GNU ARM汇编--(十)s3c2440的RTC

RTC


概述
    在系统电源关掉时RTC可以在备份电池的支持下来工作.RTC可以使用STRB/LDRB指令传输8bit的BCD值到CPU.数据包括秒,分,时,日期,天,月和年.RTC工作在外部32.768KHz的晶振下,而且有报警功能.


属性
    BCD:秒,分,时,日期,天,月和年
    闰年产生器
    报警功能:报警中断  从power-off模式唤醒
    独立的电源管脚(RTCVDD)
    为RTOS kernel time tick支持毫秒级的tick.


闰年产生器
    闰年产生器通过BCDDATA，BCDMON和BCDYEAR来决定每个月最后一天的日期.一个8bit的计数器只能表示两个BCD码,所以无法决定'00'年是否是闰年.举个例子,它不能区分1900和2000.为了解决这个问题,s3c2440的RTC模块在硬件逻辑上支持闰年是2000.1900不是闰年而2000时闰年.因此s3c2440的00表示2000,而不是1900.


READ/WRITE REGISTERS
    为了写BCD寄存器,RTCCON寄存器的第0位必须置高.为了显示秒,分,时,日期,月和年,CPU从BCDSEC,BCDMIN,BCDHOUR,BCDDAY,BCDDATE,BCDMON和BCDYEAR寄存器中读数据.然而,在读取多个寄存器时,可能会有1秒的偏移.比如,当user读数据的时候,假设结果是2059(Year),12(Month),31(Date),23(Hour)和59(Minute).当user读BCDSEC寄存器,值的范围是1--59s,到这没有问题,但是,如果这个值是0s,由于刚才提到的那一s的偏移,年月日时分就会变为2060(year),1(Month),1(Date),0(Hour)和0(Minute).在这种情况下,如果BCDSEC是0 user应该重读各个寄存器.


BACKUP BATTERY OPERATION
    RTC由备份电池驱动,及时系统电源断了,备份电池可以通过RTCVDD管脚向RTC模块供电.当系统关闭,CPU和RTC逻辑之间的接口是封闭的,备份电池只是驱动晶振电路和BCD计数器来减少电源消耗.


ALARM FUNCTION
    在power-off模式或者正常操作模式下,RTC可以在一个指定的时间产生一个报警信号.在正常操作模式下,报警中断(INT_RTC)是激活的.在power-off模式,电源管理唤醒信号(PMWKUP)和INT_RTC都是激活的.RTC报警寄存器(RTCALM)决定是否开启报警状态和报警时间的设置.


TICK TIME INTERRUPT
    RTC的tick time用于中断请求.TICNT寄存器有中断使能位和中断的计数值.当tick time中断产生计数值为0.中断的周期:
Period = (n+1)/128 second
n:Tick time count value(1~127)


REAL TIME CLOCK SPECIAL REGISTERS
RTCCON
    RTCCON控制4个bits,比如RTCEN控制BCD寄存器的读写使能,CLKSEL,CNTSEL和CLKRST是用于测试的.
    RTCEN bit控制CPU与RTC之间的所有接口,所以在系统重启后应该在RTC控制程序中将其设为1来使能数据的读写.在电源关闭前,RTCEN应该清0来防止对RTC寄存器的不经意的写入.
Register          Address             R/W          Description       Reset Value
RTCCON   0x57000040(L)/0x57000043(B)  R/W      RTC control register     0x0


RTCCON            Bit            Description               Initial State
RTCEN             [0]            RTC控制使能                   0
注意：所有的RTC寄存器都要以字节为单位来访问,可以用STRB和LDRB汇编指令或者char类型的指针.


TICNT
Register          Address                   R/W               Description             Reset Value
TICNT      0x57000044(L)/0x57000047(B)     R/W(by byte)     Tick time count register     0x0


TICNT              BIT                     Description           Initial State
TICK INT ENABLE    [7]                 tick time 中断使能             0
TICK TIME COUNT    [6:0]               tick time 计数值(1~127)       000000


RTCALM
RTCALM决定alarm使能和alarm时间.在power-off模式下RTCALM寄存器通过INT_RTC和PWMKUP产生报警信号,而在正常模式下只通过INT_RTC.


