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[Lcdproc] hd44780 aType and fli4l

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  • From: joris AT (Joris Robijn)
  • Subject: [Lcdproc] hd44780 aType and fli4l
  • Date: Sun Oct 6 20:32:05 2002

> I've a 20x4 that the documentation calls an A-Type. I can not check how
> the controllers are called, they are not labled.
> But I've written a patch to support dhe (slightly) different
> initialisation needed and had posted it to the list.

Hi Goetz,

I've looked into your patch. I see that it does two things:
1. It adds an new wiring and subdriver called fli4l.
2. It reads the aType= setting from the config file. If aType is true, it
initializes the controller with extended functionality. It also does
other positioning in that case (which looks more linear).

I have been writing a bit, but have not yet commited anything. I want to
know some things before I do.

First of all I think there is a compatibility issue with your patch. When
you set aType to true, it does initialization in common_init assuming it
is in 8 bit mode. That is not correct. It will not wirk with 4 bit wiring
schemes, of which we have at least two: 4bit and serialLpt.

I would also like to know what the controller does if you do NOT use the
aType setting. Does it work correctly without aType=true ? Because in
that case we should NOT apply the aType patch, as it would not add any

Is there any relation between the aType setting and the new wiring, other
than that they are in one patch ?

The HD44780 driver is a complicated piece of work. It cost me over a year
to understand why things are done like they are, and fully understand all
the issues that the driver carries with it. I hope you understand that
I'm only delaying the commiting your code because I want to keep the
quality that it currently has.


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