$MOD51
		RS equ 0b5h				;labelling RS of LCD
		RW equ 0b6h				;labelling RW of LCD
		EN equ 0b7h				;labelling Enable of LCD
		up equ 0a7h				;labelling UP key 
		down equ 0a6h				;labelling DOWN key 
		enter equ 0a5h				;labelling ENTER key 
		alarm_key equ 0a4h				;labelling ALARM key 
		buzzer equ 0b3h				;labelling Buzzer
		count equ 10h
		disp_data equ 11h
		lcdcom equ 12h
		disp_var1 equ 13h
		disp_var0 equ 14h
		secs equ 15h				;sec, min, hour RAM location
		mins equ 16h
		hour equ 17h
		ampm equ 18h
		temp_secs equ 19h			;RAM variable to track 1second
		temp_mins equ 1ah
		temp_hour equ 1bh
		temp_ampm equ 1ch
		alarm_secs equ 1dh			;Alarm sec, min, hour RAM location
		alarm_mins equ 1eh
		alarm_hour equ 1fh
		alarm_ampm equ 20h
		time1sec equ 21h
		TMP_3 equ 22h
		TMP_2 equ 23h
		TMP_1 equ 24h
		TMP_0 equ 25h
		tt3 equ 26h				;dec_to_hex input ,dividiend and quotient 
		tt2 equ 27h
		tt1 equ 28h
		tt0 equ 29h
		out7 equ 2ah				;don't change their location
		out6 equ 2bh
		out5 equ 2ch
		out4 equ 2dh
		out3 equ 2eh
		out2 equ 2fh
		out1 equ 30h
		out0 equ 31h
		hex1 equ 32h
		hex0 equ 33h 
		counter1 equ 34h
		alarm_status equ 35h			;Alarm flag,
		alarm_match equ 3ch			;Alarm match flag

		org 0000h					;Start of the progrma
		ljmp program_start
		org 001bh					;T1 timer interrupt vector
		ljmp intr_service
		org 0040h
	program_start:
		mov sp,#50h				;Initializing stack pointer
		clr buzzer				;stop buzzer
		mov count,#00h
		lcall lcd_initialize			;calling initialize lcd routine
		lcall delay14m
		mov counter1,#00h	
		lcall cursoroff
		lcall welcome_msg			;calling welcome message routine
	
		lcall cursoron
		mov time1sec,#64h
		lcall clear_lcd
		mov dptr,#0620h				;message "Enter Clock Time" display on LCD
		lcall display_text
		lcall enter_time			;routine to enter TIME
		lcall copy_time				;copy entered time as current time 

		setb alarm_key
		mov alarm_status,#00h			;Alarm flag, default deactivated
		mov alarm_match,#00h			;alarm match flag, default not matched

		lcall clear_lcd
		mov dptr,#0610h				;message "Time:01:00:00PM" displayed on LCD
		lcall display_text
		lcall display_time
		lcall cursoroff
		lcall load_timer			;routine to initialize T1 timer
		mov IE,#10001000b			;Initialize T1 interrupt for timer overflow
	here:	sjmp here
	