Register                     Address                      R/W           Description      Reset Value
RTCALM             0x57000050(L)/0x57000053(B)         R/W(by type)   RTC报警控制寄存器     0x0


RTCALM            Bit                            Description                       Initial State
ALMEN             [6]                            报警总开关                          0
YEAREN            [5]                            Year报警开关                        0
MONREN            [4]                            Month报警开关                       0
DATEEN            [3]                            Date报警开关                        0
HOUREN            [2]                            Hour报警开关                        0
MINEN             [1]                            Minute报警开关                      0
SECEN             [0]                            Second报警开关                      0


ALMSEC
设置Second报警的具体秒数
ALMMIN
设置Minute报警的具体分钟数
ALMHOUR
设置Hour报警的具体小时数
ALMDATE
设置Date报警的具体日期
ALMMON
设置Mon报警的具体月份
ALMYEAR
设置Year报警的具体年份


BCDSEC BCDMIN BCDHOUR BCDDATE BCDMON BCDYEAR

用BCD码表示的秒 分 时 日期 月份 年

 

给出报警中断的rtc汇编和c代码如下,在报警中断时是调用PWM的蜂鸣器来做闹钟的:

start.S:

 

/*
watchdog timer with disable reset
copyleft@  [email protected]
*/

.equ   NOINT, 0xc0

.equ    GPBCON, 0x56000010      @led
.equ    GPBDAT, 0x56000014      @led
.equ   GPBUP,        0x56000018    @led
.equ    GPFCON, 0x56000050      @interrupt config
.equ    EINTMASK, 0x560000a4
.equ    EXTINT0,  0x56000088
.equ    EXTINT1,  0x5600008c
.equ    EXTINT2,  0x56000090
.equ    INTMSK,  0x4A000008
.equ   EINTPEND,     0x560000a8

.equ    SUBSRCPND,  0x4a000018
.equ    INTSUBMSK,  0x4a00001c



.equ   SRCPND,   0X4A000000
.equ   INTPND,   0X4A000010


.equ    GPHCON, 0x56000070
.equ    GPHDAT, 0x56000074

.equ GPB5_out,  (1<<(5*2))
.equ GPB6_out,  (1<<(6*2))
.equ GPB7_out,  (1<<(7*2))
.equ GPB8_out,  (1<<(8*2))

.equ GPBVALUE,    (GPB5_out | GPB6_out | GPB7_out | GPB8_out)

.equ    LOCKTIME, 0x4c000000
.equ    MPLLCON, 0x4c000004
.equ    UPLLCON, 0x4c000008
.equ    M_MDIV, 92
.equ   M_PDIV, 1
.equ    M_SDIV, 1
.equ    U_MDIV, 56
.equ   U_PDIV, 2
.equ    U_SDIV, 2

.equ    CLKDIVN, 0x4c000014
.equ    DIVN_UPLL, 0
.equ    HDIVN,  1
.equ    PDIVN,  1    @FCLK : HCLK : PCLK = 1:2:4


.equ    WTCON,  0x53000000
.equ    Pre_scaler,  249
.equ    wd_timer,   1
.equ    clock_select,   00   @316
.equ    int_gen,    1     @开中断
.equ    reset_enable,   0  @关掉重启信号

.equ    WTDAT,0x53000004
.equ    Count_reload,50000    @定时器定为2S PCLK = 100M   PCLK/(Pre_scaler+1)/clock_select = 100M/(249+1)/16=25k   50000/25k=2s

.equ    WTCNT,0x53000008
.equ    Count,50000


.equ    TCFG0,0x51000000
.equ    Prescaler1,0x00   @[15:8]Timer234
.equ    Prescaler0,249   @[7:0]Timer01

.equ    TCFG1,0x51000004
.equ    DMA_MODE,0x0        @[23:20]no dma channal
.equ    MUX0,0x2            @[3:0]   1/8
@定时器输入时钟周期 = PCLK/(prescaler + 1)/(divider value)
@clk = 100M/(249+1)/8=25k

.equ    TCON,0x51000008
.equ    DZ_eable,0    @[4]关闭死区的操作
.equ    auto_reload,1    @[3]auto_reload
.equ    inverter,1  @[2]打开电平反转
.equ    man_update,1   @[1]手动更新
.equ   clear_man_update,0
.equ    start,1 @[0]开始
.equ    stop,0      @[0]停止

