Re: [Lcd4linux-devel] Hd44780 and I2C

[Michael R. <re...@eu...>]

Hi Luis,

nice to hear from you again!

Sorry for the delay, but, as always, I'm too busy...

> I'm designing a simple I2C-to-4bit-HD44780 interface, to be able to have a
> LCD hooked up my PcEngines router board.
Sounds cool!

> From the driver side, it will be working in userspace, using the
> /dev/i2c-(0|1) access.
This looks interesting! How fast is the i2c bus? From what I've heard, 
it's quite slow...

> After having a good look into current CVS code and some conversations with
> Martin, I think the best approach is to have a drv_generic_i2c module as the
> backend, and extend the drv_HD44780 to make it possible to use this new
> backend.
Yes, correct. This would be the right approach.

> I could make it work using some sore of #ifdef constructs, but it does not
> seem to be the best way...
Shurely not. #ifdefs are very bad if you think of a binary distribution.

The current HD44780 driver is a bit of a mess, but that's because the 
different wirings and modes and stuff are a mess. This won't get better 
with a new backend (which nobody had in mind when writing the driver. So 
nobody is to blame. Especially not me :-)

There should be some more levels of abstraction inside, to encapsulate 
the parport driver a bit. This abstraction could be used for the i2c 
backend.

As soon as you got your i2c backend working, just check it in, and let 
me know about the interface. I'll have a look at this internal cleanup.


bye, Michael

-- 
Michael Reinelt                                         ICQ #288386781
e-mail: re...@eu...                          Tel: +43 676 3079941
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