PATENT DOCUMENT

Publication Number: US-8174380-B2
Application Number: US-48590309-A
Country: US
Kind Code: B2

Title: Electronic device dock with replicating status indicator

Abstract:
An adapter may couple an electronic device to a host such as a computer. When coupled in this way, the host may transfer media files to the device. The host may also supply power to the electronic device using power lines in the adapter. The electronic device may have a status indicator such as a light-emitting diode status indicator. The adapter may also have a status indicator. During operation, the electronic device may transmit coded information on the current state of the status indicator in the electronic device by modulating the status indicator or other load in the device at a selected frequency. Control circuitry in the adapter may detect the transmitted state information by monitoring the power lines. The control circuitry may control the status indicator in the adapter so that the status indicator in the adapter replicates the current state of the status indicator in the electronic device.

Claims:
1. An accessory for use with an electronic device that has a status indicator with a state, comprising:
 a power line path that supplies power to the electronic device; 
 a status indicator; and 
 control circuitry that receives signals on the power line path from the electronic device that are indicative of the state and that controls the status indicator of the accessory based on the received signals. 
 
     
     
       2. The accessory defined in  claim 1  wherein control circuitry is configured to process the received signals to determine whether the received signals contain frequency components at any of a plurality of predefined tone frequencies. 
     
     
       3. The accessory defined in  claim 1  wherein the status indicator of the accessory comprises a light-emitting diode status indicator and wherein the control circuitry is configured to adjust the light-emitting diode status indicator in response to detection of a frequency component in the received signals on the power line path by the control circuitry that matches a predefined tone frequency. 
     
     
       4. The accessory defined in  claim 1  further comprising an audio connector with which the power line path supplies power to the electronic device, wherein the status indicator of the accessory comprises a light-emitting diode status indicator and wherein the control circuitry is configured to adjust the light-emitting diode status indicator to replicate the state of the status indicator on the electronic device when the control circuitry detects a frequency component in the received signals on the power line path that matches a predefined tone frequency. 
     
     
       5. The accessory defined in  claim 1  wherein the accessory comprises a dock having a male four-contact audio connector with which the power line is coupled to the electronic device. 
     
     
       6. An adapter that can couple an electronic device to a host, wherein the electronic device has an audio connector to which the adapter may be connected and has a status indicator with a current state and wherein the host has a data port to which the adapter may be connected, the adapter comprising:
 a status indicator; and 
 control circuitry that receives power line information from the electronic device and that uses the power line information to adjust the status indicator on the adapter to replicate the current state of the status indicator in the electronic device. 
 
     
     
       7. The adapter defined in  claim 6  wherein the adapter comprises a dock adapter having a housing with a planar surface and having a male audio connector that protrudes from the planar surface and that is configured to mate with the audio connector of the electronic device. 
     
     
       8. The adapter defined in  claim 7  wherein the male audio connector comprises a four-contact tip-ring-ring-sleeve connector. 
     
     
       9. The adapter defined in  claim 8  further comprising a data port cable having a data port connector that is adapted to plug into the data port. 
     
     
       10. The adapter defined in  claim 9  wherein the data port connector comprises a universal serial bus connector. 
     
     
       11. The adapter defined in  claim 10  wherein the status indicator comprises a light-emitting diode indicator. 
     
     
       12. The adapter defined in  claim 10  wherein the status indicator comprises two light-emitting diodes of different colors. 
     
     
       13. The adapter defined in  claim 6  wherein the control circuitry is configured to recognize different coded tones on a positive power supply voltage line. 
     
     
       14. The adapter defined in  claim 6  wherein the adapter comprises an audio connector that mates with the audio connector in the electronic device and wherein the adapter comprises:
 a positive power supply line coupled to a first contact in the audio connector of the adapter; 
 a ground power supply line coupled to a second contact in the audio connector of the adapter; and 
 a resistor in the power supply line that generates an alternating current voltage signal in response to transmitted status indicator state information tone signals from the electronic device. 
 
     
     
       15. The adapter defined in  claim 6  wherein the adapter comprises an audio connector that mates with the audio connector in the electronic device and wherein the adapter comprises:
 a positive power supply line coupled to a first contact in the audio connector of the adapter; and 
 a ground power supply line coupled to a second contact in the audio connector of the adapter, wherein the power line information is received by the control circuitry as alternating-current tones on the positive and ground power supply lines. 
 
     
     
       16. The adapter defined in  claim 15  wherein the control circuitry is configured to identify which alternating-current tones are present in the power line information. 
     
     
       17. The adapter defined in  claim 15  wherein the control circuitry is configured to sample signals on the positive and ground power supply lines and is configured to identify which alternating-current tones are present in the power line information by performing a discrete Fourier transform on the sampled signals. 
     
     
       18. The adapter defined in  claim 15  wherein the control circuitry is configured to sample signals on the positive and ground power supply lines and is configured to identify which alternating-current tones are present in the power line information by applying a Goertzel algorithm that is implemented on the control circuitry to the sampled signals. 
     
     
       19. The adapter defined in  claim 15  wherein the control circuitry comprises analog band-pass filter circuitry and is configured to identify which alternating-current tones are present in the power line information using the analog band-pass filter circuitry. 
     
