This application is a continuation of application Ser. No. 08/152,492, filed Nov. 15, 1993 now abandoned. 
    
    
     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™ Newton™ and the Sharp™ Expert Pad™. 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™ 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, 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 line using a built in phone modem. These added communication features greatly enhances the utility of the PDAs. Instead of having a stand-alone PDA, isolated from other data sources, such as a person&#39;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 computer communications device which is connectable to a portable computer. The communications device provides multiple alternative communication capabilities for the portable computer. The portable computer communications device comprises, in basic form, a cradle adapted to releasably retain the portable computer. The communications device has at least first and second communications devices providing first and second differing modes of communication for the portable computer. A common communications interface is coupled to the first and second communications devices and is detachably coupled to a serial port of the portable computer. A controller is coupled to the common interface. The controller selects data transfer between the first communications device and the serial port of the portable computer or selects data transfer between the second communications device and the serial port of the portable computer. 
     In one embodiment, the first communications device is a cellular telephone which can be selectively controlled to provide voice communications for the user or to be coupled to a modem to provide data communications for the portable computer. In the present embodiment, the first and second communications devices comprise two of a global positioning satellite system, a modem, a packet radio system and a cellular phone coupled to a modem. 
     In one embodiment, the controller of the portable communications device downloads operating instructions to the portable computer. The operating instructions provide the functions which enable the portable computer to utilize the communications devices via the common interface. 
     Another aspect of the present invention involves a palm computer communications device which provides a global positioning function for the palm computer. A palm computer cradle is adapted to releasably retain the palm computer. A global positioning satellite location system is positioned within the palm computer cradle. A microcontroller positioned within the palm computer cradle is detachably coupled to the palm computer and to the global positioning satellite location system. 
     In one embodiment, the palm computer communications device further comprises a packet radio communications device positioned within the palm computer cradle. In such an embodiment, the palm computer communications device, in conjunction with the palm computer, provides an automatic tracking system wherein the global positioning satellite location system periodically ascertains the location of the palm computer communications device when coupled to the palm computer and transmits the location via the packet radio to a base station. 
     Yet another aspect of the present invention involves a palm computer communications device which is connectable to a palm computer. The communications device has at least first and second wireless communications devices which provide first and second differing modes of serial data communication for the palm computer. A common interface is coupled to the first and second wireless communications devices and is detachably coupled to a serial communications port of the palm computer. The interface transfers data between the serial communications port and the first communication device and also between the serial communications port and the second communications device. In the present embodiment, the common interface comprises a microcontroller system coupled to a decoder/multiplexer circuit. 
     In one embodiment, the first communications device comprises a cellular telephone and a modem which can be selectively controlled to provide voice communications for the user or to provide data communications for the palm computer. 
     Also in the present embodiment, the palm computer communications device further comprises a pass-thru serial port for connection to at least one of a plurality of additional serial peripheral devices, such as a printer, a card reader, or a network. 
     Still another aspect of the present invention involves a palm computer cradle. The cradle has a base portion which provides a supporting surface for a personal digital assistant. The cradle further has a fixed securing member extending from a first end of the base portion and a movable securing member extending from a second end of the base portion. In the present embodiment, the second end is opposite the first end. The movable securing member is movable between at least two positions to allow insertion of the personal digital assistant in a first of the at least two positions, and to retain the personal digital assistant in a second of the at least two positions. A communication system for the personal digital assistant is housed by the cradle. The communication system provides alternative communication capabilities for the personal digital assistant. 
     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 the preferred 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. 
     FIG. 9A, 9B and 9C illustrate a flow chart of a computer program executed by the microcontroller of FIG. 4. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 illustrates a palm computer or personal digital assistant (PDA) 102 for use with the preferred embodiment of 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. 
     FIG. 2 illustrates a preferred embodiment of the portable multiple integrated communication device 100 of the present invention. 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™ Expert Pad™, for insertion of an IC card into the slot of the Expert Pad™. 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 preferred 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 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 preferred 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® 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™ 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 preferred 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 preferred 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 preferred 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 preferred 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, 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; and the microcontroller 104 can 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; and it 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 &#34;wakes up&#34; and become 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 receive 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 embodiment, 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® 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 jack 118. 
