Low-level RTC Driver for STM32L0 Series

Made by Trippingcarpet

Note: Tested with STM32L071KBT6

Features

• Compatible with all STM32L0 series.
• Fast solution for your STM projects.
• Easy integratation.

Note: The library uses LSE as a clock source. (Freq: 32.768 KHz)

Installation

1. git clone https://github.com/RedSideDevils/stm32lx-Series-RTC-Driver.git
2. move the rtc_lib directory of your STM project directory.
3. include "rtc_lib.h".

Note: Library uses definitions from main.h file.

IOC file config

1. Turn on RTC. (Timers -> RTC -> Activate Clock Source)
2. Change the Low-Speed Clock (LSE) to a Crystal/Ceramic Resonator. (RCC Section)
3. Go to "Project Manager" -> "Advanced Settings" and change the RTC code generator to LL.

Functions

1. Init library function.
   RTC_Status_t rtc_init_clock(void) Function change clock source as LSE, sets prescaler to 1Hz, and sync RTC clock.
   Call at the start of the program.
   
   

2. Start / Stop functions.
   RTC_Status_t rtc_start_clock(void) Starts RTC Clock.
   
   RTC_Status_t rtc_stop_clock(void) Stops RTC Clock.
   
   

3. Time / Date config functions.
   
   Setters
   RTC_Status_t rtc_set_time(RTC_Time_t *m_time) Sets time, but not save to backup registers. Call rtc_save_time() to save current time to memory.
   
   RTC_Status_t rtc_set_date(RTC_Date_t *m_date) Sets the date, but not save it to backup registers. Call rtc_save_date() to save the current date to memory.
   
   Getters
   RTC_Status_t rtc_set_date(RTC_Date_t *m_date) Returns the current time.
   
   RTC_Status_t rtc_get_date(RTC_Date_t *m_date) Returns the current date.
   
   Memory
   RTC_Status_t rtc_save_time(void) Saves current time to BKP0R register.
   
   RTC_Status_t rtc_save_date(void) Saves current date to BKP1R register.
   
   RTC_Status_t rtc_restore_time(void) Read the BKP3R register to validate the magic value. If the magic value is correct, load time from the BKP0R register.
   
   RTC_Status_t rtc_restore_date(void) Read the BKP4R register to validate the magic value. If the magic value is correct, load the date from the BKP1R register.
   
   

4. Alarms config functions
   The library uses ALARM A and ALARM B.
   
   RTC_Status_t rtc_bind_time_alarm(RTC_Time_t *m_time, RTC_Alarm_t alarm_type) Binds alarm for time.
   
   RTC_Status_t rtc_stop_alarm(RTC_Alarm_t alarm_type) Stops the alarm and interrupt attached to that alarm.
   
   void rtc_alarm_interrupt_handler(RTC_Alarm_t curr_alarm) Alarm handler for A and B. Call in RTC_IRQHandler or in the while loop.
   
   void rtc_alarm_callback(RTC_Time_t *m_time, RTC_Alarm_t curr_alarm) This callback calls when alarm works.
   
   

Data Types

1. Functions return status.
   

typedef enum
{
	RTC_ERROR = 0,
	RTC_OK = 1
} RTC_Status_t;

2. Time init struct.
   

typedef struct
{
	uint8_t hours;
	uint8_t minutes;
	uint8_t seconds;
} RTC_Time_t;

3. Date init struct.
   

typedef struct
{
	uint8_t year;
	uint8_t month;
	uint8_t day;
} RTC_Date_t;

4. Alarm type.
   

typedef enum
{
	ALARM_A,
	ALARM_B
} RTC_Alarm_t;

Defines

Magic values.

#define RTC_MEMORY_TIME_MAGICVALUE 0x10F2C
#define RTC_MEMORY_DATE_MAGICVALUE 0x10F3C

Backup registers memory blocks.

#define RTC_MEMORY_TIME_ADDR 	   0x0
#define RTC_MEMORY_DATE_ADDR 	   0x4
#define RTC_MEMORY_MAGIC_TIME_ADDR 0x8
#define RTC_MEMORY_MAGIC_DATE_ADDR 0xC

Timeouts

#define WAIT_LSE_ON_TIMEOUT   1000
#define WAIT_RTC_SYNC_TIMEOUT 1000
#define WAIT_RTC_INIT_TIMEOUT 1000

Example

#include "main.h"
#include "rtc_lib/rtc_lib.h"

uint8_t handle_alarm_flag = 0;

void rtc_alarm_callback(RTC_Time_t *m_time, RTC_Alarm_t curr_alarm)
{
    if(curr_alarm == ALARM_A)
    {
        handle_alarm_flag = 1;
    }
}

int main(void)
{
	RTC_Time_t time_set = {.hours=15, .minutes=8, .seconds=20};
	RTC_Time_t time_get = {0};
	
	RTC_Time_t alarm_time_a = {.hours=18, .minutes=4, .seconds=5};
	RTC_Time_t alarm_time_b = {.hours=19, .minutes=8, .seconds=25};
	
	if(!rtc_init_clock())
	{
		errno_handler();
	}
	
	if(!rtc_start_clock())
	{
		errno_handler();
	}
	
	if(!rtc_restore_time())
	{
		if(!rtc_set_time(&time_set))
		{
			errno_handler();
		}
		if(!rtc_save_time())
		{
			errno_handler();
		}
	}
	
	if(!rtc_get_time(&time_get))
	{
		errno_handler();
	}
	
	if(!(rtc_bind_time_alarm(&alarm_time_a, ALARM_A)))
	{
		errno_handler();
	}
	
	for(;;)
	{
		rtc_alarm_interrupt_handler(ALARM_A);
	}
}