BLE协议栈里有已经封装好的RTC时钟，时钟源可以是外部晶体振荡时钟也可以是内部RC时钟。

The32-kHzXOSC is designed to operate at32.768kHzand provide a stable clock signal for systems requiring time accuracy.The 32-kHz RCOS runs at32.753kHzwhen calibrated.

外部晶振更加精准一些！

主要的函数在OSAL_ClockBLE.c中;

void osalTimeUpdate( void )  
{  
  uint16 tmp;      //为暂存变量，用于临时存放时间值   
  uint16 ticks625us;  //用于存放timer2的溢出次数，每次溢出为625us，也就是说ticks625us代表了625us的个数  
  uint16 elapsedMSec = 0;//也是用来存放时间值的，只是它存放的值是上一次操作所保留下来的值，它最终存放的是时间的ms值  
  
  
  // Get the free-running count of 625us timer ticks  
  tmp = ll_McuPrecisionCount();//这个函数就是用来读取timer2溢出次数的，溢出次数存放在T2MOVF2（[23:16]）,T2MOVF2([15:8]), T2MOVF0([7:0]), 一共有24bit  
  
  if ( tmp != previousLLTimerTick )//判断时间是否有变化（正常情况下，随着程序的运行，tmp 这个值一直增大（16-bit））  
  {  
    // Calculate the elapsed ticks of the free-running timer.  
    ticks625us = tmp - previousLLTimerTick;//当前的时间值减去上一次的值，也就是代码再一次运行到这里所消耗的时间（注意单位为625us）  
  
    // Store the LL Timer tick count for the next time through this function.  
    previousLLTimerTick = tmp;//将当前值存储起来，为程序下一次运行到这里作准备  
  /* 
  下面红色部分的代码，都只是实现了一个功能，就是将ticks625us个625us 转换成 elapsedMSec 个ms（ms的整数部分）和remUsTicks 个us（ms的小数部分），“ *5 / 8” 等价于 “ *625 / 1000”（分子分母同时扩大40倍），同理“ *5 % 8” 等价于 “*625 % 1000”  至于MAXCALCTICKS ，程序中有一下两段注释，可以帮助我们理解  
  // (MAXCALCTICKS * 5) + (max remainder) must be <= (uint16 max), 
  // so: (13105 * 5) + 7 <= 65535 
  #define MAXCALCTICKS  ((uint16)(13105)) 
   
  */  
  
  
    /* It is necessary to loop to convert the usecs to msecs in increments so as 
     * not to overflow the 16-bit variables. 
     */  
    while ( ticks625us > MAXCALCTICKS )//这个while是对溢出的操作  
    {  
      ticks625us -= MAXCALCTICKS;  
      elapsedMSec += MAXCALCTICKS * 5 / 8;  
      remUsTicks += MAXCALCTICKS * 5 % 8;  
    }  
  
    // update converted number with remaining ticks from loop and the  
    // accumulated remainder from loop  
    tmp = (ticks625us * 5) + remUsTicks;  
  
    // Convert the 625 us ticks into milliseconds and a remainder  
    elapsedMSec += tmp / 8;  
    remUsTicks = tmp % 8;  
  
    // Update OSAL Clock and Timers  
    if ( elapsedMSec )//判断时间是否到了1ms，如果等于或者超过1ms（elapsedMSec  >= 1），则需要轮询任务列表  
    {  
      osalClockUpdate( elapsedMSec );//更新osal操作系统的系统时间  
      osalTimerUpdate( elapsedMSec );//这个函数和任务的轮询调度有关，即和timeout有关  
    }  
  }  
}  

当然还有设置时间函数（UTCTime是从2000年1月1日00:00：00到至今的秒数）

/********************************************************************* 
 * @fn      osal_setClock 
 * 
 * @brief   Set the new time.  This will only set the seconds portion 
 *          of time and doesn't change the factional second counter. 
 * 
 * @param   newTime - number of seconds since 0 hrs, 0 minutes, 
 *                    0 seconds, on the 1st of January 2000 UTC 
 * 
 * @return  none 
 */  
void osal_setClock( UTCTime newTime )  
{  
  OSAL_timeSeconds = newTime;  
}  