;********************************************************************************************
	welcome_msg:	 				;routine display welcome message on LCD
		nop
	flash1:
		mov dptr,#0600h				;message "Digital Clock" displayed on LCD
		lcall display_text                               
		lcall delay14m                              
		mov lcdcom,#0c0h			;command to move cursor to next line on same LCD screen
		lcall command_LCD                             
		mov dptr,#0640h				; message "With alarm" displayed on LCD
		lcall display_text                                
		lcall delay140m                           
		lcall delay140m                             
		lcall delay140m                            
		lcall clear_lcd                                
		lcall cursoroff
		lcall delay140m                            
		lcall delay140m                            
		lcall delay140m                            
		lcall delay140m                           
		inc counter1
		mov a,counter1
		cjne a,#03h,flash1	
		ret
;*********************************************************************************************
	load_timer:					;routine to initialize T1 timer to generate 10msec delay
		clr tr1							
		clr tf1
		mov tmod,#10h				;setting T1 as 16-bit timer				
	next_pulse:	
		mov th1,#0dch				;value to get 10msec delay in T1 timer		
		mov tl1,#00h				
		clr tf1		
		setb tr1					;start T1 timer
		ret
;*******************************************************************************************
	intr_service:					;T1 Timer service routine
		clr tf1
		clr tr1					;stop T1 timer
		dec time1sec
		mov a, time1sec
		cjne a,#00h,not1sec
		mov time1sec,#64h				;RAM variable to track 1second, 64h(100d)*10msec=1sec
		lcall update_time				;routine update time 
		lcall display_time				;routine display updated time on LCD
		lcall check_alarm				;routine check alarm
	not1sec:
		jb alarm_key,no_alarmkey
		lcall delay140m
		lcall delay140m
		mov a,alarm_status
		cjne a,#00h,alarm_on
		mov alarm_status,#01h			;Alarm flag ON indicating alarm activated
		lcall enter_alarm
		sjmp no_alarmkey
	alarm_on:
		mov alarm_status,#00h			
		mov alarm_match,#00h			
	no_alarmkey:
		mov th1,#0dch				;value to get 10msec delay		
		mov tl1,#00h				
		clr tf1		
		setb tr1					;start T1 timer			
	intr_over:
		reti					;return from service routine
;*********************************************************************************************
	enter_alarm:					;routine to enter ALARM time
		lcall cursoron
		mov lcdcom,#80h
		lcall command_LCD
		mov dptr,#0630h				;message "Enter alarm time" displayed on LCD
		lcall display_text
		lcall enter_time				;routine to enter TIME
		lcall copy_alarm				;copy entered time as ALARM time

		lcall clear_lcd
		mov dptr,#0610h				;message "Time12:00:00PM" displayed on LCD
		lcall display_text
		lcall display_time
		lcall cursoroff
		ret
;*************************************************************************************************
	check_alarm:					;routine ALARM function
		mov lcdcom,#0c0h
		lcall command_LCD
		mov a,alarm_status
		cjne a,#01h,no_alarm
		mov dptr,#0650h				;message "Alarm active" displayed on LCD
		lcall display_text
		mov a,alarm_match
		cjne a,#00h,buzzer_on
		mov a,hour
		cjne a,alarm_hour,notmatch
		mov a,mins
		cjne a,alarm_mins,notmatch
		mov a,secs
		cjne a,alarm_secs,notmatch
		mov a,ampm
		cjne a,alarm_ampm,notmatch
		mov alarm_match,#01h			;alram match with clock time
	notmatch:
		ret
	buzzer_on:
		setb buzzer				;alarm Buzzer on
		ret
	no_alarm:
		clr buzzer
		mov alarm_match,#00h			;no alram no match with clock time
		mov dptr,#0660h				;"         "
		lcall display_text
		ret
;**************************************************************************************************
	copy_time:					;routine copy entered time to current time variables
		mov hour,temp_hour
		mov mins,temp_mins
		mov secs,temp_secs
		mov ampm,temp_ampm
		ret
;**************************************************************************************************
	copy_alarm:					;routine copy entered time to alarm time variables
		mov alarm_hour,temp_hour
		mov alarm_mins,temp_mins
		mov alarm_secs,temp_secs
		mov alarm_ampm,temp_ampm
		ret
;***************************************************************************************************
	update_time:					;routine to update current time
		inc secs
		mov a,secs
		cjne a,#60d,secnotover
		mov secs,#00d
		inc mins
		mov a,mins
		cjne a,#60d,minsnotover
		mov mins,#00d
		inc hour
		mov a,hour
		cjne a,#12d,not12
		mov a,ampm
		cjne a,#00h,its_pm2
		mov a,#01h
		mov ampm,a
		sjmp update_over
	its_pm2:
		mov a,#00h
		mov ampm,a
		sjmp update_over
	not12:
		cjne a,#13d,hournotover
		mov hour,#01d
	secnotover:
		sjmp update_over
	minsnotover:
		sjmp update_over
	hournotover:
		sjmp update_over
	update_over:
		ret
;*********************************************************************************************	
	enter_time:					;routine to enter TIME in 12 hour format
		mov lcdcom,#0c0h
		lcall command_LCD
		mov dptr,#0610h				;message "Time:01:00:00" AM displayed on LCD
		lcall display_text                              

