Design of Single Chip Microcomputer Electronic Clock

Here is a 51 single-chip electronic clock assembly program design method:

org 00h
a_bit equ 30h ; second register
b_bit equ 31h ; 10
second register
c_bit equ 32h ; minute register d_bit equ 33h ; 10 minute register
e_bit equ 34h ; hour register
f_bit equ 35h ; 10 hour register

org 0000h
ajmp star
org 0030h

star:
mov a,#00h ; clear all bits to 0
mov a_bit,a
mov b_bit,a
mov c_bit,a
mov d_bit,a
mov e_bit,a
mov f_bit,a
stlop: acall display ; calculation part of 51 single-chip electronic clock program

inc a_bit ;add 1 to the second bit
mov a,a_bit ;send a
cjne a,#10,stlop;if the second reaches 10, then go to 10 seconds processing
mov a_bit,#00h ;clear the second bit to 0
inc b_bit ;add 1 to the 10 seconds
bit mov a,b_bit ;send a
cjne a,#6,stlop ;if the 10 seconds reaches 6, then go to minute processing
mov b_bit,#00h ;clear the 10 seconds bit to 0
inc c_bit
mov a,c_bit
cjne a,#10,stlop
mov c_bit, #00h
inc d_bit
mov a,d_bit
cjne a,#6,stlop
mov d_bit,#00h
inc e_bit
mov a,e_bit
cjne a,#10,stlop
mov e_bit,#00h
inc f_bit
mov a,f_bit
cjne a,#3,stlop
mov f_bit,#00h
ajmp stlop ; restart calculation

display: ;Display subroutine - 51 single-chip electronic clock directly displayed on the seven-segment digital tube
mov dptr,#numtab ;Specify the start address of the table lookup
mov r0,#4
dpl1: mov r1,#250 ;Display 1000 times
dplop: mov a,a_bit ;Get the value of the second digit
MOVC A,@A+DPTR ;Look up the 7-segment code of the second digit
mov p0,a ;Send to P0 port for display
clr p2.6 ;Open the unit digit display
acall d1ms ;Display 1ms
setb p2.6 ;Turn off the display

mov a,b_bit ;get the value of the 10-second bit
MOVC A,@A+DPTR ;check the 7-segment code of the 10-second bit
mov p0,a ;send the 10-second bit to port P0 for display

clr p2.5 ; open 10 seconds display
acall d1ms ; display 1ms
setb p2.5

mov a,c_bit ; get the bit position
MOVC A,@A+DPTR;

mov p0,a ;
clr p2.4 ;
acall d1ms ;

setb p2.4

mov a,d_bit ; take 10th bit
MOVC A,@A+DPTR ;

mov p0,a ;

clr p2.3 ;

acall d1ms ;

setb p2.3

mov a,e_bit ; get hour bit
MOVC A,@A+DPTR ;
mov p0,a ;
clr p2.2 ;
acall d1ms ;

setb p2.2

mov a,f_bit ; get 10 hours bit
MOVC A,@A+DPTR ;
mov p0,a ;
clr p2.1 ;
acall d1ms ;
setb p2.1

djnz r1,dplop ;100 endless loops
djnz r0,dpl1 ;4 100 endless loops
ret
D1MS: MOV R7,#20 ;1MS delay (calculated as 12MHZ)
DJNZ R7,$
RET
;Digital arrangement table of each stroke of the seven-segment digital tube - http://www.51hei.com/ provides
numtab: db 28h,7eh,0a2h,62h,74h,61h,21h,7ah,20h,60h
;0 1 2 3 4 5 6 7 8 9
end