     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 on the receive data line 404 to the receive data line 308. The transmit data line 400 is connected between the decoder/multiplexer 112 and a transmit data input of the GPS engine 120. The handshake-in line 402 is connected between a time mark output of the GPS engine 120 and the decoder/multiplexer 112. The receive data line 404 is connected between a receive data output of the GPS engine 120 and the decoder/multiplexer 112. A person of skill in the art will understand that the transmit data lines 304, 400, the handshake-in lines 306, 402 and the receive data lines 308, 404 form a serial interface between the microcontroller 104 and the GPS engine 120. 
     The GPS engine 120 comprises a Rockwell NayCore® VI MicroTracker™ Global Positioning System circuit card. The GPS engine 120 receives commands from the microcontroller 104 over the transmit data lines 304 and 400. The microcontroller 104 can use these commands to control a number of aspects of the operation of the GPS engine 120, such as a selection of the satellites utilized for computing the location of the communication device 100 and the frequency 100 at which the GPS engine 120 makes this computation. The GPS antenna 123 receives electromagnetic signals transmitted from GPS satellites. The GPS antenna 123 applies these signals to the GPS antenna line 406 connected between the GPS antenna 123 and the GPS engine 120. The GPS engine 120 utilizes the signals received from the satellites to calculate the location of the communication device 100 in terms of longitude, latitude and altitude. The GPS enable line 408 is connected between the output port 200 and the GPS engine 120. The output port 200 applies one of its eight output signals to the GPS enable line 408. As described above with reference to FIG. 4, the microcontroller 104 controls the GPS enable line 408 by controlling the set of three address lines 228, the data line 230 and the write enable line 232. The microcontroller 104 enables the GPS engine 120 to send commands to the GPS engine 120 or receive data back from the GPS engine 120. 
     FIG. 8 is a more detailed functional block diagram of the interface between the microcontroller 104 and either the packet radio 124 or the cellular telephone 126, whichever communication circuit is inserted. This interface comprises the microcontroller 104, the decoder/multiplexer 112, the packet radio 124, the cellular telephone 126, the packet radio antenna 122, the cellular telephone antenna 121, the microphone amplifier 128, the earphone amplifier 130, the microphone and earphone jack 132, the output port 200, the set of three address lines 228, the data line 230, the write enable line 232, the handshake-out line 302, a handshake-out line 500, the transmit data line 304, a transmit data line 502, the handshake-in line 306, a handshake-in line 504, the receive data line 308, a receive data line 506, a packet radio antenna line 508, a ring indicator line 510, a cellular telephone antenna line 514, a cellular telephone/packet radio enable line 512, a set of two microphone audio lines 516 and 522, an LPS control line 518, and a set of two earphone audio lines 520 and 524. 
     The microcontroller 104 generates signals on the handshake-out line 302 and on the transmit data line 304, which are 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 packet radio 124 or the cellular telephone 126 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 500; it transfers the signal on the transmit data line 304 to the transmit data line 502; it transfers a signal on the handshake-in line 504 to the handshake-in line 306; and it transfers a signal on the receive data line 506 to the receive data line 308. The handshake-out line 500 is connected between the decoder/multiplexer 112 and a ready-to-send input of the packet radio 124. The transmit data line 502 is connected between the decoder/multiplexer 112 and a transmit data input of the packet radio 124 or a DTMS input of the cellular telephone 126. The handshake-in line 504 is connected between a clear-to-send output of the packet radio 124 or an SWDC5 output of the cellular telephone 126 and the decoder/multiplexer 112. The receive data line 506 is connected between a receive data output of the packet radio 124 or a DFMS output of the cellular telephone 126 and the decoder/multiplexer 112. A person of skill in the art will understand that the handshake-out lines 302, 500, the transmit data lines 304,502, the handshake-in lines 306,504 and the receive data lines 308, 506 form a serial interface between the microcontroller 104 and either the packet radio 124 or the cellular telephone 126. 
     In the preferred embodiment, the packet radio 124 comprises a GE/Ericson Moby Pack. The packet radio 124 is connected to the antenna 122 by the packet radio line 508. The microcontroller 104 sends control commands and packets of data to the packet radio 124 over the above-described serial interface. The packet radio 124 generates a signal on the antenna line 508 to the antenna 122 to transmit the data to a base unit, as is well-known in the art. The antenna 122 also receives data from base units and applies the data to the antenna line 508. The packet radio 124 receives this data and relays the data to the microcontroller 104 over the above-described serial interface. When the packet radio 124 initially receives data from a remote source, the packet radio 124 activates a ring indicator output signal. The ring indicator output signal is applied to the ring indicator line 510 connected between the packet radio 124 and the microcontroller 104. This signal alerts the microcontroller 104 to receive the incoming data. 
