MSAN-108 Zarlink Semiconductor, Inc., MSAN-108 Datasheet - Page 19

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

Application Note
the rising edge of StD.
checks for a valid password sequence and decodes
subsequent commands. A command can be entered
to put the system into remote-control mode. In this
case the crosspoint switch is configured to route
DTMF signals into the FM-over-mains transmitter as
well as the system tone receiver.
control signals is accomplished by applying an FM
carrier to the power line. This eliminates the need to
string control wires haphazardly about the house.
The appropriate device is selected by its unique
DTMF I.D. code. The microcomputer keeps track of
all device locations and their I.D. codes since it must
decide when to supply function outputs to the
”nearby“ devices and when to let the ”remote“
receivers handle the data.
transmitted to a selected device until a ’reset‘
command is entered.
Upon receiving any DTMF signal, answer back tones
are returned by the microprocessor to acknowledge
valid or invalid operations and to indicate the state of
an interrogated device. For example, a low to high
tone transition could indicate that a particular device
is on, a high to low transition indicating the off state.
A command could be entered to put the system in an
’external‘ mode which would allow communications
through the data port. A host computer could be
connected to this port to broaden the scope of the
system.
The resident microprocessor unit contains the
software and hardware to control ringing verification,
CASHIER’S
PHONE
OPTIONAL
DIALER
Figure 22 DTMF Data Communications For An Auto Verification Line
AUTO
The microprocessor then
Subsequent data is
Forwarding of
TERMINATION
ANSWER/
CREDIT CARD COMPANY - AUTO VERIFICATION LINE
AUTO
LINE
password and command decoding, answer back tone
generation, audio routing, output function latches
and an optional data port. Output drivers buffer the
latches and switch relays or SCRs to control
peripheral devices.
An infinite variety of devices could be controlled by
such a system, the spectrum of which is limited only
by the ability to provide appropriate interfacing. This
system could also be the heart of a DTMF intercom
system
patching
locations. This type of system concept is, of course,
anything but limited to home use. Many applications
can
salespeople and executives.
For example, a merchant could verify credit card
accounts quickly utilizing only a telephone keypad for
data entry (Fig. 22). Each credit card company could
reserve one or more telephone lines to provide this
function, reducing the human effort required. The
receiving end system would be required to answer
the call, provide a short answer back tone or
message, receive and decode the credit card
account number, verify it, verify the owner’s name
and give a go/no-go authorization. This return data
could easily be provided with the aid of a voice
synthesizer. An auto-dialler containing appropriate
phone numbers could be installed at the merchant
end as an added time saver.
provide
"
, and remote control from varied household
allowing
RECEIVER
MT8870
DTMF
conveniences
intercommunication,
AUTHORIZATION
VERIFICATION/
SYTHESIZER
CREDIT CARD
ACCOUNTING
MSAN-108
ALGORITHM
COMPUTER
SPEECH
to
consumers,
"
phone-
A-63