AT 89c51 and LCD

Hi every single one how r u doing??

Well i have an LCD HD44780U (16 pin) and i wanna connect it to the AT 89c51 and so i did but the problem is when i open the cct. nothing at all appears on the LCD although every thing is connected very well so if u PlZ read my program and tell me if there is any thing wrong with it thax a loooooot

ORG 0H ;
Mov A, #38 H ; Init LCD 2 lines, 5*7 Matrix
LCALL Command ; Issue command
LCALL Sarah ;
Mov A, # 'A' ;
Mov R0, # 30 H; RAM address pointer
Mov R1, # 40 ; counter
Again: Mov @R0, A ;
I NC R0;
DJNZ R1, Again
Mov R2, # 16 ; counter
Mov R0, # 30 H ; RAM address pointer
LCALL Juliet
Mov A, # 40 ; write at the second line
LCALL Command
Mov R2, #16 ; counter
Mov R0, # 30 H ; pointer
LCALL Juliet

Juliet: Mov A, @R0 ; Move from RAM to A
LCALL Romeo
INC R0 ; increment pointer
DJNZ R2, Juliet ;
LCALL LCD_Delay ; 2 Seconds delay
RET

Sarah: Mov A, #0E H ; LCD on, cursor on
LCALL Command ; issue command
Mov A, #01 H ; Clear LCD command
LCALL Command ; issue command
Mov A, #06 H ; Shift cursor right
LCALL Command ; issue command
Mov A, #80H ; Move to the 2nd line
LCALL Command ; issue command
RET


Command: ACALL Ready
Mov P1, A
CLR P2.5
CLR P2.6
SETB P2.7
CLR P2.7
RET

Romeo: ACALL Ready
Mov P1, A
SETB P2.5
CLR P2.6
SETB P2.7
CLR P2.7
RET

Ready: SETB P1.7
CLR P2.5
SETB P2.6
Back: CLR P2.7
SETB P2.7
JB P1.7, Back
RET
LCD_Delay: Mov R4, #07
Pet: Mov R5, #255
Mag: Mov R6, #255
Hera: NOP
NOP
DJNZ R6, Hera
DJNZ R5, Mag
DJNZ R4, Pet
RET
END



Thx again








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Can't help with your code, but if you turn the contrast up you should get solid black characters displayed - this happens even without the display connected to a micro.

The HD44780 needs a very complicated initialization procedure upon power ON.

It is not simply as just sending one command. You have to do it several times with some waiting in between.

I suggest you read its datasheet and follow the words on how to initialise the chip to the letter.

Here is my version.

Edited: "unitl" corrected to read "until" in code comment.

The wait_ms routine waits for a certain milliseconds based on the value in wait_count.

Just curious, why did you eblc1388 made that strange "double post"? :lol:

Jay.slovak said:

Just curious, why did you eblc1388 made that strange "double post"? :lol:

Click to expand...

I saw a spelling mistake "unitl" in the code comment but what I really meant is "until".

I have not logged in so when I submit I double posted. I cannot delete my post.

eblc1388 said:

Jay.slovak said:

Just curious, why did you eblc1388 made that strange "double post"? :lol:

Click to expand...

I saw the a spelling mistake "unitl" in the comment but what I really meant is "until".

I have not logged in so double posted. I cannot delete my post.

Click to expand...

Oh, that explains it... np

BTW I really hate that we are unable to delete our own posts... :cry: