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HELP on using LDR and ADC0804 in 8051 Assembly


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mark_627

Mon Nov 02 2009, 07:59AM

Registered Member #23415

Joined: Mon Nov 02 2009, 03:30AM

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Hi everyone.

I need help on how to use LDR and ADC0804 in 8051 microcontroller.
So far I have this in my project but I want to replace the switch with LDR(dark activated).

What happens here (attached file) is that I use the switch to decrement/increment the number of cars and when it reaches zero (meaning no available space) the LCD will prompt that it is full.

What I want is using a sensor (ldr) and a laser light so that when a car passes (the light will be broken) the ldr will send a signal and decrement the number of spaces and vice versa ( i'll be using two ldr one for exit the other for entrance).

attached is my design. Im using Isis Proteus 7.4 and the code below

CODE:

DB0 EQU P1.0

DB1 EQU P1.1

DB2 EQU P1.2

DB3 EQU P1.3

DB4 EQU P1.4

DB5 EQU P1.5

DB6 EQU P1.6

DB7 EQU P1.7

EN EQU P3.7

RS EQU P3.6

RW EQU P3.5

DATA EQU P1

;7-Segment Display

enableDIGIT3 EQU P3.2

enableDIGIT4 EQU P3.3

ZERO    EQU   10001000b

ONE     EQU   10111110b

TWO     EQU   11000100b

THREE   EQU   10010100b

FOUR    EQU   10110010b

FIVE    EQU   10010001b

SIX     EQU   10000001b

SEVEN   EQU   10111100b

EIGHT   EQU   10000000b

NINE    EQU   10010000b

DOT     EQU   01111111b

MOV 20h,#ZERO

MOV 21h,#ONE

MOV 22h,#TWO

MOV 23h,#THREE

MOV 24h,#FOUR

MOV 25h,#FIVE

MOV 26h,#SIX

MOV 27h,#SEVEN

MOV 28h,#EIGHT

MOV 29h,#NINE

MOV R0, #20h

MOV R1, #22h

PDATA EQU P2 ; Connect 8 pins here

CLR 51h

LCALL LCD_WELCOME

Start:

        JB P3.1, check1

                SETB 50h

        check1:

        JB P3.0, check2

                SETB 52h

        check2:

                JNB P3.1, cont1

                        JNB 50h, cont1

                                CLR 50h

                                LCALL INC_7SEGMENT     

        cont1:

                JNB P3.0, cont2

                        JNB 52h, cont2

                                CLR 52h

                                LCALL DEC_7SEGMENT

        cont2:

                LCALL SHOW_7SEGMENT

                LCALL SHOW_LCD

SJMP Start  

SHOW_LCD:

        CJNE @R0, #ZERO, welcome

        CJNE @R1, #ZERO, welcome

                JB 51h, done_showlcd

                LCALL LCD_FULL

        sjmp done_showlcd

        welcome:

                JNB 51h, done_showlcd

                LCALL LCD_WELCOME

        done_showlcd:

RET

LCD_FULL:      

        LCALL CLEAR_LCD

        LCALL INIT_LCD

        CLR RS

        MOV DATA,#086H

        SETB EN

        CLR EN

        LCALL WAIT_LCD

        MOV A,#'F'

        LCALL WRITE_TEXT

        MOV A,#'U'

        LCALL WRITE_TEXT

        MOV A,#'L'

        LCALL WRITE_TEXT

        MOV A,#'L'

        LCALL WRITE_TEXT

        MOV A,#'!'

        LCALL WRITE_TEXT

        MOV A,#'!'

        LCALL WRITE_TEXT

        SETB 51h

RET

LCD_WELCOME:

        LCALL CLEAR_LCD

        LCALL INIT_LCD

        CLR RS

        MOV DATA,#081h

        SETB EN

        CLR EN

        LCALL WAIT_LCD

        MOV A,#'P'

        LCALL WRITE_TEXT

        MOV A,#'A'

        LCALL WRITE_TEXT

        MOV A,#'R'

        LCALL WRITE_TEXT

        MOV A,#'K'

        LCALL WRITE_TEXT

        MOV A,#'I'

        LCALL WRITE_TEXT

        MOV A,#'N'

        LCALL WRITE_TEXT

        MOV A,#'G'

        LCALL WRITE_TEXT

        MOV A,#' '

        LCALL WRITE_TEXT

        MOV A,#'S'

