Now let's look at how we can get access to GPIOs using both the command line (using Bash) and then using the C language.
Now it's time for an example. A very simple usage is the following one, where we use the
gpio91 of the Wandboard to turn an LED on and off. The circuitry is reported in the following figure:
To control the LED, we must set the line as the output, so we should write
out in the
/sys/class/gpio/gpio91/direction file, but if we wish to set the LED to a precise state by default, it is better to write
low, as show here:
root@wb:~# echo low > /sys/class/gpio/gpio91/direction
You can now observe that the ...