Specifications

BASIC Stamp II Application Notes
Parallax, Inc. • BASIC Stamp Programming Manual 1.8 • Page 361
2
3: Phoneline Interface
numbers inside the square brackets are the numbers to dial. Values of
0-9 represent those same buttons on the phone keypad; 10 is the star (*)
key; 11 is the pound sign (#); and 12 through 15 are additional tones that
aren’t meant for phone-subscriber use. They’re included primarily for
non-phone DTMF applications like remote controls and ham-radio
purposes. You may specify values as literal numbers, as we did above,
or as variables. Nibble-sized variables are perfect for holding DTMF
digits.
For each digit in square brackets, DTMFout sends the corresponding
tone for 200 milliseconds (ms), followed by a silent pause of 50 ms. This
timing gives the phone company equipment plenty of time to recognize
and respond to the tones. If you want some other timing scheme, you
can place on and off times between the pin numbers and the tone list,
like so:
DTMFout 0,1000,500,[6,2,4,8,3,3,3]
That instruction would transmit each tone for a full second (1000 ms),
and pause in silence for a half second (500 ms) after each tone.
Sources. Components needed for the simple phone-line interface are
available from Digi-Key and Jameco; see the contact information in the
schematic. For commercial applications, one manufacturer of DAAs is
Cermetek Microelectronics, 406 Pasman Drive, Sunnyvale, CA 94089;
phone [phone]; fax [phone].