     The cellular telephone/packet radio enable line 512 is connected between the output port 200 and a DTR input of the packet radio 124 or an ON SRQ input of the cellular telephone 126. The DTR input of the packet radio 124 is active low, while the ON SRQ input of the cellular telephone 126 is active high. Thus, when the signal on the cellular telephone/packet radio enable line 512 is low, the packet radio 124 is enabled and the cellular telephone 126 is disabled. Conversely, when the signal is high, the packet radio 124 is disabled and the cellular telephone 126 is enabled. Thus, it is necessary for the microcontroller 104 to send the correct enable signal to whichever communication circuit (either the packet radio 124 or the cellular telephone 126) is installed in order to activate the installed circuit. This helps preclude having the wrong software attempt to operate the installed circuit. This signal is one of the eight output signals of the output port 200. As described above, the microcontroller 104 can control this signal by controlling the set of address lines 228, the data line 230 and the write enable line 232. Thus, the microcontroller 104 can enable the desired communication circuit 124 or 126. 
     In the preferred embodiment, the cellular telephone 126 comprises a GE/Ericson Mary Beth circuit card. The microphone and earphone jack 132 is mounted at an outside surface of the communication device 100, as illustrated in FIGS. 2 and 3. An external microphone and earphone set can be plugged into the microphone and earphone jack 132 to allow a telephone conversation between the user of the PDA 102 and a remote party, using the cellular telephone 126. The external microphone applies an audio signal to the audio line 522, through the microphone and earphone jack 132. The audio line 522 is connected between the earphone amplifier 128 and microphone and earphone jack 132. The microphone amplifier 128 receives the signal on the audio line 522 and amplifies the signal to generate a signal on the audio line 516. The audio line 516 is connected between the microphone amplifier 128 and the cellular telephone 126. The cellular telephone 126 then receives the audio signal from the audio line 516. 
     The cellular telephone 126 generates a signal on the cellular telephone antenna line 514 that is connected to the antenna 121, for transmission to a cellular cell site. The signal generated by the cellular telephone 126 on the antenna line 514 represents audio signals received from the microphone and earphone jack 132. 
     The antenna 121 also receives signals from the cellular cell site and applies these signals to the antenna line 514. The cellular telephone 126 receives the signal on the line 514 and, in response thereto, generates an audio signal on the earphone audio line 520. The audio line 520 is connected between the cellular telephone 126 and the earphone amplifier 130. The earphone amplifier 130 amplifies the signal on the audio line 520 and generates a new signal on the audio line 524. The audio line 524 is connected between the earphone amplifier 130 and the microphone and earphone jack 132. The signal on the audio line 524 drives the external earphone connected to the microphone and earphone jack 132 to allow the user of the PDA 102 to listen to a remote party. 
     The cellular telephone 126 receives commands from the microcontroller 104 over the transmit data lines 302 and 502 to control the operation of the cellular telephone 126. The cellular telephone 126 also communicates information to the microcontroller 104 via the above-described serial interface. 
     The LPS control line 518 is connected to the microphone amplifier 128, the earphone amplifier 130 and the ring indicator line 510. The cellular telephone 126 activates a signal on the LPS control line 518 in response to either a command from the microcontroller 104 or in response to receiving an incoming telephone call. An active signal on the LPS control line 518 enables the amplifiers 128 and 130. In addition, an active signal on the LPS control line 518 is received at a ring indicator input of the microcontroller 104, over the ring indicator line 510. Thus, the cellular telephone 126 alerts the microcontroller 104 upon receiving an incoming call. 
     FIGS. 9A, 9B and 9C illustrate a flow chart representing the software that is executed by the microcontroller 104 of the communication device 100. When the communication device 100 is initially powered up, the microcontroller 104 begins executing at a block 600, as shown in FIG. 9A. At a process block 602, the microcontroller 104 accesses the ROM 134 and loads small portions of the software into RAM inside the microcontroller 104. Preferably, the software routines that are loaded into internal RAM are the routines that are generally executed most frequently. The microcontroller 104 executes routines that are not loaded into RAM by directly accessing the ROM 134. 
