Monday, January 19, 2015

RTC using Ds1307 and 89c52 with Multiplex 7-segment display

  RTC using Ds1307 and 89c52 with Multiplex 7-segment display

Salam ....Friends in this tutorial ,we are interfacing real time clock Ds1307 with 89c52 and displaying time on multiplex 7-segment display .In google there are many related projects about the Real Time Clock but no one use the 7-segment display so my method  is different and less expensive ,because i don't use the crystal LCD. step1 is about RTC and I2c .

RTC  is an electronic device which  plays an essential role in realtime embedded system design. It provides a  precise time and date in various applications such as system clock, student attendance system and alarm etc, that keep track on current time and provides consistent result to the respective task. This article presents RTC interfacing with 8051microcotrollerand basic accessing of internal registers.

RTC Programming and Interfacing

RTC  interfacing with 89c52 microcontroller is similar to all other kinds of  “Real Time Clocks” interfaced to it. So let us look on simple RTC interfacing with 89c52 microcontroller and programming procedure involving in it.

Step1: Select RTC Device

The various kinds of RTC chips are available in the real time embedded world, which are classified based on various criteria such as package type, supply voltage and pin configuration etc.  A few types of RTC devices are;
  • Two-Wire Serial Interface (I2C Bus)
  • Three-Wire Serial Interface (USB BUS)
  • Four-wire Serial interface (SPI BUS)
First, we need to select type of RTC device by category based on requirement like I2C Bus RTC or SPI Bus RTC or other, which suitsfor interfacingwith respective microcontroller. Then we can select features of RTC device depending on requirement of application such as battery life, suitable package and clock frequency. Let us consider two-wire interfacing RTC with 8051 microcontroller such as DS1307.


Step2: Internal Register and Address of the RTC Device

RTC stands for real time clock  which provides years, months, weeks, days, hours, minutes and seconds based on crystal frequency. RTC consists of inbuilt RAM memory for data storage. A battery backup will be provided in case of failure of main power supply by connecting a battery to RTC device.

RTC DB1307 Configuration:

RTC Internal Blocks and Pin Diagram
RTC Internal Blocks and Pin Diagram
A0, A1, A2: are address pins of RTC DB1307 chip, which can be used to communicate with the  master device. We can control eight devices with RTC interfacing with 89c52 microcontroller by A0, A1, A2 bits using I2C protocol.
VCC and GND: VCC and GND are power supply and ground pins respectively. This device operated with 1.8V to 5.5V range.
VBT: VBT is a battery power supply pin. Battery power source must be held between 2V to 3.5V.
SCL: SCL is a serial clock pin and it is used to synchronize data on serial interface.
SDL: It is a serial input and output pin. It is used to transmit and receive the data on serial interface.
Clock Out: It is an optional square wave  output pin.
OSC0 and OSC1: These are crystal oscillator pins which are used to provide the clock signals to the RTC device. The standard quartz crystal frequency is 22.768KHzs.

Device Addressing:

I2C bus protocol allows many slave devices at a time. Every slave device must consist of own address to represent on it. The master device communicates with particular slave device by an address. RTC device address  is “0xA2”  wherein “1010” is given by manufacturer  and A0, A1, A2 are user define address, which is used to communicate eight RTC devices on the I2C bus protocol.
Device Addresing
Device Addresing
R/W bit is used to perform read and write operations in RTC. If R/W=0, write operation is performed and R/W=1 for read operation.
Address of Read operation of RTC= “0xA3”
Address of Write operation of RTC= “0xA2”

Memory Registers and Address:

RTC registers are located in address locations from 00h to 0Fh and RAM memory registers are located in address locations from 08h to3Fh as shown in figure. RTC registers are used to provide calendar functionality and drive time of day and to display the weekends.
Memory Registers and Address
Memory Registers and Address
Control/Status Registers:
DB1307 consists of two additional registers such as control/status1 and control/status2 which are used to control real time clock and interrupts.
Control/Status Register1:
Control Status Register1
Control Status Register1
  • TEST1=0 normal mode
             =1 EXT-clock test mode
  • STOP=0 RTC starts
              =1 RTC stop
  • TESTC=0 power on reset disabled
              = power on reset enabled
Control/Status Register2:
Control Status Register2
Control Status Register2
  • TI/TP= 0 INT active all the time
=1 INT active required time
  • AF=0 Alarm does not match
=1 Alarm match
  • TF=0 Timer overflow does not occur
=1 Timer overflow occurs
  • ALE=0 Alarm interrupts disable
             =1 Alarm interrupts enabled
  • TIE=0 Timer interrupts disable
              =1 Timer interrupts enable

