`
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`
`U.S. Patent
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`Sep. 4, 2001
`
`Sheet 1 of 5
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`US 6,285,890 B1
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`U.S. Patent
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`Sep. 4, 2001
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`Sheet 3 of 5
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`US 6,285,890 B1
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`U.S. Patent
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`Sep. 4, 2001
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`Sheet 5 of 5
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`US 6,285,890 B1
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`218
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`US 6,285,890 B1
`
`1
`AUTOMATIC SENSING OF
`COMMUNICATION OR ACCESSORIES FOR
`MOBILE TERMINALS
`BACKGROUND OF THE INVENTION
`
`The present invention relates to improvements in mobile
`phones which have system connectors to permit auxiliary
`components to be connected to them.
`Mobile phones have become popular in recent years
`because they free the user from fixed communications
`networks. The user is not required to wait at the home or
`office for an anticipated call. Instead, the call can be for-
`warded to the user at whatever location the user happens to
`be.
`
`A wide variety of phone accessories are available to
`enhance the usefulness of mobile phone. Common accesso-
`ries for mobile phones include hand sets, vibrators, speech
`recognition units, hands-free kits for vehicles, and battery
`chargers. Typically, the phone accessories plug into a system
`connector on the body of the telephone to connect
`the
`electrical circuit within the accessory to the circuit inside the
`telephone. Telephones manufactured by Ericsson, Inc., for
`example, have a class of such accessories known generally
`as “Ericsson Accessories” which can be connected using the
`phone’s existing system connector.
`It is also known to use the telephone as a transmission
`medium for a connected computer to enable the user to send
`and receive data and fax communications. One approach
`used in the past is to connect the phone to an external modem
`or modem equipped computer. This approach uses the
`mobile phone merely for transmission of signals that are
`modulated by the modem in the computer. For example,
`some phones implement a PC card form factor to provide
`data/fax functionality for a mobile computer equipped with
`a PC card slot. However, the PC card adds an additional
`expense for users that want data/fax functionality.
`Another approach is to incorporate an internal modem
`into the mobile phone and provide an interface for accessing
`the phone’s internal modem using a computer or other
`external device. This approach can be implemented using a
`dedicated port on the phone or the phone’s built-in system
`connector for communications with the external device. For
`example, some phones use an infrared data port for com-
`munications with the external device. In the past, phones
`adopting this approach have required that special protocol
`drivers be installed in the external device in order to operate
`properly. Thus, the manufacturer was required to write and
`distribute drivers for many different operating systems such
`as Windows 3.1, Windows 95, Windows 98, Palm Pilot,
`Windows CE, etc. Moreover,
`if the user installs a new
`operating system, there is no guarantee that the driver will
`operate. Thus, the user may be required to obtain and install
`a new infrared driver when a new operating system is
`installed.
`
`Another drawback to using a dedicated port for commu-
`nications with an external device, is that the dedicated port
`requires additional space and adds to the cost of the phone.
`In particular, the use of a separate infrared data port requires
`a separate transmitter in the phone and significantly
`increases its cost and weight.
`Accordingly, it would be preferable to have a telephone
`design in which a single system connector could be used to
`connect accessories as well as computing devices, without
`the need to provide additional drivers for the mobile com-
`puter to properly operate with the telephone.
`SUMMARY OF THE INVENTION
`
`The present invention is a mobile communication device,
`such as a cellular telephone, equipped to handle data/fax
`
`2
`communications. The phone includes a transceiver, a
`modem, and a system connector for connecting the mobile
`communication device to external devices. The system con-
`nector serves a dual function. In a default mode of operation,
`the system connector may be used to connect the phone to
`a phone accessory, such as hands-free kit, charger, etc. In a
`communications mode,
`the system connector is used to
`connect the phone to an external communication terminal
`that uses the phone’s internal modem for data/fax commu-
`nications.
