HK1140285B - Systems and methods for providing device-to-device handshaking through a power supply signal - Google Patents

Description

System and method for providing handshaking between devices via a power supply signal

Cross Reference to Related Applications

This application claims benefit of U.S. provisional application N60/934,733, filed on 15/6/2007, the disclosure of which is incorporated herein by reference in its entirety.

Technical Field

The invention relates to power regulation. More particularly, the present invention relates to safe power transfer.

Background

A conventional Universal Serial Bus (USB) socket continuously supplies a power signal of a specific voltage to any cable connected to the USB socket through a USB plug. However, the electrical contacts of conventional USB plugs are protected by a protective housing so that a user cannot inadvertently touch the electrical contacts of the USB plug.

However, not all cables operable to mate with a USB receptacle utilize a USB plug at each end. In practice, some cables include a protected USB plug at one end and an unprotected plug at the other end. Such a cable can connect a USB device and a device without a USB socket. However, such cables are deficient because power signals may be provided to unprotected plugs when they are not mated with the device. A person who contacts an unprotected plug may be injured because an unwanted power signal may flow directly into the person's body. Such cables are also deficient because unwanted power signals may be provided to the device even if the unprotected plug does not properly mate with the device. A device may be severely damaged if a power signal is provided to the wrong contactor of the device or an unwanted power signal is provided to the correct contactor of the device. Accordingly, there is a need to provide a cable with improved security measures for human and device interaction.

In addition, companies occasionally try to create accessories for such devices without the permission of the device manufacturer. However, such accessories are defective and may damage the device by providing data and power signals that can damage the device. Therefore, to protect such devices from receiving data and power signals that could damage the device, it is desirable to eliminate the ability of third party accessories to enter the device.

Conventional USB protocols include ACK (receipt of error-free packets), NAK (receiving device cannot accept data), STALL (end delayed), and NYET (no response yet). However, such protocols are deficient because they do not provide enhanced functionality. It is therefore desirable to provide a circuit having an extended range of communication capabilities and device functions.

Disclosure of Invention

Handshaking circuits are provided that are capable of identifying each other with a power supply signal. Such handshaking circuits may also be capable of controlling the characteristics of the power supply signal to deliver a desired power supply signal at a desired time. Such handshaking circuits may, for example, adjust the voltage or current of a power supply signal, or may be capable of embedding information into a power supply signal by manipulating the voltage or current of the power supply signal. Accordingly, handshaking circuits are provided that allow devices to identify each other through signals (e.g., power signals) or additional communications (e.g., power control information).

The handshaking circuits may receive information embedded in the power supply signal from each other and may then utilize the received information to perform different types of operations. For example, based on information received from a different handshaking circuit, the handshaking circuit may vary the voltage of the power supply signal provided to the different handshaking circuit. For example, a handshaking circuit may introduce current pulses into a power supply signal that the handshaking circuit receives. Such current pulses may be detected and identified by the circuitry providing the power supply signal. The information sent to the circuit providing the power supply signal may indicate to the circuit, for example, to increase or decrease the voltage of the power supply signal to a particular amount. Alternatively, such information may, for example, instruct a circuit that provides a power supply signal of a particular voltage to continue to provide the power supply signal of the particular voltage.

Handshaking circuits may be provided in a cable having a power supply line. In doing so, the cable is able to change the characteristics of any power signal provided through the cable, independent of any device connected to the cable. Handshaking circuits may be provided on any portion of the cable. For example, handshaking circuitry may be provided as a flexible integrated circuit located in a portion of the cable body or plug. Thus, an on-cable handshaking circuit is provided.

Handshaking circuits may be provided in devices such as portable devices. The on-device handshaking circuit may interact with the on-cable handshaking circuit to ensure that the desired power supply signal is provided to the device at the desired time. In addition to power, data may also be provided over the cable, and the handshaking circuits may, or may not, control or manipulate the flow of data through the data path of the cable. For example, one device that includes a handshaking circuit may take the form of a portable music player. On-cable and on-device handshaking circuits may be utilized to ensure that a power supply signal is properly provided to a device before allowing the initial circuitry of the device to connect to the cable and receive a data portion of a communication (e.g., music data).

A cable is provided that includes a USB plug at one end and an unprotected multi-zone plug at the other end. Handshaking circuitry is provided within the cable. Another handshaking circuit is provided in a portable device. The on-cable handshaking circuit may receive a relatively high power signal (e.g., 5V500mA) and may step down the voltage of this relatively high power signal to a particular, relatively low power signal (e.g., 2.9V, which is current limited). The on-device handshaking circuit may be configured to look for characteristics of the particular, relatively low power signal, such as the voltage of this power supply signal. Once the particular, relatively low power signal is identified for a certain time (e.g., 0.5 seconds), the on-device handshaking circuit may introduce a current pulse to the power supply signal that the on-device handshaking circuit is receiving from the on-cable handshaking circuit. These current pulses may then be subsequently recognized by the on-cable handshaking circuit providing the power supply signal. The current pulses provided by the on-device handshaking circuit may, for example, communicate control information to the on-cable handshaking circuit. For example, a current pulse may indicate to the on-cable handshaking circuit: handshaking circuits on a device need to receive a high power signal instead of a low power signal. Thus, for example, once the on-cable handshaking circuit recognizes a current pulse, the on-cable handshaking circuit may step up a particular, relatively low power signal (e.g., 2.9V, which is current limited) to a relatively high power signal (e.g., 5V500 mA).