        LCALL WRITE_TEXT

        MOV A,#'P'

        LCALL WRITE_TEXT

        MOV A,#'A'

        LCALL WRITE_TEXT

        MOV A,#'C'

        LCALL WRITE_TEXT

        MOV A,#'E'

        LCALL WRITE_TEXT

        CLR RS

        MOV DATA,#0C3h

        SETB EN

        CLR EN

        LCALL WAIT_LCD

        MOV A,#'A'

        LCALL WRITE_TEXT

        MOV A,#'V'

        LCALL WRITE_TEXT

        MOV A,#'A'

        LCALL WRITE_TEXT

        MOV A,#'I'

        LCALL WRITE_TEXT

        MOV A,#'L'

        LCALL WRITE_TEXT

        MOV A,#'A'

        LCALL WRITE_TEXT

        MOV A,#'B'

        LCALL WRITE_TEXT

        MOV A,#'L'

        LCALL WRITE_TEXT

        MOV A,#'E'

        LCALL WRITE_TEXT

        CLR 51h

RET

INC_7SEGMENT:

        CJNE @R1, #TWO, increment

        sjmp doneinc

        increment:

                CJNE @R0, #NINE, incr0

                MOV R0, #20h

                INC R1

                SJMP doneinc

                incr0:

                        INC R0

        doneinc:

RET

DEC_7SEGMENT:

        CJNE @R0, #ZERO, dec0

        CJNE @R1, #ZERO, dec1

        sjmp donedec

        dec1:

                MOV R0, #29h

                DEC R1

                SJMP donedec

        dec0:

                DEC R0

        donedec:

RET

SHOW_7SEGMENT:

        MOV PDATA,#00h

        setb enableDIGIT3

        MOV     A,@R1

        MOV PDATA,A

        LCALL smallDelay

        clr enableDIGIT3

        setb enableDIGIT4

        MOV     A,@R0

        MOV PDATA,A

        LCALL smallDelay        

        clr enableDIGIT4

RET    

INIT_LCD:

        CLR RS

        MOV DATA,#38h

        SETB EN

        CLR EN

        LCALL WAIT_LCD

        CLR RS

        MOV DATA,#0Ch

        SETB EN

        CLR EN

        LCALL WAIT_LCD

RET

CLEAR_LCD:

        CLR RS

        MOV DATA,#01h

        SETB EN

        CLR EN

        LCALL WAIT_LCD

RET

WRITE_TEXT:

        SETB RS

        MOV DATA,A

        SETB EN

        CLR EN

        LCALL WAIT_LCD

RET

WAIT_LCD:

        CLR EN ;Start LCD command

        CLR RS ;It's a command

        SETB RW ;It's a read command

        MOV DATA,#0FFh ;Set all pins to FF initially

        SETB EN ;Clock out command to LCD

        LCALL smallDelay

        MOV A,DATA ;Read the return value

        JB ACC.7,WAIT_LCD ;If bit 7 high, LCD still busy

        CLR EN ;Finish the command

        CLR RW ;Turn off RW for future commands

RET  

smallDelay:

                CLR TF1

                CLR TR1

                MOV TH1,#76

                MOV TL1,#01

                MOV TMOD,#01

                SETB TR1

                JNB TF1,$

RET

[ Edited Mon Nov 02 2009, 08:10AM ]

Embedded Systems present themselves as a challenge.

mark_627

Mon Nov 02 2009, 08:19AM

Registered Member #23415

Joined: Mon Nov 02 2009, 03:30AM

Posts: 3
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Im sorry about the photo.when i resized it to fit the screen in the attachment the connections of the wires got blurry you cant even see them but they are there.. :|

Embedded Systems present themselves as a challenge.

Arun Kumar V

Mon Nov 02 2009, 05:01PM

Registered Member #426

Joined: Sun Jan 28 2007, 11:50PM

Posts: 752
Thanked 295 times in 250 posts

you don't have to use an ADC or LDR, you can use a photo transistor or photodiode and connect to port pin via a transistor. its better to use modulated IR bcoz it provides immunity to day light.

Arun

mark_627

Tue Nov 03 2009, 08:03AM

Registered Member #23415

Joined: Mon Nov 02 2009, 03:30AM

Posts: 3
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@Arun:

Sir, thanks for the reply.:)
Can you provide me a circuit diagram on using the photodiode and transistor to the port pin? I would very much appreciate it.

THANKS a million.