Abstract:
A consumer electronics device includes a universal control logic unit to interface a plurality of input controls, a display and an antenna to a host system via a bus. The host system is located within a shielded enclosure, while the remaining components (e.g., input controls, display, antenna, universal control logic) are located outside the shielded enclosure. Because a single bus preferably is used to interface the various input/output components located outside the shielded enclosure to the shielded host system, the host system can be more easily and effectively shielded than if numerous separate electrical lines and busses were used to directly connect the various input/output devices to the host system.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    Not applicable.  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not applicable.  
         BACKGROUND OF THE INVENTION  
         [0003]    1. Field of the Invention  
           [0004]    The present invention generally relates to an interface control between one or more input/output (“I/O”) devices and a host system. More particularly, the invention relates to interface logic between I/O devices and a host system that provides a single communication link to the host system. More particularly still, the invention relates to a universal control circuit that provides a single communication link to a digital host system for a plurality of I/O devices and a display for showing information provided by the host system. The invention also relates to the synchronization of volume level visual indications on the display and a separate television monitor.  
           [0005]    2. Background of the Invention  
           [0006]    Consumers today have numerous types of devices at their disposal-personal computers, televisions, VCRs, DVDs, camcorders, cameras, cable set top boxes, satellite receivers, and the like. Information is available to consumers over a wide variety of media. Television programming, for example, is available over conventional wireless broadcasting, cable, and satellite. Static information is readily available in the form of data transmissions over the Internet, and Internet connections may be over standard telephone lines using modems, dedicated high speed land lines, satellite, and digital transmissions at higher frequencies on standard telephone cables, to name a few. Consumers thus have a wealth of information available to them in various formats and requiring different devices to receive, process and view the information.  
           [0007]    In the face of the multimedia explosion, the “set top box” has been developed to simplify a user&#39;s access and control to the multimedia-based information. A set top box connects typically to a television monitor, an Internet medium (e.g., a DSL telephone line), and a television programming channel (e.g., a cable TV connection). A wireless keyboard can be provided to permit a user to operate the set top box. The set top box itself includes a host system typically comprising a central processing unit (“CPU”), memory, a fixed disk storage device, a floppy disk drive, and possibly a DVD player or other types of devices as desired. Using the wireless keyboard to control the set top box, a user can watch television programing or use the television and set top box together as a computer to perform conventional computer processing tasks, such as word processing, email, and the like. In short, the set top box and television effectively can perform the same functions as a television and separate computer system. The set top box can operate as a conventional computer system or as a consumer electronics device (e.g., DVD player). It is highly desirable in the consumer electronics market, including set top boxes, to make the equipment as “user friendly” and robust as possible. To make it easier on the user to operate the set top box, the keyboard, as noted above, may have a wireless link to the set top box. The wireless link may be a radio frequency (“RF”) or infrared (“IR”) link between the keyboard or handheld remote controller and the set top box. Other devices, such as a mouse, may also have an RF or IR link to the set top box. Having wireless links between the control devices the user operates and the set top box eliminates annoying cables draped across the room in which the user has the television and set top box (e.g., living room or bed room).  
           [0008]    To further make operation of the set top box as user friendly as possible and in case of a battery failure or damaged remote control, one or more controls may be placed on the front panel of the box itself. Such controls may be used to operate the set top box&#39;s DVD player, and, accordingly, the buttons may be for functions such as “stop,” “play,” “pause,” “fast forward,” and the like. These types of buttons should be as easy to use as the comparable buttons on a conventional VCR.  
           [0009]    The set top box also includes a host system board on which the CPU, memory and other digital electronic components are mounted. To protect the digital signals on the host system board from outside RF interference, the host system board preferably is contained within a metal housing. The metal surface of the housing acts as a shield against the intrusion and containment of electromagnetic interference. Although desirable to shield the digital electronics, the metal housing presents a problem for the wireless communication to the keyboard, remote control, or other peripherals. Both devices must have an antenna to provide the communication link. The RF antenna or IR receiver mounted in the set top box, however, cannot be located inside the metal housing, otherwise the metal housing will preclude RF signals from the keyboard from reaching the set top box antenna, and vice versa.  
