EBC Exercise 10 Flashing an LED Embedded Linux Class by Mark A.
Yoder The "Hello World" program is the traditional first program
for many classes. Flashing an LED is the embedded equivalent.
Here we will explore a few ways to flash and LED on the Beagle
and explore General Purpose I/O (gpio) along the way. This will
call be done from the command line of the Beagle, so there is no
need for the host computer. gpio via the Shell Command Line and
sysfs (Note: Draw the new diagrams with this.) The easiest way
to do general purpose I/O (gpio) on the Beagle is through a
terminal window and a shell prompt. In Linux most everything is
treated as a file. Even things that aren't files. In our class
we'll use a virtual file system called sysfs. sysfs exposes the
drivers for the hardware so you get easily use them. Try this,
open a terminal and type: beagle$ cd /sys beagle$ ls -F block/
bus/ class/ dev/ devices/ firmware/ fs/ kernel/ module/ power/
Here we see several directories that represent hardware we can
control. Ex