STM32 HAL RTC配置及优化

STM32内部的RTC实时时钟模块，可以配置实现日历和时间的运转，并在外部备用电池的辅助下，可以在主电源关闭的情况下保持运行，且RTC备份寄存器也可以在电池供电状态保持数据不丢失。
RTC的配置涉及模式初始化，日期和时间的配置，如果想要在主电源恢复或复位产生之后，RTC只配置模式初始化，而不因重置而中断原来的日期和时间的计数运行，则需要做代码调整优化。

这里以STM32L476RGT6开发板和STM32CUBEIDE开发环境，实现RTC配置和优化。

RTC配置

首先建立工程并设置时钟系统，这里采用外部32.768KHz的晶体作为RTC时钟，所以后面配置时会设置32768的分频到1Hz。RTC输入时钟还有其它选项，如HSI RC，其频率为32KHz，相应的后面配置时做32000的分频即可。

配置RTC初始配置，这里只配置用到的时钟和时间功能：

General选项组里配置小时模式，有24小时制和12小时制可选，后面的127和255组合成分频系数，127实际对应128，255实际对应256，所以128×256=32768，正好实现输入32.768KHz时钟分频到1Hz。
Caalendar Time选项组里配置初始化的时间，这里配置为BCD码模式，这里的BCD码即用4位二进制表示0 ~ 9的十进制数据，因为4位二进制可以表示范围为0 ~ 15，所以BCD码里不会用到10 ~ 15的部分。初始时刻的小时，分钟和秒可以相应配置，这里简单设置为0。

Calendar Date的设置，这里将日期设置为2022年4月1日星期五。

然后使能一个UART串口，这里是USART2, 采用115200波特率，用于将时间信息输出：

保存并生成初始工程代码：

RTC代码及优化

自动生成的初始化代码相关部分如下：

  /* 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();MX_USART2_UART_Init();/* USER CODE BEGIN 2 *//* USER CODE END 2 */

其中和RTC配置有关的部分是MX_RTC_Init();：

/*** @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 */RTC_TimeTypeDef sTime = {0};RTC_DateTypeDef sDate = {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 Check_RTC_BKUP *//* USER CODE END Check_RTC_BKUP *//** Initialize RTC and set the Time and Date*/sTime.Hours = 0x0;sTime.Minutes = 0x0;sTime.Seconds = 0x0;sTime.DayLightSaving = RTC_DAYLIGHTSAVING_NONE;sTime.StoreOperation = RTC_STOREOPERATION_RESET;if (HAL_RTC_SetTime(&hrtc, &sTime, RTC_FORMAT_BCD) != HAL_OK){Error_Handler();}sDate.WeekDay = RTC_WEEKDAY_FRIDAY;sDate.Month = RTC_MONTH_APRIL;sDate.Date = 0x1;sDate.Year = 0x22;if (HAL_RTC_SetDate(&hrtc, &sDate, RTC_FORMAT_BCD) != HAL_OK){Error_Handler();}/* USER CODE BEGIN RTC_Init 2 *//* USER CODE END RTC_Init 2 */}

其中包含RTC模式初始化，时间初始值配置，日期初始值配置，因此，只要发生任何类型的复位，时间和日期会被重置，而不是保持运行，这样就使得备用电池对RTC时间的保持运行失去价值，因此，需要进行代码调整，使得初始配置值只执行一次，在以后的复位时只进行RTC模式初始化，不打扰时间和日期的继续累加。
这里用RTC备用寄存器存储判断标志，实际上，也可以用断电不失型存储单元（包括内外FLASH, EEPROM等）存储判断标识，操作内部FLASH作为用户数据单元可参考：STM32 内部FLASH用作用户数据区Byte操作函数设计 (HAL)
RTC备用寄存器初始值为全0，判断RTC备用寄存器为0，则识别为第一次运行，会进行时间和日期的配置，然后修改RTC备用寄存器值，这样再以后的复位启动后，判断RTC备用寄存器不为0，则不进行时间和日期的配置，从而时间和日期一直保持累加。

