Hi,
I'm trying to write a lcd driver for a HD44780 compatible display.
Basicaly it will be the only screen available on my linux board.
My problem is that I don't know which desgin I should use when
implementing the lcd's driver, because several choices are possible:
1) implementing a dumb char device "/dev/lcd"
2) implementing a console driver
3) implementing a tty driver
I can't find any documentation on vt that makes the choice quite
hard but when looking at the code it may be the best choice for
user-space. Do you think it's the good direction ?
Thanks for your advices,
Francis.
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Hi Francis,
There already are several drivers for this display, why write another one ?
One I use and know (because I wrote it :-)) is available here :
http://linux.exosec.net/kernel/lcdpanel/
It works with any combination of data and control bits from a parallel port,
and can initialize early in the kernel to display a booting message. It also
supports a keypad. I know that several appliance makers who use it. It uses
/dev/lcd to send data and some ANSI codes to move the cursor, and to define
up to 8 graphics characters. It uses /dev/keypad for keypad input.
Another one exists, I don't remember its name but it used to be announced
on freshmeat. It emulates a vt52 terminal IIRC.
Hoping this helps,
Willy
On Sun, May 08, 2005 at 12:33:30PM +0200, moreau francis wrote:
> Hi,
>
> I'm trying to write a lcd driver for a HD44780 compatible display.
> Basicaly it will be the only screen available on my linux board.
> My problem is that I don't know which desgin I should use when
> implementing the lcd's driver, because several choices are possible:
>
> 1) implementing a dumb char device "/dev/lcd"
> 2) implementing a console driver
> 3) implementing a tty driver
>
> I can't find any documentation on vt that makes the choice quite
> hard but when looking at the code it may be the best choice for
> user-space. Do you think it's the good direction ?
>
> Thanks for your advices,
>
> Francis.
>
>
>
>
>
>
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Hi Willy
--- Willy Tarreau <[email protected]> a ?crit:
> Hi Francis,
>
> There already are several drivers for this display, why write another one ?
> One I use and know (because I wrote it :-)) is available here :
sorry I wasn't clear in my last email, when I said 'HD44780 compatible display'
I was talking about electrical signals compatibity.
Actually I will use a lcd that supports graphical or text (80x20) mode.
I assume that a design for this kind of lcd is different from hd44780's one.
And that's the reason I want to use kernel vc...
Francis
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