`
`The phone initially operates in a default mode to enable
`use of the phone with a phone accessory in a conventional
`manner. The phone automatically switches to a communi-
`cations mode when a connected communication terminal is
`
`detected by the phone. The presence of an external commu-
`nication terminal is detected, for example, by looking at the
`input signals on the system connector. The connected com-
`munication terminal will generate certain known signals
`when it initiates a communication session. For example, a
`communication terminal implementing the IS-135 protocol
`will send AT commands to the phone’s internal modem over
`the system connector. When the input signal (AT command)
`is received on the system connector the phone automatically
`switches to the communication mode to enable communi-
`
`cations by said external communications terminal via said
`modem. When the communication session is terminated, the
`phone automatically switches back to the default mode of
`operation.
`The present invention is convenient for users since the
`user does not need to manually configure the phone for
`data/fax communications. It is also advantageous from a
`manufacturer’s viewpoint since no drivers are needed to
`facilitate communications with the connected device.
`
`These and other aspects of the present invention will
`become apparent to those skilled in the art after reading the
`following description of the preferred embodiments when
`considered with the drawings.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The invention will be better understood after a reading of
`the Detailed Description of the Preferred Embodiment and a
`review of the drawings in which:
`FIG. 1 is a schematic block diagram of a mobile phone
`according to an embodiment of the invention;
`FIG. 2A is a schematic block diagram of the system
`interface in Default mode;
`FIG. 2B is a schematic block diagram of the system
`interface in Communication mode;
`FIG. 3 is a flow chart illustrating a procedure for changing
`from Default mode to Communication mode.
`
`FIGS. 4A and 4B are flow charts illustrating a procedure
`for changing from Communication mode to Default mode.
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENT
`
`Referring now to the drawings, the mobile communica-
`tion device of the present invention is shown therein and
`indicated generally by the numeral 10. The mobile commu-
`nication device 10 can be used in a Default mode as a
`
`conventional mobile telephone to transmit and receive voice
`and data signals according to known standards, such as
`IS-136. Alternately, the mobile communication device 10
`can be used in a Communication mode as a facsimile
`machine or modem to send and receive data and fax com-
`munications. In the Communication mode, the mobile com-
`
`10
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`US 6,285,890 B1
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`3
`munication device 10 functions as the Data Communications
`
`Equipment (DCE) for a connected computer or Data Ter-
`minal Equipment (DTE). The term mode when used in
`reference to the mobile communication device 10 refers to
`
`the overall operating mode of the device.
`FIG. 1 is a block diagram showing the basic components
`of a mobile communication device 10 of the present inven-
`tion. The mobile communication device 10 includes a trans-
`
`ceiver 12, a modem 14, a control unit 16, a memory 18, a
`keypad 20, a display 22, audio processing circuits 24, a
`speaker 26, and a microphone 28. A system interface 30 is
`provided for connecting phone accessories and other exter-
`nal devices 50 to the mobile communication device 10.
`
`Examples of phone accessories include a battery charger, a
`portable hands-free kit, a car kit for a vehicle, and an AMPS
`modem. The system interface 30 can also be used to connect
`a computer or other external communication device 50 to the
`mobile communication device 10. The computer or other
`external communication device can then use the internal
`modem 14 of the mobile communication device 10 for data,
`facsimile, or voice communications as will be hereinafter
`described.
`
`The RF transceiver 12 may be, for example, a class 1
`mobile phone transceiver capable of transmitting radio sig-
`nals to and receiving radio signals from remote stations. In
`the preferred embodiment of the invention, the transceiver
`12 is a fully functional digital transceiver implementing the
`IS-136 protocol which is incorporated herein by reference.
`However those skilled in the art will recognize that the
`present invention is not limited to digital transceivers. Also,
`there are numerous protocols that could be used in connec-
`tion with the present invention other than IS-136.
`The modem 14 handles data communications between the
`mobile communication device 10 and the external device 50
`in both the Default mode and in the Communication mode.