例程代码如下：

/* 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;UART_HandleTypeDef huart2;/* 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);
static void MX_USART2_UART_Init(void);
/* USER CODE BEGIN PFP */
uint32_t bkdata=0;
void PY_RTC_Init(void)
{/** 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();}HAL_PWR_EnableBkUpAccess();bkdata=HAL_RTCEx_BKUPRead(&hrtc, 0);if(bkdata==0x00000000){HAL_RTC_DeInit(&hrtc);MX_RTC_Init();HAL_PWR_EnableBkUpAccess();HAL_RTCEx_BKUPWrite(&hrtc, 0, 0x5555aaaa);}}
/* USER CODE END PFP *//* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
uint8_t py_date[4];
uint8_t py_time[3];
/* 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 */#if 0/* USER CODE END SysInit *//* Initialize all configured peripherals */MX_GPIO_Init();MX_RTC_Init();MX_USART2_UART_Init();/* USER CODE BEGIN 2 */
#elseMX_GPIO_Init();PY_RTC_Init();MX_USART2_UART_Init();#endif/* USER CODE END 2 *//* Infinite loop *//* USER CODE BEGIN WHILE */while (1){HAL_UART_Transmit(&huart2, &bkdata, 4, 2720);HAL_Delay(2500);HAL_RTC_GetDate(&hrtc, py_date, RTC_FORMAT_BCD);HAL_UART_Transmit(&huart2, py_date, 4, 2000);HAL_Delay(2500);HAL_RTC_GetTime(&hrtc, py_time, RTC_FORMAT_BCD);HAL_UART_Transmit(&huart2, py_time, 3, 2000);HAL_Delay(5000);/* USER CODE END WHILE *//* USER CODE BEGIN 3 */}/* USER CODE END 3 */
}/*** @brief System Clock Configuration* @retval None*/
void SystemClock_Config(void)
{RCC_OscInitTypeDef RCC_OscInitStruct = {0};RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};/** Configure the main internal regulator output voltage*/if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1) != HAL_OK){Error_Handler();}/** 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_ON;RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;RCC_OscInitStruct.PLL.PLLM = 1;RCC_OscInitStruct.PLL.PLLN = 10;RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV7;RCC_OscInitStruct.PLL.PLLQ = RCC_PLLQ_DIV2;RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV2;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_PLLCLK;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_4) != 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 */RTC_TimeTypeDef sTime = {0};RTC_DateTypeDef sDate = {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 Check_RTC_BKUP *//* USER CODE END Check_RTC_BKUP *//** Initialize RTC and set the Time and Date*/sTime.Hours = 0x0;sTime.Minutes = 0x0;sTime.Seconds = 0x0;sTime.DayLightSaving = RTC_DAYLIGHTSAVING_NONE;sTime.StoreOperation = RTC_STOREOPERATION_RESET;if (HAL_RTC_SetTime(&hrtc, &sTime, RTC_FORMAT_BCD) != HAL_OK){Error_Handler();}sDate.WeekDay = RTC_WEEKDAY_FRIDAY;sDate.Month = RTC_MONTH_APRIL;sDate.Date = 0x1;sDate.Year = 0x22;if (HAL_RTC_SetDate(&hrtc, &sDate, RTC_FORMAT_BCD) != HAL_OK){Error_Handler();}/* USER CODE BEGIN RTC_Init 2 *//* USER CODE END RTC_Init 2 */}/*** @brief USART2 Initialization Function* @param None* @retval None*/
static void MX_USART2_UART_Init(void)
{/* USER CODE BEGIN USART2_Init 0 *//* USER CODE END USART2_Init 0 *//* USER CODE BEGIN USART2_Init 1 *//* USER CODE END USART2_Init 1 */huart2.Instance = USART2;huart2.Init.BaudRate = 115200;huart2.Init.WordLength = UART_WORDLENGTH_8B;huart2.Init.StopBits = UART_STOPBITS_1;huart2.Init.Parity = UART_PARITY_NONE;huart2.Init.Mode = UART_MODE_TX_RX;huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;huart2.Init.OverSampling = UART_OVERSAMPLING_16;huart2.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;huart2.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;if (HAL_UART_Init(&huart2) != HAL_OK){Error_Handler();}/* USER CODE BEGIN USART2_Init 2 *//* USER CODE END USART2_Init 2 */}/*** @brief GPIO Initialization Function* @param None* @retval None*/
static void MX_GPIO_Init(void)
{/* GPIO Ports Clock Enable */__HAL_RCC_GPIOC_CLK_ENABLE();__HAL_RCC_GPIOA_CLK_ENABLE();}/* USER CODE BEGIN 4 *//* 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 */

用串口工具设置115200波特率进行数据接收：

程序第一次运行，不断将RTC备用寄存器值00 00 00 00，4个字节的日期，3个字节的时间输出。当按了一次复位按钮，则输出的RTC备用寄存器值变为55 55 aa aa, 且3个字节的时间输出是从之前的值上继续累加的状态，而不是从初始态开始，实现了设计的目标。

