I have an STM32F103C8T6 Blue Pill board, and I'm trying to get the RTC to function correctly when Vdd is removed. However, when I disconnect Vdd, the RTC doesn't operate as expected. Sometimes, when Vdd is supplied, the RTC starts counting from the time I disconnected Vdd, or it begins from an entirely different time. Additionally, I'm observing a voltage of 2.2V on Vdd when only Vbat is connected. Interestingly, the contents of the RTC backup registers are saved when only Vbat is supplied but the RTC doesn't work.
/* USER CODE BEGIN Header */
/**
******************************************************************************
* @file : main.c
* @brief : Main program body
******************************************************************************
* @attention
*
* Copyright (c) 2024 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 */
#include <stdio.h>
#include <string.h>
/* USER CODE END Includes */
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
/* USER CODE END PTD */
/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
RTC_TimeTypeDef Time = {0};
RTC_DateTypeDef Date = {0};
/* USER CODE END PD */
/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
int _write(int file, char *ptr, int len)
{
int DataIdx;
for (DataIdx = 0; DataIdx < len; DataIdx++)
{
ITM_SendChar(*ptr++);
}
return len;
}
/* USER CODE END PM */
/* Private variables ---------------------------------------------------------*/
RTC_HandleTypeDef hrtc;
UART_HandleTypeDef huart1;
/* 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_USART1_UART_Init(void);
/* USER CODE BEGIN PFP */
/* USER CODE END PFP */
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
static void SetTime()
{
RTC_TimeTypeDef sTime = {0};
RTC_DateTypeDef DateToUpdate = {0};
sTime.Hours = 0x23;
sTime.Minutes = 0x59;
sTime.Seconds = 0x50;
if (HAL_RTC_SetTime(&hrtc, &sTime, RTC_FORMAT_BCD) != HAL_OK)
{
Error_Handler();
}
DateToUpdate.WeekDay = RTC_WEEKDAY_WEDNESDAY;
DateToUpdate.Month = RTC_MONTH_OCTOBER;
DateToUpdate.Date = 0x2;
DateToUpdate.Year = 0x24;
if (HAL_RTC_SetDate(&hrtc, &DateToUpdate, RTC_FORMAT_BCD) != HAL_OK)
{
Error_Handler();
}
}
/* 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 */
__HAL_RCC_BKP_CLK_ENABLE();
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_RTC_Init();
MX_USART1_UART_Init();
/* USER CODE BEGIN 2 */
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
// SET_BIT(RCC->APB1ENR, RCC_APB1ENR_PWREN);
char buff[200] = {0};
while (1)
{
HAL_RTC_GetTime(&hrtc, &Time, RTC_FORMAT_BIN);
HAL_RTC_GetDate(&hrtc, &Date, RTC_FORMAT_BIN);
snprintf(buff, 200, "%02d/%02d/%02d %02d:%02d:%02d\r\n", Date.Date,
Date.Month, Date.Year, Time.Hours, Time.Minutes, Time.Seconds);
HAL_UART_Transmit(&huart1, buff, strlen(buff), 100);
HAL_UART_Receive(&huart1, buff, 1, 1000);
if (buff[0] == 'A')
{
SetTime();
}
else if (buff[0] == 'B')
{
HAL_RTC_GetDate(&hrtc, &Date, RTC_FORMAT_BCD);
HAL_RTCEx_BKUPWrite(&hrtc, RTC_BKP_DR2, Date.WeekDay);
HAL_RTCEx_BKUPWrite(&hrtc, RTC_BKP_DR3, Date.Month);
HAL_RTCEx_BKUPWrite(&hrtc, RTC_BKP_DR4, Date.Date);
HAL_RTCEx_BKUPWrite(&hrtc, RTC_BKP_DR5, Date.Year);
HAL_Delay(100);
HAL_PWR_EnterSTANDBYMode();
}
// HAL_Delay(1000);
/* 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};
RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
/** 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_DIV2;
RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL16;
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_DIV2;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != 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 */
// #ifdef RTC_SET_VALUES
/* USER CODE END RTC_Init 0 */
RTC_TimeTypeDef sTime = {0};
RTC_DateTypeDef DateToUpdate = {0};
/* USER CODE BEGIN RTC_Init 1 */
/* USER CODE END RTC_Init 1 */
/** Initialize RTC Only
*/
hrtc.Instance = RTC;
hrtc.Init.AsynchPrediv = RTC_AUTO_1_SECOND;
hrtc.Init.OutPut = RTC_OUTPUTSOURCE_ALARM;
if (HAL_RTC_Init(&hrtc) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN Check_RTC_BKUP */
// HAL_RTCEx_BKUPRead(&hrtc, RTC_BKP_DR1);
// HAL_RTC_WaitForSynchro(&hrtc);
// #ifdef RTC_SET_VALUES
if (HAL_RTCEx_BKUPRead(&hrtc, RTC_BKP_DR1) != 0x32F2)
{
if (HAL_RTC_WaitForSynchro(&hrtc) != HAL_OK)
{
Error_Handler();
}
/* USER CODE END Check_RTC_BKUP */
/** Initialize RTC and set the Time and Date
*/
sTime.Hours = 0x23;
sTime.Minutes = 0x59;
sTime.Seconds = 0x50;
if (HAL_RTC_SetTime(&hrtc, &sTime, RTC_FORMAT_BCD) != HAL_OK)
{
Error_Handler();
}
DateToUpdate.WeekDay = RTC_WEEKDAY_WEDNESDAY;
DateToUpdate.Month = RTC_MONTH_OCTOBER;
DateToUpdate.Date = 0x2;
DateToUpdate.Year = 0x24;
if (HAL_RTC_SetDate(&hrtc, &DateToUpdate, RTC_FORMAT_BCD) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN RTC_Init 2 */
// #endif
HAL_RTCEx_BKUPWrite(&hrtc, RTC_BKP_DR1, 0x32F2);
}
else
{
DateToUpdate.WeekDay = HAL_RTCEx_BKUPRead(&hrtc, RTC_BKP_DR2);
DateToUpdate.Month = HAL_RTCEx_BKUPRead(&hrtc, RTC_BKP_DR3);
DateToUpdate.Date = HAL_RTCEx_BKUPRead(&hrtc, RTC_BKP_DR4);
DateToUpdate.Year = HAL_RTCEx_BKUPRead(&hrtc, RTC_BKP_DR5);
if (HAL_RTC_SetDate(&hrtc, &DateToUpdate, RTC_FORMAT_BCD) != HAL_OK)
{
Error_Handler();
}
}
/* USER CODE END RTC_Init 2 */
}
/**
* @brief USART1 Initialization Function
* @PAram None
* @retval None
*/
static void MX_USART1_UART_Init(void)
{
/* USER CODE BEGIN USART1_Init 0 */
/* USER CODE END USART1_Init 0 */
/* USER CODE BEGIN USART1_Init 1 */
/* USER CODE END USART1_Init 1 */
huart1.Instance = USART1;
huart1.Init.BaudRate = 9600;
huart1.Init.WordLength = UART_WORDLENGTH_8B;
huart1.Init.StopBits = UART_STOPBITS_1;
huart1.Init.Parity = UART_PARITY_NONE;
huart1.Init.Mode = UART_MODE_TX_RX;
huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
huart1.Init.OverSampling = UART_OVERSAMPLING_16;
if (HAL_UART_Init(&huart1) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN USART1_Init 2 */
/* USER CODE END USART1_Init 2 */
}
/**
* @brief GPIO Initialization Function
* @PAram None
* @retval None
*/
static void MX_GPIO_Init(void)
{
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOC_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}
/* 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 */
