hi all

Currently im doing a project for my final year. My project have two infrared sensor. Which i put sensor 1 at entrance and sensor 2 at the exit. I mean like visitor counter. I use atmel 8052 microcontroller (AT89S52) and i program it in assembly language. I program port 2 as sensor input,port 1 is output and port 3 as counter which give 8 bit binary code from P3.0 to P3.7. Im stuck with the counter part only. The others all ok. I want to display from 00 to 99. So,the 8 bit binary will display until 99. I already done with two common anode 7 segment display and two SN74LS47N ic which is BCD to 7 segment decoder. The display will display from 0 to F. In BCD,it just display 0 to 9 right? how do i skip from A to F? I mean,i just want to display 0 to 9 only. I also try using common cathode 7 segment with 74HC4511.The ic is the same with 74LS47. The result is the same. But when the counter reach 10 to 15. It will give blank display for A,B,C,D,E,F and come back to 0. so it will count until 15 too. Suppose after 9 it will display 0 and another one 7 segment will display 1. it will display 10 by using two 7 segment and it will count until 99. Can anyone please help me.. how do i skip A(1010),B (1011),C (1100),D (1101),E (1110), F (1111) and just displaying 0 to 9. Another things is how do i convert from binary to BCD? someone expert in assembly please help me. Sorry for my bad english.

here is my program i wrote in keil μvision assembly.

ORG 0000H
MOV P0,#0H
MOV P1,#0H
MOV P2,#0H
MOV R3,#0H

MAIN:    JB P2.0, INCRES
         JB P2.1, DECRES
         SJMP MAIN

INCRES: INC R3
        MOV P3,R3
        ACALL  DELAY       
        SJMP MAIN
        

DECRES: DEC R3
        MOV P3,R3
        ACALL  DELAY   
        SJMP MAIN


DELAY:  MOV    R0,#20
LOOP3:  MOV    R1,#255
LOOP2:  MOV    R2,#255
LOOP1:  DJNZ   R2,LOOP1
        DJNZ   R1,LOOP2
        DJNZ   R0,LOOP3
        
    RET    

    END

please help me to convert from binary to bcd.

thanks in advance.

 

Try serching for AN526 on the Microchip site. It is a different processor with different assembler instructions but it explains the algorithm.

 

INCLUDE 8051.mc
ORG 0000H
MOV P0,#0H
MOV P1,#0H
MOV P2,#0H
MOV R3,#0H

MAIN: JB P2.0, INCRES
JB P2.1, DECRES
SJMP MAIN

INCRES: INC R3
MOV A,R3
DA A
MOV P3,A
ACALL DELAY
SJMP MAIN


DECRES: DEC R3
MOV A,R3
DA A
MOV P3,A
ACALL DELAY
SJMP MAIN


DELAY: MOV R0,#20
LOOP3: MOV R1,#255
LOOP2: MOV R2,#255
LOOP1: DJNZ R2,LOOP1
DJNZ R1,LOOP2
DJNZ R0,LOOP3

RET

END