The handshaking circuit may provide, for example, two handshaking steps. In a first handshaking step, for example, an on-cable handshaking circuit may identify itself by transmitting a particular voltage for at least a certain time. The first handshaking step may be completed when the on-device handshaking circuit recognizes that a particular voltage has been sent for at least a certain amount of time. In a second handshaking step, the on-device handshaking circuit may identify itself by introducing a current spike into the power supply signal. The second handshaking step may be completed when the on-cable handshaking circuit recognizes a current spike from the on-device handshaking circuit. Different types of current spikes may be sent from the on-device handshaking circuit to instruct the on-cable handshaking circuit to perform different types of operations. Similarly, for example, different (e.g., predetermined) voltages may be sent from the on-cable handshaking circuit to instruct the on-device handshaking circuit to perform different types of information. Additional handshaking steps may be included as part of the overall handshaking routine.

Drawings

The above and other objects and advantages of the present invention will be apparent upon consideration of the following detailed description taken in conjunction with the accompanying drawings, in which like reference characters refer to like parts throughout, and in which:

FIG. 1 is a diagrammatic representation of a data and power delivery topology constructed in accordance with an embodiment of the invention;

FIG. 1A is a diagrammatic view of a power delivery topology constructed in accordance with an embodiment of the invention;

FIG. 2 is a diagram of a data and power delivery topology including on-cable and on-device handshaking circuits constructed in accordance with an embodiment of the present invention;

FIG. 3 is an illustration of a process flow diagram constructed in accordance with an embodiment of the invention; and

figures 4 and 5 are schematic diagrams of handshaking circuits constructed in accordance with an embodiment of the present invention.

Detailed Description

Fig. 1 shows a topology 100 that may include a device 101 and a device 103 electrically connected together by a cable 102.

Device 101 and device 103 may be coupled together such that, for example, data and/or power may be transferred between devices 101 and 103. Devices 101 and 103 may beAny type of device such as a portable laptop computer, a stationary personal computer, a telephone device, an audio/video playback device, an accessory, or any other type of device. For example, device 101 may be a computer and device 103 may be an audio playback device, such as an iPod^TM(available from Apple inc., Cupertino, California). Likewise, device 101 may utilize cable 102 to power and recharge device 103 while transmitting audio data to device 103.

The cable 102 may be, for example, a USB cable. Such a USB cable may be utilized to provide a power signal from one device (e.g., a laptop) to another device (e.g., an accessory or portable electronic device). Thus, the on-cable handshaking circuit may step down the power signal supplied by a device (e.g., a laptop) to a portable electronic device, wait to recognize the appropriate current spike provided by the accessory, and step up the voltage to the appropriate level in response to the appropriate current spike. In doing so, for example, only authorized devices may utilize a USB cable with an on-cable handshaking circuit. Unrecognized devices do not have the ability to, for example, send appropriate current spikes that may be recognized by on-cable handshaking circuits. Accordingly, on-cable (e.g., on a USB cable) and on-device (e.g., on a portable electronic device) handshaking circuitry may be provided to ensure that only authorized devices have the ability to properly mate and operate with one another.

Those skilled in the art will recognize that: the device may receive too much power through the cable (e.g., a USB cable), receive an incorrectly adjusted power signal through the cable, or otherwise be exposed to a potentially harmful power signal. Accordingly, handshaking circuits may be included in cables and devices such that a device may identify and authenticate a cable through the handshaking circuit prior to utilizing a power supply signal. As such, the device may be protected from damage by accessories that may damage the device power conditioning and delivery circuitry.

Alternatively, handshaking circuits in the cable may reduce the power supply signal for a particular device based on the identification of current pulses provided by the device. In doing so, for example, the cable may step down the voltage to an appropriate level in response to appropriate identification of current spikes associated with such a regulation scheme. As such, the power supply signal may be changed to a predetermined value based on the received handshake.

The on-cable handshaking circuit may include, for example, on-cable memory that includes a table that correlates particular types of current spikes to particular actions. Such a table, for example, may include the following data: this data is associated with how the on-cable handshaking circuit should operate when connected to different accessories or portable electronic devices.

FIG. 1A illustrates an example of two devices each having a handshaking circuit in accordance with an embodiment of the present invention. As shown, the power providing device 140 includes a handshaking circuit 142 (e.g., circuit 500 in fig. 5) that may be provided in the device providing the power signal. Power providing device 140 may receive power from external power source 160 (e.g., a wall outlet, a battery, etc.) and adjust how much power is provided to power receiving device 150, which includes handshaking circuitry 152 (e.g., circuitry 400 in fig. 4). Device 140 and device 150 may be directly connected together through interfaces 144 and 154, or devices 140 and 150 may be connected with a cable having appropriate connectors such that devices 140 and 150 may not have any handshaking circuitry by mating interfaces 144 and 154 through the cable, including its connectors. For example, device 140 may be any suitable device, such as an accessory (e.g., a wall-mounted charger, a car charger, a docking station, a speaker docking system) or a computer, and device 150 may be a portable electronic device, such as an iPod or iPhone. The interfaces 144 and 154 may be proprietary multi-contact connectors (e.g., 30-pin connectors), USB connectors, Firewire connectors, 3.5 or 2.5 millimeter receptacle connectors, combinations thereof, or any other suitable connector.