           [0010]    A solution to this problem is to locate the antenna outside the metal enclosure. One suitable solution would be to provide the metal set top box with an electromagnetically transparent front panel (i.e., one that is made from a material that does not interfere dramatically with the RF link). The set top box&#39;s RF antenna can then be mounted on the inside of the front panel. The front panel also provides a convenient location to mount the various buttons noted above (play, pause, etc.). All of the controls, however, must be electrically coupled in some way to the host system board located inside the metal enclosure. Routing numerous electrical lines from potentially numerous controls through openings in the metal enclosure tends to decrease the ability of the metal housing to adequately shield the electronics. Accordingly, a solution to this problem is needed.  
           [0011]    Also, it would be desirable to provide a consumer electronics device, such as a set top box, with a display that includes controls (e.g., buttons, knobs) that can control the presentation of multimedia and provide a visual indication of changes in settings on a local display and/or television monitor. For example, if the consumer electronics device includes a volume knob for controlling the volume level of sound associated with a video, it would be desirable for the consumer device to provide an indication of the change in volume level locally and/or on the television monitor.  
         BRIEF SUMMARY OF THE INVENTION  
         [0012]    The problems noted above are solved in large part by a consumer electronics device that includes a universal control logic unit to interface a plurality of input controls, a display and an antenna to a host system via a bus. The host system is located within a shielded enclosure, while the remaining components (e.g., input controls, display, antenna, universal control logic) are located outside the shielded enclosure. Because a single bus preferably is used to interface the various input/output components located outside the shielded enclosure to the shielded host system, the host system can be more easily and effectively shielded than if numerous separate electrical lines and busses were used to directly connect the various input/output devices to the host system.  
           [0013]    An embodiment of the invention is in the context of a “set top” box which couples to a television monitor, a pair of speakers and other multi-media devices. The set top box also includes a mass storage device, a DVD drive and other components as desired. The input controls and display preferably are located on the front panel of the set top box. The front panel preferably comprises a material through which wireless signals (e.g., radio frequency) can propagate. Behind the front panel is a metal enclosure which houses the host system. The universal control logic is located within the interstitial space between the metal enclosure and the front panel. In the context of a set top box, the input controls may be used for such functions as “play,” “stop,” “fast forward,” and the like. A volume knob also is provided on the front panel to control the level of sound to the speakers.  
           [0014]    With the structure described herein, the universal control logic circuit can accommodate input and output devices having varying types of electrical interfaces. The universal control logic provides a single common interface to the host system. The host system preferably responds to user activation of the input controls and generates the information to be shown on the display.  
           [0015]    The universal control logic preferably connects to the host system via a universal serial bus (“USB”) and preferably includes a USB hub, a USB interface circuit and a microcontroller. The input/output devices connect to general purpose input/output pins on the microcontroller. Status flag registers internal to the microcontroller are associated with each of the input and output devices. Whenever a user activates an input device (as detected by the microcontroller), the microcontroller sets the status flag associated with the activated input control. The microcontroller then alerts the host system over the single bus connection that a control has been activated and the host system determines which control was activated and performs the function associated with that particular control.  
           [0016]    These and other advantages will become apparent upon reviewing the following description and drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]    For a detailed description of the preferred embodiments of the invention, reference will now be made to the accompanying drawings in which:  
         [0018]    [0018]FIG. 1 shows a block diagram of a set top box of the preferred embodiment;  
         [0019]    [0019]FIG. 2 shows the front panel of the preferred set top box;  
         [0020]    [0020]FIG. 3 shows a block diagram of an interface control circuit including a universal control logic unit;  
         [0021]    [0021]FIG. 4 shows a block diagram of the universal control logic unit of FIG. 3;  
         [0022]    [0022]FIGS. 5 and 6 show preferred methods illustrating the operation of the set top box and, in particular, the universal control logic;  
         [0023]    [0023]FIGS. 7A and 7B illustrate the operation of the volume control on the set top box; and  
         [0024]    [0024]FIG. 8 illustrates synchronizing dual volume level indicators on the set top box and a television monitor.  