Step3: Interfacing RTC ds1307 with 89c52

RTC can be interfaced to microcontroller by using different serial bus protocols such as I2C and SPI protocols that provide communication link between them. The figure shows,  real time clock interfacing with 89c52/8051 microcontroller using I2C bus protocol. I2C is a bi-directional serial protocol, which consist of two wires such as SCL and SDA to transfer data between devices connected to bus. 89c52 microcontroller has no inbuilt RTC device therefore we have connected externally through a serial communication for ensuring the consisting data.



I2C devices have open drain outputs therefore, a pull-up resistors must be connected to the I2C bus line with a voltage source. If the resistors are not connected to the SCL and SDL lines, the bus will not work.

Step4: RTC Data Framing Format

Since RTC  interfacing with 89c52 microcontroller uses I2C bus therefore the data transfer is in the form of bytes or packets and each byte is followed by an acknowledgement.
Transmitting Data Frame:
In transmitting mode, the master release the start condition after selecting slave device by address bit. The address bit contains 7-bit, which indicate the slave devices as ds1307 address. Serial data and serial clock are transmitted on SCL and SDL lines. START and STOP conditions are  recognized as beginning and ending of a serial transfer.  Receive and transmit operations are followed by the R/W bit.
Transmitting Data Frame
Transmitting Data Frame
Start: Primarily, the data transfer sequence initiated by the master generating the start condition.
7-bit Address: After that the master sends the slave address in two 8-bit formats instead of a single 16-bit address.
Control/Status Register Address: The control/status register address is to allow the control status registers.
Control/Status Register1: The control status register1 used to enable the RTC device
Control/Status Register2: It is used to enable and disable interrupts.
R/W: If read and write bit is low, then the write operation is performed.
ACK: If write operation is performed in the slave device, then the receiver sends 1-bit ACK to microcontroller.
Stop: After completion of write operation in the slave device, microcontroller sends stop condition to the slave device.
Receiving Data Frame:
Receiving Data Frame
Receiving Data Frame
Start: Primarily, the data transfer sequence initiated by the master generating the start condition.
7-bit Address: After that the master sends slave address in two 8-bit formats instead of a single 16-bit address.
Control/Status Register Address: The control/status register address is to allow control status registers.
Control/Status Register1: The control status register1 used to enable the RTC device
Control/Status Register2:  It is used to enable and disable interrupts.
R/W: If read and write bit is high, then the read operation is performed.
ACK: If write operation is performed in the slave device, then the receiver sends 1-bit ACK to microcontroller.
Stop: After completion of write operation in the slave device, microcontroller sends stop condition to the slave device.

Step5: RTC Programming

Write Operation from Master to Slave:
  1. Issue the start condition from master to slave
  2. Transfer the slave address in write mode on SDL line
  3. Send the control register address
  4. Send the control/status register1value
  5. Send the control/status register2 value
  6. Send the date of the like  minutes, seconds and hours
  7. Send the stop bit

    Coding :

    MAIN CODE :