To protect the device 103 from receiving unwanted power supply signals, for example, handshaking circuitry may be provided to ensure that the appropriate power supply signal is provided to the device 103 at the appropriate time. Handshaking circuits may also, for example, allow devices to identify each other so that devices without handshaking circuits cannot be utilized.

The handshake protocol may include any number of stages. For example, the handshaking protocol may be initiated by an initiating handshaking circuit that provides a power supply signal. This initiating handshaking circuit may, for example, alter the characteristics of the power supply signal in a particular manner. For example, initiating handshaking circuit may reduce the voltage of the power supply signal to a particular value that a responding handshaking circuit may expect to see, instead of the initial power supply signal being boosted.

The responding handshaking circuit may receive the power supply signal and may determine whether a characteristic of the power supply signal is within a particular range. For example, the response handshake circuit may determine whether the voltage of the power supply signal is within a particular range. Such voltage ranges may, for example, not be based on the voltage (e.g., 2.9 volts) and margin of error (e.g., +0.2 volts and-0.2 volts) that the handshaking circuit will provide in initiating the handshaking routine. If, for example, the responsive handshaking circuit receives a power supply signal having a voltage within this voltage range, the responsive handshaking circuit may wait a certain amount of time (e.g., 0.5 seconds) in order to verify that the voltage of the power supply signal is stable. Once the time required for the handshaking procedure has been reached, the responding handshaking circuit may manipulate the power supply signal in a manner that is recognizable by the initiating handshaking circuit. For example, a current pulse may be introduced into a power supply signal that may be detected by the initiating handshaking circuit. Once the initiating handshaking circuit detects such a current pulse, the initiating handshaking circuit may, for example, change a characteristic of the power supply signal. More specifically, for example, initiating handshaking circuitry may increase the voltage of a power supply signal to a power supply signal that powers and recharges a particular device.

Those skilled in the art will recognize that: if, for example, the responding handshaking circuit does not receive a voltage within the desired range, the handshaking circuit does not forward the power supply signal to other circuitry, such as the primary circuitry (primary circuit) of the device. Alternatively, the initial circuitry of the device may not allow the power supply signal to power the initial circuitry, for example, if the characteristic of the power supply signal does not meet the threshold. For example, if the voltage of the power supply signal does not exceed a predetermined voltage (e.g., 4.5 volts), it is not possible for the initial circuitry of the device to utilize the power supply signal received from the handshaking circuit.

Handshaking circuits may be dedicated to initiating or responding functions. Alternatively, the handshaking circuit may include both start and response functionality. Still alternatively, the handshaking circuit may be manufactured with the start and respond functions, but only one of these functions is enabled during manufacture or sale. Additionally, any portion of the handshaking device may be implemented in hardware (e.g., analog and/or digital circuitry) and/or software. For example, handshaking devices may be fabricated as flexible integrated circuits.

Those skilled in the art will recognize that: the handshake protocol may be performed over a data line, rather than over a power line. Similarly, the data lines may not be affected by the handshake protocol over the power lines, or the transfer over the data lines may be controlled/stopped by the handshake protocol.

Electrical cable 102 may be any type of electrical cable, such as a wire or fiber optic cable. Similarly, the cable 102 may include plugs at each end. Such plugs may be the same type or different types of plugs. For example, the plug of the cable 102 may be a USB plug, according to another example, one plug of the cable 102 may be a USB plug, and another plug of the cable 102 may be a multi-zone vertical plug (e.g., a four-zone vertical plug). Those skilled in the art will recognize that: the cable may have more than two plugs. For example, the cable may have one primary USB plug, and the cable may separate from this plug into multiple plugs (e.g., microphone plug, firewire plug, USB 2.0 plug, a/V plug, component plug, HDMI plug). According to another example, the end of the cable may be open in such a way that the end does not include a plug, but allows direct access to the internal passage of the cable. Cable 102 may include any number of power and/or data paths.

The cable 102 may be, for example, a cable 110 that includes a protected USB plug 111 that may be connected to a USB receptacle 112. Cable 110 may also include a multi-region vertical male plug (male plug) that may be connected to a multi-region vertical female receptacle (femalejack). The multi-region plug may include a plurality of contacts for the transmission of power and data signals. For example, the multi-region plug may be a four-region plug. The contactor 121 may be a power supply contactor. The contact 122 may be a ground contact. The path 123 may be a data contact. Contact 124 may be another data contact. A quad zone plug is operable to connect to an associated quad zone receptacle. A four-zone plug may be considered a vertical plug in that at least one contact on the plug must pass through an unrelated contact on the receptacle in sequence so that contact is electrically connected to the correct contact on the receptacle. For example, contact 124 must pass through contacts 131, 132, and 133 in order to make electrical contact with via 134. As such, contacts on a vertical plug may often connect to undesired contacts on an associated receptacle while the plug mechanically mates with the receptacle.