     
    
     NOTATION AND NOMENCLATURE  
       [0025]    Certain terms are used throughout the following description and claims to refer to particular system components. As one skilled in the art will appreciate, different companies may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not function. In the following discussion and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ”. Also, the term “couple” or “couples” is intended to mean either an indirect or direct electrical connection. Thus, if a first device couples to a second device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]    The following description describes the preferred embodiment of the invention in the context of a set top box. However, it should be noted that the principles described herein are not limited to just set top box technology. In general, the apparatus and methods described herein can be applied to numerous types of consumer electronics and computer devices.  
         [0027]    Referring now to FIG. 1, set top box  100  constructed in accordance with the preferred embodiment generally includes an enclosure  102 , a front bezel member  118  and various electrical and mechanical components. As shown in the exemplary embodiment of FIG. 1, such components may include a host control system  110 , a mass storage device  113 , a universal control logic unit  116 , a video device (e.g., DVD)  126 , and various controls  120  and  130 . Host system  110  preferably couples to the mass storage device  113 , universal control logic unit  116 , and DVD  126 . One or more connectors  134  coupled to host system  110  may also be provided if desired. Host system  110  also provides a video and/or audio interface connection  106  to a television monitor (not shown). As such, interface  106  may comprise a video interface and right and left audio channels. The television interface may be the well-known NTSC standard or any other suitable television interface now known or later developed and used anywhere in the world. One or more audio speakers (not shown) can be coupled to the host system  110  via one or more audio connections  112 .  
         [0028]    Enclosure  102  in the preferred embodiment is manufactured from metal, such as bent sheet aluminum, to shield electronics contained therein, such as host system  110  and mass storage device  113  as shown. However, it should be understood that the enclosure  102  may also be constructed of other materials such as alloys, composites, or polymer-based materials, provided the internal electronics are adequately shielded. The bezel  118  preferably is constructed of plastic, or other material through which energy (e.g., RF energy) can propagate. Bezel  118  may also provide a “window” transparent to IR energy for communication with an IR control device. The front bezel  118  defines an interstitial space  101  between the bezel  118  and the front face  114  of enclosure  102 . Various components such as universal control logic  116  discussed below are located within interstitial space  101 . Those components are generally not shielded, but the components located within the enclosure  102  are shielded.  
         [0029]    Referring still to FIG. 1, host system  110  preferably comprises a suitable type of control logic. One suitable implementation of host system  110  comprises a microprocessor and associated devices such as random access memory, bridge devices, modems, network interface devices, audio controllers, and the like. Other implementations, such as those including discrete devices and analog circuitry are also permissible.  
         [0030]    Mass storage device  113  preferably comprises a suitably-sized hard disk drive. Other types of mass storage devices (e.g., CD ROM) can also be used as a mass storage device. Mass storage device could also comprise a floppy drive if desired, or alternatively, set top box  100  may include a floppy drive in addition to a hard drive  113 . Host system  110  preferably communicates with mass storage device  113  to retrieve information from the storage device and store information on the storage device.  
         [0031]    A DVD drive  126  is preferably also included to permit a user to watch video on a monitor (not shown) coupled to set top box  100  via interface connector  106 . For ease of use, DVD drive  126  is located at or adjacent the front bezel  118 . Connectors  134  are used to provide connectivity for IEEE  1394  and USB interfaces, or other types of interfaces.  
         [0032]    Referring now to FIG. 2, the front bezel  118  of set top box  100  is shown. As shown, various input/output devices are included to permit a user to control the operation of the set top box. As can be seen, DVD  126 , input controls  120 , a display  124 , volume control  130 , and connectors  134  preferably are provided. Input controls  120  preferably comprise push buttons, but can be implemented as any suitable type of input control. Volume control  130  preferably comprises a knob that can be turned one way to increase volume and the other way to decrease volume. Display  124  preferably comprises a liquid crystal display (“LCD”) or other suitable type of display device. Each of the input/output devices  120 ,  126 ,  124 , and  130  preferably is electrically coupled to host system  110  located inside the metal enclosure  102 .  