		mov temp_hour,#01h
		mov lcdcom,#0c5h				;entring  hour
		lcall command_LCD                                 
		mov disp_var1,#30h
		mov disp_var0,#31h
		mov disp_data,disp_var1
		lcall data_LCD            
		mov disp_data,disp_var0
		lcall data_LCD              
	inc_hour:
		mov lcdcom,#0c6h				
		lcall command_LCD                                 
		lcall chk_keys
		cjne a,#01h,dec_hour
		inc temp_hour
		mov a,temp_hour
		cjne a,#13d,x111h				;limit to 12 hour
		mov temp_hour,#01h
	x111h:
		mov a,temp_hour
		lcall chk_timedisp
		mov lcdcom,#0c5h		
		lcall command_LCD                             
		mov disp_data,disp_var1
		lcall data_LCD             
		mov disp_data,disp_var0
		lcall data_LCD             
		sjmp inc_hour

	dec_hour:
		cjne a,#02h,end_hour
		dec temp_hour
		mov a,temp_hour
		cjne a,#00h,x121h
		mov temp_hour,#12d
	x121h:
		mov a,temp_hour
		lcall chk_timedisp
		mov lcdcom,#0c5h		
		lcall command_LCD                              
		mov disp_data,disp_var1
		lcall data_LCD             
		mov disp_data,disp_var0
		lcall data_LCD              
		sjmp inc_hour

	end_hour:
		cjne a,#03h,inc_hour
;*********************************************************end of hour entry*****************************
		mov temp_mins,#00h
		mov lcdcom,#0c8h				;entring  mins
		lcall command_LCD                                
		mov disp_var1,#30h
		mov disp_var0,#30h
		mov disp_data,disp_var1
		lcall data_LCD             
		mov disp_data,disp_var0
		lcall data_LCD              
	inc_mins:
		mov lcdcom,#0c9h			
		lcall command_LCD                                 
		lcall chk_keys
		cjne a,#01h,dec_mins
		inc temp_mins
		mov a,temp_mins
		cjne a,#60d,x111m					;limit of 60 mins
		mov temp_mins,#00h
	x111m:
		mov a,temp_mins
		lcall chk_timedisp
		mov lcdcom,#0c8h		
		lcall command_LCD                                 
		mov disp_data,disp_var1
		lcall data_LCD            
		mov disp_data,disp_var0
		lcall data_LCD             
		sjmp inc_mins

	dec_mins:
		cjne a,#02h,end_mins
		dec temp_mins
		mov a,temp_mins
		cjne a,#0ffh,x121m
		mov temp_mins,#59d
	x121m:
		mov a,temp_mins
		lcall chk_timedisp
		mov lcdcom,#0c8h		
		lcall command_LCD                                
		mov disp_data,disp_var1
		lcall data_LCD             
		mov disp_data,disp_var0
		lcall data_LCD             
		sjmp inc_mins
	end_mins:
		cjne a,#03h,inc_mins
;******************end of minutes entry******************************************************
		mov temp_secs,#00h
		mov lcdcom,#0cbh				;entring  secs
		lcall command_LCD                            
		mov disp_var1,#30h
		mov disp_var0,#30h
		mov disp_data,disp_var1
		lcall data_LCD             
		mov disp_data,disp_var0
		lcall data_LCD             
	inc_secs:
		mov lcdcom,#0cch		
		lcall command_LCD                               
		lcall chk_keys
		cjne a,#01h,dec_secs
		inc temp_secs
		mov a,temp_secs
		cjne a,#60d,x111s					;limit of 60 secs
		mov temp_secs,#00h
	x111s:
		mov a,temp_secs
		lcall chk_timedisp
		mov lcdcom,#0cbh		
		lcall command_LCD                                 
		mov disp_data,disp_var1
		lcall data_LCD             
		mov disp_data,disp_var0
		lcall data_LCD             
		sjmp inc_secs

	dec_secs:
		cjne a,#02h,end_secs
		dec temp_secs
		mov a,temp_secs
		cjne a,#0ffh,x121s
		mov temp_secs,#59d
	x121s:
		mov a,temp_secs
		lcall chk_timedisp
		mov lcdcom,#0cbh		
		lcall command_LCD                                
		mov disp_data,disp_var1
		lcall data_LCD             
		mov disp_data,disp_var0
		lcall data_LCD             
		sjmp inc_secs
	end_secs:
		cjne a,#03h,inc_secs
;*****************************end of seconds entry*********************************************************	
		mov temp_ampm,#00h
	inc_am_pm:
		mov lcdcom,#0ceh					;entrying  am_pm
		lcall command_LCD                                 
		mov a,temp_ampm
	its_am:
		cjne a,#00h,its_pm
		mov disp_data,#'A'
		lcall data_LCD             
		sjmp x131
	its_pm:
		mov disp_data,#'P'
		lcall data_LCD             
	x131:
		lcall chk_keys
		cjne a,#01h,dec_am_pm
		inc temp_ampm
		mov a,temp_ampm
		cjne a,#02h,x111am
		mov temp_ampm,#00h
	x111am:
		sjmp inc_am_pm

	dec_am_pm:
		cjne a,#02h,end_am_pm
		dec temp_ampm
		mov a,temp_ampm
		cjne a,#0ffh,x121am
		mov temp_ampm,#01h
	x121am:
		sjmp inc_am_pm

	end_am_pm:
		cjne a,#03h,inc_am_pm
		ret
;********************************************************************************************************
	display_time:						;routine to display updated time on the LCD
		mov a,hour
		lcall chk_timedisp
		mov lcdcom,#85h
		lcall command_LCD
		mov disp_data,disp_var1
		lcall data_LCD
		mov disp_data,disp_var0
		lcall data_LCD

		mov a,mins
		lcall chk_timedisp
		mov lcdcom,#88h
		lcall command_LCD
		mov disp_data,disp_var1
		lcall data_LCD
		mov disp_data,disp_var0
		lcall data_LCD

		mov a,secs
		lcall chk_timedisp
		mov lcdcom,#8bh
		lcall command_LCD
		mov disp_data,disp_var1
		lcall data_LCD
		mov disp_data,disp_var0
		lcall data_LCD

		mov lcdcom,#8eh
		lcall command_LCD
		mov a,ampm
		cjne a,#00h,its_pm1
		mov disp_data,#'A'
		lcall data_LCD
		sjmp xc112
	its_pm1:
		mov disp_data,#'P'
		lcall data_LCD
	xc112:
		mov disp_data,#'M'
		lcall data_LCD
		ret		
;**********************************************************************************************
	chk_timedisp:
		mov b,#0ah
		div ab
		orl a,#30h
		orl b,#30h
		mov disp_var1,a
		mov disp_var0,b
		ret
;*********************************************************************************************
	chk_keys:						;rountine to find  which button is pressed
		mov p2,#0ffh
		nop
		mov a,#00h
	key_again:
		jb up,xdown	
		mov a,#01h				;if UP pressed Acc=01h 
		sjmp key_over
	xdown:
		jb down,xenter
		mov a,#02h				;if DOWN pressed Acc=02h 
		sjmp key_over
	xenter:
		jb enter,key_again
		mov a,#03h				;if ENTER pressed Acc=03h 
	key_over:
		lcall delay140m                             		;debounce delay
		lcall delay140m 
		ret
;**************************************************************************************************
;**************************************************************************************************
;************************MATH ROUTINES*********************************************************
;***************************************************************************************************
	hex_to_dec:					;routine to convert 32 bit hex number to 8 digit ASCII decimal number	
		mov out7,#00h
		mov out6,#00h
		mov out5,#00h
		mov out4,#00h
		mov out3,#00h
		mov out2,#00h
		mov out1,#00h
		mov out0,#00h