Figure 2 illustrates various handshaking circuit topologies 200. For example, plug 210 may include handshaking circuit 211 that may communicate with handshaking circuit 270 of device 250. As such, plug 210 may include a handshaking circuit on the plug, while device 250 includes a handshaking circuit on the device. Handshaking circuit 270 may be in communication with, for example, circuitry 260. Memory 261 and/or processor 262 may be included in circuitry 260.

On-cable handshaking circuits may be provided on any portion of a cable. For example, cable 220 provides handshaking circuit 240 on a plug other than a plug that is operatively connected to receptacle 280 of device 250, such that cable 220 may also include a plug that does not have handshaking circuit 240 operatively connected to receptacle 280 of device 250. In doing so, for example, cable 220 may be connected to receptacle 280 of device 250 through a plug that does not include a handshaking circuit while having a plug that includes a handshaking circuit so that a handshaking process may still be performed. As another example, handshaking circuit 240 may be provided on the body of a cable rather than on a plug of a cable (e.g., in handshaking circuit 231 of cable 230). In yet another example, cable 290 may be equipped to include a plug without handshaking circuit 240 that splits into two different plugs that each include a handshaking circuit (e.g., handshaking circuits 291 and 292). When multiple plugs are provided with different handshaking circuits, the device may identify each plug separately because the handshaking circuits may operate differently (e.g., provide different initial handshaking voltages).

Those skilled in the art will recognize that: the cable may include any number of plugs and such plugs may be of different types. Thus, for example, one end of the plug may be a wireless receiver/transmitter for wirelessly receiving/transmitting communication signals, such as handshaking signals.

The plug may be, for example, a multi-pin connection plug, such as 30-pin connection plug 242. One example of a 30-pin connection plug is described in U.S. patent publication No.2004/0224638 to Fadell et al, which is incorporated herein by reference in its entirety. Further discussion of 30-pin connection plugs may be found in U.S. patent No. 7,293,122, which is incorporated herein by reference in its entirety. The 30-pin connector may exist in male and female form. Female form 30-pin connectors are typically located in portable electronic devices. In some embodiments, the female 30-pin connector may have a key structure to guide a corresponding male connector therein, a first-mate (first mate), a last-break (last break) ground contact pin, and several pins arranged in a row in a sequential order.

The male form of the 30-pin connector is typically included in accessories such as docking stations, speaker systems, cables, car chargers, or any other suitable device, some of which may receive power from an external power source. The accessory typically includes a circuit board to which a 30-pin connector is mounted. The 30-pin connector may include a housing designed to accommodate at least 30 contacts spaced apart in a single row of sequentially numbered contact positions including a digital contact position, an analog contact position, and a ground contact position. The contact locations may be selectively populated with one or more electrical contacts. The male 30-pin may also include a keying feature. In some embodiments, a handshaking circuit (e.g., an on-cable handshaking circuit) may be included in an accessory and electrically connected to at least one electrical contact.

As noted above, those skilled in the art will recognize that the cable may include any number of plugs, and that such plugs may be of different types. For example, one end of the cable 240 may be a 30-pin connection plug 242 and the other end may be a USB plug 241. As such, handshaking circuit 243 may be located within one or more of cable 240, 30-pin connection plug 242, and USB plug 241.

Those skilled in the art will also recognize that: the device that provides power to the second device may be connected by a cable that includes two handshaking circuits. Handshaking circuits may, for example, be included in both a device that provides a power signal and a device that receives a power signal. Thus, the cable may identify devices connected to the cable through the varying handshaking circuits. In this way, the cable can be aware of its operating environment and can autonomously change its own operation. For example, the cable may include a microprocessor, memory, and a power source such as a battery. The cable may be programmed to provide different functions depending on the operating environment. For example, consider a user having a secure laptop computer that includes a handshaking circuit operable to provide a particular identification of the laptop computer. Thus, it is envisaged that the user needs to use a secure accessory, such as a secure backup storage device. This secure backup storage device may include a handshaking circuit that may provide a special identification of the storage device. Thus, the cable may issue to the user that one or more signals are allowed, e.g., transmitted over the cable, whenever a particular laptop and a particular storage device are used. Thus, an administrator may program a cable with information indicating the identity of different devices and how the cable should operate once the operating environment is recognized. Using the above example, it is contemplated that the secure storage device is connected to the laptop computer through a programmed cable rather than the secure laptop computer. Thus, the cable may not allow a signal, such as a power signal, to be provided to the secure storage device since the cable may identify that the laptop is not a secure laptop. Such a solution provides, for example, increased security.

Those skilled in the art will recognize that: if the cable includes, for example, a rechargeable power source, such a rechargeable power source may be recharged while the cable is provided with a power signal. A cable with handshaking circuitry may be used to prevent an unauthorized third party accessory from damaging the device. Handshaking circuits may be used to identify any type of accessory or may be provided in any type of accessory and may be used to identify any particular accessory for any type of accessory. Such accessories may include, for example, headphones, portable media devices, speaker systems, microphones, storage devices, projectors, docking stations, display systems, radio systems, wireless communication systems, or any other device. Such accessories may, for example, be constantly powered or may receive power from the parent device to operate.