     At a process block 604, the microcontroller 104 sends messages over each of the above-described serial interfaces between the microcontroller 104 and the communication circuits 114, 120, 124, 126. The microcontroller 104 waits for a response from each of the communication circuits 114, 120, 124, 126. This exchange of messages allows the microcontroller 104 to determine which of the communication circuits 114, 120, 124, 126 have been installed inside the communication device 100. 
     At a process block 606, the microcontroller 104 sends a message to the PDA 102 over the primary serial port 106. The response from the PDA 102 indicates whether software must be uploaded to the PDA 102. Upon receiving this response from the PDA 102, the microcontroller 104 proceeds to a process block 608. At the process block 608, the microcontroller 104 reads code from the ROM 134 and transfers it to the PDA 102 over the primary serial port 106, if the previous response from the PDA 102 indicated that an upload was necessary. The required software can be uploaded to the PDA 102 by an appropriate method, as required by the PDA 102. For example, the Apple™ Newton™ has a well-defined method for uploading software from its serial port. As described above, the software that is uploaded to the PDA 102 provides the user of the PDA 102 with access to the functions provided by the communication device 100. The software uploaded into the PDA 102 provides an interface with the hardware and the software of the communication device 100. 
     At a process block 610, the microcontroller 104 sends messages to any attached external devices through the pass-thru serial port 110. Each of the attached external devices, if any, responds to the microcontroller 104 through the pass-thru serial port 110. These responses allow the microcontroller 104 to determine the types of external devices that are attached to the pass-thru serial port 110. 
     The microcontroller 104 proceeds to a process block 612. As described above, the ROM 134 may contain code that can be downloaded to external devices through the pass-thru serial port 110. If the ROM 134 contains code for one or more of the attached external devices, and one or more of those attached external devices require a software download, the microcontroller 104 reads the appropriate code from the ROM 134 and transfers it to the appropriate external devices through the pass-thru serial port 110. 
     At a process block 614, the microcontroller 104 initializes each of the installed communication circuits 114, 120,124,126, as required. For example, the microcontroller 104 may initiate a warm start in the GPS engine 120 by sending an appropriate command over the serial interface connecting the microcontroller 104 with the GPS engine 120. This warm start allows the GPS engine 120 to respond more quickly to a request from the PDA 102 for location data. As another example, the microcontroller 104 may send appropriate commands to program the cellular telephone 126, if the cellular telephone 126 has not yet been programmed. 
     At a process block 616, as shown in FIG. 9B, the microcontroller 104 powers up the phone modem 114 by activating the signal on the modem enable line 334, as shown in FIG. 6. At a process block 618, the microcontroller 104 causes the decoder/multiplexer 112 to select the phone modem 114 for on-line operation by applying appropriate signals to the select lines 140 and 142, as shown in FIG. 4. 
     At a process block 620, the microcontroller 104 enters a monitor mode. In the monitor mode, the microcontroller 104 emulates a modem and relays data between the PDA 102 and the communication circuit 114, 120, 124, 126 that is currently on-line, while monitoring the communication stream generated by the PDA 102 for escape codes. The microcontroller 104 continues to relay data between the PDA 102 and the on-line communication circuit 114, 120, 124, 126, until it receives either an escape code from the PDA 102 or an interrupt from one of the communication circuits 114, 120, 124 or 126 that is not selected for on-line operation. The phone modem 114 can interrupt the microcontroller 104 by applying an active signal to the ring indicator line 332, as shown in FIG. 6. Either the packet radio 124 or the cellular telephone 126 can interrupt the microcontroller 104 by activating the signal on the ring indicator line 510. Upon receiving either an escape code from the PDA 102 or an interrupt from an off-line communication circuit 114, 120, 124 or 126, the microcontroller 104 advances to a decision block 622. 
     At the decision block 622, the microcontroller 104 determines whether it received an escape code or an interrupt. If the microcontroller 104 received an escape code, then the microcontroller 104 advances to a process block 624. Otherwise, the microcontroller 104 advances to a decision block 628, as shown on FIG. 9C. At the process block 624, the microcontroller 104 reports any prior interrupts that have not yet been reported to the PDA 102. Specifically, the microcontroller 104 sends a message to the PDA 102 indicating which communication circuits 114,120,124 or 126 have interrupted the microcontroller 104. After reporting the prior interrupts, the microcontroller 104 advances to a process block 626. 