.equ    TCNTB0,0x5100000c
.equ    TCMPB0,0x51000010

.equ    TCNTO0,0x51000014


.equ    ULCON0, 0x50000000
.equ    IR_MODE,    0x0   @[6]正常模式
.equ    Parity_Mode,    0x0 @[5:3]无校验位
.equ    Num_of_stop_bit,  0x0  @[2]一个停止位
.equ    Word_length,    0b11    @[1:0]8个数据位

.equ    UCON0,  0x50000004
.equ    FCLK_Div,   0   @[15:12]  时钟源选择用PCLK,所以这里用默认值
.equ    Clk_select, 0b00    @[11:10] 时钟源选择使用PCLK
.equ    Tx_Int_Type, 1  @[9]  中断请求类型为Level
.equ    Rx_Int_Type, 0 @1  @[8]  中断请求类型为Level
.equ    Rx_Timeout, 0  @[7]
.equ    Rx_Error_Stat_Int, 1 @[6]
.equ    Loopback_Mode, 0 @[5]  正常模式
.equ    Break_Sig,  0 @[4] 不发送终止信号
.equ    Tx_Mode,    0b01 @[3:2]  中断请求或轮循模式
.equ    Rx_Mode,    0b01 @[1:0]  中断请求或轮循模式

.equ    UFCON0, 0x50000008
.equ    Tx_FIFO_Trig_Level, 0b00 @[7:6]
.equ    Rx_FIFO_Trig_Level, 0b00 @[5:4]
.equ    Tx_FIFO_Reset,  0b0 @[2]
.equ    Rx_FIFO_Reset,  0b0 @[1]
.equ    FIFO_Enable,    0b0 @[0] 非FIFO模式

.equ    UMCON0, 0x5000000C    @这个寄存器可以不管的
.equ    UTRSTAT0,   0x50000010
.equ    UERSTAT0,   0x50000014
.equ    UFSTAT0,    0x50000018
.equ    UMSTAT0,    0x5000001C
.equ    UTXH0,      0x50000020   @(L 小端)
.equ    URXH0,      0x50000024   @(L 小端)

.equ     UBRDIV0,    0x50000028
.equ     UBRDIV,    0x35   @PCLK=400M/4=100M   UBRDIV = (int)(100M/115200/16) - 1 = 53 = 0x35


.equ    BCDMIN,0x57000074

.equ    BCDSEC,0x57000070

//.global Buzzer_Freq_Set

.global _start
_start:     b   reset
        ldr     pc, _undefined_instruction
        ldr     pc, _software_interrupt
        ldr pc, _prefetch_abort
        ldr pc, _data_abort
        ldr pc, _not_used
        @b  irq
        ldr     pc, _irq
        ldr     pc, _fiq



_undefined_instruction:     .word undefined_instruction
_software_interrupt:        .word software_interrupt
_prefetch_abort:        .word prefetch_abort
_data_abort:            .word data_abort
_not_used:          .word not_used
_irq:               .word irq
_fiq:               .word fiq

.balignl 16,0xdeadbeef

reset:


    ldr     r3, =WTCON
    mov r4, #0x0
    str r4, [r3]    @ disable watchdog

    ldr r0, =GPBCON
    ldr r1, =0x15400     @这个时候暂不配置GPB0为TOUT0
    str r1, [r0]

    ldr r2, =GPBDAT
    ldr r1, =0x160
    str r1, [r2]

    bl clock_setup
    bl uart_init
    bl delay


    msr cpsr_c, #0xd2 @进入中断模式
    ldr sp, =3072 @中断模式的栈指针定义

    msr cpsr_c, #0xd3 @进入系统模式
    ldr sp, =4096 @设置系统模式的栈指针

@--------------------------------------------

    ldr r0, =GPBUP
    ldr r1, =0x03f0
    str r1, [r0]

    ldr r0, =GPFCON
    ldr r1, =0x2ea@0x2
    str r1, [r0]

    ldr r0, =EXTINT0
    @ldr    r1, =0x8f888@0x0@0x8f888      @~(7|(7<<4)|(7<<8)|(7<<16))   //低电平触发中断
    ldr r1, =0xafaaa@0x0@0x8f888      //下降沿触发中断
    str r1, [r0]

    ldr r0, =EINTPEND
    ldr r1, =0xf0@0b10000
    str r1, [r0]

    ldr r0, =EINTMASK
    ldr r1, =0x00@0b00000
    str r1, [r0]



    ldr r0, =SRCPND
    ldr r1, =0x3ff | (1<<30) @0x1@0b11111
    str r1, [r0]

    ldr r0, =SUBSRCPND
    ldr r1, =0x1<<13
    str r1, [r0]

    ldr r0, =INTPND
    ldr r1, =0x3ff | (1<<30) @0x1@0b11111
    str r1, [r0]

    ldr r0, =INTSUBMSK
    ldr r1, =0x0<<13
    str r1, [r0]

    ldr r0, =INTMSK
    ldr r1, =0x1ffff000@0b00000
    str r1, [r0]