    #include <AT89X52.h>
    #define DS1307_ID 0xD0     // DS1307 ID
    #define SEC_ADDRESS   0x00 // Address to access Ds1307 SEC register
    #define DATE_ADDRESS  0x04 // Address to access Ds1307 DATE register
    #define CONTROL 0x07       // Address to access Ds1307 CONTROL register
    #define DELAY 1000
    sbit seg_1= P2^0;      
    sbit seg_2= P2^1;      
    sbit seg_3= P2^2;
    sbit seg_4= P2^3; 
    sbit SCL=P1^0;      //SCL Connected to P1.0
    sbit SDA=P1^1;      //SDA Connected to P1.1
    sbit mode = P2^4;
    sbit set_low = P2^5;
    sbit set_high = P2^6;


    extern void delay_sec(unsigned char sec_count);
    extern void delay_ms(unsigned int ms_count);
    extern void delay_for_segments(unsigned int ms_count);
    extern void delay_us(unsigned int us_count);
    extern void delay_us_seg(unsigned int us_count);
    extern void I2C_Clock(void);
    extern void I2C_Start();
    extern void I2C_Stop(void);
    extern void I2C_Write(unsigned char dat);
    extern unsigned char I2C_Read(void);
    extern void I2C_Ack();
    extern void I2C_NoAck();
    extern void DS1307_Init();
    extern void DS1307_Write(unsigned char dat);
    extern unsigned char DS1307_Read();
    extern void DS1307_SetTime(unsigned char hh, unsigned char mm, unsigned char ss);
    extern void DS1307_SetDate(unsigned char dd, unsigned char mm, unsigned char yy);
    extern void DS1307_GetTime(unsigned char *h_ptr,unsigned char *m_ptr,unsigned char *s_ptr);
    extern void DS1307_GetDate(unsigned char *d_ptr,unsigned char *m_ptr,unsigned char *y_ptr);
    unsigned char hex2bcd (unsigned char x);              
    unsigned char bcd_value;
    unsigned char hour,min,sec,year,month,date,set_h,set_m,set_s,set_d,set_mon,set_y,blank=11;
    unsigned char hour_tens,min_tens,sec_tens,month_tens,year_tens,date_tens;
    const unsigned char bcd_to_segment[12]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90,0x7F,0xFF};
    unsigned char D1,D2,D3,D4;
    enum states {
      SHOW_TIME,
      SHOW_DATE,
      SHOW_YEAR,
        SETL_TIME,
        SETH_TIME,
        SET_DATE,
        SET_YEAR
      };

    void timer2() interrupt 5
    {
       
       
        seg_1=0;
      seg_2=0;
      seg_3=0;
        seg_4=0;
       
        delay_ms(1);  
        P0 = bcd_to_segment[D1];
        seg_1 = 1;
     
        delay_us(DELAY);
        seg_1 = 0;

        delay_ms(1);  
        P0 = bcd_to_segment[D2];
        seg_2 = 1;
       
      delay_us(DELAY);
        seg_2 = 0;
       
        delay_ms(1);  
        P0 = bcd_to_segment[D3];
        seg_3 = 1;
       
        delay_us(DELAY);
        seg_3 = 0;
       
        delay_ms(1);  
        P0 = bcd_to_segment[D4];
        seg_4 = 1;
       
        delay_us(DELAY);
        seg_4 = 0;
        delay_ms(1);                        
        TF2=0;                                             //clear Timer2 flag
    }                                                   // interrupt closed

    /*  
    void timer0(void) interrupt 1
    {
          


    void ISR_ex0(void) interrupt 0
    {
        led=0;delay_sec(1);led=1;
    }*/
    void main()
    {
        enum states state = SHOW_TIME;

        D1 = D2 = D3 = D4 = 0;
        RCAP2L = 0x30;                   // lower value
        RCAP2H = 0xf8;                 // Specific values for 10ms
      ET2 = 1; 
        /*TMOD=0x01;
        TH0=0x18;
        TL0=0xfc;
        TR0=1;
        ET0=1;
                           
        //IE0=1;                      
               */
       
        set_h=0x12,set_m=0x11,set_s=0x00,set_d=0x17,set_mon=0x01,set_y=0x15; // setting time
        DS1307_Init();
        DS1307_SetTime(set_h,set_m,set_s);
        DS1307_SetDate(set_d,set_mon,set_y);
        set_low = 1;
        set_high = 1;
        mode = 1;
        TR2 = 1;
      EA = 1;  
       
        while(1)
        {   
            DS1307_GetTime(&hour,&min,&sec);
            sec_tens = sec & 0x0F;
            sec     = sec >> 4 ;
            min_tens = min & 0x0F;
            min     = min >> 4 ;
            hour_tens = hour & 0x0F;
            hour     = hour >> 4 ;
          
