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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is in the field of portable communication devices for
providing a computer with multiple integrated communication media, such as
a phone modem, a cellular telephone, a packet radio and a Global
Positioning System engine. In particular, the present invention relates to
a portable multiple integrated communication device for a palm computer.
2. Background Information
Recent advances in the manufacture of integrated circuit components have
allowed ever increasing functional capabilities to be performed by fewer
integrated circuit components. This increased density of processing power
in modern electronic equipment allows for the design of small, portable
instruments with impressive processing capabilities. Advances in other
technological areas, such as LCD displays, pen-based input devices and
handwritten character recognition, have also contributed to a new
generation of truly portable computers that are aptly described as palm
computers or personal digital assistants (PDAs), but which have sufficient
processing capabilities for numerous tasks. Examples of such PDAs include
the Apple.TM. Newton.TM. and the Sharp.TM. Expert Pad.TM.. These computers
allow a user to take notes, store data, retrieve data, run certain
application programs and interface with external devices, such as
printers, modems or an Appletalk.TM. network.
Summary of the Invention
The present invention connects to and interfaces with a PDA to dramatically
increase the functional capabilities of the PDA. The present invention
adds multiple integrated communication media to the resources currently
available to the PDA, while maintaining a compact, portable size. For
example, the combination of the present invention with a PDA can be used
to place or receive a cellular telephone call or a land line telephone
call, to transmit or receive packet radio data, to obtain
three-dimensional location data from the Global Positioning System (GPS)
and to send or receive data over a telephone cellular link or over a land
line using a built in phone modem. These added communication features
greatly enhance the utility of the PDAs. Instead of having a stand-alone
PDA, isolated from other data sources, such as a person's office computer
network, the combined PDA and multiple integrated communication device
provides a powerful processing device with convenient access to vast
stores of information over a variety of possible media.
One aspect of the present invention involves a portable communication
device. The communication device comprises first and second communication
circuits providing first and second differing modes of communication, a
first generic emulator coupled to the first communication circuit and a
second generic emulator coupled to the second communication circuit, a
first interface unit coupled to the first generic emulator and a second
interface unit coupled to the second generic emulator, and an application
program. The application program accesses the first interface unit to
generate a first command to control the operation of the first
communication circuit. The application program accesses the second
interface unit to generate a second command to control the operation of
the second communication circuit. The first interface unit communicates
the first command to the first generic emulator. The second interface unit
communicates the second command to the second generic emulator. The first
generic emulator reformats the first command and communicates the first
command to the first communication circuit. The second generic emulator
reformats the second command and communicates the second command to the
second communication circuit. The first communication circuit executes the
first command and the second communication circuit executes the second
command.
Additional aspects of the present invention will be apparent in the
following detailed description of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a palm computer for use with the portable
multiple integrated communication device of the present invention.
FIG. 2 is a perspective view of the communication device of the present
invention.
FIG. 3 is a perspective view of a palm computer mounted inside the
communication device of the present invention.
FIG. 4 is a general functional block diagram of a first embodiment of the
communication device of the present invention, connected to a palm
computer.
FIG. 5 is a more detailed functional block diagram of the serial interface
between the microcontroller and the pair of serial ports of FIG. 4.
FIG. 6 is a more detailed functional block diagram of the phone modem
interface of FIG. 4.
FIG. 7 is a more detailed functional block diagram of the GPS engine
interface of FIG. 4.
FIG. 8 is a more detailed functional block diagram of the packet radio
interface and the cellular telephone interface of FIG. 4.
FIGS. 9A, 9B and 9C illustrate a flow chart of a computer program executed
by the microcontroller of FIG. 4.
FIG. 10 is a functional block diagram of a second embodiment of the
communication device of the present invention connected to a palm computer
that has been programmed to implement an improved interface with the
communication device.
FIG. 11 is a functional block diagram of the application server of FIG. 10.
FIG. 12 is a functional block diagram of the software of the communication
server of FIG. 10.
FIG. 13 is a functional block diagram of the hardware of the communication
server of FIG. 10.
FIG. 14 is a functional block diagram of the interconnections between the
cellular telephone, the phone modem, the microphone and earphone jack and
the phone jack of the second embodiment.
FIGS. 15A, 15B, and 15C illustrate a flow chart of the method implemented
by the arbitrator of FIG. 11.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 illustrates a palm computer or personal digital assistant (PDA) 102
for use with the present invention. The PDA 102 comprises an LCD display
78, a light pen 76, a DC power connector 50 and a serial interface
connector 52. The PDA 102 provides an operator with a variety of data
processing and data storage functions in a lightweight, portable device.