         [0033]    The functions performed by the buttons  120  preferably are identified on the display  124 . In accordance with the preferred embodiment of the invention, the display  124  is mounted adjacent buttons  120  to permit the host system  110  to display suitable information on the display  124  to inform the user as to the function performed by each button. As shown, the display is mounted immediately over the buttons, but many other configurations are possible as well. The 13 buttons  120  shown in FIG. 1 may be associated with the following 13 functions:  
         [0034]    1. Play  
         [0035]    2. Stop  
         [0036]    3. Pause  
         [0037]    4. Fast Forward  
         [0038]    5. Reverse  
         [0039]    6. Eject  
         [0040]    7. DVD  
         [0041]    8. Internet  
         [0042]    9. TV  
         [0043]    10. Games  
         [0044]    11. CD  
         [0045]    12. My Media (Files, JPEGs, etc)  
         [0046]    13. AUX-auxiliary Host system  110  can cause the word “PLAY” or the well-known play-icon (rightward pointing arrow) to be displayed adjacent the button  120  identified to perform the play function. The functions performed by the other buttons  120  are similarly identified by descriptive words or symbols shown adjacent the buttons. Further, the function associated with the selected button can be shown on the television monitor coupled to the set top box  100  by overlaying such information on the video signal provided to the monitor over interface  106 .  
         [0047]    If desired, during operation of the set top box, the functions associated with the buttons  120  can be altered via programming executed by the host system. A change in functions can be identified to the user by changing the words or symbols shown on display  124  adjacent the effected buttons.  
         [0048]    The host system  110  preferably includes an audio controller (i.e., an audio driver) to drive one or more speakers connected to ports  112 . As noted above, volume control  130  preferably permits a user to adjust the volume level of sound generated by the speakers. A graphic representation of the level of sound preferably is shown on display  124  and changed as the volume control  130  is adjusted.  
         [0049]    The DVD  126  preferably includes a dedicated eject button  128  that causes a tray (not specifically shown) to extend out to the user. As is well known, the tray is used to hold the disk. After a disk is placed on the tray by the user, pressing the button  128  again causes the tray to retract into the DVD device  126  in accordance with customary operation of DVD/CD ROM devices.  
         [0050]    Referring now to FIGS. 1 and 3, the problem noted above regarding the need to adequately shield the electronics in the metal enclosure  102  despite numerous input/output devices (e.g., buttons  120 , display  124 , volume control  130 ) need to be coupled to the host system  110  are solved by including a universal control logic unit  116  (referred to herein as “UCL  116 ”). Broadly, UCL  116  interfaces the various input/devices on front bezel  118  to the host system  110  located inside the metal enclosure via preferably a single communications link  122 . In accordance with a preferred embodiment of the invention discussed in greater detail below, communications link  122  comprises a standard bus connection such as a universal serial bus (“USB”), although other types of links now known or later developed can be used as well. Accordingly, UCL  116  performs one or more of the following functions:  
         [0051]    Provides a single communication link to the host system  110  from a plurality of input/output devices;  
         [0052]    Translates multiple disparate electrical input/output devices to a common format over the communication link;  
         [0053]    Permits information shown on display  124  to be synchronized with comparable information shown on a television monitor coupled to the set top box  100 . As shown in FIG. 3, UCL  116  bridges a plurality of input devices  120 ,  130 , a display  124  and a communication unit  134  to single communication link  122 . The communication link  122  may comprise a standard bus (e.g., USB) as noted above and, as such, may comprise a multi-conductor connection. Although link  122  may include more than one conductor, it still nevertheless comprises a single coordinated communication link.  
