RTC initialisation (инициализация часов) STM32F (STM32F103)

#include "stm32F10x.h"
#include "rtc.h"

//************************** Часы реального времени **************************

//****************************************************************************
//             Инициализация часов                            //
//****************************************************************************  
int  RtcInit  (void)
{
  //разрешить тактирование модулей управления питанием и управлением
  //резервной областью - enable APB1 clocks
  RCC->APB1ENR |= RCC_APB1ENR_PWREN | RCC_APB1ENR_BKPEN;
  // disable backup domain write protection
//разрешить доступ к области резарвных данных
  PWR->CR |= PWR_CR_DBP;
  //если часы выключены - инициализировать их
//Bit 15 RTCEN: RTC clock enable
//Set and cleared by software.
//0: RTC clock disabled
//1: RTC clock enabled
if ((RCC->BDCR & RCC_BDCR_RTCEN) != RCC_BDCR_RTCEN)
{
//выполнить сброс области резервных данных
// reset Backup Domain
//Bit 16 BDRST: Backup domain software reset
//Set and cleared by software.
//0: Reset not activated
//1: Resets the entire Backup domain
RCC->BDCR |= RCC_BDCR_BDRST;
RCC->BDCR &= ~RCC_BDCR_BDRST;
//выбрать источником тактовых импульсов внешний кварц 32768 и подать тактирование
//Bit 15 RTCEN: RTC clock enable
//Set and cleared by software.
//0: RTC clock disabled
//1: RTC clock enabled
//Bits 9:8 RTCSEL[1:0]: RTC clock source selection
//Set by software to select the clock source for the RTC. Once the RTC clock source has been selected,
// it cannot be changed anymore unless the Backup domain is reset. The BDRST bit can be used to reset them.
//00: No clock
//01: LSE oscillator clock used as RTC clock10: LSI oscillator clock used as RTC clock
//11: HSE oscillator clock divided by 128 used as RTC clock
RCC->BDCR |= RCC_BDCR_RTCEN | RCC_BDCR_RTCSEL_LSE;
//установка маски разрешения секундных прерываний
//Bit 0 SECIE: Second interrupt enable
//0: Second interrupt is masked.
//1: Second interrupt is enabled.
RTC->CRH |= RTC_CRH_SECIE; ///!!!!!!!!!!!!SECOND INTERRUPT ENABLE
//Bit 4 CNF: Configuration flag
//This bit must be set by software to enter in configuration mode so as to allow new values to
//be written in the RTC_CNT, RTC_ALR or RTC_PRL registers. The write operation is only
//executed when the CNF bit is reset by software after has been set.
//0: Exit configuration mode (start update of RTC registers).
//1: Enter configuration mode.
RTC->CRL |= RTC_CRL_CNF;
//If the input clock frequency (fRTCCLK) is 32.768 kHz, write 7FFFh in this register to get a
//signal period of 1 second.
RTC->PRLH = 0;
RTC->PRLL = 0x8000;         //тактирование от внешнего кварца

AFIO->EVCR =0xAD; //PC13-calibration clock output enable

BKP->RTCCR |= BKP_RTCCR_CCO; //Setting this bit outputs the
//RTC clock with a frequency divided by 64 on the TAMPER pin
BKP->RTCCR |= BKP_RTCCR_ASOS | BKP_RTCCR_ASOE;
//0: Exit configuration mode (start update of RTC registers).
RTC->CRL &= ~RTC_CRL_CNF;
    //установить бит разрешения работы и дождаться установки бита готовности
RCC->BDCR |= RCC_BDCR_LSEON;
while ((RCC->BDCR & RCC_BDCR_LSEON) != RCC_BDCR_LSEON){}

//while ((RCC->BDCR & RCC_BDCR_LSERDY) != RCC_BDCR_LSERDY); //вариант

//Bit 3 RSF: Registers synchronized flag
//This bit is set by hardware at each time the RTC_CNT and RTC_DIV registers are updated
//and cleared by software. Before any read operation after an APB1 reset or an APB1 clock
//stop, this bit must be cleared by software, and the user application must wait until it is set to
//be sure that the RTC_CNT, RTC_ALR or RTC_PRL registers are synchronized.
//0: Registers not yet synchronized.
//1: Registers synchronized.
RTC->CRL &= (uint16_t)~RTC_CRL_RSF;
while((RTC->CRL & RTC_CRL_RSF) != RTC_CRL_RSF){}
return 0;
}
   return 1;
}


void RtcCorr (void)
{

/*
//разрешить тактирование модулей управления питанием и управлением
//резервной областью
RCC->APB1ENR |= RCC_APB1ENR_PWREN | RCC_APB1ENR_BKPEN;
//разрешить доступ к области резарвных данных
PWR->CR |= PWR_CR_DBP;

