' Name        : T246_1934X.pbp
' Compiler    : PICBASIC PRO Compiler 2.6
' Assembler   : MPASM
' Target PIC  : 40-pin 16F1934 or similar
' Hardware    : LAB-X1 Experimenter Board
' Oscillator  : 4MHz external crystal
' Keywords    : LCDOUT
' Description : PICBASIC PRO program to demonstrate using Timer2 for a
' 24 hour format clock. Time is shown on the LCD as Time = 11:14 with
' hours : minutes.
'

' Define LCD pins
Define LCD_DREG  PORTD
Define LCD_DBIT  4
Define LCD_RSREG PORTE
Define LCD_RSBIT 0
Define LCD_EREG  PORTE
Define LCD_EBIT  1
      
' setup vars for clock
Time    Var Word      ' accumulates TMR2 to PR2 match counts
Minutes Var Byte      ' minutes
Hours   Var Byte      ' hours
Match   Var PIR1.1    ' TMR2 to PR2 match interrupt flag bit
IocFlag Var INTCON.0  ' portb int-on-change flag bit
   
   Gosub Init         ' jump to hardware initialization routine
     
   Lcdout $fe,1,"Time = ", #Hours DIG 1,#Hours DIG 0,":",#Minutes DIG 1,#Minutes DIG 0

    ' setup & start TMR2 after Lcdout
   T2CON = %01110110  ' set 1:16 prescale, 1:15 postscale, TMR2 on

' =============\ Main Program Start /============= ' 
Main:
   ' every 60mS the TMR2IF flag is set, and this routine is entered.
   ' Plenty of time to do other stuff.
   If Match = 1 Then           ' has TMR2 matched PR2? (should happen every 60mS)
      Match = 0                ' yes. clear TMR2 to PR2 match flag bit PIR1.1
      Time = Time + 1          ' increment 60mS count    
      If Time = 1000 Then      ' has 60 seconds (1000*60mS) passed?
         Time = 0              ' yes. clear count
         Minutes = Minutes + 1 ' increment Minutes
         If Minutes = 60 Then  ' roll-over from 59 to 0
            Minutes = 0        ' zero Minutes count
            Hours = Hours + 1  ' and increment Hours count
            If Hours = 24 Then ' roll-over from 23 to 0
               Hours = 0       ' zero Hours count
            Endif
         Endif
         ' Update time on LCD every 60 seconds
         Lcdout $fe,$87,#Hours DIG 1,#Hours DIG 0,":",#Minutes DIG 1,#Minutes DIG 0
      Endif   
   Endif
     
      ' test for key press
   If IocFlag Then    ' if keys SW13, 14, 15 or 16 were pressed,
      Gosub GetKeys   ' get the button/buttons pressed
   Endif
   Goto Main
          
' ===========\ Get Keypad Switch Presses /=========== '   
GetKeys:
   Pause 500              ' crude debounce for key press
   
   ' SW13 increments Hours
   If IOCBF.4 Then       ' IOCBF.4 = 1 when low edge detected on RB4
      While PORTB.4 = 0  ' wait for key release        
      Wend               ' 
      Hours = Hours + 1 : Time = 0
      If Hours = 24 Then Hours = 0
   Endif
   
   ' SW14 increments Minutes
   If IOCBF.5 Then       ' IOCBF.5 = 1 when low edge detected on RB5
      While PORTB.5 = 0  ' wait for key release
      Wend               '         
      Minutes = Minutes + 1 : Time = 0
      If Minutes = 60 Then Minutes = 0
   Endif
   
   ' SW15 zeros Time "tick" counter
   If IOCBF.6 Then       ' IOCBF.6 = 1 when low edge detected on RB6
      While PORTB.6 = 0  ' wait for key release
      Wend               '      
      Time = 0
   Endif
   
   ' SW16 rests clock to 12:00
   If IOCBF.7 Then       ' IOCBF.7 = 1 when low edge detected on RB7
      While PORTB.7 = 0  ' wait for key release
      Wend               '         
      Hours = 12 : Minutes = 0 : Time = 0
   Endif
   IOCBF = 0             ' reset all int-on-change bits on exit
   IocFlag = 0
   ' Update LCD on each change
   Lcdout $fe,$87,#Hours DIG 1,#Hours DIG 0,":",#Minutes DIG 1,#Minutes DIG 0
   Return

' ===========\ Hardware Initialization Routine /=========== '   
Init:
   ANSELA = 0    ' porta all digital
   ANSELB = 0    ' portb all digital
   ANSELD = 0    ' portd all digital
   ANSELE = 0    ' porte all digital
   
   OPTION_REG.7 = 0    ' enable PORTB pullups   
   PORTB = 0           ' RB3 low
   TRISB = %11110111   ' RB3 = 0 for output to keys 13, 14, 15, 16
   WPUB = %11110000    ' weak pull-ups on for ----> RB4, 5,  6,  7
   IOCBP = 0           ' positive edge disabled
   IOCBN = %11110000   ' negative edge int-on-change enabled for keys
   
   TRISD = 0           ' PORTD all outputs
   
   INTCON = 0          ' not using interupts. Just monitoring int flag bits
   Time = 0            ' clear TMR2 to PR2 match counter
   Hours = 10          ' set clock starting hour to 13 here
   Minutes = 16        ' set clock starting minutes to 56 here
   
   ' TMR2 increments from 0 until it matches the value in the PR2 register.
   ' The match automatically resets Timer2 and sets the Timer2 interrupt flag
   ' bit PIR1.1.
   
   PR2 = 249           ' 0 to 249 = 250. 250*16*15*1uS=60mS
   Match = 0           ' clear PIR1.1 match flag bit

   Pause 100           ' Wait for LCD to start
   
   Return              ' Return to caller
   
   End