?RTC(Real-Time Clock) 實時時鐘。RTC是集成電路，通常稱為時鐘芯片。在一個嵌入式系統中，通常采用RTC來提供可靠的系統時間，包括時分秒和年月日等，而且要求在系統處于關機狀態下它也能正常工作（通常采用后備電池供電）。它的外圍也不需要太多的輔助電路，典型的就是只需要一個高精度的32.768kHz 晶體和電阻電容等。

?

一、RTC 控制器

??????? 實時時鐘（RTC）單元可以通過備用電池供電，因此，即使系統電源關閉，它也可以繼續工作。RTC可以通過STRB/LDRB 指令將8位BCD碼數據送至CPU。這些BCD數據包括秒、分、時、日期、星期、月和年。RTC單元通過一個外部的32.768kHz 晶振提供時鐘。RTC具有定時報警的功能。

??????? 其功能說明如下：

1 -- 時鐘數據采用BCD編碼。

2 -- 能夠對閏年的年月日進行自動處理。

3 -- 具有告警功能，當系統處于關機狀態時，能產生警告中斷。

4 -- 具有獨立的電源輸入。

5 -- 提供毫秒級時鐘中斷，該中斷可以用于作為嵌入式操作系統的內核時鐘。

?

二、RTC 控制器寄存器詳解

1 、Time Tick Generator?

???????

?

下面是示例程序：

頭文件定義：

[cpp]?view plaincopy

/**********************************RTC?independ?register********************************/??

#define?????RTCINTP?????????__REG(0X10070030)??

#define?????RTCCON??????????__REG(0X10070040)??

#define?????TICCNT??????????__REG(0X10070044)??

#define?????CURTICCNT???????__REG(0X10070090)??

??

typedef?struct?{??

????????????????unsigned?int?ALM;??

????????????????unsigned?int?SEC;??

????????????????unsigned?int?MIN;??

????????????????unsigned?int?HOUR;??

????????????????unsigned?int?DAY;??

????????????????unsigned?int?MON;??

????????????????unsigned?int?YEAR;??

}rtclam;??

??

#define?????RTCALM?(*?(volatile?rtclam?*)0X10070050)??

??

??

typedef?struct?{??

??

????????????????unsigned?int?BCDSEC;??

????????????????unsigned?int?BCDMIN;??

????????????????unsigned?int?BCDHOUR;??

????????????????unsigned?int?BCDWEEK;??

????????????????unsigned?int?BCDDAY;??

????????????????unsigned?int?BCDMON;??

????????????????unsigned?int?BCDYEAR;??

}rtcbcd;??

#define?????RTC?(*?(volatile?rtcbcd?*)0X10070070)??

C程序如下：

[cpp]?view plaincopy

#include?"exynos_4412.h"??

??

void?mydelay_ms(int?time)??

{??

????int?i,?j;??

????while(time--)??

????{??

????????for?(i?=?0;?i?<?5;?i++)??

????????????for?(j?=?0;?j?<?514;?j++);??

????}??

}??

//*(volatile?unsigned?int?*)(0x11000c20)?=?0;??

/*??

?*??裸機代碼，不同于LINUX?應用層，?一定加循環控制??

?*/??

void?do_irq(void)??

{??

????static?int?a?=?1;??

????int?irq_num;??

????irq_num?=?CPU0.ICCIAR&0x3ff;??//獲取中斷號??

????switch(irq_num)??

????{??

????case?57:??

????????printf("in?the?irq_handler\n");??

????????????EXT_INT41_PEND?=?EXT_INT41_PEND?|((0x1?<<?1));?//清GPIO中斷標志位??

????????????ICDICPR.ICDICPR1?=?ICDICPR.ICDICPR1?|?(0x1?<<?25);?//清GIC中斷標志位??

????????break;??

????case?76:??

????????printf("in?the?alarm?interrupt!\n");??

????????RTCINTP??=?RTCINTP?|?(1?<<?1);??

????????ICDICPR.ICDICPR2?=?ICDICPR.ICDICPR2?|?(0x1?<<?12);?//清GIC中斷標志位??

????????break;??

????case?77:??

????????????printf("in?the?tic?interrupt!\n");??

????????????RTCINTP??=?RTCINTP?|?(1?<<?0);??