//выполнить сброс области резервных данных
RCC->BDCR |= RCC_BDCR_BDRST;
RCC->BDCR &= ~RCC_BDCR_BDRST;
//выбрать источником тактовых импульсов внешний кварц 32768 и подать тактирование
RCC->BDCR |= RCC_BDCR_RTCEN | RCC_BDCR_RTCSEL_LSE;
//Bit 4 CNF: Configuration flag
//This bit must be set by software to enter in configuration mode so as to allow new values to
//be written in the RTC_CNT, RTC_ALR or RTC_PRL registers. The write operation is only
//executed when the CNF bit is reset by software after has been set.
//0: Exit configuration mode (start update of RTC registers).
//1: Enter configuration mode.
RTC->CRL |= RTC_CRL_CNF;
//If the input clock frequency (fRTCCLK) is 32.768 kHz, write 7FFFh in this register to get a
//signal period of 1 second.
RTC->PRLL = 0x7FF0;         //тактирование от внешнего кварца
//0: Exit configuration mode (start update of RTC registers).
RTC->CRL &= ~RTC_CRL_CNF;
    //установить бит разрешения работы и дождаться установки бита готовности
RCC->BDCR |= RCC_BDCR_LSEON;
while ((RCC->BDCR & RCC_BDCR_LSEON) != RCC_BDCR_LSEON){}

//while ((RCC->BDCR & RCC_BDCR_LSERDY) != RCC_BDCR_LSERDY); //вариант

//Bit 3 RSF: Registers synchronized flag
//This bit is set by hardware at each time the RTC_CNT and RTC_DIV registers are updated
//and cleared by software. Before any read operation after an APB1 reset or an APB1 clock
//stop, this bit must be cleared by software, and the user application must wait until it is set to
//be sure that the RTC_CNT, RTC_ALR or RTC_PRL registers are synchronized.
//0: Registers not yet synchronized.
//1: Registers synchronized.
RTC->CRL &= (uint16_t)~RTC_CRL_RSF;
while((RTC->CRL & RTC_CRL_RSF) != RTC_CRL_RSF){}
*/


// enable APB1 clocks
RCC->APB1ENR |= RCC_APB1ENR_PWREN | RCC_APB1ENR_BKPEN;

// disable backup domain write protection
PWR->CR |= PWR_CR_DBP;

// set RTC prescaler: set RTC period to 1sec
RTC->CRL |= RTC_CRL_CNF; // enter config mode
RTC->PRLH = 0;
RTC->PRLL = 0x8000;

AFIO->EVCR =0xAD; //PC13-calibration clock output enable
BKP->RTCCR |= BKP_RTCCR_CCO; //Setting this bit outputs the
//RTC clock with a frequency divided by 64 on the TAMPER pin

RTC->CRL &= ~RTC_CRL_CNF; // exit config mode

// reset Backup Domain
// RCC->BDCR |= RCC_BDCR_BDRST;
// RCC->BDCR &= ~RCC_BDCR_BDRST;

RCC->BDCR &= ~(RCC_BDCR_LSEON | RCC_BDCR_LSEBYP);
// enable LSE
RCC->BDCR |= RCC_BDCR_LSEON;
// wait till LSE is ready
while (!(RCC->BDCR & RCC_BDCR_LSERDY)) ;
// select LSE as RTC clock source
RCC->BDCR |= RCC_BDCR_RTCSEL_LSE;

// enable RTC clock
RCC->BDCR |= RCC_BDCR_RTCEN;

// wait for RTC registers synchronization
    RTC->CRL &= ~RTC_CRL_RSF;
    while (!(RTC->CRL & RTC_CRL_RSF));

// set RTC prescaler: set RTC period to 1sec
RTC->CRL |= RTC_CRL_CNF; // enter config mode
RTC->PRLH = 0;
RTC->PRLL = 0x8000;

AFIO->EVCR =0xAD; //PC13-calibration clock output enable
//BKP->RTCCR |= BKP_RTCCR_CCO; //Setting this bit outputs the
//RTC clock with a frequency divided by 64 on the TAMPER pin

BKP->RTCCR |= BKP_RTCCR_ASOS | BKP_RTCCR_ASOE;

RTC->CRL &= ~RTC_CRL_CNF; // exit config mode
    while (!(RTC->CRL & RTC_CRL_RTOFF));
// enable backup domain write protection
PWR->CR &= ~PWR_CR_DBP;
    while (!(RTC->CRL & RTC_CRL_RTOFF));
}