     At the process block 626, the microcontroller 104 enters a command mode. In this mode, the PDA 102 can send a series of commands to the microcontroller 104 for controlling the communication circuits 114, 120, 124 and 126. Examples of possible commands that can be sent to the microcontroller 104 include commands to power off the communication device 100, to wake up the PDA 102 upon receipt of an incoming cellular call, to select a communication circuit 114, 120, 124, 126 for on-line operation, to idle at low power and to check different status conditions. The microcontroller 104 continues to execute commands received from the PDA 102 until the microcontroller 104 has selected a communication circuit 114, 120, 124 or 126 for on-line operation in response to a command from the PDA 102. At this point, the microcontroller 104 returns to the process block 620. 
     At the decision block 628, the microcontroller 104 checks the service response code for the communication circuit 114, 120, 124 or 126 that generated the interrupt. The service response code indicates whether there are any actions that the microcontroller 104 should automatically perform in response to the interrupt. If the service response code indicates that the interrupt does not require service, then the microcontroller 104 advances to a decision block 636. If the service response code indicates that the interrupt does require servicing, then the microcontroller 104 advances to a process block 630. 
     At the process block 630, the microcontroller 104 disables the serial interface between the PDA 102 and the communication circuit 114, 120, 124 or 126 that is currently selected for on-line operation. The microcontroller 104 disables this interface using the handshake lines 204, 208, 302 and 306, as is well known in the art. At a decision block 632, the microcontroller 104 performs the appropriate steps to service the current interrupt from the communication circuit 114,120, 124 or 126. The steps performed during the process block 632 depend on the particular communication circuit 114, 120, 124 or 126 generating the interrupt and on the instructions that have been previously received from the PDA 102 related to the particular communication circuit 114, 120, 124 or 126. For example, the cellular telephone 126 generates an interrupt to the microcontroller 104 on the ring indicator line 510 upon receiving an incoming call. If the PDA 102 has previously set the cellular telephone 126 to an automatic answering mode inside the microcontroller 104, the microcontroller 104 causes the cellular telephone 126 to answer the incoming call during the process block 632. Specifically, the microcontroller 104 temporarily disables the interface between the PDA 102 and the communication circuit 114, 120 or 124 that has been selected for on-line operation and causes the decoder/multiplexer 112 to select the cellular telephone 126. The microcontroller 104 then generates appropriate commands to cause the cellular telephone 126 to answer the incoming call. The user of the PDA 102 can then begin a telephone conversation with the remote caller using an external microphone and earphone connected to the microphone and earphone jack 132. After controlling the cellular telephone 126 to answer the incoming call, the microcontroller 104 controls the decoder/multiplexer 112 to again select the communication circuit 114, 120 or 124 that had previously been selected for on-line operation. At a process block 634, the microcontroller 104 again enables the interface between the PDA 102 and the communication circuit 114,120, 124 or 126 by controlling the handshake lines 204,208,302 and 306. After the process block 634, the microcontroller 104 advances to the decision block 636. 
     At the decision block 636, the microcontroller 104 checks the interrupt response code corresponding to the communication circuit 114, 120, 124 or 126 that generated the interrupt. The interrupt response code has been previously set by the PDA 102 by a command to the microcontroller 104. The interrupt response code indicates whether the microcontroller 104 should immediately interrupt the PDA 102, whether it should cause a delayed interrupt of the PDA 102, or whether it should not interrupt the PDA 102 at all. If the interrupt response code indicates that the microcontroller 104 should not interrupt the PDA 102, the microcontroller 104 returns to the process block 620. If the interrupt response code indicates that the microcontroller 104 should immediately interrupt the PDA 102, then the microcontroller 104 advances to a process block 640. If the interrupt response code indicates that the microcontroller 104 should perform a delayed interrupt, the microcontroller 104 advances to a process block 638. At the process block 638, the microcontroller 104 monitors the communication stream between the PDA 102 and the communication circuit 114, 120, 124 or 126 that has been selected for on-line operation. When the microcontroller 104 detects a break in the communication stream, the microcontroller 104 advances to the process block 640. At the process block 640, the microcontroller 104 activates the GPI line 206, illustrated in FIG. 5, to cause an interrupt to the PDA 102. The response of the PDA 102 to the interrupt on the GPI line 206 depends on the application program running on the PDA 102, if any. After the process block 640, the microcontroller 104 returns to the process block 620 of FIG. 9B. 
