GNU ARM汇编--(十)s3c2440的RTC

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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 resetcopyleft@  dndxhej@gmail.com*/.equ   NOINT, 0xc0.equ GPBCON,0x56000010  @led.equGPBDAT,0x56000014  @led.equ   GPBUP,        0x56000018    @led.equ GPFCON, 0x56000050  @interrupt config.equEINTMASK, 0x560000a4.equ EXTINT0,  0x56000088.equ EXTINT1,  0x5600008c.equ EXTINT2,  0x56000090.equINTMSK, 0x4A000008.equ   EINTPEND,     0x560000a8.equSUBSRCPND,  0x4a000018 .equINTSUBMSK,  0x4a00001c.equ   SRCPND,   0X4A000000.equ   INTPND,   0X4A000010.equGPHCON,0x56000070.equGPHDAT,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)  .equLOCKTIME, 0x4c000000.equMPLLCON, 0x4c000004.equUPLLCON, 0x4c000008.equM_MDIV, 92.equ   M_PDIV, 1.equM_SDIV, 1.equU_MDIV, 56.equ   U_PDIV, 2.equU_SDIV, 2.equCLKDIVN, 0x4c000014.equDIVN_UPLL, 0.equHDIVN,1.equPDIVN,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.equTCFG0,0x51000000.equPrescaler1,0x00   @[15:8]Timer234.equPrescaler0,249   @[7:0]Timer01.equTCFG1,0x51000004.equDMA_MODE,0x0        @[23:20]no dma channal.equMUX0,0x2            @[3:0]   1/8@定时器输入时钟周期 = PCLK/(prescaler + 1)/(divider value)@clk = 100M/(249+1)/8=25k.equTCON,0x51000008.equDZ_eable,0    @[4]关闭死区的操作.equauto_reload,1    @[3]auto_reload.equinverter,1@[2]打开电平反转.equman_update,1   @[1]手动更新.equ   clear_man_update,0.equstart,1@[0]开始.equstop,0@[0]停止.equTCNTB0,0x5100000c       .equTCMPB0,0x51000010.equTCNTO0,0x51000014.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.equBCDMIN,0x57000074.equBCDSEC,0x57000070//.global Buzzer_Freq_Set.global _start_start:bresetldr     pc, _undefined_instructionldr pc, _software_interruptldrpc, _prefetch_abortldrpc, _data_abortldrpc, _not_used@birqldr pc, _irqldr 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 16,0xdeadbeefreset:ldr     r3, =WTCONmovr4, #0x0                     strr4, [r3]@ disable watchdog    ldrr0, =GPBCONldrr1, =0x15400     @这个时候暂不配置GPB0为TOUT0strr1, [r0]ldrr2, =GPBDATldrr1, =0x160strr1, [r2]bl clock_setupbl uart_initbl 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@--------------------------------------------ldrr0, =GPBUPldrr1, =0x03f0  strr1, [r0]         ldrr0, =GPFCONldrr1, =0x2ea@0x2    strr1, [r0]  ldrr0, =EXTINT0@ldrr1, =0x8f888@0x0@0x8f888      @~(7|(7<<4)|(7<<8)|(7<<16))   //低电平触发中断ldrr1, =0xafaaa@0x0@0x8f888      //下降沿触发中断strr1, [r0]  ldrr0, =EINTPENDldrr1, =0xf0@0b10000strr1, [r0]  ldrr0, =EINTMASKldrr1, =0x00@0b00000strr1, [r0]  ldrr0, =SRCPNDldrr1, =0x3ff | (1<<30) @0x1@0b11111strr1, [r0]  ldrr0, =SUBSRCPNDldrr1, =0x1<<13strr1, [r0]  ldrr0, =INTPNDldrr1, =0x3ff | (1<<30) @0x1@0b11111strr1, [r0]  ldrr0, =INTSUBMSKldrr1, =0x0<<13strr1, [r0]  ldrr0, =INTMSKldrr1, =0x1ffff000@0b00000strr1, [r0]  MRS r1, cpsrBIC r1, r1, #0x80MSR cpsr_c, r1bl     mainirq:sub lr,lr,#4stmfdsp!,{r0-r12,lr}bl irq_isrldmfd  sp!,{r0-r12,pc}^ irq_isr:ldrr2, =GPBDATldrr1, =0x0e0strr1, [r2]ldr r3,=0xffffffdelay2:sub r3,r3,#1cmp r3,#0x0bne 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] ldrr0, =SRCPNDldrr1, =0x3ff | (1<<30) @0b11111strr1, [r0]  ldrr0, =SUBSRCPNDldrr1, =0x1<<13strr1, [r0]  ldrr0, =INTPNDldrr1, =0x3ff | (1<<30) @0b11111strr1, [r0]  ldrr2, =GPBCONldrr1,[r2]ldrr1,[r1]//ldrr1, =0x15400bicr1,r1,#0x3orrr1,r1,#0x2strr1,[r2]ldrr2, =GPBDATldrr1, =0x1a0strr1, [r2]ldr r1,=TCFG0ldr r2,=(Prescaler0<<0)str r2, [r1]ldr