;Binary Clock 2009
	LIST	p=16F628A		;tell assembler what chip we are using
	include "P16F628A.inc"		;include the defaults for the chip
	__config 0x3D18			;sets the configuration settings 
					;(oscillator type etc internal.)

	Ticks 		EQU 20h
	Seconds  	EQU 21h
	Minutes  	EQU 22h
	Hours		EQU 23h
	Delay		EQU 24h
	Delay1		EQU 25h	
	BCD			EQU 26h
	BCDCount	EQU 27h
	BCDSeconds  EQU 28h
	BCDMinutes	EQU 29h
	BCDHours	EQU 30h
	Count		EQU 31h
	abuff		EQU 32h
	bbuff		EQU 33h
	TenSeconds  EQU 34h
	TenMinutes	EQU 35h
	TenHours	EQU 36h
	push_w		EQU 37h
    push_status EQU 38h

	org	0x0000			;org sets the origin, 0x0000 for the 16F628,
					;this is where the program starts running	

	goto start

; *****************************************
; Interrupt Service Routine
; *****************************************
          org 0x004
_intserv
          ; Save W and Status
          movwf     push_w
          swapf     STATUS,W
          bcf       STATUS,RP0          ; Sel bank 0
          movwf     push_status
		  
		  incf Ticks ; Increment the tick 
          bcf  INTCON,1		 ;Clear flag
	  bsf PORTA,4

          swapf     push_status,W
          movwf     STATUS
          swapf     push_w,F
          swapf     push_w,W
          retfie                        ; This instruction sets the GIE bit
                                        ; in INTCON register and returns from
                                        ; interupt
          



start

	bsf                    INTCON,7      ;GIE – Global interrupt enable (1=enable)
	bsf                    INTCON,4     ;INTE - RB0 interrupt enable (1=enable)
    	bcf                    INTCON,1		 ;Clear flag
	





	movlw	0x07
	movwf	CMCON			;turn comparators off (make it like a 16F84)

   	bsf 	STATUS,		RP0	;select bank 1
	Movlw b'11000000'
	movwf OPTION_REG
   	movlw 	b'00000001'		;set PortB to outputs interrupt to input
   	movwf 	TRISB
	movlw 	b'00011000'
	movwf	TRISA			;set PortA all outputs
	bcf	STATUS,		RP0	;select bank 
	movlw 0
	movwf Ticks
	movwf Seconds
	movwf Minutes
	movwf Hours
	movwf TenSeconds
	movwf TenMinutes
	movwf TenHours

	movwf BCDSeconds
	movwf BCDMinutes
	movwf BCDHours

Loop

Display

	btfss PORTA,3
	Call  Settime
	
	bcf PORTA,4

	movlw	b'11111110'
	movwf	PORTA			;set all bits on
	Movlw	b'11111111'
	xorwf	BCDHours,0
	movwf	PORTB

	Movlw b'11111111'
	movwf	PORTB
	


	movlw	b'11111101'
	movwf	PORTA			;set all bits on
	Movlw	b'11111111'
	xorwf	BCDMinutes,0
	movwf	PORTB

	Movlw b'11111111'
	movwf	PORTB	
	movlw	b'11111011'
	movwf	PORTA			;set all bits on
	Movlw	b'11111111'
	xorwf	BCDSeconds,0
	movwf	PORTB

	Movlw b'11111111'
	movwf	PORTB
	
	nop				;the nop's make up the time taken by the goto
	nop				;giving a square wave output
	
