I am designing a project which is a keypad lock My problem is that if i want to hide the password being displayed by ******,how can i write the program? actually it is aimed to ensure that the persons standing behind cant see the passoword entered by the users.
thanks

what is your display device??

lcd 32X04

well for every key pressed, display * instead of the key value.

yeah, exactly........how can we do?we write asm format

There really isn't a problem if you understand how the program works.
If you don't, this is a good time to study it and find out

Find the code where you get a character from the keyboard and pass it to the display routine.

Set a flag to show whenever you are in "Password" mode.
Whenever this flag is set, pass a "*" instead of the proper character.

are you designing your own project or you're using the one on website?

i am designing..but no clue on doing that function

Do you have any LCD display code written ?.
If so, please post it.
If not, take a look at the LCD tutorials in the tutorial section.

its better if you post your code here. to see what you have done and guide you better.

I have another problem with the same project... I want to use a speaker using the free port(p3.4) and I already have my own code to make a sound but I dont know where to put it... I wanna use the frequecy out of the p3.4 to connect it through a resistance which is connected to the base of a transistor, the emitter is connected to ground and the colector is connected to the negative side of the speaker and the positive to 5V.

Plz, I really need help with this... I've tried to figure it out but with no successful results...

here's my code to make a sound using a speaker and a frequency as input... also i'm using a led the check if everything is ok..

org 00h
jmp INIC
t2ms:
mov R1, #230
LX: nop
nop
nop
nop
nop
nop
DJNZ R1, LX
MOV R2, #230
LB: NOP
NOP
NOP
NOP
NOP
NOP
DJNZ R2, LB
ret


t1.5ms:
mov R1, #230
L3: nop
nop
nop
nop
nop
nop
DJNZ R1, L3
MOV R2, #115
LZ: NOP
NOP
DJNZ R2, LZ
ret

t50ms: mov R2, #50
L8: mov R1, #230
L6: nop
nop
nop
nop
nop
nop
DJNZ R1, L6
DJNZ R2, L8
ret




LEDON2: setB p3.4
call t1.5ms

clr p3.4

call t1.5ms
ret

LEDON3: setB p3.4
call t2ms

clr p3.4

call t2ms
ret

INIC:
MOV R4, #166
LEDON:
CALL LEDON2
DJNZ R4, LEDON


MOV R5, #120
LAZO1: CALL LEDON3
DJNZ R5,LAZO1


SJMP INIC



;sjmp ledon
unseg:
MOV R3, #240
L7: call t2ms
djnz r3, L7
ret

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