Hello everyone,

I am trying to emulate an SPI interface using four GPIO pins. This is a desktop computer with linux 2.6.28 kernel.

The problem is I don't know if the pins are working. I read that if I have the sysfs support for the kernel (which I do :D) all I have to do

is enable the respectiv pin using 

echo N > /sys/class/gpio/export

And I would get a gpioN directory 

But I always get: "write error : invalid argument."

Is there some other option i need to enable first? The people I am working with assured me that these pins are not used by any other device and they haven't found anything to suggest that they were turned off manualy.

Please help,