;*************************************************************************
;
; KEYPAD subroutine: INTERRUPTS WHEN A key  IS pressed and returns it
; in ACC.
;
;*************************************************************************
$NOMOD51		; omit assembler micro definitions
$Include(reg515.inc)	; define 515 micro

;*********************************************
;EXTRN CODE ()
EXTRN DATA (KEYPAD_FLAG)
;*********************************************

Name	keypad
PUBLIC	keypad,KBDINIT

pad_key	SEGMENT	CODE
RSEG	pad_key	; switch to this code segment
USING	0 		; use register_bank 0 


; Dempsey Note:
; This code was provided by EMAC
; It is not an efficient way to use keypad
; Normally must do other main code processing  
;
; local definitions

KEYSEL	EQU      38H      	; KEYPAD PORT


KBDINIT:
		SETB	IT1
 		SETB	EX1
  		RET

keypad:
	
       	PUSH	ACC
		PUSH	B
		MOV		A,R0
		PUSH	ACC
       	PUSH  	DPH
      	PUSH  	DPL   			; SAVE DPTR
      	MOV   	DPTR,#KEYTABL	; POINT TO TRANSLATE TABLE
      	MOV   	P2,#KEYSEL    	; POINT TO KEYPAD PORT
      	MOVX  	A,@R1         	; GET KEY FROM PORT
      	ANL   	A,#00011111B	; ONLY 5 BITS
     	MOVC  	A,@A+DPTR     	; TRANSLATE TO KEY FROM TABLE (ASCII)
      	LCALL	KEYFUNCTION      	
      	POP   	DPL
      	POP   	DPH
      	POP		ACC
		MOV		R0,A
   		POP		B
		POP		ACC
      	RETI

KEYTABL: DB       '123C456D789EA0BF'

KEYFUNCTION:
KEY0:
	CJNE	A,#30H,KEY1
	MOV		A,#0
 	MOV		KEYPAD_FLAG,A
 	RET
KEY1:
    CJNE	A,#31H,KEY2
	MOV		A,#1
 	MOV		KEYPAD_FLAG,A
 	RET
KEY2:
	CJNE	A,#32H,KEY3
  	MOV		A,#2
 	MOV		KEYPAD_FLAG,A
   	RET
KEY3:
	CJNE	A,#33H,KEY4
 	MOV		A,#3
 	MOV		KEYPAD_FLAG,A
  	RET
KEY4:
	CJNE	A,#34H,KEY5
 	MOV		A,#4
 	MOV		KEYPAD_FLAG,A
  	RET
KEY5:
	CJNE	A,#35H,KEY6
 	MOV		A,#5
 	MOV		KEYPAD_FLAG,A
  	RET
KEY6:
	CJNE	A,#36H,KEY7
	MOV		A,#6
 	MOV		KEYPAD_FLAG,A
	RET
KEY7:
	CJNE	A,#37H,KEY8
    MOV		A,#7
 	MOV		KEYPAD_FLAG,A
  	RET
KEY8:
	CJNE	A,#38H,KEY9
 	MOV		A,#8
 	MOV		KEYPAD_FLAG,A
    RET
KEY9:
	CJNE	A,#39H,KEYA
 	MOV		A,#9
 	MOV		KEYPAD_FLAG,A
    RET
KEYA:
	CJNE	A,#41H,KEYB
 	MOV		A,#0AH
 	MOV		KEYPAD_FLAG,A
    RET
KEYB:
	CJNE	A,#42H,KEYC
	MOV		A,#0BH
 	MOV		KEYPAD_FLAG,A
    RET
KEYC:
	CJNE	A,#43H,KEYD
 	MOV		A,#0CH
 	MOV		KEYPAD_FLAG,A
  	RET
KEYD:	
	CJNE	A,#44H,KEYE
 	MOV		A,#0DH
 	MOV		KEYPAD_FLAG,A
  	RET
KEYE:
	CJNE	A,#45H,KEYF
 	MOV		A,#0EH
 	MOV		KEYPAD_FLAG,A
  	RET
KEYF:	
    CJNE	A,#46H,NOKEY
 	MOV		A,#0FH
 	MOV		KEYPAD_FLAG,A
  	RET
NOKEY:
	RET

END