hex to bcd?

pranitamm

pranitamm

@pranitamm-fXl1v3 • Oct 26, 2024
in my project i require bcd at port 0 and 3 of microcontroller 89s52 since there are three 7447 connected
(i.e p0.0-p0.3 to 7447(1) lsb,
p0.4-p0.7 to7447(1),
p3.0-p3.3 to7447(3)msb)
which drive three 7 segment displays
now suppose i want to display (240)d then in the accumulator there is its hex equivalent i.e (F0)h which is proper but now when i convert it to bcd using the instruction DA A i get 50 in the accumulator with a carry.now this is the problem instead of having 240 at the o/p there comes 150
please can anybody help me to splve this problem??????
please its very urgent!!!!!!
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  • binu_ji

    binu_ji

    @binu-ji-93Lo05 • Nov 2, 2008

    Use this subroutine to convert HEX to BCD
    Hex2BCD:
    MOV R1,#00H        ;  MSByte
        MOV R2,#0F0H       ;  LSByte
 
        MOV R3,#00D
        MOV R4,#00D
        MOV R5,#00D
        MOV R6,#00D
        MOV R7,#00D
        CALL H2B
        RET
        
H2B:        MOV B,#10D
        MOV A,R2
        DIV AB
        MOV   R3,B              ;   
        MOV   B,#10             ; R7,R6,R5,R4,R3
        DIV   AB
        MOV   R4,B
        MOV   R5,A
        CJNE R1,#0H,HIGH_BYTE   ; CHECK FOR HIGH BYTE
        SJMP ENDD
 
HIGH_BYTE:
MOV   A,#6
        ADD   A,R3
MOV   B,#10
DIV   AB
        MOV   R3,B
ADD   A,#5
        ADD   A,R4
MOV   B,#10
DIV   AB
        MOV   R4,B
ADD   A,#2
        ADD   A,R5
MOV   B,#10
DIV   AB
        MOV   R5,B
        CJNE R6,#00D,ADD_IT
        SJMP CONTINUE
ADD_IT:
        ADD A,R6
CONTINUE:
        MOV R6,A
        DJNZ R1,HIGH_BYTE
        MOV B, #10D
        MOV A,R6
        DIV AB
        MOV R6,B
        MOV R7,A
ENDD:   RET
    Just call this routine by loading the value into the R2 and you will get the result like this
    R3=0
    R4=4
    R5=2