First Embodiment
FIGS. 2 to 9C illustrate a first embodiment 100 of the portable multiple
integrated communication device of the present invention. FIG. 2
illustrates a perspective view of the communication device 100.
Externally, the communication device 100 comprises a fixed securing
surface 56, a supporting surface 57, a movable securing surface 58, a GPS
antenna 123 (FIG. 7), either a cellular telephone antenna 121 (FIG. 8) or
a packet radio antenna 122, a microphone and earphone jack 132, a
serial/power interface connector 60, a serial/power interface cable 62, a
phone jack 118, a pass-thru serial interface connector 68, a DC power
connector 70 and a set of three LEDs 71, 72 and 73. The LEDs 71, 72 and 73
indicate a low battery, power-on and packet radio transmit condition.
FIG. 3 illustrates the PDA 102 of FIG. 1 inserted into the communication
device 100 of FIG. 2. The PDA 102 is inserted into the communication
device 100 by pressing the bottom end of the PDA 102 against the securing
surface 58 to rotate the securing surface 58 toward its open position
(shown by the phantom lines in FIG. 2) until the top end of the PDA 102
clears the fixed securing surface 56, lowering the PDA 102 against the
supporting surface 57, with the orientation of FIG. 3. The PDA 102 is then
released, and a spring (not shown) rotates the securing surface 58 to its
closed position, as shown by the solid lines in FIGS. 2 and 3, pressing
the top end of the PDA 102 against the securing surface 56. Next, the
remote serial/power interface connector 60 of the communication device 100
is inserted into both the DC power connector 50 and the serial interface
connector 52 of the PDA 102. The combination of the PDA 102 and the
communication device 100 forms a small, lightweight unit that is
convenient to carry around and to use.
The structure of the communication device 100 is preferably designed to
allow access to connectors and controls of the PDA 102. For example, the
securing surface 56 of the communication device 100 preferably has an
opening corresponding to a slot in the top end of the Sharp.TM. Expert
Pad.TM., for insertion of an IC card into the slot of the Expert Pad.TM..
The packet radio antenna 122 and the cellular telephone antenna 121 (shown
in FIG. 8) of the communication device 100 are preferably mounted so that
they can be rotated between an active position and an inactive position.
In the active position, the antenna 122 or 123 is generally perpendicular
to the main structure of the communication device 100, as shown in FIG. 3,
to achieve optimal reception. In the inactive position, the antenna 122 or
123 is adjacent to a side of the communication device 100 that is directly
opposite the side with the phone jack 118. The GPS antenna 123 may be
mounted on the frame of the communication device 100, or it may be a
separate device.
FIG. 4 illustrates a general functional block diagram of the first
embodiment of the portable multiple integrated communication device 100 of
the present invention, connected to a PDA 102. The communication device
100 comprises a primary serial port 106, a buffer 108, a pass-thru serial
port 110, a DC power connector 148, a power supply 146, a power connector
144, a microcontroller 104, a read-only memory (ROM) 134, a lamp 135, a
decoder/multiplexer 112, a phone modem 114, a Data Access Arrangement
(DAA) 116, the phone jack 118, a Global Positioning System (GPS) engine
120, the GPS antenna 123, either a packet radio 124 or a cellular
telephone 126, a microphone amplifier 128, an earphone amplifier 130, the
microphone and earphone jack 132, and either the packet radio antenna 122
or the cellular telephone antenna 121. The decoder/multiplexer 112
comprises a dual 1:4 decoder or demultiplexer 136 and a dual 4:1
multiplexer or selector 138. In the first embodiment of the present
invention, the communication device 100 comprises either the packet radio
124 or the cellular telephone 126, but not both. In one embodiment, the
circuit card implementing the packet radio 124 occupies the same physical
space inside the communication device 100 as the circuit card implementing
the cellular telephone 126, thus conserving space and reducing the size of
the communication device 100.
The microcontroller 104 preferably comprises an Intel.RTM. 80C320
microcontroller, although numerous other processors could be used. The
microcontroller 104 communicates with the PDA 102 through the primary
serial port 106. The serial/power interface cable 62 of FIGS. 2 and 3 is
connected to the primary serial port 106 and the power connector 144 of
FIG. 4. The primary serial port 160 is used for the communication of
commands and data between the microcontroller 104 and the PDA 102, as well
as for the downloading of program code from the ROM 134 to the PDA 102.