#define FIRSTYEAR   2000 // start year
#define FIRSTDAY    1 // 0 = Sunday

static const uint8_t DaysInMonth[] = { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };

/*******************************************************************************
* Function Name  : isDST
* Description    : checks if given time is in Daylight Saving time-span.
* Input          : time-struct, must be fully populated including weekday
* Output         : none
* Return         : false: no DST ("winter"), true: in DST ("summer")
*  DST according to German standard
*  Based on code from Peter Dannegger found in the microcontroller.net forum.
*******************************************************************************/
static uint8_t isDST( const RTC_t *t )
{
uint8_t wday, month; // locals for faster access

month = t->month;

if( month < 3 || month > 10 ) { // month 1, 2, 11, 12
return 0; // -> Winter
}

wday  = t->wday;

if( t->mday - wday >= 25 && (wday || t->hour >= 2) ) { // after last Sunday 2:00
if( month == 10 ) { // October -> Winter
return 0;
}
} else { // before last Sunday 2:00
if( month == 3 ) { // March -> Winter
return 0;
}
}

return 1;
}

/*******************************************************************************
* Function Name  : adjustDST
* Description    : adjusts time to DST if needed
* Input          : non DST time-struct, must be fully populated including weekday
* Output         : time-stuct gets modified
* Return         : false: no DST ("winter"), true: in DST ("summer")
*  DST according to German standard
*  Based on code from Peter Dannegger found in the microcontroller.net forum.
*******************************************************************************/
static uint32_t adjustDST( RTC_t *t )
{
uint32_t hour, day, wday, month; // locals for faster access

hour  = t->hour;
day   = t->mday;
wday  = t->wday;
month = t->month;

if ( isDST(t) ) {
t->dst = 1;
hour++; // add one hour
if( hour == 24 ){ // next day
hour = 0;
wday++; // next weekday
if( wday == 7 ) {
wday = 0;
}
if( day == DaysInMonth[month-1] ) { // next month
day = 0;
month++;
}
day++;
}
t->month = month;
t->hour  = hour;
t->mday  = day;
t->wday  = wday;
return 1;
} else {
t->dst = 0;
return 0;
}
}
/*******************************************************************************
* Function Name  : counter_to_struct
* Description    : populates time-struct based on counter-value
* Input          : - counter-value (unit seconds, 0 -> 1.1.2000 00:00:00),
*                  - Pointer to time-struct
* Output         : time-struct gets populated, DST not taken into account here
* Return         : none
*  Based on code from Peter Dannegger found in the microcontroller.net forum.
*******************************************************************************/
static void counter_to_struct( uint32_t sec, RTC_t *t )
{
uint16_t day;
uint8_t year;
uint16_t dayofyear;
uint8_t leap400;
uint8_t month;

t->sec = sec % 60;
sec /= 60;
t->min = sec % 60;
sec /= 60;
t->hour = sec % 24;
day = (uint16_t)(sec / 24);

t->wday = (day + FIRSTDAY) % 7; // weekday

year = FIRSTYEAR % 100; // 0..99
leap400 = 4 - ((FIRSTYEAR - 1) / 100 & 3); // 4, 3, 2, 1

for(;;) {
dayofyear = 365;
if( (year & 3) == 0 ) {
dayofyear = 366; // leap year
if( year == 0 || year == 100 || year == 200 ) { // 100 year exception
if( --leap400 ) { // 400 year exception
dayofyear = 365;
}
}
}
if( day < dayofyear ) {
break;
}
day -= dayofyear;
year++; // 00..136 / 99..235
}
t->year = year + FIRSTYEAR / 100 * 100; // + century

if( dayofyear & 1 && day > 58 ) { // no leap year and after 28.2.
day++; // skip 29.2.
}

for( month = 1; day >= DaysInMonth[month-1]; month++ ) {
day -= DaysInMonth[month-1];
}

t->month = month; // 1..12
t->mday = day + 1; // 1..31
}
/*******************************************************************************
* Function Name  : struct_to_counter
* Description    : calculates second-counter from populated time-struct
* Input          : Pointer to time-struct
* Output         : none
* Return         : counter-value (unit seconds, 0 -> 1.1.2000 00:00:00),
*  Based on code from "LalaDumm" found in the microcontroller.net forum.
*******************************************************************************/
static uint32_t struct_to_counter( const RTC_t *t )
{
uint8_t i;
uint32_t result = 0;
uint16_t idx, year;

year = t->year;