         [0054]    Communication unit  134  preferably comprises a transceiver  136  coupled to an antenna  138 . Antenna  138  may include a patch antenna or any other antenna suitable for RF communication. Transceiver  136  may be any suitable transceiver for driving RF energy through the antenna  138  and receiving RF signals from the antenna from external sources.  
         [0055]    Referring now to FIG. 4, UCL  116  is shown as comprising a USB hub  140 , a USB interface  144 , and a microcontroller  146 . USB hub  140  couples to the transceiver  136 , communication link  122  and USB interface  144 . USB interface  144  couples to the microcontroller  146  which also couples to the inputs  120 ,  130  and display  124 . Microcontroller  146  can be any suitable type of microcontroller such as Intel&#39;s 8051 microcontroller. The USB interface  144  preferably is the PDIUSBD12 provided by Philips, but other suitable USB interface circuits may be acceptable as well. Among other things, the USB interface  144  includes an interrupt bit  152  which preferably is periodically checked by the host system  110  to determine whether it is set. When the interrupt bit  152  is set, the host system  110  determines that the UCL  116  requests a service of some type from the host system  110 . The USB interface  144  thus can use the interrupt bit  152  to initiate communication with the host system  110 . The USB hub  140  preferably is the ISP1122 provided by Philips, but can be implemented with any suitable interface device. The datasheet for the ISP 1122 is incorporated herein by reference in its entirety.  
         [0056]    In accordance with the preferred embodiment of the inventor, host system  110  generally receives indications from the UCL  116  when the inputs  120 ,  130  are activated (i.e., a button  120  is pressed or volume knob  130  is turned). Host system  110  preferably coordinates the activities of the set top box  100  to perform the functions intended by the user when activating controls  120 ,  130 . For example, if the user presses the “play” button for the DVD, host system  110  responds by causing DVD  126  to enter its play mode. Similarly, if the user turns the volume knob  130  in the direction of increased sound level, the host system  110  responds by causing the sound level to increase by a corresponding amount.  
         [0057]    Referring still to FIG. 4, microcontroller  146  preferably facilitates communication of input control information between inputs  120 ,  130  and the host system  110 . Preferably, microcontroller  146  includes one or more registers  148  for registering when an input control as been activated by a user. Register  148  preferably comprises a means for storing information which identifies when an input control has been activated and which control was activated. One suitable embodiment of register  148  is for the register to include at least one bit (and more if desired) associated with each input control  120 ,  130 . As such, the “play” button has an associated bit as well as the “rewind” button, “pause” button, etc. The input signals from the controls  120 ,  130  preferably are provided to general purpose inputs of the microcontroller  146 . The microcontroller  146  maps the general purpose inputs to corresponding bits in register  148 . The bits in register  148  are referred to herein as “status flags.” 
         [0058]    The microcontroller  146  executes code which may be stored in internal or external ROM (external ROM not shown in FIG. 4). At least one of the functions of the code is to “poll” the input signals from the input controls  120 ,  130 . Polling means that the microcontroller periodically checks each input signal to determine which, if any, signal is asserted. Preferably, each input control signal normally is in an unasserted state (e.g., logic low) when the buttons are not pressed. When a button is pressed by a user, the input signal to the microcontroller  146  from the pressed button transitions to an asserted state (e.g., logic high). By repeatedly checking each input signal, the microcontroller will detect an asserted signal when the button associated with that input signal has been pressed. Because microcontrollers typically operate much faster than a human being is capable of pressing a button, it is virtually impossible for a human being to press and release a button before the microcontroller has an opportunity to check that signal.  
         [0059]    When the microcontroller determines that a particular input signal is asserted (caused by its associated input control having been activated), the microcontroller sets the bit in register  148  associated with the activated input control. FIG. 5 illustrates this in greater detail.  