            DS1307_GetDate(&date,&month,&year);           
            date_tens = date & 0x0F;
            date     = date >> 4 ;
            month_tens = month & 0x0F;
            month     = month >> 4 ;
            year_tens = year & 0x0F;
            year     = year >> 4 ;
              
            switch(state)
            {
                case SHOW_TIME:
                    D1=hour;D2=hour_tens;D3=min;D4=min_tens;
                            if(set_low==0)                               // if the lower buuton is pressed
                                {
                                        set_h++;                                    // then after some delay ,  increment the hour
                                        hex2bcd(set_h);                             // convert the hex value into bcd value
                                        if(set_h<=12)                              // this is check for hours
                                            DS1307_SetTime(bcd_value,set_m,set_s);        // now the hour is updated with return bcd value
                                        else set_h=0;                             // if values (hour value greater than 12 then hour=00 )
                                }
                              
                                if(set_high==0)                               // if the higer button is pressed
                                {
                                        set_m++;                                    // then after some delay ,  increment the hour
                                        hex2bcd(set_m);                             // convert the hex value into bcd value
                                        if(set_m<=59)                               // check for mints
                                            DS1307_SetTime(set_h,bcd_value,set_s);        // now the mints is updated with return bcd value
                                        else set_m=0;                             // if mins greater than 59 then makes mints =00
                                }
                              
                             if(mode==0)
                                {
                                    state = SHOW_DATE;
                                }
                          
                    break;
               
              
                case SHOW_DATE:
                    D1=date;D2=date_tens;D3=month;D4=month_tens;
                            if(set_low==0)                               // if the lower buuton is pressed
                                {
                                        set_d++;                                    // then after some delay ,  increment the date
                                        hex2bcd(set_d);                             // convert the hex value into bcd value
                                        if(set_d<=30)
                                            DS1307_SetDate(bcd_value,set_mon,set_y);        // now the date is updated with return bcd value
                                        else set_d=0;
                                }
                              
                                if(set_high==0)                               // if the higher buuton is pressed
                                {
                                        set_mon++;                                    // then after some delay ,  increment the month
                                        hex2bcd(set_mon);                             // convert the hex value into bcd value
                                        if(set_mon<=12)
                                            DS1307_SetDate(set_d,bcd_value,set_y);        // now the month is updated with return bcd value
                                        else set_mon=0;
                                }
                    
                    if(mode==0)
                            {
                                state = SHOW_YEAR;
                            }
                        break;
          
                case SHOW_YEAR:
           D1=2;D2=0;D3=year;D4=year_tens;
                            if(set_high==0)                               // if the higer buuton is pressed
                            {
                                    set_y++;                                    // then after some delay ,  increment the year
                                    hex2bcd(set_y);                             // convert the hex value into bcd value
                                    if(set_y<=99)
                                        DS1307_SetDate(set_d,set_mon,bcd_value);        // now the year is updated with return bcd value
                                    else set_y=0;
                            }
                          
                     if(mode==0)
                             {
                                state = SHOW_TIME;
                             }
                          
                            break;
          }                                                    //switch close            
        }                                                     //while loop close
    }                                                      // main close
       


    unsigned char hex2bcd (unsigned char x)
    {
      
        bcd_value = (x / 10) << 4;
        bcd_value = bcd_value | (x % 10);
        return (bcd_value);
    }

    Functions Used In RTC Code :