`
`The modem 14 may, for example, be a conventional modem
`that implements the IS-135 standard, which is incorporated
`herein by reference, although the invention is not limited to
`modems 14 using this standard. Functions performed by the
`modem include character
`formatting,
`framing, parity
`checking, autobauding, and flow control. Also, those skilled
`in the art will recognize that the mobile communication
`device 10 may include only the front end of the modem 14.
`The back end of the modem 14 may be located elsewhere in
`the communication network. Thus, the essential aspect of
`the invention is that the mobile communication device have
`
`circuits providing, either alone or in conjunction with the
`communication network, modem/fax capability.
`The control unit 16 controls the operation of the trans-
`ceiver 12 and modem 14 according to instructions stored in
`memory 18. One function performed by the control unit 16
`that is pertinent to the present invention is AT command
`processing. AT command processing is handled by the
`control unit 16 according to known standards, such as TIA
`IS-136 and IS-707, which are incorporated herein by refer-
`ence. Memory 18 is used for temporarily storing data that is
`needed by the control unit 16 during operation of the mobile
`communication device 10. Memory 18 includes both per-
`manent ROM memory for program storage and RAM
`memory. Memory 18 is used to store a list of AT modem
`commands, that is used to detect the presence of an external
`computer or other DTE equipment, as will be hereinafter
`described.
`
`The keypad 20, display 22, microphone 28 and speaker 26
`provide an man-machine interface (MMI) for the user of the
`mobile communication device 10. The keypad 20 is used by
`
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`the user to enter data and commands. For example, a
`common use for the keypad 20 would be to enter a telephone
`number and “send” command to place an outgoing call. The
`display 22 is used to display information, such as the number
`dialed and call status information, to the user. The display 22
`can also be used to display prompts or other messages.
`Microphone 28 converts the user’s voice into audio signals
`that are to be transmitted by the mobile communication
`device 10. The speaker 26 converts audio signals received
`by the mobile communication device 10 into audible sounds
`that can be heard by the user. Audio processing unit 24
`interfaces with the microphone 28 and speaker 26 with the
`control unit 16. Audio processing unit 24 processes voice
`and data signals that are transmitted to and received by the
`mobile communication device 10.
`
`The system interface 30 is used to connect the mobile
`communication device 10 to external devices 50, such as a
`phone accessory, computer, or DTE equipment. The system
`interface 30 is used to connect phone accessories to the
`mobile communication device 10 in for use in the Default
`
`mode, and to connect an external computer or other DTE in
`the Communication mode. The signals present at the system
`interface 30 will change depending on the type of external
`device, i.e. phone accessory or DTE device.
`The system interface 30 includes a system connector 32
`and switching circuits 34 as shown in FIGS. 2A and 2B. The
`system connector 32 is a physical connector in any suitable
`form, such as a plug, that connects to the external device 50.
`The system connector 32 is interfaced with the control unit
`16, modem 14, audio processing circuit 24, and memory 18
`by the switching circuit 34. The switching circuit 34 func-
`tions to redirect the inputs and outputs at the system con-
`nector 32 depending on the type of external device 50 that
`is connected. When a phone accessory or AMPS modem is
`connected,
`the switching circuits 34 are configured in a
`Default mode, as shown in FIG. 2A. When an external
`communication terminal is connected, the switching circuits
`34 are configured in a Communication mode, as shown in
`FIG. 2B. The term mode when used in reference to the
`
`system interface means the configuration of the system
`interface 30 when the mobile communication device 10 is in
`
`the various operating modes. Thus, the Default mode of the
`system interface 30 means the configuration of the interface
`when the phone is in the Default mode of operation.
`The control unit 16 monitors signals present at the system
`connector 32 and automatically configures the system inter-
`face 30 depending on the signals detected so that the signals
`are routed to the appropriate destinations. A phone
`accessory, for example, will generate different signals than
`an external computer attempting a data/fax communication.
