Re: [Lcd4linux-devel] connecting i2c lcd

[paul k. <pau...@xs...>]

Hi,

Sorry for the delay. I had some other things to care of. (work.. :-) )

>Ok then, did you found out which header files to include?
>It should be something like <i2c.h> and not <linux/12c.h> as I had
>before. It was even commented out because it did not really compile...
>
>  
>
No i did include <linux/i2c.h> and <linux/i2c-dev.h>. I have no other 
i2c.h header files available.
You need to include <linux/compiler.h> before them to make them compile 
correctly.
But it is no longer possible to use the i2c_smbus functions. You need 
that ioctrl function for that now.

>Anyway, from my experiences, you must create a very static 
>lcd4linux.conf file, just as a test. No bars, no scrollers no
>moving icons, just something like showing the Linux kernel version.
>
>  
>
I'll have to check on how to create such a config file. Is only a 
display configuration sufficient?

>About the display connections, how did you wired it? In my driver
>I used the same type of connections that Martin Hejl uses in his
>GPIO driver for Soekris boards (http://soekris.hejl.de/wiring.gif)
>
>  
>
No, I use a different wiring. I use a display unit from a project I did 
2 years ago. It is from an ergometer 
(http://www.relitech.nl/nl/PAG16.HTM, it is in dutch from our 'old' 
company website. The new site is almost ready)
It has to PCF8574 devices connected to the i2c bus. One for the display 
and the other for a Led-bar graph and 3 input control keys. I checked 
that I could control the PCF8574 by using the led-bar graph.

The display is connected like this:

PCF8574            Display
P0                        DB4
P1                        DB5
P2                        DB6
P3                        DB7
P4                        R/W
P5                        RS
P6                        E
P7                        -

The display is powered by 5 V and and the PCF8574 by 3.3V (from the i2c 
interface on my VIA EPIA board).
It could be that this is part of the problem. In the original design the 
PCF8574 was powered by 5 V. So the output might be to low voltage for 
the display to see it correctly.

I verified the initialisation/command sequence in lcd4linux. It is 
nearly the same as I used on the original project.

cheers,

Paul