RE: [Lcd4linux-devel] RE: [lcd4linux] problem with i2c connected LCD display

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

Hi!

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>From: paul kamphuis [mailto:pau...@xs...] 
>Sent: Friday, February 11, 2005 11:39 AM
>To: lcd...@li...
>Subject: Re: [Lcd4linux-devel] RE: [lcd4linux] problem with i2c connected
LCD display
>
>	Thanks for the answers.
>	
>	If I understand correctly there is no longer a userspace layer for
the i2c 
>	interface. (or at least not supposed to be) 
>
	 
Wrong, there is a userspace layer!!! What is not suppose to happen is we
communicate
with the hardware directly. (kernel space)

You must use the I2C infrastructure as is provided by the i2c project.
Start here: http://secure.netroedge.com/~lm78/download.html

If you are using any 2.6 kernel you will not need the i2c-2.9.0 package.

Now try to compile i2c against your kernel sources, but without patching the
kernel.
Then load the appropriate i2c modules that support your bus type. Load the
PCF7584
module and try to access it (read/write via /sys interface).

If you can access it, try to write some values and see if the chip pins
reflect those
values.

If all goes ok, then start to investigate how to access it programaticly
from the i2c
API.	 
	 
	 
>	If I understand the pcf8574 kernel module correctly. Is this no more
then a wrapper 
>	around these i2c_smb functions. So it can't be much slower then
calling them directly.
>	The main advantage of this concept it that all (byte) devices have
these read and 
>	write files. So you could use any device available.
>	
>	So for a start, I give the pcf8574 a try. Shouldn't take to long to
test.
>	Lets see if you are right that it is too slow. ;-) 
>	
>	Paul
	
	
Best of luck!

Luis