    #include <AT89X52.h>
    #define DS1307_ID 0xD0     // DS1307 ID
    #define SEC_ADDRESS   0x00 // Address to access Ds1307 SEC register
    #define DATE_ADDRESS  0x04 // Address to access Ds1307 DATE register
    #define CONTROL 0x07       // Address to access Ds1307 CONTROL register
    sbit seg_1= P2^0;      
    sbit seg_2= P2^1;      
    sbit seg_3= P2^2;
    sbit seg_4= P2^3; 
    sbit SCL=P1^0;      //SCL Connected to P1.0
    sbit SDA=P1^1;      //SDA Connected to P1.1

    void delay_sec(unsigned char sec_count);
    void delay_ms(unsigned int ms_count);
    void delay_us(unsigned int us_count);
    void I2C_Clock(void);
    void I2C_Start();
    void I2C_Stop(void);
    void I2C_Write(unsigned char dat);
    unsigned char I2C_Read(void);
    void I2C_Ack();
    void I2C_NoAck();
    void DS1307_Init();
    void DS1307_Write(unsigned char dat);
    unsigned char DS1307_Read();
    void DS1307_SetTime(unsigned char hh, unsigned char mm, unsigned char ss);
    void DS1307_SetDate(unsigned char dd, unsigned char mm, unsigned char yy);
    void DS1307_GetTime(unsigned char *h_ptr,unsigned char *m_ptr,unsigned char *s_ptr);
    void DS1307_GetDate(unsigned char *d_ptr,unsigned char *m_ptr,unsigned char *y_ptr);

    void delay_sec(unsigned char sec_count)
     {
         while(sec_count!=0)
          {
             delay_ms(1000);    //delay_ms is called to generate 1sec delay
             sec_count--;
            }
     }


    void delay_ms(unsigned int ms_count)
     {
            while(ms_count!=0)
             {
                delay_us(112);   //delay_us is called to generate 1ms delay
                 ms_count--;
                }
                        }
                       
                       
                   
                       
    void delay_us(unsigned int us_count)
     { 
        while(us_count!=0)
          {
             us_count--;
           }
       }

       
    /*I2c Library .............................................................................*/
       
    void I2C_Clock(void)
       
    {
        delay_us(1);
        SCL = 1;        // Wait for Some time and Pull the SCL line High

        delay_us(1);        // Wait for Some time
        SCL = 0;        // Pull back the SCL line low to Generate a clock pulse
    }

    void I2C_Start()
    {
        SCL = 0;        // Pull SCL low

        SDA = 1;        // Pull SDA High
        delay_us(1);

        SCL = 1;        //Pull SCL high
        delay_us(1);

        SDA = 0;        //Now Pull SDA LOW, to generate the Start Condition
        delay_us(1);

        SCL = 0;        //Finally Clear the SCL to complete the cycle
    }

    void I2C_Stop(void)
    {
        SCL = 0;            // Pull SCL low
        delay_us(1);

        SDA = 0;            // Pull SDA  low
        delay_us(1);

        SCL = 1;            // Pull SCL High
        delay_us(1);

        SDA = 1;            // Now Pull SDA High, to generate the Stop Condition
    }

    void I2C_Write(unsigned char dat)
    {
        unsigned char i;

        for(i=0;i<8;i++)         // loop 8 times to send 1-byte of data
         {
            SDA = dat & 0x80;    // Send Bit by Bit on SDA line
            I2C_Clock();         // Generate Clock at SCL
            dat = dat<<1;
          }
            SDA = 1;                 // Set SDA at last
    }

    unsigned char I2C_Read(void)
    {
        unsigned char i, dat=0x00;

           SDA=1;               //Make SDA as I/P
        for(i=0;i<8;i++)        // loop 8times to read 1-byte of data
         {
           delay_us(1);
            SCL = 1;            // Pull SCL High
            delay_us(1);

            dat = dat<<1;       //dat is Shifted each time and
            dat = dat | SDA;    //ORed with the received bit to pack into byte

            SCL = 0;            // Clear SCL to complete the Clock
           }
       return dat;               // Finally return the received Byte*
    }

    void I2C_Ack()
    {
        SDA = 0;        //Pull SDA low to indicate Positive ACK
        I2C_Clock();    //Generate the Clock
        SDA = 1;        // Pull SDA back to High(IDLE state)
    }

    void I2C_NoAck()
    {
        SDA = 1;        //Pull SDA high to indicate Negative/NO ACK
       I2C_Clock();     // Generate the Clock 
        SCL = 1;        // Set SCL */
    }

    /*...............................1307 library ...............................*/

    void DS1307_Init()
    {
        I2C_Start();            // Start I2C communication

