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.
#include "main.h"
#include <stdio.h>
#include <string.h>
RTC_TimeTypeDef Time = {0};
RTC_DateTypeDef Date = {0};
int _write(int file, char *ptr, int len)
{
int DataIdx;
for (DataIdx = 0; DataIdx < len; DataIdx++)
{
ITM_SendChar(*ptr++);
}
return len;
}
RTC_HandleTypeDef hrtc;
UART_HandleTypeDef huart1;
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_RTC_Init(void);
static void MX_USART1_UART_Init(void);
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();
}
}
int main(void)
{
HAL_Init();
SystemClock_Config();
__HAL_RCC_BKP_CLK_ENABLE();
MX_GPIO_Init();
MX_RTC_Init();
MX_USART1_UART_Init();
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();
}
}
}
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
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();
}
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();
}
}
static void MX_RTC_Init(void)
{
RTC_TimeTypeDef sTime = {0};
RTC_DateTypeDef DateToUpdate = {0};
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();
}
if (HAL_RTCEx_BKUPRead(&hrtc, RTC_BKP_DR1) != 0x32F2)
{
if (HAL_RTC_WaitForSynchro(&hrtc) != HAL_OK)
{
Error_Handler();
}
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();
}
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();
}
}
}
static void MX_USART1_UART_Init(void)
{
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();
}
}
static void MX_GPIO_Init(void)
{
__HAL_RCC_GPIOC_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
}
void Error_Handler(void)
{
__disable_irq();
while (1)
{
}
}
#ifdef USE_FULL_ASSERT
void assert_failed(uint8_t *file, uint32_t line)
{
}
#endif
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