`When an accessory is connected to the system connector 32,
`the control unit 16 configures the system interface 30 in a
`Default mode for use with the accessory and routes the
`signals accordingly. When an external computer or other
`DTE is connected to the system connector 32, the control
`unit 16 configures the system interface 30 in a Communi-
`cation mode for data/fax communications. In the preferred
`embodiment of the invention,
`the system interface 30 is
`configured as an RS-232 interface in the Communication
`mode. One advantage of configuring the system interface 30
`as an RS-232 interface is that no drivers are required to be
`installed on the computer or DTE for it to operate properly.
`In the preferred embodiment of the invention, the control
`unit 16 initially configures the system interface 30 in the
`Default mode. The system interface 30 remains in Default
`mode until the control unit 16 detects certain standard AT
`
`commands at the system interface 30 that are sent by a
`
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`US 6,285,890 B1
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`5
`computer attempting to initiate a communication session.
`These AT commands are listed in Table 1 in the attached
`Appendix. These commands are referred to herein as modem
`commands or AT commands. When one of the AT com-
`mands listed in Table 1 is detected, the mobile communi-
`cation device 10 switches from the Default mode to the
`Communication mode. The mobile communication device
`10 switches back to Default mode when the control unit 16
`senses that the computer or DTE is no longer connected. The
`mobile communication device 10 also switches to Default
`
`mode when powered on/off or when receiving certain AT
`commands generated by an AMPS modem.
`In the disclosed embodiment, the system interface 30 has
`12 I/O ports. The system connector has 12 pins (not shown),
`each one corresponding to a particular I/O port. Table 2
`contains a listing of the signals at each I/O port in both the
`Default mode and Communication mode. The disclosed
`
`embodiment is merely one representative embodiment and
`those skilled in the art will recognize that the particular
`signals and how the signals are used is not an essential
`aspect of the invention.
`In the Default mode, the signals present at the system
`interface 30 include the ATMS signal (port 3), the AFMS
`signal (port 4), the EXTAUD signal-(port 7), the PORTHF
`signal (port 9),
`the MUTE signal (port 8),
`the DTMS
`signal-(port 10), the DFMS signal-(port 11), the VPPFLASH
`signal (port 12), and the AGND signal (port 2). This group
`of signals is used in phones manufactured by Ericsson, Inc.
`and represents only one exemplary embodiment. Phones
`made by other manufacturers may use a completely different
`set of signals in the Default mode of operation. In other
`words, the particular signals used in the Default mode will
`generally vary from one manufacturer to the next.
`The AFMS (audio from mobile station) and ATMS (audio
`to mobile station) signals are used in Default mode to
`interface the phone’s audio circuits 24 with the phone
`accessory in the Default mode of operation. The EXTAUD
`and PORTHF signals are inputs used to detect when the
`mobile communication device 10 is connected to a car kit or
`
`portable hands-free kit respectively. When either the
`EXTAUD or PORTHF signals are present, the phone’s audio
`circuits 24 direct audio output to the AFMS line and receive
`audio input on the ATMS line. The AFMS and ATMS signals
`are not used in Communications mode. The MUTE signal is
`an output used when the mobile communication device 10 is
`connected to a car kit to mute the car’s stereo system when
`a call is in progress. The DTMS (data to mobile station) and
`DFMS (data from mobile station) signals are used in the
`Default mode to transfer data signals between the phone and
`the connected phone accessory. The VPPFLASH signal is an
`input that is used to load programs in flash memory. The
`AGND (audio ground) signal is used to ground the audio
`circuits 24 of the mobile communication device 10 when a
`
`phone accessory is attached.
`In Communication mode, the signals present at the system
`interface include the RTS signal (port 7), the CTS signal
`(port 8), the DTR signal (port 9), the TD signal (port 10), the
`RD signal (port 11), and the CD signal (port 12). These
`signals are described in TIA IS-135 which is incorporated
`herein by reference. To briefly summarize, the RTS signal is
`an input that is used for flow control by the modem’s flow
`control circuit when receiving data. The CTS signal is an
`output that is used by the modem’s flow control circuit when
`transmitting data. The DTR signal is an input that is used to
`indicate the readiness of the data terminal equipment. The
`TD (transmit data) signal and RD (receive data) signal are
`used to transfer data between the connected communication
`
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`6
`terminal and the mobile communication device 10. The TD
`
`signal is the data being transmitted. The RD signal is the data
`being received. The CD (carrier detect) signal is an output
`that is passed from the phone’s modem 14 to the connected
`communication terminal to indicate connection to a carrier.