Those skilled in the art will recognize that: a device receiving power from a device in one mode may provide power to a different device in another mode. For example, the portable media player may receive power from a personal computer (e.g., a laptop computer) via a cable. However, that portable media player may then power the device through the same or a different cable, for example. Accordingly, the handshaking circuit of the cable and/or the handshaking circuit of the associated device may be aware of the operational environment in which the cable and device are operating. Additionally, the portable media device may be affiliated with and an accessory to a laptop computer, but that portable media device may mate with a microphone and speaker headset. The portable media player may, for example, utilize an accessory device, such as a docking station, and handshaking circuitry may be provided in the docking station, the portable media device, and/or an associated cable. A 30-pin connector may be used to connect two devices together via a plug. Thus, for example, it may be desirable for the portable media device to send a handshaking signal to the docking station before the docking station can receive a signal from the portable music device (and vice versa). Such signals may include, for example, media information signals, control signals for any of the devices, appropriate ground signals, power signals, or any other type of signal. For example, the portable electronic device may require a suitable handshake from the accessory before transferring power to the portable electronic device. According to another example, the device may require an appropriate handshake from the accessory before transmitting data (e.g., accepting the data transfer). Thus, an authentication method is provided that can help ensure secure transfer of power and/or data between a host device (e.g., via a handshaking circuit on device 103 of FIG. 1) and an accessory (e.g., handshaking circuit 106 of device 105 of FIG. 1, which may be connected to device 103 via cable 107, for example), and help prevent an improper accessory device from accidentally or intentionally damaging the host device or an associated user.

The handshaking circuit may be included in a power supply or power adapter of a device. For example, handshaking circuit 109 of fig. 1 may be provided in wall power plug 108 of fig. 1, and handshaking circuit 109 of plug 108 of fig. 1 may perform a suitable handshake with a wall socket having a handshaking device.

The power adapter may be connected between the device and an external or portable power source. Such power adapters and power supplies may include handshaking circuitry. Such power sources may include, for example, batteries, wall sockets, or lighters. The power adapter may be located on a power cord connecting the device to an external power source. Thus, for example, when the handshaking circuit is located in a power supply or power adapter, the device may require the power supply (or power adapter) to send a handshaking signal before the device receives power from the power supply.

Fig. 3 shows flow diagrams 310, 320, 330 and 340, each of which includes a number of steps. Those skilled in the art will appreciate that the flow chart may include additional steps, fewer steps, altered steps, and/or the order of steps may be rearranged. Flowchart 310 may begin at step 311 when handshaking circuit receives an initial power in the form of a power supply signal. Such handshaking circuit may step down the voltage of the power supply signal in step 312 to provide protected power to the device in step 313. The handshaking circuit may then wait until receiving returned information from the device in step 314. This information may take the form of current pulses in the protected power provided to the device. In response to receiving the appropriate information, the handshaking circuit may step up the protected power to the initial power voltage. The handshaking circuit may step up the protected power by providing the initial power received by the handshaking circuit to the device in step 315. Those skilled in the art will recognize that: the initial power source may be a DC signal from a battery, such as a battery that simultaneously powers a laptop computer, or an AC power signal from a wall outlet.

Flowchart 320 may begin when handshaking circuit receives a power supply signal, for example, in step 321. The handshaking circuit determines whether the received power supply signal is within a particular range in step 322. For example, if the characteristic of the power signal is within a particular range, the power signal may be within the particular range. For example, step 322 may determine whether the voltage of the power supply signal received by the handshaking circuit is within a particular voltage range. Alternatively, step 322 may determine that a characteristic such as voltage is above or below a particular threshold, for example. Step 322 may also determine whether the detected condition persists for a period of time. Once the condition of step 322 is satisfied, step 323 may begin, where the characteristic of the power supply signal is changed in such a way that the device providing the power supply signal may detect the changed characteristic. Thus, for example, step 323 may vary the current of the power supply signal by introducing current pulses in the signal that are detectable at the device supplying power to the handshaking circuit. Once the pulse is generated and detected by the device, the device may connect the power signal to the initial circuitry of the device in step 324. A determination of whether the power supply signal exceeds a particular voltage or is within a particular range may be included in step 324 to ensure that a handshaking circuit at a device providing the power supply signal has recognized the receipt of a current pulse. The initial circuitry of the device may include circuitry that only allows a supply voltage signal having a particular characteristic (e.g., a suitable voltage) to be connected to the initial circuitry (e.g., step 325).

Those skilled in the art will recognize that: once the handshaking circuit in a device completes the handshaking process and begins receiving a power supply signal suitable for powering the device, the handshaking circuit may continue to manipulate the protected power supply signal in the same manner that the handshaking circuit receives a suitable power supply signal. In other words, the handshaking circuit may continue to introduce current pulses into the power supply signal all the time the device receives the power supply signal. In so doing, the initiating handshaking circuit providing the power supply signal may continuously recognize that a responding handshaking circuit is electrically coupled to the initiating handshaking circuit. If two handshaking circuits are disconnected, an initiating handshaking circuit may recognize that the connection is disconnected by recognizing the absence of a current pulse (or any information provided by a device connected to the initiating handshaking circuit). In doing so, initiating handshaking circuit may recognize that initiating handshaking circuit should step down the voltage of the provided power supply signal to a suitable, protected power supply signal.