		mov hex1,#00h
		mov hex0,#0ah
		
		mov a,tt2
		cjne a,#00h,xbn56
		mov a,tt1
		cjne a,#00h,xbn57			
		lcall division_16            
		mov out0,r6
		lcall division_16            
		mov out1,r6
		mov out2,tt0
		sjmp over56
	xbn57:
		lcall division_16               
		mov out0,r6
		lcall division_16              
		mov out1,r6
		lcall division_16              
		mov out2,r6
		lcall division_16               
		mov out3,r6
		mov out4,tt0
		sjmp over56
	xbn56:
		lcall division_16              
		mov out0,r6
		lcall division_16             
		mov out1,r6
		lcall division_16              
		mov out2,r6
		lcall division_16              
		mov out3,r6
		lcall division_16             
		mov out4,r6
		lcall division_16             
		mov out5,r6
		lcall division_16             
		mov out6,r6
		mov out7,tt0
	over56:
		orl out7,#30h
		orl out6,#30h
		orl out5,#30h
		orl out4,#30h
		orl out3,#30h
		orl out2,#30h
		orl out1,#30h
		orl out0,#30h
		ret
;**********************************************************************************************************
division_16:						;routine to divide 3 bit divided by 16 bit divisor to provide 16 bit Quotent and reminder		
        MOV     R7,#0			;msb rem
        MOV     R6,#0           	;lsb rem	;zero out partial remainder
        MOV     TMP_0,#0
        MOV     TMP_1,#0
        MOV     TMP_2,#0
        MOV     TMP_3,#0
        MOV     R1,hex1			 ;load divisor
        MOV     R0,hex0
        MOV     R5,#32         			 ;loop count
  Div_loop:
        LCALL    Shift_D         ;shift the dividend and return MSB in C
        MOV     A,R6             ;shift carry into LSB of partial remainder
        RLC     A
        MOV     R6,A
        MOV     A,R7
        RLC     A
        MOV     R7,A
        CLR     C
        MOV     A,R7            ;subtract R1 from R7 to see if R1 < R7
        SUBB    A,R1            ; A = R7 - R1, carry set if R7 < R1
        JC      Cant_sub
        JNZ     Can_sub         ;jump if R7>R1
     	CLR     C
        MOV     A,R6
        SUBB    A,R0            ; A = R6 - R0, carry set if R6 < R0
        JC      Cant_sub

Can_sub:
        CLR     C
        MOV     A,R6
        SUBB    A,R0            ; A = R6 - R0
        MOV     R6,A
        MOV     A,R7
        SUBB    A,R1            ; A = R7 - R1 - Borrow
        MOV     R7,A
        SETB    C               ; shift a 1 into the quotient
        ljmp     Quot

Cant_sub:
	  CLR     C
Quot:
	LCALL    Shift_Q
        			; Test for competion
        DJNZ    R5,Div_loop
			        ; Now we are all done, move the TMP values back into OP
        MOV     tt0,TMP_0
        MOV     tt1,TMP_1
        MOV     tt2,TMP_2
        MOV     tt3,TMP_3
        RET
Shift_D:
        CLR     C
        MOV     A,tt0
        RLC     A
        MOV     tt0,A
        MOV     A,tt1
        RLC     A
        MOV     tt1,A
        MOV     A,tt2
        RLC     A
        MOV     tt2,A
        MOV     A,tt3
        RLC     A
        MOV     tt3,A
        RET
 Shift_Q:
        MOV     A,TMP_0
        RLC     A
        MOV     TMP_0,A
        MOV     A,TMP_1
        RLC     A
        MOV     TMP_1,A
        MOV     A,TMP_2
        RLC     A
        MOV     TMP_2,A
        MOV     A,TMP_3
        RLC     A
        MOV     TMP_3,A
        RET
;**************************************************************************************************
;**************************************************************************************************
;************************LCD ROUTINES***********************************************************
;***************************************************************************************************
	display_text:					;routine to display 16 characters stored in ROM on LCD		
		mov count,#0fh
	nextchar:
		mov a,#00h					
		movc a,@a+dptr			
		mov disp_data,a 			
		lcall data_LCD      	        	
		inc dptr				
		mov a,count			
		cjne a,#00h,next1			
		ljmp here11			
	next1:
		dec count			
		ljmp nextchar			
	here11:
		ret				
;*********************Initialize LCD******************************************************************
	lcd_initialize:					;routine to initialize LCD
		mov lcdcom,#38h
		lcall command_LCD                                 
		lcall delay40u               

