Driver for the real-time clock chip DS1302 based on single-chip microcomputer-EEWORLD

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This program realizes the rotation display of time and calendar.

Since it was debugged on January 5, 2011, the initial time is set to 11:59:58, and the calendar is 11-01-05

// Title: Experiment with digital tube display clock

// Through this routine, you can understand the basic principles and usage of the DS1302 clock chip, understand and master the DS1302 clock chip

// Write the driver and implement the display of digital characters in the digital tube.

// Please digest this example carefully and understand the operation of DS1302 in C language

#include //Include the header file. Generally, no modification is required. The header file contains the definition of special function registers.

#include

sbit SCK=P3^6; //clock

sbit SDA=P3^4; //data

sbit RST = P3^5; // DS1302 reset

sbit LS138A=P2^2; //74LS138 and MCU interface

sbit LS138B=P2^3;

sbit LS138C=P2^4;

bit ReadRTC_Flag; //define read DS1302 flag

unsigned char l_tmpdate[7]={88,89,17,5,1,3,17}; //seconds, minutes, days, months, and years 11-01-05 Wed 11:59:58

//unsigned char l_tmpdate[7]={88,89,9,5,1,3,17}; //seconds, minutes, days, months, and years 11-01-05 Wed 9:59:58

unsigned char l_tmpdisplay[8]; //Display intermediate variables

code unsigned char write_rtc_address[7]={0x80,0x82,0x84,0x86,0x88,0x8a,0x8c};

code unsigned char read_rtc_address[7]={0x81,0x83,0x85,0x87,0x89,0x8b,0x8d};

//Seconds, minutes, hours, days, months, and years lowest digit read and write register

code unsigned char table[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x40};

//Common cathode digital tube 0-9 '-' 'off' table

// Function declaration //

void Write_Ds1302_byte(unsigned char temp);

void Write_Ds1302( unsigned char address,unsigned char dat );

unsigned char Read_Ds1302 ( unsigned char address );

void Read_RTC(void);//read RTC

void Set_RTC(void); //set RTC

void InitTIMER0(void);//inital timer0

// Main function //

delay(char m)

{

int i,j,k;

for(i=m;i>0;i--)

for(j=255;j>0;j--)

for(k=255;k>0;k--);

}

void main(void)

{

int i,j;

InitTIMER0(); //Initialize timer 0

Set_RTC();

//Write the clock value. If you use a backup battery, you don't need to write it every time you power on. This program should be blocked.

while(1)

{

if(ReadRTC_Flag)

{

ReadRTC_Flag=0;

//The hour, minute, second, year, month, and day registers store binary BCD codes. The processing method is as follows:

//Data conversion, because we use digital tube 0~9 to display, separate the data

//Read time

for(i=0;i<2000;i++)

{ l_tmpdisplay[0]=l_tmpdate[2]/16;

l_tmpdisplay[1]=l_tmpdate[2]&0x0f;

l_tmpdisplay[2]=10; //加入"-"

l_tmpdisplay[3]=l_tmpdate[1]/16;

l_tmpdisplay[4]=l_tmpdate[1]&0x0f;

l_tmpdisplay[5]=10;

l_tmpdisplay[6]=l_tmpdate[0]/16;

l_tmpdisplay[7]=l_tmpdate[0]&0x0f;

Read_RTC();

}

for(j=0;j<1000;j++) //Read date

{

l_tmpdisplay[0]=l_tmpdate[6]/16;

l_tmpdisplay[1]=l_tmpdate[6]&0x0f;

l_tmpdisplay[2]=10; //加入"-"

l_tmpdisplay[3]=l_tmpdate[4]/16;

l_tmpdisplay[4]=l_tmpdate[4]&0x0f;

l_tmpdisplay[5]=10;

l_tmpdisplay[6]=l_tmpdate[3]/16;

l_tmpdisplay[7]=l_tmpdate[3]&0x0f;

Read_RTC();

}

// Timer 0 initialization //

void InitTIMER0(void)

{

TMOD|=0x01; //Timer setting 16 bits

TH0=0xef; //initialization value

TL0=0xf0;

ET0=1;

TR0=1;

EA=1;

}

// Write a byte //

void Write_Ds1302_Byte(unsigned char temp)

{

unsigned char i;

for (i=0;i<8;i++) //Loop 8 times to write data

{

SCK=0;

SDA=temp&0x01; //Transmit low byte each time

temp>>=1; //Move right one bit

SCK=1;

}

// Write to DS1302 //

void Write_Ds1302( unsigned char address,unsigned char dat )

{

RST=0;

_nop_();

SCK=0;

_nop_();

RST=1;

_nop_(); //Start

Write_Ds1302_Byte(address); //Send address

Write_Ds1302_Byte(dat); //Send data

RST=0; //Resume

}

// Read DS1302 data //

unsigned char Read_Ds1302 ( unsigned char address )

{

unsigned char i,temp=0x00;

RST=0;

_nop_();

SCK=0;

_nop_();

RST=1;

_nop_();

Write_Ds1302_Byte(address);

for (i=0;i<8;i++) //Loop 8 times to read data

{

if(SDA)

temp|=0x80; //transmit low byte each time

SCK=0;

temp>>=1; //Move right one bit

_nop_();

SCK=1;

}

RST=0;

return (temp); //Return

}

// Read clock data //

void Read_RTC(void) //Read calendar

{

unsigned char i,*p;

p=read_rtc_address; //address transfer

for(i=0;i<7;i++) //Read the second, minute, hour, day, month, and year in 7 times

{

l_tmpdate[i]=Read_Ds1302(*p);

p++;

}

// Set clock data //

void Set_RTC(void) //Set the calendar

{

unsigned char i,*p,tmp;

Write_Ds1302(0x8E,0X00); //Disable write protection

p=write_rtc_address; //Transfer address

for(i=0;i<7;i++) //Write the second, minute, hour, day, month, and year for 7 times

{

Write_Ds1302(*p,l_tmpdate[i]);

p++;

}

Write_Ds1302(0x8E,0x80); //Open write protection

}

//Timer interrupt function//

void tim(void) interrupt 1 using 1

//Interrupt, used for digital tube scanning

{

static unsigned char i,num;

TH0=0xf5;

TL0=0xe0;

P0=table[l_tmpdisplay[i]];

//Look up the table to get the digital segment of the number to be displayed

switch(i)

{

case 0:LS138A=0; LS138B=0; LS138C=0; break;

case 1:LS138A=1; LS138B=0; LS138C=0; break;

case 2:LS138A=0; LS138B=1; LS138C=0; break;

case 3:LS138A=1; LS138B=1; LS138C=0; break;

case 4:LS138A=0; LS138B=0; LS138C=1; break;

case 5:LS138A=1; LS138B=0; LS138C=1; break;

case 6:LS138A=0; LS138B=1; LS138C=1; break;

case 7:LS138A=1; LS138B=1; LS138C=1; break;

}

i++;

if(i==8)

{

i=0;

num++;

if(10==num) //Read the data of 1302 at intervals. The time interval can be adjusted

{

ReadRTC_Flag=1; //Use flag bit to judge

num=0;

}

Keywords：MCU Reference address：Driver for the real-time clock chip DS1302 based on single-chip microcomputer

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