/* Calculate days of years before */
result = (uint32_t)year * 365;
if (t->year >= 1) {
result += (year + 3) / 4;
result -= (year - 1) / 100;
result += (year - 1) / 400;
}

/* Start with 2000 a.d. */
result -= 730485UL;

/* Make month an array index */
idx = t->month - 1;

/* Loop thru each month, adding the days */
for (i = 0; i < idx; i++) {
result += DaysInMonth[i];
}

/* Leap year? adjust February */
if (year%400 == 0 || (year%4 == 0 && year%100 !=0)) {
;
} else {
if (t->month > 1) {
result--;
}
}

/* Add remaining days */
result += t->mday;

/* Convert to seconds, add all the other stuff */
result = (result-1) * 86400L + (uint32_t)t->hour * 3600 +
(uint32_t)t->min * 60 + t->sec;

return result;
}
/*******************************************************************************
* Function Name  : rtc_gettime
* Description    : populates structure from HW-RTC, takes DST into account
* Input          : None
* Output         : time-struct gets modified
* Return         : always true/not used
*******************************************************************************/
void rtc_gettime (RTC_t *rtc)
{
uint32_t t;
t = ((uint32_t)RTC->CNTH << 16) | RTC->CNTL;
counter_to_struct( t, rtc ); // get non DST time
adjustDST( rtc );
}

/*******************************************************************************
* Function Name  : SetCounterRTC
* Description    : sets the hardware-counter
* Input          : new counter-value
* Output         : None
* Return         : None
*******************************************************************************/
 void SetCounterRTC(uint32_t cnt)
{
/* Change the current time */
RTC->CRL |= RTC_CRL_CNF;// заходим в режим конфигурации
  RTC->CNTH = cnt>>16;
RTC->CNTL = cnt;
RTC->CRL &= ~RTC_CRL_CNF; // выходим из режима конфигурации
}

/*******************************************************************************
* Function Name  : rtc_settime
* Description    : sets HW-RTC with values from time-struct, takes DST into
*                  account, HW-RTC always running in non-DST time
* Input          : None
* Output         : None
* Return         : not used
*******************************************************************************/
void rtc_settime (const RTC_t *rtc)
{
uint32_t cnt;
volatile uint16_t i;
RTC_t ts;
cnt = struct_to_counter( rtc ); // non-DST counter-value
counter_to_struct( cnt, &ts );  // normalize struct (for weekday)
if ( isDST( &ts ) ) cnt -= 60*60; // Subtract one hour
    SetCounterRTC( cnt );
}


void RTC_setup_SPL(void)
{

  /* Allow access to Backup Registers */
  PWR_BackupAccessCmd(ENABLE);

//  if(BKP_ReadBackupRegister(BKP_DR1) != CONFIGURATION_DONE)
//  {
    /* Enable Backup and Power Interface Peripheral Clocks */
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_BKP | RCC_APB1Periph_PWR, ENABLE);

    /* Backup Domain Reset */
    BKP_DeInit();

#ifdef USE_LSE_FOR_RTC

    /* Enable 32.768 kHz external oscillator */
    RCC_LSEConfig(RCC_LSE_ON);

    /* Wait for LSE to become ready */
    while (RCC_GetFlagStatus(RCC_FLAG_LSERDY) == RESET) continue;

/////////////////////////////////////////////////////////////////////
//// When 'USE_LSE_FOR_RTC' defined, code stops in previous call ////
//// whilst waiting for LSERDY flag to assert.                   ////
/////////////////////////////////////////////////////////////////////

    /* Set LSE as RTC clock source */
    RCC_RTCCLKConfig(RCC_RTCCLKSource_LSE);

#elif defined USE_LSI_FOR_RTC

    /* Enable 32.000kHz internal oscillator */
    RCC_LSICmd(ENABLE);

    /* Wait until LSI is ready */
    while (RCC_GetFlagStatus(RCC_FLAG_LSIRDY) == RESET) continue;

    /* Select LSI as RTC Clock Source */
    RCC_RTCCLKConfig(RCC_RTCCLKSource_LSI);

#endif

    /* RTC Enabled */
    RCC_RTCCLKCmd(ENABLE);

    /* Wait for RTC registers synchronisation */
    RTC_WaitForSynchro();

/////////////////////////////////////////////////////////////////////
//// When 'USE_LSI_FOR_RTC' defined, code stops in previous call ////
//// whilst waiting for RSF flag to assert.                      ////
/////////////////////////////////////////////////////////////////////

    /* Wait for last RTC operation to finish */
    RTC_WaitForLastTask();
//------------------------------------------------------------------------------
// }
}