		mov lcdcom,#01h
		lcall command_LCD                               
		lcall delay14m                             
		
		mov lcdcom,#0Eh
		lcall command_LCD                             
		lcall delay40u              		
					
		mov lcdcom,#06h
		lcall command_LCD                              
		lcall delay40u               		
		ret
;****************************************************************************************************
	cursoroff:						;routine to switch cursor of LCD off
		mov lcdcom,#0ch
		lcall command_LCD
		ret
;*****************************************************************************************************
	cursoron:						;routine to switch cursor of LCD ON
		mov lcdcom,#0Eh
		lcall command_LCD
		ret
;******************************************************************************************************
	clear_lcd:						;routine to clear LCD 
		mov lcdcom,#01h		
		lcall command_LCD                    		
		lcall delay14m		
		mov lcdcom,#80h		
		lcall command_LCD                   
		ret			
;*****************************************************************************************************
	command_LCD:					;routine to send command to LCD
		clr RS				
		clr RW					
		lcall delay10u          	
		setb EN					
		lcall delay10u              	
		mov p1,lcdcom			
		lcall delay10u            	
		clr EN				
		lcall delay10u              	
		setb RW				
		lcall delay40u               	
		ret			
;******************************************************************************************************
	data_LCD:					;routine to ASCII data to LCD display	
		setb RS				
		clr RW				
		lcall delay10u                  
		setb EN					
		lcall delay10u                  
		mov p1,disp_data		
		clr EN				
		lcall delay40u                	
		nop			
		ret	
;********************************************************************************************************
;***********************sofware delays generated by nested loops***********************************************
;********************************************************************************************************		
	 delay1sec:					;Delay of 1second	
		mov r3,#07h			
	here1_1s:
		mov r4,#0ffh
	here2_1s:
		mov r5,#0ffh
	here3_1s:
		djnz r5,here3_1s
		djnz r4,here2_1s
		djnz r3,here1_1s
		ret
;*******************************************************************************************************
	delay140m:					;Delay of 140msec			
		mov r3,#01h
	here1_140m:
		mov r4,#0ffh
	here2_140m:
		mov r5,#0ffh
	here3_140m:
		djnz r5,here3_140m
		djnz r4,here2_140m
		djnz r3,here1_140m
		ret
;*******************************************************************************************************
	 delay14m:					;Delay of 14msec			
		mov r3,#1ch
	here1_14m:
		mov r4,#0e6h
	here2_14m:
		djnz r4,here2_14m
		djnz r3,here1_14m
		ret	
;******************************************************************************************************
	delay40u:            					;Delay of 40usec			
		mov r4,#11h		
	here40u:
		djnz r4,here40u		
		ret		
;******************************************************************************************************
	delay10u:						;Delay of 10usec
		mov r4,#03h		
	here10u:
		djnz r4,here10u		
		ret			
;******************************************************************************************************
		org 0600h
	db  '  Digital Clock '
	org 0610h
	db  'Time:01:00:00 AM'   
	org 0620h
	db 'Enter Clock Time'
	org 0630h
	db 'Enter Alarm Time'
	org 0640h
	db '  With Alarm    '
	org 0650h
	db 'Alarm active    '
	org 0660h
	db '                '
	end							;END of program