;********************************************************;
;  Code snippet for reading 7 switches on a single PIN
;    Routine assumes that ADCON0 and ADCON1 are set to
;       appropriate values for the PIC used.
;    The routine tests 8bit ADC value against the voltage
;    level presented. If it is LOWER than the test then
;    that switch is grounded. NOTE: This can be minimized
;    further. NOTE: this should be executed during an 
;    interrupt to make sure that the snippet is not missed. 
;********************************************************;
;process keyboard: inside ints only
keybd:
	clrf	status
	rrf		adresh,w
	movwf	tmp1_
	bank1
	rrf		adresl,w
	clrf	status
	movwf	tmp_
	rrf		tmp1_,f
	rrf		tmp_,f		;now fixed to 8 bits, NOT 10 bits
	clrf	tmp1_			;used to locate switch  number
	incf	tmp1_,f	;=SW1	
	movlw	-d'18'	; 0.0V + 0.7V/2 = 0.35V Test limit
	addwf	tmp_,w		;OK Pressed?
	btfss	status,c	;check if LESS 
	goto	keybd0		;jump if OK SW pressed
	incf	tmp1_,f
	movlw	-d'54'	; 0.7V + 0.35V = 1.05V 
	addwf	tmp_,w		;DN Pressed?
	btfss	status,c	;check if LESS 
	goto	keybd0		;jump if DN SW pressed
	incf	tmp1_,f
	movlw	-d'90'	; 1.4v + 0.35V = 1.75V
	addwf	tmp_,w		;<< Pressed?
	btfss	status,c	;check if LESS 
	goto	keybd0		;jump if << SW pressed
	incf	tmp1_,f
	movlw	-d'125'	; 2.1V + 0.35V = 2.45V
	addwf	tmp_,w		;< pressed?
	btfss	status,c	;check if LESS 
	goto	keybd0		;jump if < SW pressed
	incf	tmp1_,f
	movlw	-d'161'	;2.8V + 0.35V = 3.15V
	addwf	tmp_,w		;> pressed?
	btfss	status,c	;check if LESS 
	goto	keybd0		;jump if > SW pressed
	incf	tmp1_,f
	movlw	-d'197' ;3.5V + 0.35V = 3.85V
	addwf	AN0,w		;>> pressed?
	btfss	status,c	;check if LESS 
	goto	keybd0		;jump if >> SW pressed
	incf	tmp1_,f
	movlw	-d'233'	;4.2V + 0.35V = 4.55V
	addwf	AN0,w		;UP pressed?
	btfsc	status,c	;check if LESS 
; no switches are pressed, so done
	goto	keybd1
; now process the switches
keybd0:
	incf	tmp1,w
	movwf	KEY				;value will read 1 to 7 for appropriate SW
	bsf		flags,KYPRESS	;tell system it is time to service keypress
keybd1:
	bsf		adcon0,GO	;read for next time
	return			
;********************************************************;
;   end of snippet
;********************************************************;