In Reply to: Re: Need help to implement and design Alarm sensors circuit using microntroller and telephon line posted by khalifa on 02/07/02 at 11:38 PM:
What is a DAA?
Commercial DAA modules:
DAA chips: www.silabs.com
If you want to build your own DAA, ehckk out epanorama.net (telephone section). Note that with most "simple" DAA, there are always safety issues (lightning surges, electrical isolation etc.)., and no way will you be able to get certification, if that's your goal.
If you plan to go the DTMF route, you can always check www.teltone.com or www.holtek.com to get decent DTMF decoders.
If you plan to use a modem, just doa Google search for Hayes & Modem & codes. You will need to learn the Hayes "AT", and "S" codes to write your modem driver.
Hope this helps,