Arduino due Square Pulse generator with Timer Interrupt

-I need to make a square pulse generator on Arduino Due, so that I can control this functions frequency and duty cycle.

-The frequency must be between 1 Hz and 50 KHz (must be really really close to 50).

-It has to be done using Due Timer Interrupt and digital IO.

-Arduino software (IDE) is to implement the codes.

-There are 3 days for this task.

Dont send messages if you wont work on this properly,  I have to get good grade on this to graduate!!!!