The power connector 144 provides DC power from the power supply 146 to the
PDA 102. The power supply 146 also provides DC power to circuitry in the
communication device 100. The power supply 146 preferably comprises
batteries. However, DC power can also be provided by an external source
through the DC power connector 148 to the power supply 146. The
microcontroller 104 can cause the power supply 146 to power down, either
as a result of a command from the PDA 102 or after a period of inactivity,
to conserve battery power.
The communication device 100 also has the separate pass-thru serial port
110 to allow other external devices to communicate with the PDA 102. Such
devices may include printers, phone modems or an Appletalk.TM. network.
The pass-thru serial port 110 is connected to the pass-thru serial
interface connector 68 of FIGS. 2 and 3. The buffer 108 is used to enable
or disable the serial port 110. In the first embodiment, the buffer 108
comprises an LTC1032 component. If the microcontroller 104 needs to
transmit data to the PDA 102 or receive data from the PDA 102, the
microcontroller 102 disables the buffer 108. Otherwise, the buffer 108 is
enabled to allow an external device to communicate with the PDA 102
through the serial port 110 and the primary serial port 106. The serial
interfaces between the microcontroller 104, the PDA 102 and external
devices are described in greater detail below with reference to FIG. 5.
The ROM 134 comprises a 27C1001 128Kx8 ultraviolet erasable EPROM from NEC,
or the like, in the first embodiment. The ROM 134 contains code for both
the microcontroller 104 and the PDA 102. The ROM 134 may also contain code
for standard external devices. The microcontroller 104 executes code in
the ROM 134 to implement the described functions of the communication
device 100. The microcontroller 104 also uploads code from the ROM 134
through the primary serial port 106 into the PDA 102. The PDA 102 executes
this code to provide an interface with the microcontroller 104 and to
support and control the functions of the communication device 100. After
the code in the ROM 134 is loaded into the PDA 102, an operator of the
combined PDA 102 and the communication device 100 can utilize the
functions provided by both the PDA 102 and the communication device 100 by
providing appropriate input commands to the PDA 102. The PDA 102 sends
appropriate commands and data to the microcontroller 104 to control the
functions of the communication device 100, as provided by the code in the
ROM 134. The program executed by the microcontroller 104 is described in
greater detail below with reference to FIG. 9. The microcontroller 104 can
also download code to attached external devices.
The first embodiment of the communication device 100 provides the PDA 102
with access to three different communication media through the
microcontroller 104 and the decoder/multiplexer 112. Specifically, the
communication media include the phone modem 114, the GPS engine 120, and
either the packet radio 124 or the cellular telephone 126. Each of the
communication media is implemented in a separate communication circuit. As
described above, the decoder/multiplexer 112 comprises a dual 1-to-4
decoder 136 and a dual 4-to-1 multiplexer 138. In the first embodiment,
the decoder comprises a 74HC139 from Texas Instruments, or the like, while
the multiplexer 138 comprises a 74HC153, also from Texas Instruments, or
the like. The communication device 100 has a separate serial interface
from the microcontroller 104, through the decoder/multiplexer 112 to each
of the communication circuits 114,120, 124 and 126. To implement these
serial interfaces, the microcontroller 104 generates a single handshake
signal and a single data signal to the decoder 136. The decoder 136 has
four pairs of handshake and data outputs (output pair A, output pair B,
output pair C and output pair D), to which the signals from the
microcontroller 104 may be connected. The microcontroller 104 generates a
pair of select signals on a pair of select lines 140 and 142 to the
decoder 136. The two select signals have logical values of 00, 01, 10, or
11 to control the selection of one of the four output pairs of the decoder
136 to which the input pair is connected. The output pair A is connected
to both the packet radio 124 and the cellular telephone 126; however, as
discussed above, only one of the two devices is installed at any
particular time in the present embodiment. The output pair B has only one
line which is connected to the GPS engine 120. The output pair C is
connected to the phone modem 114. The output pair D is unconnected in the
present embodiment. Thus, the microcontroller 104 can send serial data to
any of the installed communication circuits 114, 120 and either 124 or 126
by selecting the appropriate select signals.