	Movlw	.100			;Change this to 120 if building in the USA
	XORWF	Ticks,0
	BTFSS	STATUS,Z
	Goto Loop
	clrf 	Ticks
	Incf	Seconds,1
	movf	Seconds,0
	Addlw	.6			;Test to see if between A-F
	BTFSC   STATUS,DC		;Did it cause a carry ?
	Call	Incrementtenseconds
	Movf	Seconds,0
	Call	Spin      		;Move seconds to MSB  
	Movwf	BCDSeconds		; Move seconds to BCB Seconds
	bcf BCDSeconds,3
	bcf BCDSeconds,2
	bcf BCDSeconds,1
	btfsc TenSeconds,0
    bsf BCDSeconds,3
    btfsc TenSeconds,1
    bsf BCDSeconds,2
    btfsc TenSeconds,2
    bsf BCDSeconds,1		
	Movlw	.6
	XORWF	TenSeconds,0
	BTFSS	STATUS,Z
	Goto Loop
	Clrf 	Seconds
	Clrf	TenSeconds
	Clrf    BCDSeconds
	Incf	Minutes,1
	movf	Minutes,0
	Addlw	.6			;Test to see if between A-F
	BTFSC   STATUS,DC		;Did it cause a carry ?
	Call	IncrementtenMinutes
	Movf	Minutes,0
	Call	Spin      		;Move seconds to MSB  
	Movwf	BCDMinutes		; Move seconds to BCB Seconds
	bcf BCDMinutes,3
	bcf BCDMinutes,2
	bcf BCDMinutes,1
	btfsc TenMinutes,0
    bsf BCDMinutes,3
    btfsc TenMinutes,1
    bsf BCDMinutes,2
    btfsc TenMinutes,2
    bsf BCDMinutes,1		
	Movlw	.6
	XORWF	TenMinutes,0
	BTFSS	STATUS,Z
	Goto Loop

	Clrf 	Minutes
	Clrf	TenMinutes
	Clrf	BCDMinutes
	Incf	Hours,1
	movf	Hours,0
	Addlw	.6			;Test to see if between A-F
	BTFSC   STATUS,DC		;Did it cause a carry ?
	Call	IncrementtenHours
	Movf	Hours,0
	Call	Spin      		;Move seconds to MSB  
	Movwf	BCDHours		; Move seconds to BCB Seconds
	bcf BCDHours,3
	bcf BCDHours,2
	bcf BCDHours,1
	btfsc TenHours,0
    bsf BCDHours,3
    btfsc TenHours,1
    bsf BCDHours,2
    Movlw	.2
	XORWF	TenHours,0
	BTFSS	STATUS,Z
	Goto Loop
	Movlw	.4
	XORWF	Hours,0
	BTFSS	STATUS,Z
	Goto Loop
	Clrf	Hours
	Clrf	TenHours
	Goto Loop



Movlw	.60
	XORWF	Minutes,0
	BTFSS	STATUS,Z
	Goto Loop
		
	
	Movlw 0
	Movwf 	Minutes
	Incf	Hours,1
	Movlw	.24
	XORWF	Hours,0
	BTFSS	STATUS,Z
	Goto Loop
	Movlw 0
	Movwf 	Hours
	goto	Loop			;go back and do it again

BinBCD

	clrf BCD
	clrf BCDCount
	Movwf	BCD
again

	movlw	.10
	subwf	BCD,F
	btfss STATUS,C
	Return
	Incf	BCDCount
	goto again

Spin


	;Reverse bit order code here
			   movwf abuff
			   bsf Count,3  ;count = 8
bitcount       rrf abuff
               rlf bbuff
               decfsz Count
               goto bitcount
			   movf bbuff,0
			   Return

				bcf bbuff,3
			   bcf bbuff,2
			   bcf bbuff,1
			   btfsc BCDCount,0
			   bsf bbuff,3
     		   btfsc BCDCount,1
			   bsf bbuff,2
			   btfsc BCDCount,2
			   bsf bbuff,1	
			   movf bbuff,0

	return

Incrementtenseconds

			  incf TenSeconds
			  clrf Seconds
			  Return
IncrementtenMinutes

			  incf TenMinutes
			  clrf Minutes
			  Return

IncrementtenHours

			  incf TenHours
			  clrf Hours
			  Return


Settime
	incf Ticks
	
	
	Movlw	.100
	Movwf	Delay
Loop1	
	Decfsz	Delay,1	
	

	Goto Loop1
	Return

	end