     
       20. The adapter defined in  claim 15  wherein the status indicator in the adapter comprises a light-emitting diode status indicator and wherein the control circuitry is configured to identify alternating-current tones that are present in the power line information and is configured to control the light-emitting diode status indicator based on which of the alternating-current tones are identified as being present in the power line information. 
     
     
       21. The adapter defined in  claim 6  wherein the adapter comprises:
 a dock housing in which the control circuitry is mounted, wherein the dock housing has planar upper surface that blocks the status indicator from view when adapter is plugged into the electronic device; 
 a universal serial bus cable having a universal serial bus connector that mates with the data port and having a positive power supply line and a ground power supply line coupled to the control circuitry; and 
 a tip-ring-ring-sleeve audio connector protruding from the planar upper surface that mates with the audio connector of the electronic device and that is coupled to the positive power supply line and the ground power supply line, wherein the status indicator in the adapter comprises a light-emitting diode status indicator and wherein the control circuitry is configured to identify alternating-current tones that are present in the power line information by monitoring the positive and ground power supply lines and is configured to control the light-emitting diode status indicator based on which of the alternating-current tones are identified as being present in the power line information. 
 
     
     
       22. An electronic device dock that may be coupled between a computer and an electronic device, the electronic device dock comprising:
 a cable that is adapted to plug into a port on the computer; 
 a male audio connector having at least a first contact that is coupled to a positive power supply line in the cable and at least a second contact that is coupled to a ground power supply line in the cable; 
 a status indicator; and 
 control circuitry that is coupled to the positive and ground power supply lines to detect transmitted alternating-current tones from the electronic device and that is configured to control the status indicator based on the detected transmitted alternating-current tones. 
 
     
     
       23. The electronic device dock defined in  claim 22  wherein the alternating-current tones comprise tones of less than 1000 Hz in frequency. 
     
     
       24. The electronic device dock defined in  claim 22  wherein the status indicator comprises a light-emitting diode status indicator. 
     
     
       25. The electronic device dock defined in  claim 22  wherein the male audio connector comprises a 3.5 mm tip-ring-ring-sleeve audio connector. 
     
     
       26. The electronic device dock defined in  claim 22  further comprising a dock housing from which the male audio connector vertically protrudes. 
     
     
       27. The electronic device dock defined in  claim 22  further comprising a resistor coupled in the positive power line, wherein the control circuitry detects alternating-current ripple signals on the resistor from which the control circuitry extracts the alternating-current tones. 
     
     
       28. The electronic device dock defined in  claim 27  wherein the control circuitry is configured to perform a Fourier transform on the alternating-current ripple signals to detect the transmitted alternating-current tones. 
     
     
       29. A media player that may be coupled to an accessory having a positive power supply voltage line and a ground power supply voltage line, the media player comprising:
 a status indicator having a state; 
 an audio connector having at least first and second contacts that receives power from the positive and ground power supply lines when the media player is coupled to the adapter; and 
 control circuitry that transmits a power line signal representing the state of the status indicator over the positive and ground power supply lines. 
 
     
     
       30. The media player defined in  claim 29  wherein the control circuitry is configured to modulate power consumed by the status indicator to transmit the power line signal. 
     
     
       31. The media player defined in  claim 30  wherein the status indicator comprises a light-emitting diode and wherein the control circuitry is configured to modulate the power consumed by the status indicator by driving the light-emitting diode at a frequency selected from multiple predefined tone frequencies.