     As discussed above, the PDA 102 executes software that allows the PDA 102 to interface with and control the communication device 100. This software sends commands to the microcontroller 104 when the microcontroller 104 is in the command mode, and it sends data to the on-line communication circuit 114, 120, 124, 126 when the microcontroller 104 is in the monitor mode. The format and the content of the data sent to the different communication circuits 114, 120, 124, 126 complies with the requirements of the particular communication circuits 114, 120, 124, 126. For example, the data sent to the phone modem 114 complies with the standard Hayes® format for modems. 
     As described above, the communication software for the PDA 102 is uploaded to the PDA 102 from the ROM 134, and the software extends the capabilities of the PDA 102. As an example, the software is described in terms of using an Apple™ Newton® as the PDA 102. In this case, the system preferences are extended to provide user access to the functions of the communication device. For example, the standard functions of Print, Fax, Mail and Call are modified to operate the communication circuits 114, 120, 124, 126 of the communication device 100. Thus, the Call function places a cellular telephone call if the cellular telephone 126 is currently on-line. Alternatively, the Fax function sends a facsimile over the phone modem 114 if the phone modem is currently on-line. The system preferences are also extended to display information about the communication device 100. For example, if a packet of data is received at the packet radio 124, the In Box of the PDA 102 reflects the reception of this message. 
     Although extending the Newton system preferences provides a powerful interface with the communication device 100, not all of the functions of the communication device 100 can be conveniently controlled by this method. Consequently, one or more application programs are also provided that allow more complete control of the functions of the communication device 100. For example, one application program can be used to control different functions of the cellular telephone 126, such as programming the cellular telephone 126 or placing a phone call. 
     The Intelligent Assistant™ of the Newton is also extended to understand commands for the communication device 100. Thus, for example, a user can write the phrase &#34;Where am I?&#34; on the LCD display 78 using the light pen 76. The extended Intelligent Assistant™ understands this as a command to activate the GPS engine 120 to determine the current location of the communication device 100. The PDA 102 generates the appropriate commands to the communication device 100 to obtain the requested data from the GPS engine 120. The Intelligent Assistant™ preferably utilizes the above-described application programs to control many functions of the communication device 100. 
     The software uploaded to the PDA 102 also includes proto end points, as defined by Apple™ specifications, that facilitate interfacing with the communication device 100 and controlling the operation of the communication device 100. These proto end points can be used by other application programs to access the communication device 100. 
     The portable multiple integrated communication device 100 of the present invention provides versatile utilization of the communication circuits 114, 120, 124, 126. Data is channeled from a communication circuit 114, 120, 124, 126, through the microcontroller 104, to the PDA 102. The data can then be rerouted to any of the other communication circuits 114, 120, 124, 126. This data flow versatility allows the different functions of the communication device 100 to be utilized in various combinations to provide numerous more complex functions. For example, the GPS engine 120 can be used in conjunction with the packet radio 124 to form an automated tracking system. The GPS engine 120 can periodically generate location data to the PDA 102. This information can automatically be transmitted to an office computer using the packet radio 124, providing personnel at the office with continuous access to data indicating the location of the communication device 100, and consequently, the person using it. Also, in the alternative embodiment described above, involving a phone modem 114 that has analog audio input and output capabilities, data can be transferred directly between the cellular telephone 126 and the phone modem 114, further expanding the possibilities. For example, digital data can be transmitted over the cellular interface by routing the data from the PDA 102, through the microcontroller 104 and the phone modem 114, to the cellular telephone 126. The phone modem 114 converts the digital data into a format that is compatible with cellular technology. 
     The communication device 100 of the present invention can also be implemented with other optional devices or features. For example, an optional lamp (not shown) can be controlled by the microcontroller 104 to illuminate the LCD display 78. Also, other units can be used to replace the communication circuits 114, 120, 124, 126 of the present embodiment. These other units need not be communication circuits, either.
The present invention relates to a communication device for a personal digital assistant (PDA). The PDA mounts within the communication device and the communication device connects electronically to a serial port on the PDA. Through this single serial port, the communication device provides the user of the PDA with access to multiple communication media, such as a telephone modem, a Global Positioning System engine, a packet radio and a cellular telephone. Data from the PDA is directed to a decoder that routes the data to the appropriate communication medium, while data from the communication media are multiplexed onto the single serial interface of the PDA. The communication device also provides a pass-thru serial interface that allows other external devices to communicate directly with the serial port of the PDA. In addition, the communication device can upload software to the PDA that facilitates communications between the PDA and the communication device, and allows the PDA to control the operation of the communication device.