David,

You can detect the tones directly with the micro controller. Just feed them
via an op-amp comparator.

I use the PCD3312 as the generator and 75T203 as the single ended receiver.
I have had four versions of dialler based on this chip set approved for
Telepermit in New Zealand and meet approvals for Australia also.

I may be able to fish out the Ademco format for you.

Email me info@orbitcoms.com
www.orbitcoms.com

Regards

David Huisman

--
http://www.piclist.com hint: To leave the PICList
mailto:piclist-unsubscribe-request@mitvma.mit.edu