????????????ICDICPR.ICDICPR2?=?ICDICPR.ICDICPR2?|?(0x1?<<?13);?//清GIC中斷標志位??

????????????break;??

????}??

????CPU0.ICCEOIR?=?CPU0.ICCEOIR&(~(0x3ff))|irq_num;?//清cpu中斷標志位??

}??

void?rtc_init(void)??

{??

????RTCCON?=?1;??

????RTC.BCDYEAR?=?0x16;??

????RTC.BCDMON?=?0x2;??

????RTC.BCDDAY?=?0x25;??

????RTC.BCDHOUR?=?0x15;??

????RTC.BCDMIN?=?0x24;??

????RTC.BCDSEC?=?0x50;??

????RTCCON?=?0;??

}??

void?rtc_tic(void)??

{??

????RTCCON?=?RTCCON?&?(~(0xf?<<?4))?|?(1?<<?8);??

????TICCNT?=?32768;??

??

????ICDDCR?=?1;??//使能分配器??

????ICDISER.ICDISER2?=?ICDISER.ICDISER2?|?(0x1?<<?13);?//使能相應中斷到分配器??

????ICDIPTR.ICDIPTR19?=?ICDIPTR.ICDIPTR19?&?(~(0xff?<<?8))|(0x1?<<?8);?//選擇CPU接口??

????CPU0.ICCPMR?=?255;?//中斷屏蔽優先級??

????CPU0.ICCICR?=?1;???//使能中斷到CPU??

}??

void?rtc_alarm(void)??

{??

????RTCALM.ALM?=?(1?<<?6)|(1?<<?0);??

????RTCALM.SEC?=?0x58;??

????ICDDCR?=?1;??//使能分配器??

????ICDISER.ICDISER2?=?ICDISER.ICDISER2?|?(0x1?<<?12);?//使能相應中斷到分配器??

????ICDIPTR.ICDIPTR19?=?ICDIPTR.ICDIPTR19?&?(~(0xff?<<?0))|(0x1?<<?0);?//選擇CPU接口??

????CPU0.ICCPMR?=?255;?//中斷屏蔽優先級??

????CPU0.ICCICR?=?1;???//使能中斷到CPU??

}??

int?main?(void)??

{??

????rtc_init();??

????rtc_alarm();??

????rtc_tic();??

????while(1)??

????{??

????????printf("%x?%x?%x?%x?%x?BCDSEC?=?%x\n",RTC.BCDYEAR,??

????????RTC.BCDMON,??

????????RTC.BCDDAY,??

????????RTC.BCDHOUR,??

????????RTC.BCDMIN,RTC.BCDSEC);??

????????mydelay_ms(1000);??

??

????}??

???return?0;??

}??

執行結果如下：

[cpp]?view plaincopy

16?2?5?15?24?BCDSEC?=?50??

in?the?tic?interrupt!??

16?2?5?15?24?BCDSEC?=?51??

in?the?tic?interrupt!??

16?2?5?15?24?BCDSEC?=?52??

in?the?tic?interrupt!??

16?2?5?15?24?BCDSEC?=?53??

16?2?5?15?24?BCDSEC?=?53??

16?2?5?15?24?BCDSEC?=?54??

in?the?tic?interrupt!??

16?2?5?15?24?BCDSEC?=?55??

in?the?tic?interrupt!??

16?2?5?15?24?BCDSEC?=?56??

in?the?tic?interrupt!??

in?the?alarm?interrupt!??

16?2?5?15?24?BCDSEC?=?58??

in?the?tic?interrupt!??

16?2?5?15?24?BCDSEC?=?59??

in?the?tic?interrupt!??

16?2?5?15?25?BCDSEC?=?0??

in?the?tic?interrupt!??

16?2?5?15?25?BCDSEC?=?1??

in?the?tic?interrupt!??

16?2?5?15?25?BCDSEC?=?2??

in?the?tic?interrupt!??

16?2?5?15?25?BCDSEC?=?3??

in?the?tic?interrupt!??

16?2?5?15?25?BCDSEC?=?4??

in?the?tic?interrupt!??

16?2?5?15?25?BCDSEC?=?5??

in?the?tic?interrupt! ?

總結

以上是生活随笔為你收集整理的Exynos4412裸机开发 —— RTC 实时时钟单元的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。