`
`The VDD signal, DGND signal, and DCIO signal are used
`in both Default mode and Communication mode. The VDD
`
`port on the system interface 30 is used to output a reference
`voltage to a connected device, either a phone accessory or a
`communication terminal. The DGND/GND (digital ground)
`port is used as a ground in both Default mode and Com-
`munication mode. DCIO is used as a power input to the
`mobile communication device 10 in both Default mode and
`
`Communication mode. These ports are not reconfigured
`when the mobile communication device 10 changes mode.
`
`In Default mode, ports 7 (EXTAUD), 8 (MUTE), and 9
`(PORTHF) serve as an interface between the phone acces-
`sory and the audio circuits 24 of the mobile communication
`device 10. In Communication mode, ports 7-(RTS), 8 (CTS),
`and 9 (DTR) interface the communication terminal to the
`modem 14 in the mobile communication device 10.
`
`Therefore, it is necessary to redirect the signals at these ports
`when changing modes. Similarly, in Default mode, port 12
`(VPPFLASH) is connected to flash memory 18. In Com-
`munication mode, port 12 (CD) is connected to the modem
`14. Thus, the signal at port 12 (VPPFLASH/CD) must also
`be redirected. Redirection of the signals is accomplished by
`switching the inputs and outputs as shown schematically in
`FIGS. 2A and 2B when changing between modes. The
`switching function is performed by the switching circuit 34
`in response to a control signal from the control unit 16.
`However, it is not essential that the control unit 16 control
`the switching circuit 34. The switching circuit 34 could, for
`example, include its own hardwired logic. Also, the switch-
`ing circuit 34 could comprise a transistor network that
`automatically redirects the signals without external (to the
`switching circuit) input. These switching techniques are
`well-known to those skilled in the art.
`
`TABLE 2
`
`System Connector Interface Signals
`Port No. Default Mode
`Communication Mode
`
`1
`
`2
`
`3
`
`4
`
`5
`
`6
`
`7
`
`DGND
`Usec as ground for digital
`circuits
`AGND
`Usec as ground for audio
`circuit
`ATMS
`Usec to input audio signal to
`mobile terminal
`AFMS
`Usec to output audio from
`mobile terminal
`DCIO
`Usec to charge mobile
`terminal battery
`VDD
`Usec to output voltage
`reference
`EXTAUD
`Inpu used to indicate
`connection to car kit
`
`GND
`Used as ground for all
`RS-232 signals
`
`DCIO
`Power input to the cable for
`level shifting
`VDD
`Used to output voltage
`reference
`RTS
`Input used for the Ready for
`Receiving hardware flow
`control circuit. The RTS
`signal is held in the Space
`state and not used for flow
`control if an AT +IFC or
`
`Page 00009
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`US 6,285,890 B1
`
`7
`
`TABLE 2-continued
`
`System Connector Interface Signals
`Port No. Default Mode
`Communication Mode
`
`8
`
`9
`
`10
`
`11
`
`12
`
`MUTE
`Output used to mute car
`stereo
`
`AT_FLO command is
`received that disables
`harc ware flow control.
`CI‘S
`Outout used for the Ready for
`Sending hardware flow
`con rol circuit. The CTS
`signal is not use for flow
`con rol if an AT +IFC or
`AT +FLO command is
`received that disables
`harcware flow
`con rol.
`DT 1
`PORTHF
`Input used for the Data
`Input used to indicate
`connection to portable hands- Terminal Ready circuit.
`free kit, such as a headset
`The interpretation of the
`DT{ signal can be repro-
`grammed when the AT
`&Dn command.