The responding handshaking circuit may continue to send current pulses through the power supply signal even after the voltage of the power supply signal has stepped up to a level outside the voltage range required to begin introducing current pulses into the power supply signal. In this way, the responding handshaking circuit may continue to provide information to the initiating handshaking circuit such that the initiating handshaking circuit knows that the device is still connected. Those skilled in the art will recognize that: the disconnection may be determined in various ways. For example, an interruption of data transferred between two devices may be used as an indication of a disconnection and a new handshake procedure may be started. When a new handshaking procedure begins, for example, the voltage (and/or current) of the power supply signal provided by the initiating handshaking circuit may be stepped down to a predetermined level.

Flowchart 330 may be utilized, for example, as part of a handshaking protocol between two devices. For example, flowchart 330 may be utilized as part of a cable-to-device handshaking protocol over a power supply signal. The flowchart 330 may include a step 331 in which characteristics of the power supply signal are analyzed. Thus, for example, step 331 may analyze the voltage of the power supply signal to determine whether the voltage is above (or below) a particular threshold (e.g., 2.7 volts). Once the voltage of the power supply signal is determined to be within a particular range, the power supply signal may be provided to the timing circuit in step 332. The circuit may then determine whether the characteristic of the power supply signal is below (or above) a particular threshold. Thus, for example, step 333 may determine whether the voltage of the power supply signal is below a particular threshold (e.g., 3.1 volts). Those skilled in the art will recognize that: a determination of whether the voltage is within a particular range may be made by first determining whether the voltage is above a threshold and then determining whether the voltage is below a different threshold (or vice versa). Such a voltage range may be of any size. Preferably, the voltage range does not include a voltage intended as an initial power supply signal (e.g., 5 volts), and preferably the range is relaxed to account for the desired margin of error for the particular environment. Once the characteristic (e.g., voltage) is determined to be within a particular range, the counting circuit may be started in step 334.

Such a counting circuit may count based on the speed of the clock signal driving the counting circuit. This counting circuit may, for example, be connected to a locking circuit which may lock the counter at a particular value when this value is reached. A single output bit from the counter, or any number of output bits, may be used as the control signal. For example, once the counter reaches 128, the seventh bit (i.e., the most significant bit) may change from a logic "0" to a logic "1". Once the bit becomes a logic "1," a locking circuit may be used to hold the value of the counter and may be used to determine when a characteristic (e.g., voltage) of the power supply signal remains within a particular voltage range for a particular period of time. Those skilled in the art will recognize that: the dynamics of the counting circuit and/or clock may be changed such that a particular count (e.g., 128) reflects a particular amount of time (e.g., 1/2 seconds).

Once the counting circuit reaches a particular count, step 335 may begin. In step 335, a characteristic (e.g., current) of the power supply signal may be changed such that the device transmitting the power supply signal may recognize that the appropriate device has received the power supply signal for at least a particular period of time. Such a device may then change the characteristics of the supply voltage. For example, such a device may increase the supply voltage from a safe, protected voltage level for identification to a voltage level for powering the device. Those skilled in the art will recognize that: the safe, protected voltage level may be a voltage level that is unlikely to cause physical damage or pain. Such safe, protected voltage levels may also be unlikely to cause damage to circuits that are not intended to receive the increased voltage levels.

The flow chart 340 may be used to distinguish between different types of devices that are utilized through a universal plug and socket interface. Step 341 may occur, for example, when two handshaking circuits are communicating with each other via a power supply signal. Once step 341 is complete, the device that the handshaking circuit is attempting to protect may transfer both power and data. For example, a laptop computer may transfer music data to a portable music player in step 342 while providing a power signal to the portable music player in order to recharge the battery of the portable music player. The handshaking circuits may then be disconnected by removing the cable that connects the two handshaking circuits.

A different device, one without a handshaking circuit, may then be placed in the plug and may still be used by the portable music player in step 343. For example, an earphone or speaker may be connected to the plug in step 343. Here, the portable device may provide, for example, an analog music signal to the plug, and may turn off the handshaking circuit or not use the handshaking circuit in order to deliver such a signal. Those skilled in the art will recognize that: the headset and/or speaker may provide information to a device to which the headset and/or speaker is connected. For example, the volume control signal may be provided in turn to the headphones and/or speakers via a plug that provides a music signal, such as an analog or digital music signal.

However, another type of device may be connected to the plug at 344. For example, a microphone may be placed in the plug via 344. Such devices may or may not include handshaking circuitry. For example, the microphone may provide a signal to a power supply signal contact that is not in the range of any handshaking circuit or initial power supply signal. Thus, a handshaking circuit in a device receiving a microphone signal may recognize such a voltage and, in doing so, may recognize that a microphone is connected to a plug. Likewise, the handshaking circuit may allow the device to use the plug as a microphone plug and, for example, receive an analog microphone signal in step 345. As indicated above, a device having a handshaking circuit and a single plug may use the same plug for many different types of devices that require different types of interaction with the plug.

Figure 4 illustrates handshaking circuit 400, which handshaking circuit 400 may communicate with another handshaking circuit, for example, via a power signal, and, in so doing, provide a provider of the power signal with an indication of how to provide the power signal in the future. For example, handshaking circuit 400 may protect a device from receiving a relatively high voltage until the device is ready to receive such a high voltage. Handshaking circuit 400 may, for example, be included in a device that receives a power signal and a device that provides a power signal may include another handshaking circuit.

Those skilled in the art will recognize that: the device and/or cable may include two handshaking circuits, where one handshaking circuit is used when supplying power and the other handshaking device is used when receiving power. Alternatively, for example, a handshaking circuit may be provided that includes the ability to perform the steps of initiating a handshake (e.g., by varying the supply voltage to a predetermined level) and responding to the handshake (e.g., by supplying appropriate current pulses). In doing so, for example, a device (e.g., a portable media device) may communicate with a power supply device (e.g., a laptop computer) that provides power to a rechargeable battery located on the device, and an accessory that requires power (e.g., a microphone/speaker accessory). Thus, for example, the inclusion of these two functions allows the device to communicate with power supply devices and devices requiring power through a common outlet such as a microphone outlet or a 30-pin connector.

Handshaking circuit 400 may determine whether the power supply signal is within a particular voltage range for a period of time. If so, handshaking circuit 400 may manipulate the current of the power supply signal by introducing identifiable current pulses into the power supply signal to instruct the provider of the power supply signal to perform an operation. For example, the provider of the power supply signal may recognize the current pulse and step up the voltage of the power supply signal from a relatively low voltage (e.g., 2.9 volts) to a relatively high voltage (e.g., 5 volts).

Handshaking circuit 400 may include an input node 491 that is electrically coupled to a power contact of an input/output receptacle. When the input/output plug of a device is properly mated with such an input/output socket, a power signal from the device may be received on node 491.

Voltage detection circuit 410 may be included in handshaking circuit 400. Voltage detection circuit 410 may utilize voltage detector 411 to determine whether the voltage of the power supply signal on node 491 has reached a particular threshold. For example, voltage detector 411 may determine whether the voltage of the power supply signal on node 491 is above a particular threshold (e.g., 2.7 volts). If the threshold is reached, voltage detector 411 may provide a signal to turn on switch 413. Those skilled in the art will recognize that some voltage detectors (e.g., comparators) may provide signals of incorrect polarity to turn on some switching circuits (e.g., transistors). In these cases, for example, an inverting circuit 412 may be provided to invert the polarity of the signal supplied from the voltage detector 411 to turn on the switch 413.

Once switch 413 is turned on, switch 413 may allow the power supply signal on node 491 to flow to node 492. Oscillator circuit 420 may be included in handshaking circuit 400. The oscillator circuit 420 may be, for example, a low power oscillator circuit operating at a fixed frequency in time (e.g., 200 Hz). Tank circuit 420 may be configured to operate, for example, only when a supply voltage is provided to node 492 via switch 413. In particular, node 492 may provide a power signal to oscillator 421. The output of oscillator 421 of oscillation circuit 420 may be provided to a logic gate, such as NOR gate 441.

In this way, the supply voltage may be stepped down to provide handshaking functionality, yet still provide sufficient power to power the circuitry of the handshaking device. Thus, a device having a handshaking circuit may have a battery that is fully depleted of power, but may still be powered for the handshaking circuit of the device even if the supply voltage is stepped down for the purpose of handshaking.

The power supply signal provided to node 492 through switch 413 may also be provided to voltage detector 431. Voltage detector 431 may determine whether the voltage of the power supply signal provided to node 492 reaches a particular threshold. For example, voltage detector 431 may determine whether the voltage of the power supply signal drops below a particular threshold (e.g., 3.1 volts). Those skilled in the art will recognize that: when used together, voltage detectors 411 and 431 may determine whether the voltage of the power supply signal falls within a predetermined voltage range (e.g., 2.7 volts to 3.1 volts). Such a range may take into account margin of error for a particular environment. For example, if handshaking circuit 400 expects to receive a power supply signal having a voltage of 2.9 volts, however the margin of error is determined to be 0.2 volts, then handshaking circuit may relax the expected voltage (2.9 volts) to include the margin of error (e.g., 2.7 volts to 3.1 volts).

The output of voltage detector 431 may be provided, for example, to the same logic gate that receives the output of oscillator circuit 420. For example, the outputs of voltage detectors 431 and 420 may be provided to NOR gate 441.

Nor gate 441 may have any number of inputs (e.g., three). Since gate 441 has a nor function, the output of nor gate 441 goes low whenever either input of the nor gate is high. Those skilled in the art will recognize that: voltage detector 431 may be configured as, or may be connected to, a circuit such that if the threshold of voltage detector 431 is reached, a low signal may be provided to NOR gate 441. Thus, NOR gate 441 may clock counter 451 at the frequency of oscillator 421 whenever the threshold of voltage detector 431 is reached.

Those skilled in the art will also recognize that: node 493 may be configured to initially provide a low signal to nor gate 441 such that counter 451 may be enabled. In particular, node 493 may be electrically coupled to an output bit of counter 451 (e.g., the seventh most significant output bit of counter 451). Thus, counter 451 may begin with an initial count of 0. As such, each output bit of counter 451 may include a low signal (e.g., a 0 volt or logic "0" voltage signal).

