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GPIO( n )

  • Logic level (3.3V) signals
  • 3-4mA max

all GPIO's information and examples should go here


According to the PXA270 datasheet:,%20Mechanical,%20and%20Thermal%20Specification%20%5b280002-005%5d.pdf most of the pins are limited to 3mA, and a few can go upto 4 mA (see page 5-9)

Accessing GPIO's from userland

If proc-gpio is a module, add it to /etc/modules or do a modprobe proc-gpio.

A number of files exist under /proc/gpio, one for each GPIO on the PXA processor.

If you cat one of these files, you get, eg:

# cat /proc/gpio/GPIO12
12 GPIO in set

That tells you — GPIO number, function (either GPIO, AF 1, AF 2, or AF 3), in|out, set|clear.

You can change any of those values, by writing to the file, eg:

# echo "AF1 out" > /proc/gpio/GPIO12

This sets GPIO12 to AF1, out mode. (In the case of GPIO12, the PXA defines this function as putting out the 32kHz clock signal.) this is currently case-sensitive

If you have the GPIO set to an output, and GPIO mode, you can set or clear the signal:

# echo "GPIO out set" > /proc/gpio/GPIO12
# echo "GPIO out clear" > /proc/gpio/GPIO12

The alternative functions are described in the PXA255 Developer's Manual (link should be found in the Featured links-box) section 4.1.2.


Related pages on the old wiki: