MOBILE TELEPHONE ADAPTER
The invention relates to an adapter for use with a device. Preferred examples relate to an adapter for a mobile or portable device, such as a mobile telephone or personal digital assistant (PDA). The invention finds particular use with devices having rechargeable batteries.
Electronic devices, such as mobile telephones and PDAs, often comprise data input/output connections based on communication standards such as RS232 or the like, allowing them to be connected to computers (for example, desktop or laptop PCs) for the purposes of data transfer. For example, when connected to a computer, many mobile telephones provide internet access functionality. Although mobile devices are typically powered by rechargeable batteries, these do not always provide sufficient charge for prolonged use, especially when a mobile telephone is used for purposes such as internet access. Battery chargers are typically provided to recharge the battery from the mains; however, these can be bulky and expensive, as they typically comprise AC/DC transformers. In addition, suitable power outlets are not always available, especially whilst on the move, for example on a train or aeroplane. Additionally, many mobile telephones are designed in such a way that data and power connectors cannot be connected simultaneously, meaning that use of the data connection needs to be interrupted if recharging becomes necessary. If the battery does run out, then the device, for example the mobile telephone, will typically turn itself off, which may lead to interrupted communications and/or data loss.
It is an object of the present invention to address some of the above problems.
Accordingly, in a first aspect of the invention, there is provided an adapter for use with a wireless communications device, the adapter comprising: means for connecting to a host using a powered communication channel; means for supplying power from the powered communication channel to the device; and means for transmitting data between the powered communication channel and the device.
In this way, power may be supplied to the device during data transmission, which may enable the device to operate for longer and/or more reliably.
Preferably, the adapter comprises means for connecting to the device using a further communication channel. This can enable the adapter to be used to connect a host and device using different communication channels. Preferably, the transmitting means comprises a data interface between the powered communication channel and the further communication channel. By providing a data interface between the two communication channels, data transfer may be more easily managed.
This feature is of particular importance and is therefore also provided independently. Accordingly, in a further aspect of the invention, there is provided an adapter for use with a device having a data connector and a power connector, the adapter comprising: means for connecting to a host using a powered communication channel; means for connecting to the data connector of the device using a further communication channel; means for supplying power from the powered communication channel to the power connector of the device; and a data interface between the powered communication channel and the further communication channel.
The adapter may be provided in the form of a box having suitable connectors to which the device and host may be connected (for example, via suitable cables), or it may be provided in the form of a cable for connecting the host and the device. The adapter may also be provided in a form suitable for inclusion in such a cable, or in any other suitable form.
The device may, for example, be a handheld computing device such as a Personal Digital Assistant (PDA) or a communications device such as a mobile telephone.
Alternatively or in addition, power may be supplied from the device to the host.
The term 'powered communication channel' preferably refers to a communication channel comprising means for transferring power and data, preferably in the form of one or more dedicated power conductors for transferring power and one or more separate data conductors. The term 'unpowered communication channel' preferably refers to a communication channel having data conductors but no dedicated power conductors. Both powered and unpowered communication channels may additionally comprise one or more conductors for transferring control signals.
Preferably, the powered communication channel is associated with a first communication system, the further communication channel is associated with a second communication system, and the first communication system differs from the second communication system. This can enable the adapter to provide a connection between disparate, and potentially incompatible, communication systems. The data interface preferably comprises a converter for converting between the first and second communication systems. This can enable data to be transferred between the two communications systems, and may make data transfer more accurate.
The adapter may comprise a converter for converting between USB and RS232 communication standards. This may enable the device to be used to connect a host with a USB connection to a device having an RS232 connection and vice versa.
Preferably, the further communication channel is an unpowered communication channel. This may enable the adapter to provide connectivity to a device which has a connector for an unpowered communication channel, by supplying data received from the powered communication channel to the device over the unpowered communication channel, whilst providing a separate supply of power (also obtained from the powered communication channel) to the device.
Devices that normally use separate channels for power and data may thus be connected to and supplied from a single powered communication channel, for example a Universal Serial Bus (USB). Examples of such devices include many
mobile telephones, which transfer data to and from a host computer via a serial connection, but which receive their power supply from the mains supply via a transformer. Some such devices cannot be connected to the host and the mains supply at the same time. In this case, the ability to provide both power and data transfer from a single powered communication channel can be particularly advantageous, since power and data transfer can be provided simultaneously.
Preferably, the further communication channel is implemented substantially in accordance with one of the RS232, RS422, RS485 and related communication standards. Other suitable communications systems, either proprietary or based on other communication standards, may also be used.
The powered communication channel is preferably implemented substantially in accordance with a Universal Serial Bus (USB) standard or a related standard. Alternatively, the powered communication channel may be implemented substantially in accordance with an IEEE- 1394 / Firewire (TM) standard or a related standard. These standards are widely used, and many devices provide connection means based on these standards. In this way, the adapter may be used to connect to a wide variety of existing hosts. Alternatively, other proprietary or standards-based communications systems may be used.
Preferably, the power supplying means comprises a USB power supply, the USB power supply comprising means for receiving power from a Universal Serial Bus and means for supplying power to the device. This may make the adapter suitable for use with a wide variety of host devices, since USB provides power as well as data communications and is widely used in host devices such as desktop and laptop computers.
The device may be a wireless communications device, for example a mobile telephone, and preferably comprises wireless data communication means. The device may comprise a power supply, preferably a rechargeable battery. The power
supplying means is preferably adapted to charge the rechargeable battery of the device.
The adapter may be particularly useful when used with such a device, since wireless communications devices, for example mobile telephones, may often be used in conjunction with a host computer to provide access to communications networks, for example to the internet. Since wireless data communication often uses a lot of power, a wireless communications device's battery can quickly become depleted, leading to a potential loss of connection. This can be a problem especially where the design of the device prevents it from being connected to a mains supply at the same time, or in situations where a mains supply is not available (for example, on a train). By using the adapter in this context, a supply of power may be provided to power the device and/or recharge its battery during data communication, thereby reducing the likelihood of the connection being interrupted.
Preferably, the host is a computer. The host preferably comprises a USB port.
In a further aspect of the invention, there is provided a connector for use with a wireless communications device, the connector being adapted to be connected to the wireless communications device and to a host, and being further adapted to transfer power and data between the host and the wireless communications device. The connector may further comprise any of the features of the adapter described herein.
In a further aspect of the invention, there is provided a cable comprising an adapter or a connector as described herein. The cable preferably further comprises a host connector and a device connector. The host connector may comprise a USB connector. The USB connector may be a USB A-type connector or a USB B-type connector, or any other kind of USB connector.
Preferably, at least part of the adapter is located nearer the device connector than the host connector. This may reduce the amount of wiring required and thus reduce the manufacturing cost. For example, USB uses only four wires. If the adapter connects
to the host using USB, and to the device using a connection method employing more than four wires, then the amount of wiring may be reduced by locating the adapter closer to the device connector than the host connector. At least part of the adapter may form an integral part of one of the host connector and the device connector (preferably the device connector). This may simplify manufacture of the cable. Also, placing the adapter (or part of the adapter) inside the device connector may be beneficial for the above reasons. Conversely, if the adapter connects to the device using a connection method employing fewer wires than the connection method used to connect to the host, then it may be advantageous to place the adapter (or part of the adapter) nearer (or inside) the host connector for the same reasons.
In a further aspect of the invention, there is provided a method of communicating with a wireless communications device, the method comprising the steps of: connecting to a host using a powered communication channel; supplying power from the powered communication channel to the device; and transmitting data between the powered communication channel and the device.
In a further aspect of the invention, there is provided a method of communicating with a device having a data connector and a power connector, the method comprising the steps of: connecting to a host using a powered communication channel; connecting to the data connector of the device using a further communication channel; supplying power from the powered communication channel to the power connector of the device; and transmitting data between the powered communication channel and the further communication channel.
In a further aspect of the invention, there is provided a connector cable/software arrangement adapted to provide RS232 communication and power to an RS232- compatible device over a Universal Serial Bus (USB).
The invention also provides a computer program and a computer program product for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein, and a computer readable medium having stored thereon a program for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein.
The invention also provides a signal embodying a computer program for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein, a method of transmitting such a signal, and a computer product having an operating system which supports a computer program for carrying out any of the methods described herein and/or for embodying any of the apparatus features described herein.
The invention extends to methods and/or apparatus substantially as herein described with reference to the accompanying drawings.
Any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, method aspects may be applied to apparatus aspects, and vice versa.
Furthermore, features implemented in hardware may generally be implemented in software, and vice versa. Any reference to software and hardware features herein should be construed accordingly.
Where reference is made to plug / socket configurations, other suitable connection methods may be substituted, including wireless connection methods.
Revision 2.0 of the Universal Serial Bus (USB) specification is available from www.usb.org. References to USB shall preferably be taken to include any version of the USB specification (including the widely used USB versions 1.1 and 2.0) as well as any variants (for example, Mini-USB), developments or equivalent communication standards. Other suitable communications standards which provide
for a power supply alongside the data connections may be substituted for USB, for example IEEE-1394 (also known as FireWire (TM) or i.Link (TM)).
References to RS232 shall preferably be taken to include any versions, -variants, developments or equivalents of the RS232 communications standard. Other suitable communications standards may be substituted for RS232. Examples of other standards that may be suitable include RS422 and RS485. RS232, RS422 and RS485 are also known as EIA232, EIA422 and EIA485 respectively. The responsible standards organisation is the Electronics Industry Association.
Preferred features of the present invention will now be described, purely by way of example, with reference to the accompanying drawings, in which:-
Figure 1 illustrates the connection of a mobile telephone handset to a USB- enabled host using an adapter; Figure 2 is a schematic diagram of the adapter of Figure 1 ; Figure 3 illustrates a communication architecture for communicating between a handset and a host; and Figure 4 illustrates a communication architecture for communicating between a handset and a host using the adapter of Figure 1.
Figure 1 shows a mobile telephone handset 10 connected to a host computer 30 via an adapter cable 20. The handset 10 comprises a rechargeable battery 18 (indicated with dotted lines) inside the handset and a socket 12.
The adapter cable 20 provides data connectivity, enabling a variety of tasks to be performed, for example data synchronisation between host 30 and handset 10 and internet access using the handset's internet capability. Furthermore, the adapter cable 20 supplies power to the handset. This, for example, enables the handset battery 18 to be charged from host computer 30.
The host computer 30 is a Universal Serial Bus (USB) enabled computer such as a desktop PC or laptop computer. The handset 10 is mobile telephone handset having a data input/output interface based on the RS232 serial communication standard. In other examples, other communication systems providing for supply of power alongside data may be used in place of USB, and other communication systems may be used in place of RS232.
The data input/output interface comprises a number of data connectors 14 in socket 12. Socket 12 further comprises power connectors 16 for supplying power to the handset. The arrangement and number of connectors shown is purely exemplary. In other examples, data and power connections may be provided via separate sockets on the handset.
The host computer 30 comprises a CPU 32, a Random Access memory (RAM) 34, a PCI bus 36 and a USB subsystem 44 comprising a USB host controller 38 and a USB root hub 40. The host computer may further comprise other computer components. The CPU 32 communicates with USB host controller 38 via the PCI bus 36 under control of program instructions, for example USB driver software, stored in RAM 34. The USB host controller 38 is connected to the USB root hub 40 which comprises at least one USB port 42.
The host computer 30 further comprises a power supply 50 which provides power to the components of the host computer, including to the USB root hub 40 and hence to the Universal Serial Bus. The power supply 50 may be a mains power supply (for example, in the case of a desktop PC) or a battery (for example in the case of a laptop computer).
The adapter cable 20 comprises a host connector plug 22 in the form of a USB A- type plug which connects to USB port 42 in host computer 30, and a handset connector plug 24 which plugs into matching socket 12 in handset 10. Handset connector plug 24 comprises data and power connectors 14' and 16' matching the corresponding connectors 14 and 16 in socket 12 of handset 10.
The adapter cable 20 further comprises an adapter 26 which provides a data interface 27 between the Universal Serial Bus and the RS232 connection as well as, a power interface 28 between the USB. and the handset's power connectors. The adapter cable 20 and adapter 26 will now be described in more detail with reference to Figure 2.
The adapter cable comprises standard USB-A connector plug 22 and handset connector plug 24. The USB-A connector plug 22 is connected to adapter 26 via a length of USB cable comprising four conductors; namely two power conductors VBUS (102) and Ground (104), and two signal conductors D+ (106) and D- (108). The USB provides a 5V supply via the power conductors and transmits data via the signal conductors.
The four USB conductors 102, 104, 106 and 108 are connected to a data interface (shown as 27 in Figure 1) in the form of a two-way USB / RS232 converter 110 within the adapter 26. USB / RS232 converters are known in the prior art, and may, for example, comprise a USB UART or USB to RS232 bridge controller (such as the Future Technology Devices FT232BM, or the Prolific PL-2303), working in conjunction with a TTL to RS232 level converter if required (such as a Sipex SP213EHCA). The USB / RS232 converter may comprise a memory (for example a ROM or EEPROM) storing configuration information, including USB device and configuration descriptors.
The USB / RS232 converter provides a standard 9-conductor RS232 output 118 which is wired to handset connector 24, the detailed design of which is dependent upon the handset in question. In the present example, the handset connector provides both data and power connections.
In an alternative example, the USB / RS232 converter provides an RS232 output having a subset of the standard 9 conductors. For example, only outputs RD
(Received Data) and TD (Transmitted Data) may be provided, along with a common ground signal.
The adapter unit 26 further comprises a power interface (shown as 28 in Figure 1) in the form of a USB power supply 112 connected to the USB power conductors NBus 102 and Ground 104. The USB power supply provides a handset supply voltage Nπs 114 suitable for use with the handset in question from the USB. For example, some mobile telephone handsets require a supply voltage of 3.3N. Furthermore, the USB power supply ensures that the mobile telephone handset cannot exceed the current draw limits imposed by the USB specification (500mA for a high-power device). Suitable USB power supplies are known in the prior art, see, for example, Stealing USB -port power, EDΝ, June 13, 2002, pp. 71 - 79 (www.ednmag.com). The output from the USB power supply is wired to the handset connector 24.
In an alternative example, power and data conductors are wired to separate connectors at the handset end. For example, the RS232 output 118 may be wired to a dedicated data input/output connector, for example a standard 9-pin or 25-pin RS232 connector, whilst power conductors 114 and 116 are wired to a dedicated power connector. Details of the plug / socket configuration and wiring arrangement depend on the handset (or other device) being used.
The adapter 26 may be located along the length of adapter cable 20, or may be integrated into the USB connector plug 22 or the handset connector plug 24. Locating the adapter nearer the handset end of adapter cable 20 or in the handset connector plug 24 may have the advantage of reducing the wiring required since USB uses only four wires. Also, USB cable is widely available, so the cost of manufacturing the adapter cable may be reduced. Furthermore, different elements of the adapter, in particular the USB power supply and the USB / RS232 converter, may be positioned at physically separate locations along the cable.
The communication between the host computer 30 and the handset 10 will now be described with reference to Figures 3 and 4.
A conventional connection between host computer and handset via an RS232 link is illustrated in Figure 3. Here, a host application 202 communicates with the handset operating system 250 via handset driver 204. The handset driver 204 manages the RS232 link 220 between the host computer and the , handset. RS232 link 220 typically comprises an RS232 cable by which the handset is connected to the host computer.
Host application 202 is an application executed on the host computer used for interacting with the handset. The host application may, for example, be a synchronisation application, enabling a user to synchronise data between host computer 30 and handset 10. Alternatively, where the handset comprises a modem for providing internet access, host application 202 may, for example, be an internet browser application or e-mail client.
Figure 4 illustrates a communication architecture for communicating between the handset and the host using the adapter 26. In this example, the actual RS232 link 220 of Figure 3 is replaced by a virtual RS232 link 230 implemented over the USB 234. To this end, a USB driver is provided for the adapter 26, shown as USB adapter driver 206.
The adapter driver 206 accesses the USB 234 via the USB system layer 210. USB system layer 210, typically part of a computer operating system, comprises drivers for the USB host controller 38 and USB root hub 40 (shown in Figure 1), and provides an interface to the USB for higher-level USB device drivers.
The adapter driver 206 provides access to the virtual RS232 link 230 by simulating an RS232 serial port, effectively providing a virtual serial port 232 (NCOM). Data sent to this virtual serial port is received by the adapter driver 206 and re-transmitted via the USB 234 to adapter 26. Likewise, data received from the adapter 26 via the USB 234 is sent to the handset driver 204 using the virtual serial port 232.
In turn, the adapter 26 transmits data received from the USB 234 to handset 10 via the actual RS232 link 236 between adapter 26 and handset 10. Handset 10 comprises handset operating system software 250 capable of providing the required RS232 connectivity. Data sent via the RS232 link 236 from the handset 10 is received by the adapter 26 and transmitted to the host PC 30 on the USB 234.
In this example, the presence of the USB adapter 26 and the use of the USB for communication is therefore invisible to both the handset 10 and to the host software including handset driver 204 and host application 202. This makes the adapter particularly suitable for use with existing handsets and associated application and driver software. Without modification to hardware or software, the USB adapter cable 20 can be used instead of a data-only RS232 link to provide connectivity and power.
In an alternative example, the handset driver is implemented as a USB driver, effectively incorporating the functionality of handset driver 204 and USB adapter driver 206. In this example, a separate RS232 based handset driver may need to be provided if standard RS232 connectivity is also required.
The use of the USB adapter 26 to provide data communication between host PC 30 and handset 10 and power supply from host PC 30 to handset 10 will now be described with reference to Figures 1 and 4.
When the USB adapter cable 20 is plugged into a USB port 42 of host PC 30, the USB system layer 210 detects the new USB device and loads the associated driver, in this case the adapter driver 206. Adapter driver 206 establishes the virtual serial port 232. The handset driver 204 and host application 202 can then be executed to provide access to the handset.
The USB detection process comprises a procedure known as enumeration, during which the newly attached USB device is queried. The USB device, in this case the
adapter 26, then returns device and configuration descriptors defining characteristics such as device type and bandwidth and power requirements of the device.
The USB specification distinguishes between low-power USB devices (100mA maximum current draw) and high-power USB devices (500mA maximum current draw). In the present example, the USB adapter 26 returns information identifying the adapter 26 as a high power USB device. This ensures that the adapter can draw sufficient power from the USB to power the handset and/or to charge the handset battery.
Power is supplied constantly to handset 10 whilst connected to the host PC 30 through the adapter cable 20, and not only when data is transferred (assuming the host's power supply 50 is active).
The adapter cable 20 can therefore be used just as a handset charger. However, when used additionally as a data cable, the integrated power supply may prevent handset battery 18 from running out during data transfer. This can be particularly advantageous when using the handset for prolonged internet access or for large data transfers or downloads. It can also prevent problems that could potentially be caused by an interrupted synchronisation procedure between the host and handset.
Different versions of adapter cable 20 may be provided for use with different types of handset connectors. For example, for a handset having USB connectivity, the USB / RS232 converter 110 may be omitted from adapter 26, with some or all of the USB conductors 102, 104, 106 and 108 being instead connected directly to USB contacts on the handset. In this way, the adapter cable may provide for simultaneous power and data transfer between host and device, with power and data being transferred over the Universal Serial Bus.
In a further example, the adapter cable 20 may provide both standard USB data transfer and USB to RS232 conversion using converter 110. In this example, the
same cable can be used to connect to both an RS232-enabled handset and to a USB- enabled handset.
Additionally, a handset may provide both RS232 and USB connectivity, having RS232 contacts as well as USB data and power contacts. In this example, connection is provided both to the RS232 contacts on the handset (via the converter 110) and the USB contacts on the handset (directly), which may provide greater flexibility to host applications. Power may, for example, be provided via the USB power contact(s), via a separate power contact, or via a separate charger socket.
It will be understood that the present invention has been described above purely by way of example, and modification of detail can be made within the scope of the invention.
Each feature disclosed in the description, and (where appropriate) the claims and drawings may be provided independently or in any appropriate combination.