Description:
BACKGROUND 
     Electronic devices such as portable media players and cellular telephones with media playback capabilities typically contain audio jacks. Accessories such as headsets have mating plugs. A user who desires to use a headset with an electronic device may connect the headset to the electronic device by inserting the headset plug into the mating audio jack on the electronic device. Miniature size (3.5 mm) phone jacks and plugs are commonly used in electronic devices such as portable media players and cellular telephones, because audio connectors such as these are relatively compact. 
     It is often desirable to connect electronic devices such as these to a personal computer. When this type of arrangement is used, media files from the personal computer can be loaded onto the electronic device and power can be supplied to the electronic device to recharge its battery. 
     A stand-alone cable or a cable that is part of a dock accessory can be used as an adapter to connect an electronic device to a personal computer. One end of the adapter is typically provided with a universal serial bus (USB) connector to plug into the computer. The cable or dock also has a corresponding connector that plugs into the electronic device. The connector that plugs into the device is often a specialized multi-pin power and data connector. 
     Specialized connectors such as the widely used 30-pin connector on some of the media player and cellular telephone products of Apple Inc. of Cupertino, Calif. consume a relatively large amount of volume in an electronic device. It may therefore be desirable to omit these connectors to save space or to enhance device aesthetics. In a device in which a 30-pin data connector is not available, the audio plug may be temporarily used in connecting the device to the personal computer. With this type of arrangement, an adapter cable may have a USB connector on one end to plug into a personal computer and may have an audio plug on the other end to plug into the audio jack of the electronic device. 
     Adapters with audio-plug-to-USB capabilities may be helpful in coupling personal computers to electronic devices that have only audio jack ports. Care should be taken, however, to retain desired levels of functionality when using such an adapter. It would be desirable, for example, to avoid situations in which the use of the adapter interferes with a user&#39;s ability to obtain status indicator information. 
     SUMMARY 
     Electronic devices such as cellular telephones and media players may be provided with audio connectors. During normal operation, an accessory such as a headset may be plugged into the audio connector on an electronic device. When it is desired to transfer files to the electronic device from a host computer or when it is desired to recharge a battery in the electronic device using power from the host computer, an adapter may be used. 
     The adapter may have a data port connector such as a universal serial bus connector that plugs into the host computer. The adapter may also have a connector that mates with a connector in the electronic device. For example, the adapter may have a cable or dock structure with an audio connector that mates with the audio connector in the electronic device. The audio connector in the adapter may be a four-contact audio plug that protrudes vertically from a planar surface of a dock housing. Power lines in the adapter may be used to route power from the host to the electronic device. 
     The electronic device may have a status indicator such as a light-emitting diode status indicator. The status indicator may be controlled by the device to display status information for a user. The status information may include, for example, media playback information, information on power functions, data synchronization status information, or other information on the status of the device. With one suitable arrangement, the status indicator may display different colors of light to represent different states of operation. 
     The status indicator may be blocked from view when the electronic device is mounted to the adapter (e.g., when an end face of the device rests against the planar dock housing surface). Accordingly, the adapter may be provided with its own status indicator. The adapter may use its status indicator to replicate the information being displayed by the status indicator of the electronic device. This allows the user to monitor how the device is operating even if the device&#39;s status indicator is difficult or impossible to view due to the presence of the adapter. 
     When the electronic device is coupled to the adapter, the electronic device may impose a signal on the power lines in the adapter that represents the current state of the status indicator in the electronic device. The coded power line information may be based, for example, on a predetermined set of alternating-current code frequencies. With this type of arrangement, a first frequency may represent a first state for the status indicator (e.g., a first color) and a second frequency may represent a second state for the status indicator (e.g., a second color). Additional code frequencies and patterns of frequencies may be used if desired. 
     The electronic device may transmit status indicator state information to the adapter by modulating the power consumed by the status indicator or other load at a frequency that matches one of the predetermined code frequencies. If, for example, the device&#39;s status indicator is currently displaying a red light, the electronic device can inform the adapter of this condition by driving the status indicator at a particular frequency. This imposes a corresponding alternating-current ripple on the power line that can be detected by the adapter. 
     The adapter may detect transmitted status indicator state information from the electronic device by monitoring the power lines. Digital signal processing techniques or analog filtering techniques may be used to measure the presence or absence of a transmitted signal at each of a number of predetermined frequencies. When a frequency component at a particular frequency is detected, the control circuitry of the adapter may control its status indicator accordingly to replicate the state of the status indicator on the electronic device. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an illustrative electronic device that may have a status indicator in accordance with an embodiment of the present invention. 
         FIG. 2  is a perspective view of an illustrative dock with a replicating status indicator that may serve as an adapter to couple an electronic device of the type shown in  FIG. 1  to a host such as a personal computer in accordance with an embodiment of the present invention. 
         FIG. 3  is a side view of an illustrative electronic device of the type shown in  FIG. 1  connected to an illustrative adapter of the type shown in  FIG. 2  in accordance with an embodiment of the present invention. 
