Q about HD44780U User Defined Character

[aljamri]

Hi everybody,

I'm trying to get user defined characters in HD44780U using PIC 16F628. Folowing Nigel's Tutorial (9.1) and consulting EPE article by Julyan Ilet (How to use Intelligent L.C.D's) honestly referred by Nigel and published in Feb97.

The problem that the given experiment on how CGRAM addresses individual pixels is done manually using DIP switches.

My question is: How to put it into a PIC program.

Thanks

 

[ericgibbs]

Hi everybody,

I'm trying to get user defined characters in HD44780U using PIC 16F628. Folowing Nigel's Tutorial (9.1) and consulting EPE article by Julyan Ilet (How to use Intelligent L.C.D's) honestly referred by Nigel and published in Feb97.

The problem that the given experiment on how CGRAM addresses individual pixels is done manually using DIP switches.

My question is: How to put it into a PIC program.

Thanks

hi,
Look at this link:
PIC microcontrollers : chapter 7 - Examples

 

[aljamri]

Thanks ericgibbs for your interest,

But still in doubt, which part defines a new character ?

When I read EPE tutorial, came in my mind that I have to give 8-bit binary for each pixel ( a complete character composed of 8 by 5 pixels ), while in Nigels tutorial, a complete built in character is called.

 

[ericgibbs]

Thanks ericgibbs for your interest,

But still in doubt, which part defines a new character ?

When I read EPE tutorial, came in my mind that I have to give 8-bit binary for each pixel ( a complete character composed of 8 by 5 pixels ), while in Nigels tutorial, a complete built in character is called.

hi,
Look at this simple asm program I have posted, it will run.
It has some comments that should help you understand it.

 

[aljamri]

Thanks, I'll go trough and let you know the results.

Thanks a lot.

 

[aljamri]

Hi again,

I've tried your asm program, but it seems the LCD is not initialized, it is showing all the upper lines full with black squares.

BTW, I'm using PIC16F628, I've changed the first and second line of the program accordingly. Is that any thing to do with my results?

Thanks again

 

[ericgibbs]

Hi again,

I've tried your asm program, but it seems the LCD is not initialized, it is showing all the upper lines full with black squares.

BTW, I'm using PIC16F628, I've changed the first and second line of the program accordingly. Is that any thing to do with my results?

Thanks again

hi,
What is the crystal frequency of the PIC 16F628.?

 

[aljamri]

hi,
What is the crystal frequency of the PIC 16F628.?

I'm not using external crystal, 16F628 has a 4MHz internal oscillator ( or not ? )

 

[ericgibbs]

I'm not using external crystal, 16F628 has a 4MHz internal oscillator ( or not ? )

hi,
So you have programmed the 16F628 for INTRC at 4mHz.?

 

[aljamri]

hi,
So you have programmed the 16F628 for INTRC at 4mHz.?

My circuit has only PIC and a regulated 5V input beside the LCD connection. I've just put your program into MPLAB and obtained a Hex file that I put it into the PIC. Frankly speaking I don't know How to set INTRC into the required Frequency.

 

[ericgibbs]

My circuit has only PIC and a regulated 5V input beside the LCD connection. I've just put your program into MPLAB and obtained a Hex file that I put it into the PIC. Frankly speaking I don't know How to set INTRC into the required Frequency.

hi,
You need the same wiring connections to the LCD if you use the test.asm I posted.!

Change the program LCD initialise to suit suit your LCD wiring.
Also set the program for INTRC.

It works OK for me, using my LCD pin wiring