The phone modem 114 also generates a handshake signal and a data signal for
a serial interface which is connected to an input pair C on the
multiplexer 138. The GPS engine 120 also generates a handshake signal and
a data signal for a serial interface that is connected to an input pair B
on the multiplexer 138. The packet radio 124 also generates a handshake
signal and a data signal for a serial interface that is connected to an
input pair A on the multiplexer 138. The cellular telephone 126 also
generates a handshake signal and a data signal for a serial interface that
is also connected to the input pair A on the multiplexer 138. The
multiplexer 138 also has an output pair to which one of four input pairs
is internally connected. This output pair of the multiplexer 138 is
connected to the microcontroller 104. The microcontroller 104 controls the
selection of the multiplexer 138 using the same select signals as
described above with reference to the decoder 136. Thus, the
microcontroller 104 can select an input pair to receive the serial
interface signals from a selected one of the installed communication
circuits 114, 120 and either 124 or 126.
The select lines from the microcontroller 104 are preferably connected to
the decoder 136 and the multiplexer 138 so that the communication circuit
114, 120, 124 or 126 selected by the decoder 136 is also selected by the
multiplexer at all times. Thus, for example, by controlling the select
lines to select input pair C and output pair C, the microcontroller 104
generates a handshake and a data signal for a serial interface that is
received by the phone modem 114. The microcontroller 104 can also receive
a handshake and a data signal for a serial interface that are generated by
the phone modem 114. Thus, the decoder/multiplexer 112 allows the
microcontroller 104 to select between three different serial interfaces. A
first serial interface allows the microcontroller 104 to communicate with
the phone modem 114 and is described in greater detail below with
reference to FIG. 6. A second serial interface allows the microcontroller
104 to communicate with the GPS engine 120 and is described in greater
detail below with reference to FIG. 7. A third serial interface allows the
microcontroller 104 to communicate with either the packet radio 124 or the
cellular telephone 126 and is described in greater detail below with
reference to FIG. 8.
FIG. 5 is a more detailed functional block diagram of the serial interface
between the microcontroller 104, the primary serial port 106 and the
pass-thru serial port 110, shown in FIG. 4. The microcontroller 104 is
connected to the primary serial port 106 and to the buffer 108 by a
transmit data line 202, a handshake-in line 204, a handshake-out line 208
and a receive data line 210. The microcontroller 104 is connected to an
output port 200 by a set of three address lines 228, a data line 230 and a
write enable line 232. The output port 200 is connected to the primary
serial port 106 and the serial port 110 by a GPI line 206. The output port
200 is connected to the buffer 108 by a receive enable line 224 and a
transmit enable line 226. The buffer 108 is connected to the serial port
110 by a differential pair of transmit data lines 212 and 214, a
handshake-out line 216, a handshake-in line 218, and a differential pair
of receive data lines 220 and 222.
The microcontroller 104 receives an active low signal from the primary
serial port 106 on the transmit data line 202 and another signal from the
primary serial port 106 on the handshake-out line 208. The microcontroller
104 also generates an active low signal to the primary serial port 106 on
the transmit data line 210 and another signal to the primary serial port
106 on the handshake-in line 204. A person of skill in the art will
understand the use of these handshake and data signals to form a serial
interface between the microcontroller 104 and the primary serial port 106.
As described above, a serial port of a PDA 102 is connected to the primary
serial port 106, so that the microcontroller 104 can communicate with the
PDA 102 over the serial interface.
The output port 200 constitutes an eight-bit addressable latch, such as a
74HC259 from Texas Instruments, or the like. The output port 200 generates
eight output data signals, three of which are applied to the receive
enable line 224, the transmit enable line 226 and the GPI line 206,
respectively. Other output signals of the output port 200 are described
below with reference to FIGS. 6, 7 and 8. The output port 200 also
receives signals on the set of three address lines 228 for selecting among
the eight output signals. It also receives signals on the data line 230
and on the write enable line 232. The microcontroller 104 writes data to
the output port 200 one bit at a time by controlling the address lines
228, the input data line 230 and the write enable line 232. The output
port 200 decodes the signals on the address lines 228 to determine which
output signal is written. When the signal on the write enable line 232 is
activated, the output port 200 transfers the logic level at the input data
line 230 to the corresponding output data signal.
The GPI line 206 is connected to both the primary serial port 106 and the
serial port 110. The PDA 102 can receive a pulse on the GPI line 206 from
either the microcontroller 104 through the output port 200 or from an
external device through the serial port 110. Upon receiving a pulse on the
GPI line 206, if the PDA 102 has gone into a sleep mode to conserve
battery power, the PDA 102 "wakes up" and becomes fully operational.