r1,=TCFG1ldr r2,=(DMA_MODE<<20) | (MUX0<<0)str r2, [r1]//ldrr3,[r0]//strr3,[r2]//mov  r2, r0ldr r1,=TCNTB0ldr r2,=10str r2, [r1]        //r0就是c调用汇编的传递参数//mov  r0,r0,LSR #2ldr r1,=TCMPB0ldr r2,=2str r2, [r1]ldr r1,=TCONldr r2,=(DZ_eable<<4) | (auto_reload<<3) | (inverter<<2) | (man_update<<1) | (start<<0)str r2, [r1]ldr r1,=TCONldr r2,=(DZ_eable<<4) | (auto_reload<<3) | (inverter<<2) | (clear_man_update<<1) | (start<<0)str r2, [r1]ldrr2, =GPBDATldrr1, =0x1a0strr1, [r2]mov pc,lrdelay:ldr r3,=0xffffffdelay1:sub r3,r3,#1cmp r3,#0x0bne delay1mov pc,lrclock_setup:ldr r0,=LOCKTIMEldr r1,=0xffffffffstr r1, [r0]ldr r0,=CLKDIVNldr r1,=(DIVN_UPLL<<3) | (HDIVN<<1) | (PDIVN<<0)str r1, [r0]ldr r0,=UPLLCONldr r1,=(U_MDIV<<12) | (U_PDIV<<4) | (U_SDIV<<0)   @Fin=12M  UPLL=48Mstr r1, [r0]nopnopnopnopnopnopnopldr r0,=MPLLCONldr r1,=(M_MDIV<<12) | (M_PDIV<<4) | (M_SDIV<<0)    @Fin=12M  FCLK=400Mstr r1, [r0]mov pc,lruart_init:ldr r0,=GPHCONldr r1,=0x2aaaa     @配置GPIO复用规则为串口str r1, [r0]ldr r0,=ULCON0ldr r1,=(IR_MODE<<6) | (Parity_Mode<<3) | (Num_of_stop_bit<<2) | (Word_length<<0)    @str r1, [r0]ldr r0,=UCON0ldr 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,=UFCON0ldr 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,=UBRDIV0ldr r1,=(UBRDIV<<0)str r1, [r0]    mov pc,lr/*Buzzer_Freq_Set://ldrr0, =GPBCON//ldrr1, =0x15400     @这个时候暂不配置GPB0为TOUT0，这时候只是配置GPB0为TOUT0//strr1, [r0]ldrr2, =GPBCONldrr1,[r2]ldrr1,[r1]//ldrr1, =0x15400bicr1,r1,#0x3orrr1,r1,#0x2strr1,[r2]ldrr2, =GPBDATldrr1, =0x1a0strr1, [r2]ldr r1,=TCFG0ldr r2,=(Prescaler0<<0)str r2, [r1]ldr r1,=TCFG1ldr r2,=(DMA_MODE<<20) | (MUX0<<0)str r2, [r1]//ldrr3,[r0]//strr3,[r2]//mov  r2, r0ldr r1,=TCNTB0ldr r2,=10str r2, [r1]        //r0就是c调用汇编的传递参数//mov  r0,r0,LSR #2ldr r1,=TCMPB0ldr r2,=2str r2, [r1]ldr r1,=TCONldr r2,=(DZ_eable<<4) | (auto_reload<<3) | (inverter<<2) | (man_update<<1) | (start<<0)str r2, [r1]ldr r1,=TCONldr r2,=(DZ_eable<<4) | (auto_reload<<3) | (inverter<<2) | (clear_man_update<<1) | (start<<0)str r2, [r1]ldrr2, =GPBDATldrr1, =0x1a0strr1, [r2]movpc,lr*/main:ldrr2, =GPBDATldrr1, =0x1a0strr1, [r2]bl delay//ldr r1,=TCON//ldr r2,=(DZ_eable<<4) | (auto_reload<<3) | (inverter<<2) | (man_update<<1) | (stop<<0)//str r2, [r1]/*ldrr2, =GPBCONldrr1,[r2]ldrr1,[r1]//ldrr1, =0x15400bicr1,r1,#0x3orrr1,r1,#0x2strr1,[r2]ldr r0,=TCFG0ldr r1,=(Prescaler0<<0)str r1, [r0]ldr r0,=TCFG1ldr r1,=(DMA_MODE<<20) | (MUX0<<0)str r1, [r0]ldr r0,=TCNTB0ldr r1,=10str r1, [r0]ldr r0,=TCMPB0ldr r1,=2str r1, [r0]ldr r0,=TCONldr r1,=(DZ_eable<<4) | (auto_reload<<3) | (inverter<<2) | (man_update<<1) | (start<<0)str r1, [r0]ldr r0,=TCONldr r1,=(DZ_eable<<4) | (auto_reload<<3) | (inverter<<2) | (clear_man_update<<1) | (start<<0)str r1, [r0]*/                                              ldr lr, =loop   //ldrpc, _rtc_uart_test//_rtc_uart_test:.word rtc_uart_testbl rtc_uart_testldrr2, =GPBDATldrr1, =0x1c0strr1, [r2]bl delayloop:ldr r2, =BCDSEC   @BCDMINldr r1,[r2]cmp     r1, #0x06    bleq     ledon     b loop                                               @ 死循环ledon:ldrr2, =GPBDATldrr1, =0x160strr1, [r2]ldr r3,=0xffffffdelay3:sub r3,r3,#1cmp r3,#0x0bne delay3mov pc,lrundefined_instruction:nopsoftware_interrupt:nopprefetch_abort:nopdata_abort:nopnot_used:nopfiq: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  20000freq += 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～～