final version of timer.asm

8051 Asmbly Language of a Timer with Matrix Keypad Input

#include <sfr51.inc>
#include <util51.inc>
;---------------------MAIN--------------------

          ORG     00H
          SJMP    MAIN
          ORG     03H
          LJMP    RESET
          ORG     0BH
          LJMP    TIMER0
                
MAIN:     SETB    P2.0
          CLR     P2.1
          MOV     R2,#00H               ;initialization
          MOV     R4,#00H
          MOV     A,#00H

LUD:      ACALL   DISPLAY               ; wait for the num input and the operation input
          JB      P1.0,IM1
          JB      P1.1,IM2
          CJNE    R4,#01H,SCAN1
          JB      P1.2,SHIFT
          SJMP    LUD

SHIFT:    JB      P1.2,$                ;To input two digit, a shift is need
          RL      A
          RL      A
          RL      A
          RL      A
          CLR     Acc.3
          CLR     Acc.2
          CLR     Acc.1
          CLR     Acc.0
          MOV     R4,#00H
          SJMP    LUD

IM1:      JB      P1.0,$                ;a intermidiate state to jump to UP, because JB is not enough
          AJMP    UP

IM2:      JB      P1.1,$                ;a intermidiate state to jump to DOWN, because JB is not enough
          AJMP    DOWN
;----------------------SCAN INPUT----------------------------
SCAN1:    MOV     P3,#FFH               ;check the first colume
          CLR     P3.4
          MOV     R5,P3
          CJNE    R5,#EEH,SCAN4         ;Scan the input of 1
          ADD     A,#01H
          MOV     P0,A
          INC     R4
          LJMP    LUD
SCAN4:    CJNE    R5,#EDH,SCAN7         ;Scan the input of 4
          ADD     A,#04H
          MOV     P0,A
          INC     R4
          LJMP    LUD
SCAN7:    CJNE    R5,#EBH,SCAN2         ;Scan the input of 7
          ADD     A,#07H
          MOV     P0,A
          INC     R4
          LJMP    LUD

SCAN2:    MOV     P3,#FFH               ;Check the second colume
          CLR     P3.5
          MOV     R5,P3
          CJNE    R5,#DEH,SCAN5         ;Scan the input of 2
          ADD     A,#02H
          MOV     P0,A
          INC     R4
          LJMP    LUD
SCAN5:    CJNE    R5,#DDH,SCAN8         ;Scan the input of 5
          ADD     A,#05H
          MOV     P0,A
          INC     R4
          LJMP    LUD
SCAN8:    CJNE    R5,#DBH,SCAN0         ;Scan the input of 8
          ADD     A,#08H
          MOV     P0,A
          INC     R4
          LJMP    LUD
SCAN0:    CJNE    R5,#D7H,SCAN3         ;Scan the input of 0
          ADD     A,#00H
          MOV     P0,A
          INC     R4
          LJMP    LUD

SCAN3:    MOV     P3,#FFH               ;check the third colume
          CLR     P3.6
          MOV     R5,P3
          CJNE    R5,#BEH,SCAN6         ;Scan the input of 3
          ADD     A,#03H
          MOV     P0,A
          INC     R4
          LJMP    LUD
SCAN6:    CJNE    R5,#BDH,SCAN9         ;Scan the input of 6
          ADD     A,#06H
          MOV     P0,A
          INC     R4
          LJMP    LUD
SCAN9:    CJNE    R5,#BBH,IM            ;Scan the input of 9
          ADD     A,#09H
          MOV     P0,A
          INC     R4
          LJMP    LUD

IM:       AJMP    LUD
;--------------------------------------------------------------

DOWN:     MOV     R2,#00H               ;Set count down
          SJMP    LSTART

UP:       MOV     R2,#FFH               ;Set count up

LSTART:   JB      P1.0,START            ;Check start buttom
          LJMP    LSTART

LSP:      JB      P1.2,STOP             ;Check stop and pause buttom
          JB      P1.1,PAUSE
          AJMP    LSP

START:    JB      P1.0,$                ;Set the timer0 interrupt start to count
          SETB    EA
          SETB    ET0
          MOV     TMOD,#0               ;Set Mode 0
          MOV     R0,#200               ;0.005*200=1sec
          MOV     TH0,#63H              ;Set the interrupt to count 0.005 sec
          MOV     TL0,#18H
          SETB    TR0                   ;Start the interrupt
          SJMP    LSP

