[Lcd4linux-devel] Hd44780 and I2C

[Luis.F.Correia <Lui...@se...>]

Hi!

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

The interface itself is just a PCF8574 8bit I/O extender for I2C. 
It has a 8 bit port which connects directly to the HD44780, using the same
4bit pinouts that Martin used in his GPIO driver for Soekris.

From the driver side, it will be working in userspace, using the
/dev/i2c-(0|1) access.

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.

I could make it work using some sore of #ifdef constructs, but it does not
seem to be the best way...
Of course things could get tricky, and therefore I'm asking for your advice
on the best way to make this happen.

For now, all the low-level stuff is working, the needed modules are all
accounted for and my test programs make the LCD flicker.
(It isn't working yet, but that is a problem with some pullups are still
needed on the RS RW and EN lines. the PcEngines hardware works with 3.3v and
some voltage adaptation is needed)

Thanks, and I'll keep you guys posted on the results of my findings...

Luis Correia   
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