获得当前时间函数：

/********************************************************************* 
 * @fn      osal_getClock 
 * 
 * @brief   Gets the current time.  This will only return the seconds 
 *          portion of time and doesn't include the factional second 
 *          counter. 
 * 
 * @param   none 
 * 
 * @return  number of seconds since 0 hrs, 0 minutes, 0 seconds, 
 *          on the 1st of January 2000 UTC 
 */  
UTCTime osal_getClock( void )  
{  
  return ( OSAL_timeSeconds );  
}  

将秒数转换为年月日时分秒格式储存在结构体UTCTimeStruct（定义在OSAL_Clock.h）中

/********************************************************************* 
 * @fn      osal_ConvertUTCTime 
 * 
 * @brief   Converts UTCTime to UTCTimeStruct 
 * 
 * @param   tm - pointer to breakdown struct 
 * 
 * @param   secTime - number of seconds since 0 hrs, 0 minutes, 
 *          0 seconds, on the 1st of January 2000 UTC 
 * 
 * @return  none 
 */  
void osal_ConvertUTCTime( UTCTimeStruct *tm, UTCTime secTime )  
{  
  // calculate the time less than a day - hours, minutes, seconds  
  {  
    uint32 day = secTime % DAY;  
    tm->seconds = day % 60UL;  
    tm->minutes = (day % 3600UL) / 60UL;  
    tm->hour = day / 3600UL;  
  }  
  
  // Fill in the calendar - day, month, year  
  {  
    uint16 numDays = secTime / DAY;  
    tm->year = BEGYEAR;  
    while ( numDays >= YearLength( tm->year ) )  
    {  
      numDays -= YearLength( tm->year );  
      tm->year++;  
    }  
  
    tm->month = 0;  
    while ( numDays >= monthLength( IsLeapYear( tm->year ), tm->month ) )  
    {  
      numDays -= monthLength( IsLeapYear( tm->year ), tm->month );  
      tm->month++;  
    }  
  
    tm->day = numDays;  
  }  
}  

校准时间时将年月日时分秒格式转换为秒的函数;

/********************************************************************* 
 * @fn      osal_ConvertUTCSecs 
 * 
 * @brief   Converts a UTCTimeStruct to UTCTime 
 * 
 * @param   tm - pointer to provided struct 
 * 
 * @return  number of seconds since 00:00:00 on 01/01/2000 (UTC) 
 */  
UTCTime osal_ConvertUTCSecs( UTCTimeStruct *tm )  
{  
  uint32 seconds;  
  
  /* Seconds for the partial day */  
  seconds = (((tm->hour * 60UL) + tm->minutes) * 60UL) + tm->seconds;  
  
  /* Account for previous complete days */  
  {  
    /* Start with complete days in current month */  
    uint16 days = tm->day;  
  
    /* Next, complete months in current year */  
    {  
      int8 month = tm->month;  
      while ( --month >= 0 )  
      {  
        days += monthLength( IsLeapYear( tm->year ), month );  
      }  
    }  
  
    /* Next, complete years before current year */  
    {  
      uint16 year = tm->year;  
      while ( --year >= BEGYEAR )  
      {  
        days += YearLength( year );  
      }  
    }  
  
    /* Add total seconds before partial day */  
    seconds += (days * DAY);  
  }  
  
  return ( seconds );  
}  

example:

 har tempbuf[10]={0};  
 UTCTimeStruct *Ti;  
   
 osalTimeUpdate();    
 osal_ConvertUTCTime(Ti,osal_getClock());  
  tempbuf[0]=(Ti->hour)/10+'0';  
 tempbuf[1]=(Ti->hour)%10+'0';  
 tempbuf[2]=(Ti->minutes)/10+'0';  
 tempbuf[3]=(Ti->minutes)%10+'0';  
 tempbuf[4]=(Ti->seconds)/10+'0';  
 tempbuf[5]=(Ti->seconds)%10+'0';  
 Uart0Send_String(tempbuf,10);// 将时分秒在串口打印