         FIG. 4  is a schematic diagram showing how a conventional adapter may be used in connecting a media player to a personal computer host. 
         FIG. 5  is a diagram showing how an adapter may be used to connect an electronic device to a host system in accordance with an embodiment of the present invention. 
         FIG. 6  is a table showing an illustrative coding scheme that may be used in conveying status information from an electronic device to an adapter over power line paths in accordance with an embodiment of the present invention. 
         FIG. 7  is a graph showing an illustrative frequency spectrum for a power line signal in an adapter when an electronic device is transmitting a particular status indicator code to the adapter over a power line path in accordance with an embodiment of the present invention. 
         FIG. 8  is a flow chart of illustrative steps involved in measuring the frequency components of a power line signal when an electronic device is transmitting encoded status information to an adapter over a power line path in accordance with an embodiment of the present invention. 
         FIG. 9  is a circuit diagram of illustrative filtering circuitry that may be used to make frequency component measurements on power line signals received from an electronic device in an adapter accessory in accordance with an embodiment of the present invention. 
         FIG. 10  is a flow chart of illustrative steps involved in transmitting information such as status indicator state information to an adapter from an electronic device over a communications path such as a power line path and receiving this information in the adapter and taking corresponding action in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Media players and electronic devices such as cellular telephones that contain media player functionality may be used to play media content for users. Typical electronic devices of this type include audio jacks into which headsets may be plugged. 
     Audio jacks and mating audio plugs can be provided in a variety of form factors. For example, audio jacks and plugs can have different sizes (e.g., ¼″, ⅛″ or 3.5 mm, etc.). Audio jacks and plugs can also have different numbers of contacts. For example, audio connectors such as these may have two contacts for audio and ground or may have three contacts to support left and right stereo audio signals and ground. Some audio connector arrangements use four or more audio connectors. For example, a four-contact connector may have left and right audio contacts, a microphone contact, and a ground contact. 
     A typical three-pin audio connector has a tip contact, a ring contact, and a sleeve contact and is therefore sometimes referred to as a tip-ring-sleeve (TRS). A four-pin audio connectors may have a tip, two rings, and a sleeve. Four-pin audio connectors are therefore sometimes referred to as tip-ring-ring-sleeve (TRRS) connectors. 
     An illustrative electronic device that has an audio connector is shown in  FIG. 1 . Device  10  may be a media player, a cellular telephone player with media player capabilities, a portable electronic device such as a computer, a smaller portable electronic device such as a pendant or wrist device, or any other suitable electronic device. 
     The functions of device  10  may be implemented using storage and processing circuitry. Storage in the storage and processing circuitry may include volatile and non-volatile memory and may be provided using stand-alone memory chips, memory that is incorporated into a processor, application-specific integrated circuit, or other component, solid state memory devices, hard drives, or other suitable storage components. Processing circuitry in the storage and processing circuitry may be implemented using one or more processors. Examples of integrated circuits that may be used in providing processing capabilities for device  10  include microprocessors, microcontrollers, digital signal processors, audio and video chips (codecs), application-specific integrated circuits, communications circuits, etc. 
     A rechargeable battery may be used to supply device  10  with power when device  10  is not plugged into an alternate power source. 
     As shown in  FIG. 1 , electronic device  10  may have a housing  28 . Housing  28  may have any suitable shape. In the example of  FIG. 1 , device  10  has planar front and rear housing surfaces such as front planar surface  20 , left and right rounded side walls such as side wall  22 , and upper and lower end faces such as lower end face  24 . 
     Device  10  may be provided with input-output devices such as buttons, touch sensitive components, displays, speakers, microphone ports, status indicator lights, analog and digital input-output ports, keypads, keyboards, wireless communications devices such as radio-frequency transceiver circuits, sensors, infrared transmitters, etc. Input-output devices such as these may serve as user input devices for gathering user input from a user of device  10 . Some of these devices may also be used in supplying output to the user. 
     Particularly in portable devices such as the illustrative device shown in  FIG. 1 , it is not desirable to include every possible input-output component in the device. Some possible input-output devices may therefore be omitted. 
     In the example of  FIG. 1 , device  10  has switch  12 , audio jack  18 , and status indicator  26 . Switch  12  may have a switch member  14  that reciprocates between two, three, or more different positions within housing opening  16  in housing end face  24 . Audio jack  18  may be a 3.5 mm four-contact female audio connector (as an example). Status indicator  26  may be a light that can be placed in various solid or flashing states to display status information to the user. For example, status indicator light  26  may be directed to emit solid red light, solid green light, solid amber light, or flashing amber light (as an example). One or more light-emitting diodes may be used to provide light for status indicator light  26 . For example, a red light-emitting diode and a green light-emitting diode may be mounted adjacent to one another behind a transparent window in end face  24 . When the red light-emitting diode is activated and the green light-emitting diode is turned off, right light will be emitted. Green light will be emitted when the red light-emitting diode is off and the green light-emitting diode is on. Amber light may be produced by simultaneously activating both the green and red light-emitting diodes. 