Either the microcontroller 104 or an external device can wake up the PDA
102 at any time. If the PDA 102 is not in a sleep mode when a pulse is
received on the GPI line 206, the pulse will operate as an interrupt to
the PDA 102. Also, the GPI line 206 can be used to allow the
microcontroller 104 to wake up an external device. Thus, if an external
device is in a sleep mode, the external device can be activated by
receiving a pulse on the GPI line 206 from the microcontroller 104.
The transmit data line 202 carries an active low TTL signal from the
primary serial port 106 to the buffer 108. The buffer 108 transforms the
TTL signal on the transmit data line 202 to a differential signal on the
transmit data lines 212 and 214. The transmit data lines 212 and 214 are
connected between the buffer 108 and the serial port 110. The
handshake-out line 208 carries the handshake-out signal from the primary
serial port 106 to the buffer 108. The buffer 108 generates a signal on
the handshake-out line 216 in response to the signal on the handshake-out
line 208. The handshake-out line 216 is connected between the buffer 108
and the serial port 110. The output port 200 generates a signal on the
transmit enable line 226, which is connected to the buffer 108. This
signal enables or disables the gates in the buffer 108 that generate the
signals on the transmit data lines 212 and 214 and on the handshake-out
line 216. Thus, the serial port 110 receives the active low transmit data
signal and the handshake-out signal from the primary serial port 106 only
if the signal on the transmit enable line 228 is active.
If an external device is connected to the serial port 110, the external
device applies a signal through the serial port 110 to the handshake-in
line 218. The handshake-in line 218 is connected between the serial port
110 and the buffer 108. The buffer 108 generates a signal on the
handshake-in line 204 in response to the signal on the handshake-in line
218. The handshake-in line 204 is connected between the buffer 108 and the
primary serial port 106. If an external device is connected to the serial
port 110, the external device generates a differential signal through the
serial port 110 to the receive data lines 220 and 222. The receive data
lines 220 and 222 are connected between the serial port 110 and the buffer
108. The buffer 108 generates a TTL signal on the receive data line 210 in
response to the differential signal on the receive data lines 220 and 222.
The output port 200 generates a signal on the receive enable line 224,
which is connected to the buffer 108. This signal enables or disables the
gates in the buffer 108 that generate the signals on the handshake-in line
204 and on the receive data line 210. Thus, by controlling the signal on
the receive enable line 224, the microcontroller 104 can determine whether
the handshake-in signals and the receive data signals from an external
device are communicated through to the primary serial port 106. A person
of skill in the art will understand the operation of the handshake and
data signals between the serial port 110 and the primary serial port 106
for providing a serial interface between an external device and the PDA
102.
If the microcontroller 104 needs to use the serial interface between the
microcontroller 104 and the PDA 102, the microcontroller 104 causes the
signals on the transmit enable line 226 and on the receive enable line 224
to become inactive. This disables the serial interface between the
external device at the serial port 110 and the PDA 102 at the primary
serial port 106. Whenever the microcontroller 104 does not need to use the
serial interface with the PDA 102, the microcontroller 104 sets the
signals on the transmit enable line 226 and on the receive enable line 224
to active levels. This enables the buffer 108 and the serial interface
between the external device at the serial port 110 and the PDA 102 at the
primary serial port 106.
FIG. 6 is a more detailed functional block diagram of the interface between
the microcontroller 104 and the phone modem 114. This interface comprises
the microcontroller 104, the decoder/multiplexer 112, the phone modem 114,
the DAA 116, the phone jack 118, the output port 200, a sound transducer
330, a lightning suppressor 300, the set of three address lines 228, the
data line 230, the write enable line 232, a set of two handshake-out lines
302 and 310, a set of two transmit data lines 304 and 312, a set of two
handshake-in lines 306 and 314, a set of two receive data lines 308 and
316, a transmit line 318, a receive line 320, an off-hook line 322, a set
of two ring indicator lines 324 and 332, a tip line 326, a ring line 328,
an audio line 336 and an enable modem line 334.
The microcontroller 104 generates signals on the handshake-out line 302 and
on the transmit data line 304. The microcontroller 104 also receives
signals on the handshake-in line 306 and on the receive data line 308. The
handshake-out line 302, the transmit data line 304, the handshake-in line
306 and the receive data line 308 are connected between the
microcontroller 104 and the decoder/multiplexer 112. As described above
with reference to FIG. 4, if the phone modem 114 is selected for
communication with the microcontroller 104, the decoder/multiplexer 112
transfers the signal on the handshake-out line 302 to the handshake-out
line 310; it transfers the signal on the transmit data line 304 to the
transmit data line 312; it transfers a signal on the handshake-in line 314
to the handshake-in line 306; and it transfers a signal on the receive
data line 316 to the receive data line 308. The handshake-out line 310 is
connected between the decoder/multiplexer 112 and a ready-to-send input of
the phone modem 114. The transmit data line 312 is connected between the
decoder/multiplexer 112 and a transmit data input of the phone modem 114.