    MRS r1, cpsr
    BIC r1, r1, #0x80
    MSR cpsr_c, r1


    bl     main

irq:
    sub     lr,lr,#4
    stmfd   sp!,{r0-r12,lr}


    bl irq_isr
    ldmfd  sp!,{r0-r12,pc}^


irq_isr:

    ldr r2, =GPBDAT
    ldr r1, =0x0e0
    str r1, [r2]

    ldr r3,=0xffffff

delay2:
    sub r3,r3,#1

    cmp r3,#0x0

    bne delay2

    //这上面的延时必须要，否则蜂鸣器的声音有问题
         ldr r0,=EINTPEND
         ldr r1,=0xf0
         str r1,[r0]

    ldr r0, =SRCPND
    ldr r1, =0x3ff | (1<<30) @0b11111
    str r1, [r0]

    ldr r0, =SUBSRCPND
    ldr r1, =0x1<<13
    str r1, [r0]

    ldr r0, =INTPND
    ldr r1, =0x3ff | (1<<30) @0b11111
    str r1, [r0]



    ldr r2, =GPBCON
    ldr r1,[r2]
    ldr r1,[r1]
    //ldr   r1, =0x15400
    bic r1,r1,#0x3
    orr r1,r1,#0x2
    str r1,[r2]

    ldr r2, =GPBDAT
    ldr r1, =0x1a0
    str r1, [r2]

    ldr r1,=TCFG0
    ldr r2,=(Prescaler0<<0)
    str r2, [r1]

    ldr r1,=TCFG1
    ldr r2,=(DMA_MODE<<20) | (MUX0<<0)
    str r2, [r1]

//  ldr r3,[r0]
//  str r3,[r2]



    //mov  r2, r0

    ldr r1,=TCNTB0
    ldr r2,=10
    str r2, [r1]        //r0就是c调用汇编的传递参数

    //mov  r0,r0,LSR #2

    ldr r1,=TCMPB0
    ldr r2,=2
    str r2, [r1]



    ldr r1,=TCON
    ldr r2,=(DZ_eable<<4) | (auto_reload<<3) | (inverter<<2) | (man_update<<1) | (start<<0)
    str r2, [r1]

    ldr r1,=TCON
    ldr r2,=(DZ_eable<<4) | (auto_reload<<3) | (inverter<<2) | (clear_man_update<<1) | (start<<0)
    str r2, [r1]

    ldr r2, =GPBDAT
    ldr r1, =0x1a0
    str r1, [r2]





    mov pc,lr


delay:

    ldr r3,=0xffffff

delay1:
    sub r3,r3,#1

    cmp r3,#0x0

    bne delay1

    mov pc,lr


clock_setup:

    ldr r0,=LOCKTIME
    ldr r1,=0xffffffff
    str r1, [r0]

    ldr r0,=CLKDIVN
    ldr r1,=(DIVN_UPLL<<3) | (HDIVN<<1) | (PDIVN<<0)
    str r1, [r0]

    ldr r0,=UPLLCON
    ldr r1,=(U_MDIV<<12) | (U_PDIV<<4) | (U_SDIV<<0)   @Fin=12M  UPLL=48M
    str r1, [r0]
    nop
    nop
    nop
    nop
    nop
    nop
    nop
    ldr r0,=MPLLCON
    ldr r1,=(M_MDIV<<12) | (M_PDIV<<4) | (M_SDIV<<0)    @Fin=12M  FCLK=400M
    str r1, [r0]



    mov pc,lr


uart_init:
    ldr r0,=GPHCON
    ldr r1,=0x2aaaa     @配置GPIO复用规则为串口
    str r1, [r0]

    ldr r0,=ULCON0
    ldr r1,=(IR_MODE<<6) | (Parity_Mode<<3) | (Num_of_stop_bit<<2) | (Word_length<<0)    @
    str r1, [r0]

