This project gives you a real time clock with the RTC chip DS1307. This RTC chip has inbuilt oscillator for clock and it has its own registers for full calender. In this project we dont take care about the days and we just use the time functions.

There are 3 push buttons on the circuit to change the time and the time is displayed over the LCD display. You have to provide battery backup for the RTC chip, so that the time runs inside the chip during power failure.

The code is written in Bascom basic, you can also download the proteus simulation file.

Circuit Diagram

Bascom code

$regfile = "m8def.dat"
$crystal = 1000000
'------------------------  lcd -----------------------------------------------
Config Lcd = 16 * 2
Config Lcdpin = Pin , Rs = Pind.0 , E = Pind.1 , Db4 = Pind.2 , Db5 = Pind.3 , Db6 = Pind.4 , Db7 = Pind.5
Cls

'---------------------------  ds 1307 -----------------------------------------
$lib "ds1307clock.lib"
'configure the scl and sda pins
Config Sda = Portd.7
Config Scl = Portd.6
'address of ds1307
Const Ds1307w = &HD0                                        ' Addresses of Ds1307 clock
Const Ds1307r = &HD1
'------------------------------ key --------------------------------------------
Config Pinc.1 = Input
Config Pinc.2 = Input
Config Pinc.3 = Input
Config Pinc.4 = Input
'------------------------------------------------------------------------------
Config Debounce = 30

Dim A As Byte , B As Byte , Data1 As Byte , C As Byte

Dim Seco As Byte , Mine As Byte , Hour As Byte

'----------------------------------------------------------------------------
Cursor Off
'-----------------------------
Cls
Locate 1 , 6
Lcd "Hello"
Locate 2 , 1
Lcd "avrprojects.info"
Wait 2

For A = 1 To 15
 Shiftlcd Left
Waitms 300
Next

Cls
'-------------------------------------------------------------------------------
Main:
Do
         Gosub Ds1307
         Gosub 24_12
         Gosub Chekkey

Loop
'-------------------------------------------------------------------------------
Ds1307:
        I2cstart                                            ' Generate start code
        I2cwbyte Ds1307w                                    ' send address
        I2cwbyte 0                                          ' start address in 1307
        I2cstart                                            ' Generate start code
        I2cwbyte Ds1307r                                    ' send address
        I2crbyte Seco , Ack                                 'sec
        I2crbyte Mine , Ack                                 ' MINUTES
        I2crbyte Hour , Nack                                ' Hours
        I2cstop

        Seco = Makedec(seco) : Mine = Makedec(mine) : Hour = Makedec(hour)

        If Seco > 59 Then Seco = 0
        If Mine > 59 Then Mine = 0
        If Hour > 23 Then
        Hour = 0
        Gosub Seco
        End If

Return
'-------------------------------------------------------------------------------
 24_12:
 If Pinc.4 = 1 Then Gosub Disply_24
 If Pinc.4 = 0 Then Gosub Disply_12
 Return
'-------------------------------------------------------------------------------
Disply_24:

         Locate 1 , 1
         Lcd "Time = " ; Hour ; ":" ;
         If Mine < 10 Then
            Lcd "0" ; Mine ; ":" ;
         Else
            Lcd Mine ; ":" ;
         End If

         If Seco < 10 Then
            Lcd "0" ; Seco
         Else
            Lcd Seco
         End If

         Locate 2 , 6
         Lcd "(24)"
Return

'-------------------------------------------------------------------------------
Disply_12:

         If Hour = 0 Then Hour = 12
         If Hour > 12 Then Hour = Hour - 12

         Locate 1 , 1
         Lcd "Time = " ; Hour ; ":" ;
         If Mine < 10 Then
            Lcd "0" ; Mine ; ":" ;
         Else
            Lcd Mine ; ":" ;
         End If

         If Seco < 10 Then
            Lcd "0" ; Seco
         Else
            Lcd Seco
         End If
         Locate 2 , 6
         Lcd "(12)"
Return
'-------------------------------------------------------------------------------
Chekkey:

         Debounce Pinc.1 , 0 , Seco , Sub
         Debounce Pinc.2 , 0 , Mine , Sub
         Debounce Pinc.3 , 0 , Hour , Sub


Return
'---------------------------------------------
Seco:
         Incr Seco
         If Seco > 59 Then Seco = 0
         Seco = Makebcd(seco)
         I2cstart                                           ' Generate start code
         I2cwbyte Ds1307w                                   ' send address
         I2cwbyte 0                                         ' starting address in 1307
         I2cwbyte Seco
         I2cstop
Return

'-------------------------------------
Mine:
         Incr Mine
         If Mine > 59 Then Mine = 0
         Mine = Makebcd(mine)
         I2cstart                                           ' Generate start code
         I2cwbyte Ds1307w                                   ' send address
         I2cwbyte 1                                         ' starting address in 1307
         I2cwbyte Mine