     Status indicators such as status indicator  26  may be used to convey any suitable information to a user such as information regarding the operating status of device  10 . Examples of status information that may be conveyed to a user include status indicators related to media playback functions (e.g., play, pause, stop, rewind, etc.), power functions (low battery, battery fully charged, charging operations are active or inactive, device is on or off, etc.), functions related to syncing the content of device  10  with a host (e.g., by blinking to indicate that synching operations are being performed), etc. Although the status indicator shown in the example of  FIG. 1  has a single indicator light, status indicators may, in general, have any suitable number of lights (e.g., one light, two lights, three or more lights, bar-type lights with multiple segments, etc.). Status information may be conveyed to the user with monochromatic lights or lights that can be adjusted to produce two, three, or more than three colors. If desired, the intensity of the light may be changed (e.g., from a low level to a high level) to convey information to the user. Information may also be conveyed by using different illumination patterns (solid, blinking, blinking with different patterns and/or rates, etc.). 
     A status indicator in device  10  may produce sound. For example, a speaker may be used to provide a beeping tone or other audible output that conveys status indicator information. Audible and visible status indicator output may be combined (e.g., by providing a status indicator tone in conjunction with a flashing light output). Other types of status indicator output (e.g., vibration, temperature, etc.) may be used if desired. Moreover, combinations of these approaches may also be used. The illustrative configuration of device  10  that is shown in  FIG. 1  uses only a status indicator light, but this is merely an example. Any suitable status indicator may be used in device  10  if desired (e.g., a visual status indicator, an audible status indicator, a vibrating status indicator, an indicator that moves in other ways to convey status information, etc.). 
     An illustrative adapter that may be used to connect device  10  of  FIG. 1  to a host such as a personal computer is shown in  FIG. 2 . The illustrative adapter of  FIG. 2  is a dock accessory. If desired, other types of adapters may be used to connect device  10  to a host (e.g., stand-alone cables, accessories with speakers, etc.). The use of a dock adapter is merely an example. 
     As shown in  FIG. 2 , dock  30  may have a housing such as housing  32 . Housing  32  may have any suitable shape. In the example of  FIG. 2 , housing  32  has a planar upper surface  34 . Audio plug  44  may protrude vertically in an upwards direction from surface  34 . Audio plug  44  may be a male four-contact audio connector having tip contact  52 , ring contacts  48  and  50 , and sleeve contact  46 . A status indicator such as status indicator  38  may be mounted on side wall  36  or other suitable portion of housing  32 . 
     Dock  30  may have a cable such as cable  40  and a data port connector such as universal serial bus (USB) connector  42 . When it is desired to connect device  10  ( FIG. 1 ) to a host such as a personal computer, USB plug  42  may be inserted into a corresponding USB jack in the host. Circuitry in housing  32  may be used to electrically connect plug  42  to the contacts of audio connector  44 . Cable  40  may have any suitable number of conductive lines. For example, cable  40  may have a positive power line, a ground power line, and two data lines that are used for conveying USB data. In this type of configuration, each of the four conductive lines in cable  40  may be coupled to a respective one of the four contacts in audio connector  44 . 
     As shown in  FIG. 3 , when device  10  is attached to dock  30 , audio connector  44  of  FIG. 2  mates with audio connector  18  of  FIG. 1 , thereby electrically connecting device  10  to dock  30 . Cable  40  ( FIG. 2 ) connects dock  30  to a USB port or other suitable port in the host device. 
     With this type of arrangement, end face  24  of device  10  rests against planar upper surface  34  of dock housing  32  when device  10  is docked. As a result, status indicator  26  is hidden from view. Because the user cannot see the light being emitted from indicator  26 , the user is unable to receive status information directly from status indicator  26 . Blocking the status indicator in this way could potentially interfere with the user&#39;s ability to use device  10 . 
     To make up for the inability of the user to properly receive status information from indicator  26  while device  10  is in its docked position within dock  30 , dock  30  may display the status information using status indicator  38 . Whenever device  10  and dock  30  are connected to each other, device  10  may send dock  30  information on the current state of status indicator  26 . This information may, for example, be conveyed over power lines in the path between device  10  and dock  30 . Dock  30  may use this state information to replicate the blocked status information using status indicator  38 . 
     Consider, as an example, a situation in which status indicator  26  on device  10  is producing a solid output of a given color. The user of device  10  may desire to connect device  10  to dock  30  to recharge the battery in device  10  or to sync device  10  to a library on the host. 
     When device  10  is connected to dock  30 , status indicator  26  will face downwards (in the  FIG. 3  example) and will be blocked by planar surface  34 . Because no light from status indicator  26  can be viewed by the user, status indicator  26  cannot be used to convey status information to the user. 
     Accordingly, the state of status indicator  26  may be replicated by dock  30  by placing status indicator  38  in the same state as indicator light  26 . When this is done, the same solid output of the given color that would have been visible to the user at the output of status indicator  26  on device  10  will instead be viewable to the user as the output of status indicator  38 . Other types of status indicator information can likewise be replicated. For example, if a speaker that was being used as a status indicator becomes blocked when an electronic device is connected to an adapter, a speaker on the adapter may be used to reproduce the blocked audio status information. 
     If desired, dock  30  can display additional status information using status indicator  38 . For example, the fact that device  10  is currently docked on dock  30  may be confirmed by generating a status light with status indicator  36  or other suitable status indicator device. Dock  30  can also modify the status information (e.g., by displaying a red light instead of a green light or by displaying a flashing light instead of a solid light). An advantage of displaying status information with status indicator  38  in the same way that this information would normally be displayed using status indicator  26  is that this reduces the number of different status indicator schemes to be learned by the user. Arrangements in which the status information from the device status indicator(s) are replicated exactly on corresponding dock status indicator(s) are, however, merely illustrative. The status indicator information that is conveyed from device  10  may be displayed somewhat differently on dock  30  or status information that is not normally displayed using device status indicator  26  may be displayed using dock status indicators such as status indicator  38  if desired. 
