Re: [Gumstix-users] Using Gumstix to turn on-off an external device

[Dave H. <dhy...@gm...>]

Hi,

> I've done some research on GPIO and so far it looks like its either a PC
> peripheral (some websites show it as an ISA card) or its the serial
> port/parallel port configured to work in GPIO mode. On gumstix, how do I
> software activate and physically wire a GPIO to control an external
> device? The link you gave me is useful once i've actually located the
> GPIO connections. Is this a special expansion board for Gumstix or is it
> a mode of the Gumstix serial port outputs? If it is a mode of the serial
> port outputs, how many output pins can be accessed and how can they be
> programmed?

Almost every pin can be programmed to be a GPIO pin or perform a
regular function.

Chapter 4 of the PXA255 Developer's Manual shows the various functions
each pin can have (for the connex):
<http://pubs.gumstix.com/documents/PXA%20Documentation/PXA255/>

For the verdex it's in Chapter 24 of the PXA270 Developer's Manual:
<http://pubs.gumstix.com/documents/PXA%20Documentation/PXA270/>

Most of the 60-pin daughtercards have various pins available which can
be used as GPIO pins.

For example, with the console-st has 20 pins on the back. One of those
pins is LDD02, which corresponds to GPIO-60. You can also see the
mapping on the "Charts" on this page:
<http://docswiki.gumstix.com/Gumstix_motherboard_I/O>

You can manually manipulate the GPIO pin by using:

modprobe proc_gpio
echO "GPIO out set" > /proc/gpio/GPIO60
echo "GPIO out clear" > /proc/gpio/GPIO60

set corresponds to the pin being at 3.3v and clear corresponds to the
pin being at 0v.

WARNING: DO NOT connect a GPIO pin directly to a device like a relay.
You will most likely damage your gumstix.

-- 
Dave Hylands
Vancouver, BC, Canada
http://www.DaveHylands.com/