
;-------------------------- DEVICE DIRECTIVES --------------------------

		DEVICE		SX28,OSC4MHZ,TURBO
		ID	'temp 1.0'

IFDEF	__SASM  ;SASM Directives
		DEVICE		STACKX,OPTIONX
		IRC_CAL		IRC_SLOW
		
ELSE		;Parallax Assember Directives
		DEVICE		STACKX_OPTIONX
ENDIF

		RESET		Initialize
;------------------------------ COSTANTS -------------------------------
	CE_dac		EQU	rb.2
	data_dac	EQU	rb.1
	sclk_dac	EQU	rb.0

;------------------------------ VARIABLES ------------------------------
			
		Count1	EQU	$08
		Count2	EQU	$09
			ORG	$0a
i		DS	2
isr_tmp		DS	1
isr_digi	DS	1
display		ds	2
temp		ds	2
	

;---------------------------- DEBUG SETTINGS ---------------------------

		FREQ 	4_000_000
	
		WATCH	i,16,ubin
		WATCH	display,16,udec

;-------------------------- INTERRUPT ROUTINE --------------------------

;------------------------ SUB ROUTINES ---------------------------------


;-------------------------------- MACROS -------------------------------
INCLUDE		"links_macros.SRC" ; the two macros used in this file are 
copied below.

;	Will read data from a shift register or similar device
;   -- adapted for http://www.mikroe.com/en/books/picbook/7_07chapter.htm	
;	result register to return value
;	bit_counter temp reg = number of bits > 8	
_shiftinw	MACRO	sclk,data,result,bit_counter
	LOCAL loop
	clr	result
	clr	result+1
	clc
	

:loop	clc
	setb	sclk	; toggle sclk
	jmp	$+1	;delay 3 cycles
	nop
	clrb	sclk
	rl	result
	rl	result+1
	movb	result.0, data
	decsz	bit_counter
	jmp	:loop
	
ENDM

;	makes jump+nop delays
;   -- From parallax Dev System manuel pg 68

_delay	MACRO	cycles
	IF(cycles > 0)
		REPT (cycles/3)
		jmp	$+1	; delay 3 cycels
		ENDR
		REPT (cycles//3)
		nop		; delay 1 cycles
		ENDR
	ENDIF
ENDM


;------------------------ INITIALIZATION ROUTINE -----------------------

Initialize
		;Configure port settings
		mov	ra, #%0000		;Port a output zero
		mov	!ra,#%1100		;Port a.bit7-0 output dir.
		mov	rb, #%00000100		;Port b output zero
		mov	!rb,#%00000010		;Port b output dir.
		mov	rc, #%00000000		;Port C output zero
		mov	!rc,#%00000000		;Port C.bit7-0 output dir.

		clr	i
		clr	isr_digi

		;RTCC Rollover Interrupt Configuration
		;MOV	!OPTION,#%10011111	;Enable RTCC rollover interrupt
 						;RTCC inc on clock cycle, no prescaler


;---------------------------- MAIN PROGRAM -----------------------------

Main
		
		call	delay			;delay	
		clrb	sclk_dac
		_delay	30
		mov	Count1,#10
		clrb	CE_dac		
		_delay	6
		_shiftinw	sclk_dac,data_dac,i,Count1
		_delay	6
		setb	CE_dac		
		
		; scale & format data
		mov	display,i
		mov	display+1,i+1
		break
		jmp	Main


Delay		clr	Count1  		;Initialize Count1, Count2	
		clr	Count2

Loop		nop
		nop
		nop
		djnz	Count1,loop		;Decrement until all are zero		
		djnz	Count2,loop							
		ret				;then return	


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