     Any suitable scheme may be used for conveying information from electronic device  10  to dock  30 . For example, information may be conveyed wirelessly using radio-frequency signals or light. Information may also be conveyed over an analog or digital data path. For example, mating serial bus or parallel bus connectors can be used to interconnect respective data communications circuits in device  10  and dock  30 . 
     To minimize the number of connectors that are used, it may be advantageous to convey status information between device  10  and dock  30  using an arrangement that takes advantage of the audio connectors that are already present (i.e., female audio connector  18  in device  10  and male audio connector  44  in device  30  or other suitable mating audio connectors). In a typical adapter arrangement that is based on a USB cable (e.g., cable  40  of  FIG. 2 ), there are two power lines (e.g., a positive power supply line and a ground) and two signal lines (e.g., a positive data line DP and a negative data line DN) available to convey data. The data lines can be used to convey data if desired, but to ensure compatibility with the standards that have been promulgated by the USB standards bodies, it may be preferable to convey the status information over the positive and ground power lines, rather than to modulate the data lines in a way that might be considered to not be standards compliant. 
     Information may be conveyed over the power lines by imposing data signals in the form of an alternating current (AC) signal on top of the existing direct current (DC) power supply voltage. For example, the power supply lines may be used to convey a 5 volt positive power supply voltage and a 0 volt ground voltage to two respective contacts in the audio connectors. Device  10  can convey information on the current state of status indicator  26  to dock  30  by imposing an AC signal on the 5 volt DC power supply voltage. 
     At dock  30 , an AC signal that has been transmitted from device  10  can be extracted and processed. If the AC signal indicates, for example, that the current state of status indicator  26  is “solid red,” dock  30  can place status indicator  38  in a “solid red” state. 
     Any suitable coding scheme may be used when conveying status information from device  10  to dock  30 . For example, modulation schemes such as frequency modulation (FM) schemes, amplitude modulation (AM) schemes, pulse-code modulation (PCM) schemes, code-division-multiple-access (CDMA) schemes, and phase-shift keying (PSK) schemes may be used. With one suitable arrangement, which is sometimes described herein as an example, an amplitude shift keying (ASK) modulation scheme may be used to convey status information. In particular, the presence or absence of different AC frequencies (tones) may be used to represent different corresponding states of status indicator  26 . A first tone may, for example, represent a first color for status indicator  26 , whereas a second tone may represent a second color for status indicator  26 . When dock  30  detects the first tone on the power lines, dock  30  can place status indicator  38  in the first color state. When dock  30  detects the second tone, status indicator  38  can be placed in the second color state. 
     The tones that are used in conveying the status information from device  10  to dock  30  may be generated as part of a dedicated communications operation or may be generated during the process of operating status indicator  26 . For example, tones may be imposed onto the power line path in cable  40  by modulating the light-emitting diodes in status indicator  26  and thereby modulating the power drawn by device  10 . 
     A conventional system in which an adapter cable is used to couple a media player with a status indicator to a personal computer host is shown in  FIG. 4 . As shown in  FIG. 4 , personal computer host  58  in system  54  may be coupled to media player  56  using adapter cable  60 . Cable  60  has a USB connector  64  with four pins that mate with four corresponding USB pins in USB port  62  in host  58 . Cable  60  also has a four-contact audio plug  66  that plugs into four-pin audio jack  68 . 
     Host  58  may supply the positive power supply line PWR in connector  62  with a positive power supply voltage of five volts. Cable  60  may have power line circuit  70  and media player  56  may have corresponding power line circuit  72 . When media player  56  is first coupled to host  58 , power line circuits  70  and  72  may communicate with each other to determine when it is appropriate to use circuit  70  to release the full to five volt supply from host  58 . Before the five volt power supply voltage is released, control circuitry  74  in media player  56  may be powered by battery  80 . Voltage regulator  82  may receive power from battery  80  and may produce a corresponding regulated power supply voltage on output  84 . Media player  56  can operate using this voltage. When the five volt power supply voltage is released by circuit  70 , power for operating media player  56  can be supplied from power supply line PWR and ground GND. 
     Voltage regulator  76  receives the power supply voltage from power line PWR and produces a corresponding regulated voltage on positive voltage line  90 . Current source  78  can recharge battery  80  using power from voltage regulator  76 . 
     Light-emitting diodes  86  and  88  are respective red and green light-emitting diodes that are mounted behind a common status indicator window. Diode  86  is coupled between line  90  and line  92 . Diode  88  is coupled between line  90  and line  94 . Control circuitry  74  controls the on and off states of diodes  86  and  88  by controlling the voltages on lines  92  and  94 . 
     When not attached to cable  60 , audio connector  68  may be attached to a headset. In this mode of operation, audio circuitry  90  can produce left and right channel audio for the headset. 
     A system in which status light information for device  10  can be replicated using a status indicator associated with a dock or other adapter accessory is shown in  FIG. 5 . In system  96 , personal computer host  98  may be coupled to electronic device  10  (e.g., a media player, cellular telephone, handheld electronic device, etc.) using dock  30 . Audio circuitry  150  may provide right and left audio signals to right and left audio contacts in connector  18  when a headset plug is inserted into connector  18 . 
     When it is desired to interface with host  98 , the headset plug may be removed from connector  18  and device  10  can be coupled to host  98  using dock  30 . Dock  30  has a cable  40 . Cable  40  may have a connector such as a USB connector (connector  102 ) having four pins that mate with four corresponding USB pins in USB port  100  of host  98 . If desired, connector  100  in host  98  may be associated with different types of data ports. The use of a USB port for connector  100  is merely illustrative. 
