Hi, I am a newbie in 8952. I wish to interface an LCD and a keypad. A simple program,that displays the value of the button that is pressed. I've wrote the program, but I am having some trouble. It is like entering a loop and stays in it for infinity and nothing is being displayed on the LCD.

**I tested the LCD code separately, and it worked fine.

Can somebody help me??

Thanks in advance.

This is the code:


;//THIS IS A PRGRAM THAT DISPLAYS THE NUMBER THAT IS PRESSED ON THE KEYPAD ON THE LCD
;//***********************************************************************************

;//==========================================
; LCD IS USING PORT 1 & 2
; KEYPAD IS USING PORT 3
;//==========================================

ORG 0
LJMP MAIN ;BYPASS INTERRUPT VECTOR TABLE

;///MAIN PROGRAM///

ORG 100H

RS EQU P2.0
RW EQU P2.1
EN EQU P2.2


MAIN: MOV SP,#256-32 ;DEFINE STACK 32BYTES
MOV P3,#0FFh ; CONFIGURE LOWER NIBBLE OF P3

;INITIALIZATION START FOR LCD
MOV A,#038H
LCALL COMW
MOV A,#00CH
LCALL COMW
MOV A,#001H
LCALL COMW
MOV A,#006H
LCALL COMW
MOV A,#083H
LCALL COMW
;INITIALIZATION END FOR LCD

;=============================================================
; KEYPAD PROGRAM
;=============================================================

K1: ;TO ENSURE THAT ALL SWITCHES ARE OPEN
MOV P3,#0 ;%
MOV A,P3
ANL A,#00001111B ;DISABLE UPPER NIBBLE
CJNE A,#00001111B, K1
;
K2: ;CHECK SWITCHES TO SEE IF ONE IS CLOSED
ACALL DELAY
MOV A,P3
ANL A,#00001111B
CJNE A,#00001111B,OVER
SJMP K2
;
OVER: ACALL DELAY
MOV A,P3
ANL A,#00001111B
CJNE A,#00001111B,OVER1
SJMP K2
;
OVER1: MOV P3,#11111110B
MOV A,P3
ANL A,#00001111B
CJNE A,#00001111B,ROW_0
;
MOV P3,#11111101B
MOV A,P3
ANL A,#00001111B
CJNE A,#00001111B,ROW_1
;
MOV P3,#11111011B
MOV A,P3
ANL A,#00001111B
CJNE A,#00001111B,ROW_2
;
MOV P3,#11110111B
MOV A,P3
ANL A,#00001111B
CJNE A,#00001111B,ROW_3
;
LJMP K2
;
ROW_0: MOV DPTR,#KCODE0
SJMP FIND
;
ROW_1: MOV DPTR,#KCODE1
SJMP FIND
;
ROW_2: MOV DPTR,#KCODE2
SJMP FIND
;
ROW_3: MOV DPTR,#KCODE3
SJMP FIND
;
;
FIND: RRC A
JNC MATCH
INC DPTR
SJMP FIND
MATCH: CLR A
MOVC A,@A+DPTR
ACALL DATAW, A ;//ACALL DATAWRITE,A TO SEND DATA FROM ACCUMULATOR TO LCD
LJMP K1
;
;///DELAY SUB-ROUTINE///
;
DELAY: MOV R2,#5
HERE: NOP
DJNZ R3,HERE
RET
;
;
KCODE0: DB '7','8','9'
KCODE1: DB '4','5','6'
KCODE2: DB '1','2','3'
KCODE3: DB ' ','0','='



;===========================================
; LCD PROGRAM
;===========================================


MOV A,#0C1H
ACALL DISP_STRING
HAWN: SJMP HAWN

AGAIN: SJMP AGAIN ;endless loop
COMW: MOV P1,A ;command write sequence
CLR RS ;RS=0 for command
CLR RW ;R/W=0 to write to LCD
SETB EN ;E=1 for H-to-L pulse
CLR EN ;E=0 ,latch in
LCALL DELAY2
RET

DATAW: MOV P1,A ;data write sequence
SETB RS ;RS=1 for data
CLR RW ;R/W=0 to write to LCD
SETB EN ;E=1 for H-to-L pulse
CLR EN ;E=0 ,latch in
LCALL DELAY2
RET

DISP_STRING: CLR A ;A=0
MOV R5,#00H ;R5=0
NEXT_CHAR: INC R5 ;R5+1
MOVC A,@A+DPTR
ACALL DATAW
MOV A,R5
CJNE R5,#0EH,NEXT_CHAR
RET


DELAY2: MOV R6,#50 ;simple delay routine
HERE2: MOV R7,#255 ;for 0.0124S or 124ms
HERE3: DJNZ R7,HERE3
DJNZ R6,HERE2
RET

;=============================================================


END


;=============================================================