         [0060]    Referring now to FIG. 5, and in conjunction with FIG. 4, method  200  comprises an exemplary method for the UCL  116  to determine when an input control as been activated and alert the host system  110 . In step  202 , the microcontroller  146  at a suitable time, such as during initial power up, initializes the status registers  148 . For example, the microcontroller  146  may clear all bits associated with input controls  120 ,  130  to a logic 0 state (or logic 1, if the opposite polarity is implemented). Then, in step  206  the microcontroller  146  cycles through each input signal to determine if the input is asserted. If no input control is asserted, the process in step  206  loops back and repeats itself. If, however, the microcontroller  146  detects that a button has been pressed, the microcontroller, through well-known code, performs a switch debouncing function in step  210 . Often, when a user presses a button, the contacts in the button close and open multiple times in a transitional state between open and close, or vice versa. Debouncing a switch via hardware or software is well-known to those of ordinary skill in the art to prevent the system from reacting multiple times during this transitional episode.  
         [0061]    In step  214 , the microcontroller  146  sets the status flag in register  148  associated with the activated input control  120 ,  130 . Finally, in step  218 , the microcontroller  218  communicates with the USB interface  144  to cause the interrupt bit  152  in the interface to be set. The response of the host system  110  to a set interrupt bit  152  is illustrated in method  300  (FIG. 6).  
         [0062]    Referring now FIG. 6, the host system  152 , as noted above, periodically polls the interrupt bit  152  via the USB bus  122 . When the host system  110  detects that the interrupt bit  152  is set, the host system  110  sends a USB formatted request command to the UCL  116 . In step  302  in method  300 , the UCL  116  receives the USB command from the host system  110 . In accordance with a preferred embodiment of the invention, the host system  110  sends two general types of USB commands to the UCL  116 : one type includes a request to send the states of the status flags in registers  148  to the host system  110  and the other type is to display information on the display  124  (FIG. 3) coupled to the set top box  100 . These two types of messages are differentiated by different command identifiers, such as operational codes (“opcodes”), embedded in accordance with well-known techniques in the messages themselves. In step  306 , the microcontroller  146  in the UCL  116  examines the USB message&#39;s opcode to determine the message type.  
         [0063]    Decision step  310  determines whether the opcode is a request for the UCL  116  to send the status flags or for the UCL  116  to display information on the display  124 . If the USB message is of the former type, step  314  is performed whereby the microcontroller  146  sends a USB message back to the host system  110  that includes all of the status flags. The host system  110  can then examine the status flags to determine which is set, determine which function (e.g., play, pause, etc.) is associated with that flag and perform the requested function. Alternatively, the UCL  116  may send only an indication of which button has been pressed and not all of the status flags. In general, the UCL  116  provides any suitable type of information to the host system  110  for the host system to ascertain what input control  120 ,  130  has been activated.  
         [0064]    The other type of command message the host system  110  can provide to the UCL  116 —display information on display  124 —is determined in decision step  310 . Preferably, the information to be displayed is included in the message itself from the host system  110  (e.g. ASCII or other suitable type of format). If the message type is, in fact, a display command, then in step  318  the UCL  116  extracts the information to be displayed from the message and displays it on the display  124 . The information to be displayed may include graphics information, text information, information as to location on the display  124  for the displayed information, etc.  
         [0065]    Referring briefly to FIG. 3, in accordance with the preferred embodiment of the invention, volume control  130  preferably includes a pair of signals  130 A and  130 B to the UCL  116  (and preferably the microcontroller  146  shown in FIG. 4). In accordance with the preferred embodiment, the volume control  130  comprises any suitable type of digital volume control such as that described in U.S. Pat. No. 5,963,652, incorporated herein by reference. As described in U.S. Pat. No. 5,963,652, volume control  130  includes a shaft encoder which monitors rotation of the volume knob. Through signals  130 A and  130 B, the volume control  130  informs the UCL  116  which direction the knob is being rotated (i.e., clockwise or counter-clockwise) by a user as the user attempts to increase or decrease the volume level. When the volume control  130  is stationary, the signals  130 A and  130 B are held at a constant level (e.g., logic  0 ). The control  130  includes a plurality of indents or clicks throughout its rotation. When the control  130  is turned, each discrete incremental click produces one pulse on each of the signals  130 A and  130 B. The two pulses are out of phase with respect to each other. The phase difference encodes the direction of rotation of the volume control  130 . Preferably, the UCL  116  detects the phase difference and causes an appropriate response in the sound level to occur.  
