MSAN-108 Zarlink Semiconductor, Inc., MSAN-108 Datasheet - Page 14

• Manufacturer Part Number: MSAN-108
• Description: Applications of The MT8870 Integrated DTMF Receiver
• Manufacturer: Zarlink Semiconductor, Inc.

MSAN-108
system design objective.
reserved exclusively for the ”RESET“ function then
the MT8870 outputs can be decoded directly. This
requires that the controller send a ”RESET“
command prior to sending an I.D. sequence.
Alternatively a ”time-out“ timer, triggered by StD,
could serve to generate a system reset if a certain
time lapse occurs between received signals. This
method places time constraints on the system but
eliminates the need to consume a DTMF command
for the ”RESET“ function.
The concept of using a common transmission
medium for control signalling applies to several
possible situations. Plant process control, remote
measurement
systems, institutional intercom systems, two way
radio control, pocket pagers and model car or boat
remote control, just to mention a few.
Conversely, data could be collected from distributed
sources. Implemented on a circulating wire or an RF
channel, as illustrated in Figure 17, information could
be collected by a central unit which individually polls
each monitor to ask for data.
system could be interrupt driven (Fig.18).
case each monitor, when ready to send data,
generates an interrupt request by sending a DTMF
I.D. sequence followed by a data stream. Interrupt
masking or prioritizing could be achieved from the
the central control end by applying DC levels across
A-58
SOURCE
SIGNAL
DTMF
control,
RECEIVER
MT8870
DTMF
selective
If one DTMF code is
RECEIVER
MT8870
I.D. DECODE
DTMF
Alternatively, the
Figure 15 - Distributed Control System
LOGIC
DRIVER
intercom
In this
I.D. DECODE
DRIVER
LOGIC
call
VALVE
COMPUTER
a wire pair or sending a pilot tone in an RF system.
Remote data collection units would monitor this
signal to detect when a higher priority interupt is
being handled or the communications channel is
busy.
Data Communication Using DTMF
There is a vast array of potential applications for
DTMF signalling using the existing telephone
network.
ready-made data sets installed in convenient
locations (i.e. the Touch Tone telephone) remote
control and data entry may be performed by users
without requiring them to carry around bulky data
modems.
Potential applications include:
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VALVE
home remote control
remote data entry from any Touch-Tone keypad
credit card verification and inquiry
salesman order entry
catalogue store (stock/price returned via voice
synthesis)
stock broker buy/sell/inquire -using stock
exchange listing mnemonics
answering machine message retrieval
automatic switchboard extension forwarding
RECEIVER
Considering that there are millions of
MT8870
DTMF
I.D. DECODE
DRIVER
LOGIC
Application Note
SPRINKLER
ALARM