Daiane,
Thanks for responding. The i.MX53 for example has GPIO (General Purpose I/O). Does the Ubuntu developement environment provided by FreeScale have drivers, or an API, for the GPIO? In general, you need functions to determine the direction of the I/O (input, output, tri-state), set the I/O, clear the I/O and get the current state of the I/O. Again, does FreeScale provide software to support the GPIO... as well as other peripherlas like CSPI, PWM ... etc.
bb