         [0066]    [0066]FIGS. 7A and 7B shown one exemplary embodiment of how signals  130 A and  130 B can be encoded to indicate direction of rotation of volume control  130 . For example, as shown in FIG. 7A, if the user turns the volume knob clockwise, the pulse on signal  130 A may lead the pulse on signal  130 B. The UCL  116  detects that the pulse on signal  130 A leads the pulse on signal  130 B and determines that the user wishes to increase the volume level by one increment. One or more of the status flags in register  148  can be allocated for the purpose of the UCL  116  to communicate a new desired volume setting to the host system  110 . In the manner described above, the host system  110  reads the status flag register  148  to determine the new desired volume setting and increases the volume level to the speakers (not specifically shown) appropriately. If, however, the user turns the volume control  130  counter-clockwise (volume decrease), the pulse on signal  130 B leads the pulse on signal  130 A (FIG. 7B) indicating the user&#39;s desired to decrease the volume level. This information is communicated to the host system  110  as described above and the volume to the speakers is decreased accordingly.  
         [0067]    In addition to changing the volume level, the UCL  116  preferably also displays a suitable graphic depicting the volume level on display  124  to provide a visual indication to the user of that the system has responded or is responding to the user&#39;s request. Any suitable type of graphic is acceptable. One such suitable graphic includes a bar graph (horizontally or vertically oriented). The length of the bar indicates absolute or relative volume level. Thus, as the user turns the volume control clockwise to increase the volume level at the speakers, the bar graph on the display  124  also increases in length to provide a visual feedback to the user. The opposite is true when the user turns the volume control  130  counter-clockwise-the bar decreases in length.  
         [0068]    In accordance with the preferred embodiment, the graphic feedback to the user is provided by the host system  110 . In the manner described above regarding providing text information to be shown on display  124 , the host system  110  preferably provides graphical information regarding the volume bar to the UCL  116  via the USB bus  122 .  
         [0069]    In addition to displaying volume information on display  124 , set top box  100  preferably provides volume graphical information (e.g., a bar graph) over the television connection  106  (FIG. 1) to the television monitor (not shown). Such graphical information preferably is provided by superimposing the graphical information on the video signal to the television monitor in accordance with known techniques. As such, when the user turns the volume control  130  on the set top box, three things happen: (1) the sound level changes, (2) a visual feedback is provided to the user on the set top box display  124 , and (3) visual feedback also is provided to the user on the television monitor. Thus, the user will, not only hear the volume change, but also see the bar graphs on both the set top box  100  and television monitor change in unison. This is illustrated in FIG. 8 in which the set top box  100  responds to a user adjusting volume control  130  by displaying a “4 bar” volume line  125  on set top box display  124  and, at substantially the same time, a 4 bar line  84  on the screen  82  of a television monitor  80 . Of course, the number of bars in each volume line  125  and  84  need not be identical. In fact, the size and shape of the lines can be whatever is desired. Preferably, however, a change in volume level is shown in some suitable format on both display  124  and monitor  80  at substantially the same time. “Substantially the same time” means simply that both visual representations of volume  125  and  84  are shown soon enough after the user turns volume control  130  to provide suitable feedback information to the user. It should be understood that other types of information can be originated by the set top box  100  and displayed on the television monitor as well, such as various DVD functions (e.g., play, pause, fast forward, etc.).  
         [0070]    As shown herein, UCL  116  is suitable to interface input controls having disparate electrical properties to a host system via a single communications link  122 . For example, volume control  130  has a different electrical interface than buttons  120 . In general, one or more of the controls  120 ,  130  may have different electrical interfaces for which UCL  116  has to account. UCL  116 , in effect, has to translate these varying electrical interfaces to a common format to communicate the control information over the single communication link.  
         [0071]    The above discussion is meant to be illustrative of the principles and various embodiments of the present invention. Numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.