    ldr r0,=UCON0
    ldr r1,=(FCLK_Div<<12) | (Clk_select<<10) | (Tx_Int_Type<<9) | (Rx_Int_Type<<8) | (Rx_Timeout<<7) | (Rx_Error_Stat_Int<<6) |(Loopback_Mode<<5) | (Break_Sig<<4) | (Tx_Mode<<2) | (Rx_Mode<<0)
    str r1, [r0]

    ldr r0,=UFCON0
    ldr r1,=(Tx_FIFO_Trig_Level<<6) | (Rx_FIFO_Trig_Level<<4) | (Tx_FIFO_Reset<<2) | (Rx_FIFO_Reset<<1) | (FIFO_Enable<<0)    @
    str r1, [r0]

    ldr r0,=UBRDIV0
    ldr r1,=(UBRDIV<<0)
    str r1, [r0]

        mov pc,lr

/*
Buzzer_Freq_Set:

    //ldr   r0, =GPBCON
    //ldr   r1, =0x15400     @这个时候暂不配置GPB0为TOUT0，这时候只是配置GPB0为TOUT0
    //str   r1, [r0]



    ldr r2, =GPBCON
    ldr r1,[r2]
    ldr r1,[r1]
    //ldr   r1, =0x15400
    bic r1,r1,#0x3
    orr r1,r1,#0x2
    str r1,[r2]

    ldr r2, =GPBDAT
    ldr r1, =0x1a0
    str r1, [r2]

    ldr r1,=TCFG0
    ldr r2,=(Prescaler0<<0)
    str r2, [r1]

    ldr r1,=TCFG1
    ldr r2,=(DMA_MODE<<20) | (MUX0<<0)
    str r2, [r1]

//  ldr r3,[r0]
//  str r3,[r2]



    //mov  r2, r0

    ldr r1,=TCNTB0
    ldr r2,=10
    str r2, [r1]        //r0就是c调用汇编的传递参数

    //mov  r0,r0,LSR #2

    ldr r1,=TCMPB0
    ldr r2,=2
    str r2, [r1]



    ldr r1,=TCON
    ldr r2,=(DZ_eable<<4) | (auto_reload<<3) | (inverter<<2) | (man_update<<1) | (start<<0)
    str r2, [r1]

    ldr r1,=TCON
    ldr r2,=(DZ_eable<<4) | (auto_reload<<3) | (inverter<<2) | (clear_man_update<<1) | (start<<0)
    str r2, [r1]

    ldr r2, =GPBDAT
    ldr r1, =0x1a0
    str r1, [r2]

    mov pc,lr
*/
main:

    ldr r2, =GPBDAT
    ldr r1, =0x1a0
    str r1, [r2]
    bl delay

    //ldr r1,=TCON
    //ldr r2,=(DZ_eable<<4) | (auto_reload<<3) | (inverter<<2) | (man_update<<1) | (stop<<0)
    //str r2, [r1]

/*
    ldr r2, =GPBCON
    ldr r1,[r2]
    ldr r1,[r1]
    //ldr   r1, =0x15400
    bic r1,r1,#0x3
    orr r1,r1,#0x2
    str r1,[r2]



    ldr r0,=TCFG0
    ldr r1,=(Prescaler0<<0)
    str r1, [r0]

    ldr r0,=TCFG1
    ldr r1,=(DMA_MODE<<20) | (MUX0<<0)
    str r1, [r0]


    ldr r0,=TCNTB0
    ldr r1,=10
    str r1, [r0]

    ldr r0,=TCMPB0
    ldr r1,=2
    str r1, [r0]



    ldr r0,=TCON
    ldr r1,=(DZ_eable<<4) | (auto_reload<<3) | (inverter<<2) | (man_update<<1) | (start<<0)
    str r1, [r0]

    ldr r0,=TCON
    ldr r1,=(DZ_eable<<4) | (auto_reload<<3) | (inverter<<2) | (clear_man_update<<1) | (start<<0)
    str r1, [r0]

*/







       ldr lr, =loop
 // ldr pc, _rtc_uart_test
//_rtc_uart_test:   .word rtc_uart_test
    bl rtc_uart_test

    ldr r2, =GPBDAT
    ldr r1, =0x1c0
    str r1, [r2]
    bl delay
loop:
    ldr r2, =BCDSEC   @BCDMIN
    ldr r1,[r2]
    cmp     r1, #0x06
        bleq     ledon


        b loop                                               @ 死循环

ledon:
    ldr r2, =GPBDAT
    ldr r1, =0x160
    str r1, [r2]

    ldr r3,=0xffffff

delay3:
    sub r3,r3,#1

    cmp r3,#0x0

    bne delay3
    mov pc,lr



undefined_instruction:
            nop
software_interrupt:
            nop
prefetch_abort:
            nop
data_abort:
            nop
not_used:
            nop
fiq:
            nop

rtc_uart_test.s:

 

 

#include <stdarg.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>

#include "rtc_uart_test.h"
extern void Buzzer_Freq_Set(int freq);
//extern void Buzzer_Freq_Set( void );
char uart_GetByte(void)
{
        while(!(rUTRSTAT0 & 0x1));   //Wait until THR is empty.
            return RdURXH0();
}


void uart_GetString(char *pt)
{
    while(*pt)
        uart_GetByte();
}


void uart_SendByte(int data)
{

        if(data=='\n')
        {
            while(!(rUTRSTAT0 & 0x2));
            WrUTXH0('\r');
        }
        while(!(rUTRSTAT0 & 0x2));   //Wait until THR is empty.
        WrUTXH0(data);

}

//====================================================================
void uart_SendString(char *pt)
{
    while(*pt)
           uart_SendByte(*pt++);
}

void uart_Printf(char *fmt,...)
{
    va_list ap;
    char string[256];

    va_start(ap,fmt);
    //vsprintf(string,fmt,ap);
    uart_SendString(string);
    va_end(ap);
}

void uart_test(void)
{

    char str[20] = "\nhello world\n";
    int a = 97;
    //while(1)
    //  uart_SendByte(a);
    uart_SendString(str);
    char s = uart_GetByte();
    //if(s == 'a')
    if(s == 97)
        rGPBDAT = 0x1c0;
    //uart_SendByte(a);
    //uart_SendByte(97);
    //uart_SendByte('a');
    uart_SendByte((int)s);
    uart_SendByte((int)'s');
}


void rtc_uart_test(void)
{
    rRTCCON = 0x1;
    rTICNT = 0x0;
    rRTCALM = 0x42;



    rBCDYEAR = 0x10 ;
    rBCDMON  = 0x11 ;
    rBCDDATE = 0x07 ;
    rBCDDAY  = 0x05 ;
    rBCDHOUR = 0x12 ;
    rBCDMIN  = 0x03 ;
    rBCDSEC  = 0x00 ;

    rALMMIN = 0x04;
    uart_SendString("begin\n");
    //uart_Printf("year:%d\n",rBCDYEAR);
}


void pwm_uart_test(void)
{
    int freq = 10;
    int i;
    for(i=0; i<100;i++)
    uart_SendString("app\n");
    //Buzzer_Freq_Set( freq ) ;
    //Buzzer_Freq_Set(  ) ;
    //uart_test();
    uart_SendString("start\n");
/*
    int i;
    for(i=0;i<1000;i++)
        uart_SendString("wait\n");
    while( 1 )
    {
        char key = uart_GetByte();
        uart_SendByte(key);
        if( key == 'a' || key == 'A' )
        {
            if( freq < 2000 )  //lci  20000
                freq += 10 ;
                uart_SendByte('a');
            Buzzer_Freq_Set( freq ) ;
        }

        if( key == 'b' || key == 'B' )
        {
            if( freq > 11 )
                freq -= 10 ;
                uart_SendByte('b');
            Buzzer_Freq_Set( freq ) ;
        }

        //uart_SendString( "\tFreq = %d\n", freq ) ;
        //if( key == ESC_KEY )
        //{
        //  Buzzer_Stop() ;
        //  return ;
        //}

    }

*/
}

在调这个过程中,因为RTCCON中的CLKRST最初被我置为1,导致时间根本不走,为了查这个问题,专门通过led显示来判断这个时间是不是不走:

 

ldr r2, =BCDSEC   @BCDMIN
ldr r1,[r2]
cmp     r1, #0x06
    bleq     ledon

通过这里的判断,可以明确时间有被设进去,可是时间不走.经过google,才确定是寄存器的设置问题.

 

到此,rtc的闹钟也实现了功能.明天就用这个做闹钟吧～～

 

                                                                                                          转载于：blog.csdn.net/dndxhej