//PROG. Version 11.10.23.17.. ..// interfacing ds1307 with 80C51.. ..#include<reg51.h>.. ../* pins used for external h/w */.. ..sbit RS=P2^1; //connect p2.1 to rs pin of lcd.. ..sbit EN=P2^3; //connect p2.3 to en pin of lcd.. ..sbit SCL=P2^4; //i2c clock pin.. ..sbit SDA=P2^5; //i2c data pin   .. ..sbit SET=P2^0; //set button pin.. ..sbit INR=P2^2; //increment button pin.. ../* some required define(s)*/.. ..#define delay_us _nop_(); //generates 1 microsecond delay.. ..#define LCD P1 //port1 connected to LCD data pins.. ..#define SCLHIGH  SCL=1;.. ..#define SCLLOW   SCL=0;.. ..#define SDAHIGH  SDA=1;.. ..#define SDALOW   SDA=0;.. ../*various functions used in whole program*/.. ..void _nop_(void);.. ..void init_lcd(void);.. ..void cmd_lcd(unsigned char);.. ..void write_lcd(unsigned char);.. ..void display_lcd(unsigned char *);.. ..void delay_ms(unsigned int); .. ..void init_rtc(void);.. ..void set_rtc(void);.. ..void strt_msg(void);.. ..void start(void);.. ..void stop(void);.. ..void send_byte(unsigned char);.. ..unsigned char receive_byte(unsigned char);.. ..void write_i2c(unsigned char,unsigned char,unsigned char);.. ..void set_value(void);.. ..void stpwtch(void);.. ..unsigned char read_i2c(unsigned char,unsigned char); .. ..//Give time here to set initial values to ds 1307 as specified in timekeeper register ..unsigned char clock[]={0x00,0x59,0x23,0x04,0x20,0x10,0x11};..//clock[]={seconds,minutes,hours,day_of_week,date,month,year};.. ..unsigned char stp[]={0x00,0x00,0x00};..//stopwatch initial value.. ..unsigned char *s[]={"SUN","MON","TUE","WED","THU","FRI","SAT"};.. ..unsigned char slave_ack,add=0,c,k,sas;.. ..unsigned int num;.. .. ..void main(void)..{..init_lcd();.. ..strt_msg();.. ..//COMMENT THIS SECTION WHILE TRANSFRING PROGRAM SECOND TIME IN H/W..init_rtc();.. ..//always do this..while(1)..{.. ..if(SET==0)..set_value();.. ..c=read_i2c(0xd0,0x02);//read hours register and display on LCD../* IMP rtc ds 1307 understands BCD no.sys. our 8051 uC understands HEX no.sys... and LCD requires ASCII data,,,,,,,,,,,,,,,,,,.. e.g. lets consider if data read from 1307 is 12 (BCD) i.e. 0001 0010 (BIN).. so 8051 consider it as 18 (DECIMAL).. x1=(18/16)+48=49(ASCII) i.e. lcd will show 1 and.. x2=(18%16)+48=50(ASCII) i.e. lcd will show 2.. i.e. 12 on lcd                                        */..write_lcd((c/16)+48);..write_lcd((c%16)+48);..write_lcd(':');..sas = c & 0x20;.. .. ..c=read_i2c(0xd0,0x01);//read minutes register and display on LCD..write_lcd((c/16)+48);..write_lcd((c%16)+48);..write_lcd(':');.. ..c=read_i2c(0xd0,0x00);//read seconds register and display on LCD..write_lcd((c/16)+48);..write_lcd((c%16)+48);..write_lcd(' ');                         .. ..display_lcd(s[read_i2c(0xd0,0x03)]);//read day register and display ..//write_lcd(*s[read_i2c(0xd0,0x03)]);.. ..cmd_lcd(0xc0);// Go to starting position of 2nd line of LCD.. ..c=read_i2c(0xd0,0x04);//read date register and display on LCD..write_lcd((c/16)+48);..write_lcd((c%16)+48);..write_lcd('/');.. ..c=read_i2c(0xd0,0x05);//read month register and display on LCD..write_lcd((c/16)+48);..write_lcd((c%16)+48);..write_lcd('/');.. ..write_lcd('2'); //write 1st 2 digits of year bcoz only last 2 bits are stored in rtc..write_lcd('0');..c=read_i2c(0xd0,0x06);//read year register and display on LCD..write_lcd((c/16)+48);..write_lcd((c%16)+48);.. ..write_lcd(32);   //THIS SECTION SHOWS am/pm..if(sas == 0x20)..{..display_lcd("AM");..//write_lcd(49);..}..else..{..//write_lcd(48);..  display_lcd("PM");..