User defined characters-alfanumeric LCD

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ady689

New Member

• Oct 14, 2007

• #1

Haw I write a rutine in MPASM to generate user defined charcters on a alfanumeric LCD, i find a similary example but is write in C++ and i dont undersant..nothing....Can you help me?

 

bananasiong

New Member

• Oct 14, 2007

• #2

Hi,
Perhaps you need these:

http://winpicprog.co.uk/pic_tutorial3.htm

 

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ady689

New Member

• Oct 14, 2007

• #3

I read this tutorial, and he is not what i want




Purpose: - Load a user-defined character definition into the HD44780 character generator memory.

Quick explanation on how to implement user-defined characters:

First you will need to make a pixel definition for the characters
you want to use. Below is the pixel definition for an underlined
'0' (char code 0x30) based on a 5x7 dots character definition:

| bits | byte
row | 76543210 | value
------------------------
000 | xxx | 0x0E
001 | x x | 0x11
010 | x xx | 0x13
011 | x x x | 0x15
100 | xx x | 0x19
101 | x x | 0x11
110 | xxx | 0x0E
111 | xxxxx | 0x1F

 

bananasiong

New Member

• Oct 14, 2007

• #4

Misunderstood.
I've never tried this, but is the datasheet of HD44780 helpful enough?

 

A

ady689

New Member

• Oct 14, 2007

• #5

i need a part of a code to understand how make this with mpasm

 

bananasiong

New Member

• Oct 14, 2007

• #6

I think the datasheet states clear enough.
Set DDRAM address, CGRAM address and followed by CGRAM data.

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• Oct 14, 2007

• #7

Read the EPE LCD articles mentioned on my site.

 

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ady689

New Member

• Oct 14, 2007

• #8

i dont understand very good, practicaly can you give me an concrete example?

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• Oct 14, 2007

• #9

ady689 said:

i dont understand very good, practicaly can you give me an concrete example?

Click to expand...

I've never had reason to do it, but the EPE articles explain exactly what you need to do - writing the code should be trivial?.

 

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ady689

New Member

• Oct 14, 2007

• #10

this is the problem, idont known how to write this in mpasm

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• Oct 14, 2007

• #11

If you can't write anything, how do you expect to do anything at all with a PIC?.

 

bananasiong

New Member

• Oct 14, 2007

• #12

Nigel Goodwin said:

I've never had reason to do it, but the EPE articles explain exactly what you need to do - writing the code should be trivial?.

Click to expand...

Here they are:
https://www.electronics-lab.com/forum/index.php?topic=12543.0

 

ericgibbs

Well-Known Member

Most Helpful Member

• Oct 16, 2007

• #13

ady689 said:

i dont understand very good, practicaly can you give me an concrete example?

Click to expand...

hi,
Attached is a Oshonsoft Basic program and its asm listing output.
You should be able to figure out how defined characters are created and used.

Hope this helps.

EDITED: its best to download the *.asm to view off line, else there is no formatting!

 

Last edited: Jul 7, 2008

Gordz

New Member

• Oct 30, 2007

• #14

It goes like this,

MOVLW B'01000000' ;USER GRAPHIC 0
CALL COMMAND ;SENT TO LCD AS COMMAND
MOVLW B'00000000' ;PIXEL DATA 1 OF 7
CALL DISPLAY ;SENT TO LCD AS DATA

Then to actualy print the user graphic

MOVLW .0 ;USER GRAPHIC POINTER
CALL DISPLAY ;SENT TO LCD AS DATA