其中，py_date数组对应的是结构体RTC_DateTypeDef，其定义如下：

/*** @brief  RTC Date structure definition*/
typedef struct
{uint8_t WeekDay;  /*!< Specifies the RTC Date WeekDay.This parameter can be a value of @ref RTC_WeekDay_Definitions */uint8_t Month;    /*!< Specifies the RTC Date Month (in BCD format).This parameter can be a value of @ref RTC_Month_Date_Definitions */uint8_t Date;     /*!< Specifies the RTC Date.This parameter must be a number between Min_Data = 1 and Max_Data = 31 */uint8_t Year;     /*!< Specifies the RTC Date Year.This parameter must be a number between Min_Data = 0 and Max_Data = 99 */} RTC_DateTypeDef;

而py_time数组对应的是结构体RTC_TimeTypeDef，其定义如下：

/*** @brief  RTC Time structure definition*/
typedef struct
{uint8_t Hours;            /*!< Specifies the RTC Time Hour.This parameter must be a number between Min_Data = 0 and Max_Data = 12 if the RTC_HourFormat_12 is selected.This parameter must be a number between Min_Data = 0 and Max_Data = 23 if the RTC_HourFormat_24 is selected */uint8_t Minutes;          /*!< Specifies the RTC Time Minutes.This parameter must be a number between Min_Data = 0 and Max_Data = 59 */uint8_t Seconds;          /*!< Specifies the RTC Time Seconds.This parameter must be a number between Min_Data = 0 and Max_Data = 59 */uint8_t TimeFormat;       /*!< Specifies the RTC AM/PM Time.This parameter can be a value of @ref RTC_AM_PM_Definitions */#if defined (STM32L4P5xx) || defined (STM32L4Q5xx)uint32_t SubSeconds;      /*!< Specifies the RTC_SSR RTC Sub Second register content.This field is not used by HAL_RTC_SetTime.If the free running 32 bit counter is not activated (mode binary none)- This parameter corresponds to a time unit range between [0-1] Second with [1 Sec / SecondFraction +1] granularityelse- This parameter corresponds to the free running 32 bit counter. */
#elseuint32_t SubSeconds;      /*!< Specifies the RTC_SSR RTC Sub Second register content.This parameter corresponds to a time unit range between [0-1] Secondwith [1 Sec / SecondFraction +1] granularity */
#endifuint32_t SecondFraction;  /*!< Specifies the range or granularity of Sub Second register contentcorresponding to Synchronous pre-scaler factor value (PREDIV_S)This parameter corresponds to a time unit range between [0-1] Secondwith [1 Sec / SecondFraction +1] granularity.This field will be used only by HAL_RTC_GetTime function */uint32_t DayLightSaving;  /*!< This interface is deprecated. To manage Daylight Saving Time, please use HAL_RTC_DST_xxx functions */uint32_t StoreOperation;  /*!< This interface is deprecated. To manage Daylight Saving Time, please use HAL_RTC_DST_xxx functions */
} RTC_TimeTypeDef;

RTC日期和时间的实时配置

实际上，通常需要通过一些来自外部的方式进行日期和时间的实时配置，如通过串口获得日期和时间数据，并更新RTC当前的日期和时间。
在这样的情况下，用HAL_RTC_SetDate()和HAL_RTC_SetTime()函数即可在RTC运行阶段实时更新当前的日期和时间，此操作不需要停止RTC及重启RTC，随时调用随时改。

HAL_RTC_SetDate()的函数说明如下：

/*** @brief  Set RTC current date.* @param  hrtc RTC handle* @param  sDate Pointer to date structure* @param  Format specifies the format of the entered parameters.*          This parameter can be one of the following values:*            @arg RTC_FORMAT_BIN: Binary data format*            @arg RTC_FORMAT_BCD: BCD data format* @retval HAL status*/
HAL_StatusTypeDef HAL_RTC_SetDate(RTC_HandleTypeDef *hrtc, RTC_DateTypeDef *sDate, uint32_t Format)

HAL_RTC_SetTime()的函数说明如下：

/*** @brief  Set RTC current time.* @param  hrtc RTC handle* @param  sTime Pointer to Time structure* @param  Format Specifies the format of the entered parameters.*          This parameter can be one of the following values:*            @arg RTC_FORMAT_BIN: Binary data format*            @arg RTC_FORMAT_BCD: BCD data format* @retval HAL status*/
HAL_StatusTypeDef HAL_RTC_SetTime(RTC_HandleTypeDef *hrtc, RTC_TimeTypeDef *sTime, uint32_t Format)

–End–