`TD
`Input used by the DTE to
`send data via mobile
`terminal
`RD
`Output used by the DTE to
`receive data via mobile
`terminal
`CD
`Output used to indicate
`connection to a carrier
`
`DTMS
`Used to input data to mobile
`terminal
`
`DFMS
`Used to output data from
`mobile terminal
`
`VPPFLASH
`Input used to load program
`into flash memory
`
`FIGS. 3 and 4 are flow diagrams illustrating the operation
`of the mobile communication device 10 of the present
`invention. FIG. 3 illustrates the procedure for switching
`from Default mode to Communication mode. The mobile
`
`communication device 10 begins in the Default mode (block
`100). When a computer or DTE connected to the system
`interface 30 initiates a data/fax communication, it will send
`one or more of the AT commands listed in Table 1 to the
`mobile communication device 10. The AT command will be
`
`input on the DTMS port and placed in a buffer. The control
`unit 16 reads the data in the buffer and performs AT
`command processing. If an AT command line having more
`than one AT command is received,
`the command line is
`parsed by the control unit 16. When an AT command is
`detected (block 102), the control unit 16 will compare the
`received AT command to the AT command list stored in
`
`memory 18 (block 104). If the received AT command
`matches one of the commands on the command list stored in
`
`50
`
`the control unit 16 configures the system
`memory 18,
`connector 32 in the Communication mode (block 106).
`Otherwise, the control unit 16 executes the AT command if
`the command is recognized by the control unit 16 (block
`108).
`FIG. 4 illustrates the procedure for changing from Com-
`munication mode back to the Default mode. In the Com-
`munication mode,
`the mobile communication device 10
`continuously monitors or polls the DTR, RTS, and CTS
`ports (blocks 208, 210, and 212). If the DTR, CTS and RTS
`signals are all inactive, the control unit 16 either starts or
`continues a 3 second timer (block 220). During the ensuing
`3 second interval, the control unit 16 continues to monitor
`the DTR, CTS and RTS signals. If one of these signals
`becomes active before the timer expires, the control unit 16
`resets the timer (blocks 214, 216, 218). If neither signal
`becomes active during the 3 second interval (block 222), the
`
`55
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`60
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`65
`
`8
`control unit 16 assumes that the computer has been discon-
`nected and switches to Default mode (block 224).
`If an AT command is received while the DTR, RTS and
`CTS ports are being monitored (block 202), the control unit
`16 processes the AT command. AT commands are received
`on the TD port. The control unit 16 compares the received
`AT command to a shortened command list of AMPS modem
`
`commands (block 204). If the AT command matches one of
`the commands in the AMPS modem command list, then the
`mobile communication device 10 switches back to Default
`
`10
`
`15
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`20
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`25
`
`30
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`35
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`40
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`45
`
`mode (block 224). More particularly, the control unit 16
`looks for the commands ATWS46=7 or ATWS46=243. If
`either of these AT commands is received, the control unit 16
`will assume that a standard AMPS modem, which uses the
`Default mode, is connected and will switch back to Default
`mode (block 224). Otherwise, standard AT command pro-
`cessing according to IS-135 is invoked (block 206) and the
`control unit 16 returns to monitoring the DTR, RTS, and
`CTS ports (blocks 208, 210, and 212).
`The present invention avoids the need to manually con-
`figure the mobile communication device 10 for data/fax
`communications before connecting the mobile communica-
`tion device 10 to the computer. Instead,
`the user simply
`connects the computer to the phone’s system connector 32
`and initiates communications. The phone autodetects the
`presence of the computer and automatically switches to
`Communication mode. Thus, the present invention is con-
`venient for consumers to use.
`
`The present invention is also advantageous to manufac-
`turers of phones and other mobile communication devices.
`The present invention avoids the need to develop, install and
`update drivers for various types of computing devices. The
`mobile communication device of the present invention can
`connect to any class of device that implements protocols
`recognized by the mobile communication device 10. In the
`disclosed embodiment, the mobile communication device 10
`is programmed to implement the IS-135 protocol in Com-
`munication mode. Therefore,
`the mobile communication
`device can be connected to any computing device that
`complies with IS-135 protocol.