     Cable  40  may also be coupled to the circuitry of dock  30  and a corresponding four-pin connector such as four-pin audio plug  44 . Plug  44  may plug into a corresponding audio jack in electronic device  10  such as four-contact audio connector  18 . Plug  44  and jack  18  may be, for example, 3.5 mm (⅛ inch) TRRS connectors. 
     Host  98  may supply the positive power supply line PWR in connector  100  with a positive power supply voltage of five volts or other suitable power supply voltage (i.e., a DC voltage). Dock  30  may have power line circuit  104 . Electronic device  10  may have corresponding power line circuit  124 . 
     When electronic device  10  is coupled to host  98 , power line circuits  104  and  124  may communicate with each other to determine when it is appropriate to use circuit  104  to release the positive power supply voltage on power line PWR to device  10 . 
     Control circuitry  126  in device  10  may be powered by battery  136  when power from positive power supply line PWR is not available. Before the positive power supply voltage on terminal PWR is released, voltage regulator  146  may receive power from battery  136  and may produce a corresponding regulated power supply voltage on output  148  for use in powering the circuitry of device  10 . When the positive power supply voltage on power line PWR is released by circuit  104 , power for operating device  10  can be routed to device  10  using power supply line PWR and ground GND. 
     Voltage regulator  128  may receive the power supply voltage from power line PWR and may produce a corresponding positive regulated voltage on positive voltage line  132 . Current source  134  (which may be considered to be a part of voltage regulator  128 ) can recharge battery  136  using power from voltage regulator  128 . 
     Status indicator  26  may be based on one or more light-emitting diodes. In the example of  FIG. 5 , light-emitting diodes  138  and  142  are red and green light-emitting diodes, respectively. Diodes  138  and  142  may be mounted behind a common transparent status indicator window in housing  28  ( FIG. 1 ). Diode  138  is coupled between positive power supply line  132  and line  140 , whereas diode  142  is coupled between positive power supply line  132  and line  144 . Control circuitry  126  may control diodes  138  and  142  by controlling the voltages on lines  140  and  144 . Control circuitry  126  may, for example, drive diodes  138  and  142  according to a pulse width modulation (PWM) scheme in which a high-frequency signal (e.g., a square wave signal at 100 kHz) has its pulse width adjusted up or down to control the amount of power being drawn by diodes  138  and  142 . 
     During operation of voltage regulator  128 , the current supplied on path  132  is equal to the current on path  130 . As a result, changes in the power being drawn by diodes  138  and  142  result in corresponding changes in the current drawn from power line PWR. This current can, in turn, be converted into a voltage using resistor  106  (e.g., a 0.1 ohm resistor or other suitable size). When the load current in diodes  138  and  142  changes, the voltage detected on lines  110  and  112  by control circuitry  108  will therefore change by a corresponding amount. 
     The amount of load current that is being drawn by diodes  138  and  142  can be controlled by control circuitry  126 . This allows control circuitry  126  to send coded information to dock  30 . Different tones or patterns of tones may, for example, be used to represent different states of status indicator  26 . These tones may be produced by adjusting the pulse-width modulation (PWM) control signals for diodes  138  and  142  using control circuitry  126 . 
     If desired, control circuitry  126  can modulate the amount of load current in other loads. For example, control circuitry  126  can modulate the voltage on line  158  (e.g., using a general purpose input-output line in a controller chip), thereby modulating the load current in resistor  156 . This produces corresponding fluctuations in the amount of power consumed by device  10 , as when modulating loads such as the light-emitting diodes of indicator  26 . 
     Dock adapter  30  can detect the transmitted signals from device  10  by receiving and processing the voltages across resistor  106  using control circuitry  108 . Control circuitry  108  may include analog filtering circuitry to measure frequency components at various different frequencies or may use more general purpose processing circuitry to implement digital processing algorithms. For example, control circuitry  108  may use code running on storage and processing circuitry and/or dedicated hardware to implement a discrete Fourier transform (DFT) algorithm. As an example, the Goertzel algorithm may be used by control circuitry  108  to determine the components of the received signal at each frequency of interest. 
     After processing the incoming signal to determine its frequency components and analyzing the frequency components to determine the state of status indicator  26 , control circuitry  108  may take appropriate actions. For example, control circuitry  108  can replicate the state of status indicator  26  on status indicator  36 . This can be accomplished by controlling light-emitting diodes  114  and  116 . Light-emitting diodes  114  and  116  may have the same colors as light-emitting diodes  138  and  142 . For example, light-emitting diodes  114  and  116  may be red and green diodes. Light-emitting diode  114  may be coupled between positive power supply line  118  and line  122 . Light-emitting diode  116  may be coupled between positive power supply line  118  and line  120 . By controlling the voltage on lines  120  and  122 , control circuitry  108  can control the operations of diodes  114  and  116 . Control circuitry  108  may, for example, turn diodes  114  and  116  on and off so that the visual appearance of status indicator  36  matches the visual appearance of indicator  26 . Even if indicator  26  is blocked from view, the user can still ascertain the status of device  10  by observing the state of status indicator  36 . 
     A table illustrating an illustrative coding scheme that may be used in conveying status indicator state information from device  10  to dock  30  is shown in  FIG. 6 . The illustrative example of  FIG. 6  involves four status indicator states (solid amber—where both the red and green light-emitting diodes are turned on, solid green, solid red, and blinking amber) and four corresponding tones that are transmitted on the power path of dock  30  by modulating the drive signal for a load such as the status indicator light-emitting diodes and thereby modulating the amount of power being consumed by device  10 . The alternating-current tones that are transmitted by the electronic device to the dock and that serve as power line information on the current state of the status indicator for the dock can have any suitable frequency (e.g., a frequency less than 10,000 Hz, a frequency of less than 1000 Hz, or a frequency of less than 100 Hz. If desired, other tones and patterns of one or more tones may be used. The arrangement of  FIG. 6  is merely an example. 
