Parallax BASIC Stamp 2e Programming Manual page 110

DTMFOUT - BASIC Stamp Command Reference
The following DTMFOUT instruction will generate DTMF tones on I/O
pin 0:
DTMFOUT 0, [ 6, 2, 4, 8, 3, 3, 3]
If the BASIC Stamp is connected to the phone line properly, the above
command would be equivalent to dialing 624-8333 from a phone keypad.
If you wanted to slow the pace of the dialing to accommodate a noisy
phone line or radio link, you could use the optional OnTime and OffTime
values:
DTMFOUT 0, 500, 100, [ 6, 2, 4, 8, 3, 3, 3]
In this example, on a BS2 the OnTime is set to 500 ms (1/2 second) and
OffTime to 100 ms (1/10th second).
Tone Value
0 – 9
10
11
12 – 15
from I/O pin
from I/O pin
Notes:
C1 may be omitted for piezo speakers
C2 is optional, but reduces high-frequency noise
Page 108 • BASIC Stamp Programming Manual 2.0b • www.parallaxinc.com
' Call Parallax.
' Call Parallax, slowly.
Corresponding Telephone Key
Digits 0 through 9
Star (*)
Pound (#)
Fourth column tones A through D
Driving an Audio Amplifier
1k 1k
0.1µF 0.01µF
Vss Vss
Driving a Speaker
10µF (both)
+
+
C1 C2
Vss Vss
Amplifier
(e
.g., Radio Shack
277-1008C)
Vss
≥40Ω Speaker
(or 8Ω in series
with 33Ω resistor)
Table 5.8: DTMF Tones and
Corresponding Telephone Keys.
Figure 5.2: Example RC Filter
Circuits for Driving an Audio
Amplifier or a Speaker.