The handshake-in line 314 is connected between a clear-to-send output of
the phone modem 114 and the decoder/multiplexer 112. The receive data line
316 is connected between a receive data output of the phone modem 114 and
the decoder/multiplexer 112. A person of skill in the art will understand
that the handshake-out lines 302, 310, the transmit data lines 304, 312,
the handshake-in lines 306, 314 and the receive data lines 308, 316 form a
serial interface between the microcontroller 104 and the phone modem 114.
In the preferred embodiments, the phone modem 114 comprises a Rockwell
SM224ATF single-chip modem. This phone modem 114 can perform standard
facsimile and modem functions and is controlled using a standard
Hayes.RTM. compatible protocol. In an alternative embodiment, the phone
modem 114 also generates and receives a pair of analog audio signals.
These audio signals can be applied to lines connected between the phone
modem 114 and the cellular telephone 126. In this alternative embodiment,
information can be transferred between the cellular telephone 126 and the
microcontroller 104 and between the cellular telephone 126 and the phone
modem 114.
The transmit line 318, the receive line 320, the off-hook line 322 and the
ring indicator line 324, are connected between the phone modem 114 and the
DAA 116. The phone modem 114 applies data to the transmit line 318, while
the DAA 116 applies received data to the receive line 320. The DAA 116
activates a signal on the ring indicator line 324 to alert the phone modem
114 to an incoming phone call. The phone modem 114 activates the signal on
the off-hook line 322 to cause the DAA 116 to activate the telephone
connection. A person of skill in the art will understand the operation of
the interface between the phone modem 114 and the DAA 116, as well as the
operation of the DAA 116.
The ring indicator line 332 is connected between the phone modem 114 and
the microcontroller 104. The phone modem 114 activates a signal on the
ring indicator line 332 in response to an active signal on the ring
indicator line 324 from the DAA 116. The microcontroller 104 receives the
signal on the ring indicator line 332 at a modem ring indicator input of
the microcontroller 104. The modem enable line 334 is connected between a
DTR input of the phone modem 114 and one of the eight output signals
generated by the output port 200. As described above, the microcontroller
104 controls the output signals of the output port 200 by controlling the
set of three address lines 228, the data line 230 and the write enable
line 232. The microcontroller 104 activates the signal on the modem enable
line 334 to enable the phone modem 114 to send or receive data. The audio
line 336 is connected between the phone modem 114 and the sound transducer
330. The phone modem 114 generates a signal on the audio line 336 to
activate the sound transducer 330 to provide audio indicators to the user
of the PDA 102. The tip line 326 and the ring line 328 are each connected
between the DAA 116, the phone jack 118 and the surge suppressor 300. A
person of skill in the art will understand the operation of the tip and
ring signals for incoming and outgoing calls. The lightning suppressor 300
protects the DAA 116 from voltage spikes on the telephone lines caused by
lightning. The phone jack 118 is mounted at an outside surface of the
communication device 100, as illustrated in FIGS. 2 and 3.
FIG. 7 is a more detailed functional block diagram of the interface between
the microcontroller 104 and the GPS engine 120. This interface comprises
the microcontroller 104, the decoder/multiplexer 112, the GPS engine 120,
the GPS antenna 123, the output port 200, the set of three address lines
228, the data line 230, the write enable line 232, the transmit data line
304, a transmit data line 400, the handshake-in line 306, a handshake-in
line 402, the receive data line 308, a receive data line 404, a GPS
antenna line 406 and an enable GPS line 408.
The microcontroller 104 generates a signal on the transmit data line 304,
which is connected between the microcontroller 104 and the
decoder/multiplexer 112. The microcontroller 104 also receives signals on
the handshake-in line 306 and on the receive data line 308, which are also
connected between the microcontroller 104 and the decoder/multiplexer 112.
As described above with reference to FIG. 4, if the GPS 120 is selected
for communication with the microcontroller 104, the decoder/multiplexer
112 transfers the signal on the transmit data line 304 to the transmit
data line 400; it transfers a signal on the handshake line 402 to the
handshake-in line 306; and it transfers a signal | | |