`What is claimed is:
`
`1. A mobile communication device comprising:
`a.) a transceiver for transmitting and receiving signals;
`b.) a modem operatively connected to said transceiver;
`C.) a configurable system interface comprising a plurality
`of electrical contacts and a switching circuit, said
`system interface having a default configuration corre-
`sponding to a default mode of operation for connecting
`said mobile communication device to an external phone
`accessory, and a communication configuration corre-
`sponding to a communication mode of operation for
`connecting said mobile communication device to an
`external communication terminal capable of data, fax
`and/or voice communications, wherein said switching
`circuit connects said contacts to said transceiver
`
`according to a first mapping in said default mode and
`according to a second mapping in said communication
`mode;
`d.) a control unit operative in said default mode of
`operation to enable use of a connected phone accessory
`and in said communications mode to enable data, fax
`and voice communications by a connected communi-
`cations terminal via said modem; and
`e.) wherein said control unit is operative to change said
`system interface from said default configuration to said
`communication configuration in response to receipt of
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`US 6,285,890 B1
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`9
`a first predetermined input signal on a data input circuit
`of said system interface from said connected commu-
`nication terminal.
`
`2. The mobile communication device according to claim
`1 wherein said control unit
`is operative to change said
`system interface from said communication configuration to
`said default configuration upon receipt of a second prede-
`termined input signal on a data input circuit of said system
`interface from said external communication terminal.
`
`3. The mobile communication device according to claim
`2 wherein said second predetermined input signal
`is a
`modem command from said external communication termi-
`nal.
`
`10
`
`4. The mobile communication device according to claim
`3 wherein said second predetermined input signal is an
`AMPS AT command.
`
`15
`
`5. The mobile communication device according to claim
`4 wherein said control unit is operative to configure said
`system interface in said default configuration at power on.
`6. The mobile communication device according to claim
`1 wherein said control unit
`is operative to change said
`system interface from said communication configuration to
`said default configuration upon termination of a communi-
`cation session by said external communication terminal.
`7. The mobile communication device according to claim
`1 wherein said first predetermined input signal is a modem
`command from said external communication terminal.
`
`8. The mobile communication device according to claim
`1 wherein said first predetermined input signal is a modem
`command recognized by the IS-135 protocol.
`9. A method for configuring a system interface for a
`mobile communication device comprising a plurality of
`electrical contacts and a switching circuit, that alternately
`connects to an external communication terminal or an exter-
`
`nal phone accessory comprising:
`a.) placing said system interface in a default configuration
`wherein said switching circuit connects said contacts to
`circuits within said mobile communication device
`
`according to a first mapping to enable use of said
`mobile communication device with a connected phone
`accessory;
`
`20
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`25
`
`30
`
`35
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`40
`
`10
`
`b.) receiving a first predetermined input signal on a data
`input circuit of said system interface from an external
`communication terminal attempting to initiate a com-
`munication session for a data, voice or fax communi-
`cation requiring a modem; and
`c.) placing said system interface in a communication
`configuration wherein said switching circuit connects
`said contacts to said circuits within said mobile com-
`
`munication device according to a second mapping in
`response to receipt of said first predetermined input
`signal to enable communications by said external com-
`munications terminal via said modem.
`
`10. The method according to claim 9 further including
`placing said system interface in said default configuration
`upon termination of a communication session by said exter-
`nal communication terminal.
`
`11. The method according to claim 9 further including
`changing said system interface from said communication
`configuration to said default configuration upon receipt of a
`second predetermined input signal on a data input circuit of
`said system interface from said external communication
`terminal.
`
`12. The method according to claim 11 wherein said
`second predetermined input signal is a modem command
`from said external communication terminal.
`
`13. The method according to claim 12 wherein said
`second predetermined input signal is an AMPS AT com-
`mand.
`
`14. The method according to claim 9 wherein said first
`predetermined input signal is a modem command from said
`external communication terminal.
`
`15. The method according to claim 14 wherein