PAUSE:    JB      P1.1,$                ;Pause the counting
          CLR     TR0
LSR:      JB      P1.2,STOP             ;Check stop and restart buttom
          JB      P1.3,RESTART
          AJMP    LSR

STOP:     JB      P1.2,$                ;Stop the counting and jump back to main
          CLR     TR0
          AJMP    MAIN

RESTART:  JB      P1.3,$                ;Restart the count after pause
          SETB    TR0                   ;Start to interrupt
          LJMP    LSP 

DISPLAY:  MOV     P0,A                  ;Display the value to the 7segment LED
          RET

;------------------INTERRUPT---------------------

TIMER0:   CLR     TR0                   ;Check wheather it reach 1 sec or not
          DJNZ    R0,EXIT;              ;if not yet 1 sec , jump to exit
          MOV     R0,#200;              

LCHECK:   CJNE    R2,#00H,INCREASE      ;Check count up or count down
          MOV     20H,A                 ;use to compare the less significant digit                 
          MOV     21H,A                 ;use to compare the most significant digit
          CLR     20H.7                 ;clear the most significant digit
          CLR     20H.6
          CLR     20H.5
          CLR     20H.4
          MOV     R1,#20H
          CJNE    @R1,#00H,NMALS        ;compare the less significant digit, if > 0,jump NMALS
          CLR     21H.3                 ;Clear the less significant digit
          CLR     21H.2
          CLR     21H.1
          CLR     21H.0
          MOV     R1,#21H
          CJNE    @R1,#00H,NMALT        ;compare the most significant digit,if > 0,jump NAMLT
          SETB    Acc.0                 ;if the digit is "00" move "99" to the display in next second
          CLR     Acc.1
          CLR     Acc.2
          SETB    Acc.3
          SETB    Acc.4
          CLR     Acc.5
          CLR     Acc.6
          SETB    Acc.7
          ACALL   BUZZ                  ;Call a buzz sound
          SJMP    DIS

NMALS:    DEC     A                     ;A=A-1
          SJMP    DIS                

NMALT:    SUBB    A,#10H                ;Decrease the most significant digit by 1
          SETB    Acc.0                 ;Set the less significant digit to '9'
          CLR     Acc.1
          CLR     Acc.2
          SETB    Acc.3
          SJMP    DIS

INCREASE: MOV     20H,A                 ;use to compare the less significant digit 
          MOV     21H,A                 ;use to compare the most significant digit
          CLR     20H.7                 ;Clear the most significant digit
          CLR     20H.6
          CLR     20H.5
          CLR     20H.4
          MOV     R1,#20H
          CJNE    @R1,#09H,SNMAL        ;compare the lesss significant digit,if < 9,jump SNMAL    
          CLR     21H.3                 ;Clear the less significant digit
          CLR     21H.2
          CLR     21H.1
          CLR     21H.0
          MOV     R1,#21H
          CJNE    @R1,#90H,TNMAL        ;compare the most significant digit,if < 9, Jump TNMAL
          CLR     A                     ;if the digit is "99", Move a "00" to display in the next second
          ACALL   BUZZ                  ;Call a Buzz sound
          SJMP    DIS

TNMAL:    CLR     Acc.0                 ;Increase the most significant digit by 1 and clear the less significant digit
          CLR     Acc.1
          CLR     Acc.2
          CLR     Acc.3
          ADD     A,#10H
          SJMP    DIS

SNMAL:    INC     A                     ;Increase the less significant digit by 1

DIS:      ACALL   DISPLAY
          
EXIT:     MOV     TH0,#63H              ;Set the interrupt to continue counting
          MOV     TL0,#18H
          SETB    TR0
          RETI

BUZZ:     CLR     P2.0                  ;Output to the buzzer
          CLR     P2.2
          MOV     R6,#FFH
DELAY1:   MOV     R5,#FFH
          DJNZ    R5,$
          DJNZ    R6,DELAY1
          SETB    P2.0
          SETB    P2.2
          RET

RESET:    LJMP MAIN
          RETI

END