Re: [Lcd4linux-devel] Writing new driver

[Martin H. <ma...@he...>]

Hi Harry,

> Wow - thanks for the quick response.
> When I wrote the mail I didn't notice it was to a mailing list and am 
> now embarrassed at having pretty much written :-)
> 
> 'Hey - I want to write a driver - tell me what to do' :)
Don't worry. To me, it didn't come across in a bad way - and I'm known
to be especially sensitive to "I don't know what to do, provide support
to me" questions :-)

> Anyway - the LCD is driven from the serial port. There is only windows 
> (well DOS) support atm - I have a tech spec sheet so I will dive in and 
> see where I end up :)
Have a look at the users manual available at
http://partner.advantech.com.tw/service/Unzip_ReSolution.asp?File_Id=1%2DDL8TI
(sounds like you already have).
The command description starting at page 50 should be enough to get you
started as far as the display is concerned.  To get a feel, you might
even want to write a standalone c-program, that simply sends some
commands to the LCD (just so you have some quick feedback that the
display actually works, before you dive into fitting your driver into
the lcd4linux "framework"). That way, you can quickly find out how the
commands work.

Then get the latest sources of lcd4linux (CVS is usually best - check
the bottom of http://lcd4linux.sourceforge.net/download.html for
instructions on how to get the latest version from CVS) and have a look
at the other serial displays that already are supported by lcd4linux
alread (like drv_MatrixOrbital.c or drv_Crystalfontz.c, for example -
basically, anything that includes drv_generic_serial.h) and start from
there. Don't rely too much on the "README.Drivers" file, since
unfortunately, that's out of date (there are some updates to that on the
way, but unfortunately, the guy who is working on that is on holiday for
the next 3 weeks). The one thing you need to know about how drivers in
lcd4linux work (forgive me if that was obvious) is that you need to
implement a couple of functions, and set the corresponding function
pointers in the DRIVER struct.

Once you have your driver fully (or at least mostly) coded, you'll have
to integrate it into autoconf/automake (the hardest part to me, since I
have very little knowledge about autoconf). What I usually did there was
to simply look for a driver that's already supported in all "*.in"
files, and simply add my own driver (this may be incomplete - anybody
with some better understanding of autoconf/automake, please speak up if
I'm wrong).

Don't be too intimidated - this isn't all that hard, especially since
the display is connected via serial  port (so you don't have to worry
about low-level protocols, timing issues and so on). And if you get
stuck, you can always ask on this list.

I hope that helps.

Martin