Ravi Pailoor wrote:

> For one of my projects,  I need to generate a square wave from 500 Hz
> to 1200 Hz in steps of around 2 to 3 Hz.

  What is the acceptable jitter?

  If 16µS is acceptable jitter, use a crystal which is any multiple of
65536 x 4 = 262144 Hz such as 3.670MHz and I think you can use a "phase
accumulator" technique where you add the frequency value (in Hertz) to
a 16-bit accumulator 65536 times per second, the MSB of which is your
desired square wave.

  A 3.670 MHz crytal would require this to be performed in 14 clock
cycles (and no other calculations) but if you can tolerate a jitter of
32µS or use double the crystal frequency, you have 28 clock cycles in
which to loop and it becomes much easier.
-- 
  Cheers,
        Paul B.