Device = 16F876
Xtal = 4
ALL_DIGITAL = True
PORTB_PULLUPS = True

' Setup the LCD
LCD_DTPIN = PORTB.4
LCD_RSPIN = PORTB.2
LCD_ENPIN = PORTB.3
LCD_INTERFACE = 4
LCD_LINES = 2
LCD_TYPE = 0
 

' Define I2C bus ports
SDA_Pin = PORTA.0 'DS1307 SDA pin
SCL_PIN =PORTA.1 'DS1307 SCL pin

Dim Temp1 As Byte
Dim Temp2 As Byte
Dim TempVal As Byte

Dim Secs As Byte
Dim Mins As Byte
Dim Hrs As Byte
Dim day As Byte
Dim Date As Byte
Dim Month As Byte
Dim Year As Byte
Dim Ctrl As Byte

Dim Secs_last As Byte

'Initialize LCD

Delayms 100
Cls

' Set initial DS1307 time / Date

Secs = 0                     ' Set seconds
Mins = 30                    ' Set minutes
Hrs = 12                      ' Set hours

Day = 1                       ' Set day of week value

Date = 30                     ' Day of month value
Month = 11                   ' Month value
Year = 6                       ' Year value

Ctrl = 0                        ' Set the control byte (leave as 0 in this example)


' The DS1307 works with data in BCD format, so convert BIN to BCD

TempVal=Secs
GoSub BIN_TO_BCD
Secs=TempVal

TempVal=Mins
GoSub BIN_TO_BCD
Mins=TempVal

TempVal=Hrs
GoSub BIN_TO_BCD
Hrs=TempVal

TempVal=Day
GoSub BIN_TO_BCD
Day=TempVal

TempVal=Date
GoSub BIN_TO_BCD
Date=TempVal

TempVal=Month
GoSub BIN_TO_BCD
Month=TempVal

TempVal=Year
GoSub BIN_TO_BCD
Year=TempVal

BStart

' The datasheet specifies the first byte is 1101000x where x is read(1) or write(0).
' The second byte tells the DS 1307 where to start reading, 0 is at the start.
' The Ctrl byte contains advanced features, read the datasheet for more info
Busout 11010000, 0, [Secs, Mins, Hrs, day, Date, Month, Year, Ctrl] 'Write initial values for time / Date

BStop

Delayms 20

Main:

BStart

' The datasheet specifies the first byte is 1101000x where x is read(1) or write(0).
' The second byte tells the DS 1307 where to start reading, 0 is at the start.
BusIn 11010001, 0, [Secs, Mins, Hrs, day, Date, Month, Year, Ctrl]

BStop

' The DS1307 sends it data in BCD, therefore it must be changed to
' BIN so that it can be easily used (eg, print onto an LCD)

TempVal=Secs
GoSub BCD_TO_BIN
Secs=TempVal

TempVal=Mins
GoSub BCD_TO_BIN
Mins=TempVal

TempVal=Hrs
GoSub BCD_TO_BIN
Hrs=TempVal

TempVal=Date
GoSub BCD_TO_BIN
Date=TempVal

TempVal=Month
GoSub BCD_TO_BIN
Month=TempVal

TempVal=Year
GoSub BCD_TO_BIN
Year=TempVal


 

If Secs - Secs_last = 0 Then Goto Main                'If there is update in Secs, display time and Date

' The Dec2 modifier makes sure that each value will have 2 characters, eg 1 becomes 01
Print At 1,1,"Time: ",Dec2 Hrs, ":", Dec2 Mins,":", Dec2 Secs
Print At 2,1,"Date: ", Dec2 Date, "-", Dec2 Month, "-", Dec2 Year

Secs_last = Secs

Goto Main

BCD_TO_BIN:                                    ' Convert the BCD values into BIN

     Temp1 = $0F & TempVal                     ' Clear off the top four bits
     Temp1 = DIG Temp1, 0
     Temp2 = TempVal >> 4                       ' Shift down four to read 2 BCD value
     Temp2 = DIG Temp2, 0
     TempVal = Temp2 * 10 + Temp1

     Return

BIN_TO_BCD:

     Temp1 = Dig TempVal, 0                     ' GET THE DEC DIGIT FOR THE FIRST NIBBLE
     Temp2 = Dig TempVal, 1                     ' GET THE DEC DIGIT FOR THE FIRST NIBBLE
     Temp2 = Temp2 << 4                          ' MOVE NUMBER OVER TO 2ND NIBBLE
     TempVal = Temp1 ^ Temp2                  ' XOR THEM TOGTHER TO MAKE THE WHOLE BCD NUMBER
    
     Return