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PostPosted: Sat Sep 02, 2006 15:26 
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Joined: Sat Jul 08, 2006 17:49
Posts: 25
Hi,
I have a 8x2 LCD display equipped with a HD44780.
Everything is working fine and since there is no functionality to reverse the characters I thought that I could create "user defined font" with all the characters reversed and then "upload" them to the HD44780 everytime my program run, after the initialization.
Actually I need to reverse only characters from "0" to "9" and the " " (space).
Reading the datasheet it seems it's possible but, unfortunately, it's not so clear how to do that.
Then I'm asking the experts how I can do that considering that I'm using the display in 8-bit mode.
Thank you, regards.

Bob


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PostPosted: Sat Sep 02, 2006 19:20 
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Joined: Sat Jul 08, 2006 17:49
Posts: 25
I tried the code below to redefine the character 0 but it doesn't work:

LPT= 0x0378

// set the CGRAM at the address 00

portwriteb(LPT, $40);
portwriteb(LPT+2,E_1 or RS_0);
delay(1);
portwriteb(LPT+2,E_0 or RS_0);

// this is the cycle where the character pattern is passed to the
// display 7 times, one for each row of the character matrix.
// At the end character 0 should display 3 vertical lines

for c:=0 to 7 do
begin
portwriteb(LPT, $15); // <-- bit pattern
portwriteb(LPT+2,E_1 or RS_0);
delay(1);
portwriteb(LPT+2,E_0 or RS_0);
delay(1);
end;

Where's the mistake?

Regards,

Bob


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PostPosted: Mon Sep 11, 2006 15:06 
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Joined: Sat Jul 08, 2006 17:49
Posts: 25
I found it...I should have put RS=1 instead of RS=0.
I hope it helps other users, regards.

Bob


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