}.. ..delay_ms(110);..cmd_lcd(0x01); // Go to starting position of 1st line of LCD ..}..    ..}.. .. .. ..void start(void) //starts i2c, if both SCK & SDA are idle..{ ..if(SCL==0) //check SCK. if SCK busy, return else SCK idle..return;..if(SDA==0) //check SDA. if SDA busy, return else SDA idle..return;.. ..SDALOW //High to Low transition on data line SDA makes d start condition..delay_us.. ..SCLLOW  //clock low   ..delay_us..}.. .. ..void stop(void) //stops i2c, releasing the bus..{        ..SDALOW //data low..SCLHIGH //clock high..delay_us..SDAHIGH //Low to High transition on data line SDA makes d stop condition..delay_us..}.. .. ..void send_byte(unsigned char c) //transmits one byte of data to i2c bus..{..unsigned mask=0x80;..do   //transmits 8 bits..{..if(c&mask) //set data line accordingly(0 or 1)..SDAHIGH //data high..else..SDALOW  //data low.. ..//generate colck..SCLHIGH   //clock high..delay_us.. ..SCLLOW   //clock low..delay_us.. ..mask/=2;  //shift mask..}while(mask>0);.. ..SDAHIGH  //release data line for acknowledge..SCLHIGH  //send clock for acknowledge..delay_us..slave_ack=SDA; //read data pin for acknowledge..SCLLOW  //clock low..delay_us..}.. ..unsigned char receive_byte(unsigned char master_ack) //receives one byte of data from i2c bus..{..unsigned char c=0,mask=0x80;..do   //receive 8 bits..{..SCLHIGH //clock high..delay_us.. ..if(SDA==1) //read data..c|=mask;    //store data..   SCLLOW   //clock low..   delay_us..   mask/=2; //shift mask..}while(mask>0);.. ..if(master_ack==1)..SDAHIGH //don't acknowledge..else..SDALOW //acknowledge.. ..    SCLHIGH //clock high..    delay_us..   ..    SCLLOW //clock low..    delay_us.. ..SDAHIGH //data high.. ..return c;..}.. .. ..void write_i2c(unsigned char device_id,unsigned char location,unsigned char c)..//writes one byte of data(c) to slave device(device_id) at given address(location)..{..do..{..start();       //starts i2c bus..send_byte(device_id);   //select slave device..if(slave_ack==1)   //if acknowledge not received, stop i2c bus..stop();..}while(slave_ack==1); //loop until acknowledge is received.. ..send_byte(location); //send address location..send_byte(c); //send data to i2c bus..stop(); //stop i2c bus..}.. .. ..unsigned char read_i2c(unsigned char device_id,unsigned char location)..//reads one byte of data(c) from slave device(device_id) at given address(location)..{..unsigned char c;..do..{..start();   //starts i2c bus  ..send_byte(device_id); //select slave device..if(slave_ack==1) //if acknowledge not received, stop i2c bus..stop();..}while(slave_ack==1); //loop until acknowledge is received.. ..send_byte(location);  //send address location     ..stop(); //stop i2c bus..start(); //starts i2c bus  ..send_byte(device_id+1); //select slave device in read mode..c=receive_byte(1); //receive data from i2c bus..stop(); //stop i2c bus..return c;..}.. .. ..void init_lcd(void)..//initialize lcd..{                           ..delay_ms(10); //delay 10 milliseconds.. ..cmd_lcd(0x0e); //lcd on, cursor on..delay_ms(10);.. ..cmd_lcd(0x38); //8 bit initialize, 5x7 character font, 16x2 display..delay_ms(10);.. ..cmd_lcd(0x06); //right shift cursor automatically after each character is displayed..delay_ms(10);.. ..cmd_lcd(0x01); //clear lcd..delay_ms(10);.. ..cmd_lcd (0x80);..}.. .. ..void cmd_lcd(unsigned char c)..//transmit command or instruction to lcd..{..EN=1;..RS=0; //clear register select pin..LCD=c; //load 8 bit data..EN=0; //clear enable pin..delay_ms(2); //delay 2 milliseconds..}.. .. ..void write_lcd(unsigned char c)..//transmit a character to be displayed on lcd..{..EN=1; //set enable pin..RS=1; //set register select pin..LCD=c;  //load 8 bit data..EN=0; //clear enable pin..delay_ms(2); //delay 2 milliseconds..}.. .. ..void display_lcd(unsigned char *s)..//transmit a string to be displayed on lcd..{..while(*s)..write_lcd(*s++);..}.. .. ..void delay_ms(unsigned int i)..//generates delay in milli seconds..{..unsigned int j;..while(i-->0)..{..for(j=0;j<500;j++)..{..    ;..}..}..}   .. .. ..void set_value(void)..//this function used for setting time using SET & INC buttons or pins..{..cmd_lcd(0x80);..display_lcd("WELCOME TO TIME");..cmd_lcd(0xC0);..display_lcd(" SET WIZARD !!!");..delay_ms(300);..cmd_lcd(0x01);..cmd_lcd(0x80);..display_lcd(" SET YOUR RTC ?");..cmd_lcd(0xC0);..display_lcd("YES        NEXT");..while(1)..{..if(SET==0)..{..set_rtc();..break;..}..if(INR==0)..{..cmd_lcd(0x01);..stpwtch();..break;..}..}..}.. ..void init_rtc()..{..while(add<=6)   //update real time clock ic i.e. ds1307 with time..{..write_i2c(0xd0,add,clock[add]);..add++;..}..}.. ..void strt_msg()..{..unsigned int i,j=0;..display_lcd("Welcome to RTC");..cmd_lcd(0xc0);..display_lcd("<<<<<<<<>>>>>>>");..delay_ms(300);   //"...(#@#@#)..."..cmd_lcd(0x01);..display_lcd("SKIP INTRODUCTION");..cmd_lcd(0xc0);..display_lcd("YES           NO");..while(1)..{..if(SET==0)..{..delay_ms(40);..break;..}..if(i==1000)..{..j++;..i=0;..}..if(INR==0|j==100)..{..cmd_lcd(0x01);..display_lcd("THIS PROJECT IS");..cmd_lcd(0xc0);..display_lcd("DONE BY T.E. ELN");..delay_ms(500);..cmd_lcd(0x01);..display_lcd("<ROLL NO> <NAME>");..delay_ms(250);..cmd_lcd(0x01);..display_lcd("38 AVINASH PATIL");..cmd_lcd(0xc0);..display_lcd("44 AMIT SALUNKHE");..delay_ms(550);..cmd_lcd(0x01);..display_lcd("46 SWAPNIL SANKPAL");..cmd_lcd(0xc0);..display_lcd("48 SUMIT SHEKHAR");..delay_ms(550);..cmd_lcd(0x01);..display_lcd("49 PRANAV SHINDE");..delay_ms(300);..cmd_lcd(0x01);..display_lcd("STARTING RTC....");..cmd_lcd(0xC0);..for(i=0;i<17;i++)..{..display_lcd(".");..delay_ms(15);..}..break;..}..i++;..}..cmd_lcd(0x01);..}.. ..void set_rtc()..{..    unsigned char cnt=0x00;..unsigned char q,p,i=0x00;..while(1)..{..if(SET==0x00)..{..cnt++;..delay_ms(50);..cmd_lcd(0x01); // Go to starting position of 1st line of LCD ..cmd_lcd(0xc0);..display_lcd("NEXT     INC");..cmd_lcd(0x80);..switch(cnt)..{..case 1:..  display_lcd("Minutes:");..break;..case 2:..  display_lcd("Hours  :");..break;..case 3:..  display_lcd("Day    :");..break;..case 4:..  display_lcd("Date   :");..break;..case 5:..  display_lcd("Month  :");..break;..  case 6:..  display_lcd("Year   :");..}..}..if(INR==0)..break;..if(cnt>6)..return;..}..cmd_lcd(0xc0);..display_lcd("SAVE     INC");..while(1)..{  if(INR==0).. {..      delay_ms(10);   ..  cmd_lcd(0x8A); // Go to starting position of 2nd line of LCD ..  p++;..  delay_ms(20);..   switch(cnt)..{..case 1:..if(p>59)..{..  p=0;..}..break;..case 2:..  if(p>23)..{..  p=0;..}..   break;..case 3:..  if(p>7)..{..  p=0;..}..break;..case 4:..  if(p>31)..{..  p=0;..}..break;..case 5:..  if(p>12)..{..  p=0;..}..       break;..  case 6:..  if(p>99)..{..  p=0;..}..}   ..  q=(p/10)<<4;..  q=q|(p%10);..  write_lcd((q/16)+48);..  write_lcd((q%16)+48);.. }..if(SET==0)..  break;..}..write_i2c(0xD0,cnt,q);..cmd_lcd(0x01);..display_lcd("SAVING CHAGES");..cmd_lcd(0xc0);..display_lcd("PLEASE WAIT");..// delay_ms(100);..for(i=0;i<6;i++)..{..display_lcd(".");..delay_ms(40);..}..cmd_lcd(0x01);..}