        DS1307_Write(DS1307_ID);   // Connect to DS1307 by sending its ID on I2c Bus
        DS1307_Write(CONTROL);     // Select the Ds1307 ControlRegister to configure Ds1307

        DS1307_Write(0x00);        // Write 0x00 to Control register to disable SQW-Out

        I2C_Stop();             // Stop I2C communication after initilizing DS1307

     }

    void DS1307_Write(unsigned char dat)
    {
        I2C_Write(dat);   // Connect to DS1307 by sending its ID on I2c Bus
        I2C_Clock();
     }

    unsigned char DS1307_Read()
    {
        unsigned char dat;
        dat = I2C_Read();   // Connect to DS1307 by sending its ID on I2c Bus
        return(dat);
     }

    void DS1307_SetTime(unsigned char hh, unsigned char mm, unsigned char ss)
    {
        I2C_Start();            // Start I2C communication

        DS1307_Write(DS1307_ID);    // connect to DS1307 by sending its ID on I2c Bus
        DS1307_Write(SEC_ADDRESS); // Select the SEC RAM address
        
        DS1307_Write(ss);           // Write sec on RAM address 00H
        DS1307_Write(mm);           // Write min on RAM address 01H
        DS1307_Write(hh);           // Write hour on RAM address 02H

        I2C_Stop();             // Stop I2C communication after Setting the Time
    }

    void DS1307_SetDate(unsigned char dd, unsigned char mm, unsigned char yy)
    {
        I2C_Start();            // Start I2C communication

        DS1307_Write(DS1307_ID);    // connect to DS1307 by sending its ID on I2c Bus
        DS1307_Write(DATE_ADDRESS);     // Request DAY RAM address at 04H

        DS1307_Write(dd);           // Write date on RAM address 04H
        DS1307_Write(mm);           // Write month on RAM address 05H
        DS1307_Write(yy);           // Write year on RAM address 06h

        I2C_Stop();             // Stop I2C communication after Setting the Date
    }

    void DS1307_GetTime(unsigned char *h_ptr,unsigned char *m_ptr,unsigned char *s_ptr)
    {
         I2C_Start();           // Start I2C communication

        DS1307_Write(DS1307_ID);    // connect to DS1307 by sending its ID on I2c Bus
        DS1307_Write(SEC_ADDRESS);          // Request Sec RAM address at 00H

         I2C_Stop();            // Stop I2C communication after selecting Sec Register

        I2C_Start();                // Start I2C communication
        DS1307_Write(0xD1);         // connect to DS1307( under Read mode)
                                    //by sending its ID on I2c Bus

      *s_ptr = DS1307_Read();  I2C_Ack();     // read second and return Positive ACK
      *m_ptr = DS1307_Read();  I2C_Ack();      // read minute and return Positive ACK
      *h_ptr = DS1307_Read();  I2C_NoAck();    // read hour and return Negative/No ACK

      I2C_Stop();               // Stop I2C communication after reading the Time
     }

    void DS1307_GetDate(unsigned char *d_ptr,unsigned char *m_ptr,unsigned char *y_ptr)
    {
        I2C_Start();            // Start I2C communication

        DS1307_Write(DS1307_ID);    // connect to DS1307 by sending its ID on I2c Bus
        DS1307_Write(DATE_ADDRESS);     // Request DAY RAM address at 04H

        I2C_Stop();             // Stop I2C communication after selecting DAY Register


       I2C_Start();             // Start I2C communication
       DS1307_Write(0xD1);          // connect to DS1307( under Read mode)
                                // by sending its ID on I2c Bus

      *d_ptr = DS1307_Read(); I2C_Ack();     // read Day and return Positive ACK
      *m_ptr = DS1307_Read(); I2C_Ack();     // read Month and return Positive ACK
      *y_ptr = DS1307_Read(); I2C_NoAck();   // read Year and return Negative/No ACK

      I2C_Stop();         // Stop I2C communication after reading the Time
     }
    ///////////// This project is created in Kielu vesion 4 ........thanks 
    ok friends if u have any problem in coding mail me       Lcat215@gmail.com










     

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