Re: pca953x GPIO

[Joan Pau Beltran <joanpau.beltran-i5CWTa81U/w@public.gmane.org>]

Hi everyone,

We are also working with an Advantech PCM3362 board in an underwater 
vehicle, and want to use the GPIO port to monitor the battery charge (a 
battery board is connected to the GPIO port and sets a pin to 1 when 
voltage goes below 20V).

We need to use Ubuntu, currently 10.04 with kernel 
linux-image-2.6-32-26-generic.

As Giampolo says, out of the box there aren't any chips under 
/sys/class/gpio (only import/export files).
After checking that i2c-gpio and pca953x are shipped with the kernel but 
no loaded by default, I tried to modprobe them and they load 
successfully, but the chip does not appear in /sys/class/gpio.
i2cdetect does not list any bus.

The battery board is not connected to the GPIO now. Actually nothing is 
connected to it. I suppose that the chip should be detected even if 
there is nothing attached to it. But just to be sure, do I need to 
connect it to some device to get the chip appear under /sys/class/gpio?

Giampolo (ore anyone on the list), did you success using the GPIO port 
on that board? In that case, could you point me what steps have you 
done? It's the first time I use a GPIO port and I read the Documentation 
and both examples pointed out by Jean but still can not figure out why 
the chip is not recognized under /sys/class/gpio or how to access it.

Thanks Jean for pointing out about the address alignment difference in 
Linux. For sure I won't even thought about it reading the Advantech manual.

Thanks in advance, and please excuse my English!