The Challenge

Let's make the MB2 into a siren! But not just any siren — an interrupt-driven siren. That way we can turn the siren on and the rest of our program can run on, ignoring it.

Make your siren sweep the pitch from 440Hz to 660Hz and back over a one-second period. The main program should start the siren, then print a ten-second countdown from 10 to 1, then stop the siren and print "launch!". The main program should not mess with the siren during countdown — it should just be interrupt-driven.

Hint: I found it easiest to use a global locked Siren struct that owned the state of the siren and the peripherals it needed to operate.

This is a fancy program that introduces a lot of new ideas. Don't be surprised if it takes you a bit to figure it out.