     A frequency spectrum of a typical modulated power path signal is shown in  FIG. 7 . The graph of  FIG. 7  represents the type of spectrum that may be received by control circuitry  108  when monitoring the power path while device  10  is modulating its power consumption at 85 Hz, as evidenced by the peak in received signal intensity at frequencies centered around 85 Hz. As indicated in the table of  FIG. 6 , device  10  may transmit a power line signal at 85 Hz when the state of status indicator  26  is red. By analyzing the spectrum of  FIG. 7 , control circuitry  108  can detect this transmitted state information and can replicate the current red state of status indicator light  26  on status indicator light  36 . 
     A flow chart illustrating how control circuitry  108  may use digital processing techniques to determine how much signal spectrum exits at each of the frequency entries in the code table of  FIG. 6  is shown in  FIG. 8 . At step  160 , control circuitry  108  ( FIG. 5 ) may obtain samples of the incoming power line signal. Control circuitry  108  may, for example, use a digital-to-analog converter to sample the positive power supply voltage (i.e., the voltage on power line PWR) relative to the power supply voltage on ground line GND at a series of appropriate sampling times. After the samples have been obtained, computations may be performed on the sampled data (steps  162 ,  164 , and  166 ). The analysis process may involve Goertzel algorithm computations or other suitable computations that reveal the frequency component of the received signal at each of a number of different predetermined frequencies (i.e., the code frequencies of the table of  FIG. 6 ). 
     An analog filter arrangement may also be used by control circuitry  108 . An illustrative analog filter circuit arrangement that may be used by control circuitry  108  in detecting the codes of  FIG. 6  is shown in  FIG. 9 . As shown in  FIG. 9 , incoming signals from power line PWR may be received by circuitry  168  using path  110 . The signals on path  110  may be filtered by respective band-pass filters  178 ,  180 , and  182 . Each band-pass filter may produce an output proportional to the relative frequency component at a respective one of the code frequencies of the table of  FIG. 6 . If, for example, the incoming signal is a tone at 65 Hz, band-pass filter  178  will produce an output signal that is larger than the output signals associated with filters  180  and  182 . 
     Comparators  172 ,  174 , and  176  may be used to compare the outputs of filters  178 ,  180 , and  182  to reference voltages. If a given frequency component is present in the incoming signal, the output of the corresponding comparator will go high. This high output can then be processed by control circuit  170  and a corresponding output control signal may be produce on one or more control lines (path  184 ). For example, if the incoming signal contains a tone at  75  Hz, the output of comparator  174  will be asserted and control circuit  170  will use control signals on path  184  to direct status indicator light  36  to produce a solid green output. 
     Illustrative steps involved in conveying information on the state of a status indicator or other component in device  10  to dock  30  and in replicating that status indicator state or taking other appropriate action in dock  30  is shown in  FIG. 10 . 
     As device  10  is operating at step  186 , device  10  may display status information using status indicator  26 . When driving the status indicator load, control circuitry in device  10  may modulate the current of the load according to the codes of the  FIG. 6  table or other suitable coding scheme to convey the current state of the status indicator  26  to dock  30 . The modulated load current (or other power consumption modulation in device  10 ) results in a corresponding ripple in the voltage on the positive power supply line in cable  40 . This power line signal may be detected by control circuitry  108  in dock  30 . 
     At step  188 , dock  30  may measure the frequency components of the received signal at each frequency of interest. For example, if a tone-based coding scheme of the type shown in the table of  FIG. 6  is used, control circuitry  108  may measure signal strength at frequencies of 65 Hz, 75 Hz, and 85 Hz. Digital signal processing techniques of the type described in connection with  FIG. 8  (e.g., the Goertzel algorithm) or analog filtering techniques (e.g., the analog filtering arrangement described in connection with  FIG. 9 ) may be used during step  188 . 
     After measuring the frequency components of the received signal at each predetermined frequency of interest, dock  30  can use control circuitry  108  to analyze the measured frequency components. If, for example, a 75 Hz tone has been detected, the operations of step  190  may use the table of  FIG. 6  to determine that the state of status indicator  26  in device  10  is solid green. In general, any suitable coding scheme may be used. Modulation techniques in which different discrete frequencies correspond to respective discrete states of status indicator  26  may be used, modulation techniques in which different patterns of sequential and/or simultaneous tones correspond to different status indicator states may be used, modulation techniques in which tones are used in conjunction with on/off tone patterns (e.g., at 0.5 Hz or other near-DC frequencies), etc. 
     At step  192 , dock  30  may take appropriate actions based on the results of the analysis of step  190 . If, for example, dock  30  concludes from the received power line transmission from device  10  that the status indicator in device  10  is green, dock  30  can replicate the green status indicator state of device  10  using the status indicator in dock  30 . Other actions can also be taken. For example, dock  30  may produce a sound using a sound-based input-output device, rather than replicating the same visual appearance of the status indicator of device  10 . 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention.

Metadata:
Filing Date: 20090616
Publication Date: 20120508
Grant Date: 20120508
Priority Date: 20090616
Inventors: TRAVIS WARD C.
RABU STANLEY
TIKALSKY TERRY
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F1/266", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/266", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F1/1632", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F1/1632", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 43305932