER CODE BEGIN 2 */
  printf("start\r\n");
  /* Check and handle if the system was resumed from StandBy mode */
   if(__HAL_PWR_GET_FLAG(PWR_FLAG_SB) != RESET)
   {
     /* Clear Standby flag */
     __HAL_PWR_CLEAR_FLAG(PWR_FLAG_SB);
   }
 
   /* Disable Wakeup Counter */
   HAL_RTCEx_DeactivateWakeUpTimer(&hrtc);
 
   /*## Setting the Wake up time ############################################*/
   /*  RTC Wakeup Interrupt Generation:
       Wakeup Time Base = (RTC_WAKEUPCLOCK_RTCCLK_DIV /(LSE or LSI))
       Wakeup Time = Wakeup Time Base * WakeUpCounter
                   = (RTC_WAKEUPCLOCK_RTCCLK_DIV /(LSE or LSI)) * WakeUpCounter
       ==> WakeUpCounter = Wakeup Time / Wakeup Time Base
 
       To configure the wake up timer to 4s the WakeUpCounter is set to 0x1FFF:
         RTC_WAKEUPCLOCK_RTCCLK_DIV = RTCCLK_Div16 = 16
         Wakeup Time Base = 16 /(~39.000KHz) = ~0,410 ms
         Wakeup Time = ~4s = 0,410ms  * WakeUpCounter
         ==> WakeUpCounter = ~4s/0,410ms = 9750 = 0x2616 */
   HAL_RTCEx_SetWakeUpTimer_IT(&hrtc, 0x5F46, RTC_WAKEUPCLOCK_RTCCLK_DIV16);
   __HAL_PWR_CLEAR_FLAG(PWR_FLAG_WU);
 
   HAL_RTC_DeInit(&hrtc);
   HAL_RTC_Init(&hrtc);
 
   	     	HAL_PWR_EnterSTANDBYMode();
 
  /* USER CODE END 2 */
 
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */
 
    /* USER CODE BEGIN 3 */
 
  }
  /* USER CODE END 3 */
}

Jaroslav BECKA · ‎2022-02-04

Hi,