As long as voltage detector 441 provides a low signal (e.g., the threshold of voltage detector 441 is reached), nor gate will cause counter 451 to count from a starting value (e.g., 0) at the rate of oscillator 421. As counter 451 counts up, the output bits of counter 451 may begin to change state. For example, the least significant output bit may change from a low signal to a high signal when counter 451 counts from 0 to 1. Thus, counter 451 may be used to count any value and, as a result, counter 451 may be used to count any length of time. For example, counter 451 may be configured such that after a predetermined time (e.g., 0.6 seconds), the counter reaches 128 (e.g., the seventh most significant bit changes from a low signal to a high signal). Such an output bit may be used as an input to nor gate 441 such that the output of nor gate 441 switches from high to low when counter 451 reaches count 128. In doing so, counter 451 is instructed to stop counting because pulses from oscillator 421 are no longer being transferred to counter 451, and counter 451 will hold (e.g., latch onto) the last counted value (e.g., 128). Accordingly, the output bit for turning off nor gate 441 may also be kept constant. This output bit may thus be used to provide a control signal to additional components of handshaking circuit 400 via node 493.

Node 493 may be used, for example, to turn on switch 461 once counter 451 measures a predetermined amount of time. Switch 461 may then cause switch 481 to turn on. For example, switch 461 may electrically connect the gate terminal of switch 481 to ground to turn switch 481 on.

Those skilled in the art will recognize that: initial circuitry of a device (e.g., a portable music player) may be connected to node 494. Such an initial circuit may include a voltage detector for determining whether the voltage provided to the initial circuit is an initial power supply signal (e.g., 5 volts) by including a voltage detector to detect whether the received power supply signal is sufficient (e.g., above 4.5 volts).

When switch 481 is turned on, the power supply signal on node 491 is provided to pulse generation circuit 470. The pulse generation circuit 470 operates as follows. When switch 471 is turned on, the supply voltage at node 494 dissipates across resistor 472 to ground 499 via switch 471. In doing so, resistor 472 generates current pulses in the power supply signal at the switching rate of oscillator 421.

Those skilled in the art will recognize that: to provide a handshaking function, a handshaking circuit may use power supply lines (e.g., a power contactor and a ground contactor). For example, ground 499 may be connected to a ground contact of an input/output jack on a device. In doing so, the handshaking circuit may receive information through the ground contact. For example, a handshaking circuit may receive a virtual ground at ground 499 from another handshaking circuit that has a non-zero value (e.g., 1 volt). This virtual ground may be utilized by a handshaking circuit to embed information for another handshaking circuit (e.g., to divide a current pulse to a virtual ground). In addition, handshaking circuits may utilize power and ground contacts to both send information to and receive information from any number of handshaking circuits.

A driver circuit 475 may be provided to drive the switching characteristics of switch 471 of pulse generator 470. Driver circuit 475 may include capacitor 476 which generates a pulse that turns on switch 471 by electrically connecting the gate terminal of switch 471 to ground. Those skilled in the art will recognize that: the capacitance value of capacitance 476 may determine, at least in part, the amount of time switch 471 is turned on. For example, capacitor 476 may be configured to turn switch 471 on for a particular amount of time in a particular period of time. For example, capacitor 476 may turn switch 471 on approximately 4 microseconds every 5 milliseconds (e.g., which may be set by oscillator 420). This switching characteristic of switch 471 may then produce a current pulse (based on the resistance value of resistor 472) having a duty cycle of 4 microseconds divided by 5 milliseconds (or 0.1% duty cycle). In this way, capacitor 476 may provide low duty cycle current pulses in the power supply signal. Such low duty cycle current pulses may have, for example, a duty cycle of less than 1%. The low duty cycle current pulses may, for example, have a duty cycle of less than 0.1%. Those skilled in the art will also recognize that: if resistor 472 has a resistance of about 47 ohms and 2.9 volts is applied across resistor 472, 60 milliamps of current may flow through resistor 472 since the voltage on node 491 is 2.9 volts. Thus, pulse generating circuit 470 may generate relatively high current, low duty cycle current pulses. To further illustrate this example, the handshaking circuit providing power to node 491 would also include 60 milliamps of current, since the current remains constant across the node. Handshaking circuits may be configured to send different types of current pulses (e.g., a 40 milliamp pulse and a 60 milliamp pulse) in order to provide different types of indications to a handshaking circuit providing a power supply signal. Similarly, a handshaking circuit providing a power supply signal may operate in different ways (e.g., step up or step down the voltage of the power supply signal) based on different instructions received by the handshaking circuit back through the supplied power supply signal.

Those skilled in the art will recognize that: the switch 481 may not be turned on until the handshake process is complete, for example. Thus, for example, a correct handshake may need to occur before the device's initial circuitry (e.g., a portable music player) can utilize the power supply signal from node 491. Such a handshake may, for example, cause node 491 to electrically couple to node 494. For example, current pulses may be applied continuously after the handshaking process is complete, such that when two devices are disconnected, the initiating handshaking circuit may detect the loss of receipt of the correct current pulse and may step down the voltage of the power supply voltage to a safe and protected level (e.g., 2.9 volts).

Those skilled in the art will recognize that: switch 481 may isolate node 491 from node 494 such that, for example, microphone circuit 480 may be connected to node 491. Those skilled in the art will recognize that: the frequency of current pulses in response to a handshaking circuit may also be varied, for example, to provide different types of information to an initiating handshaking circuit. To enhance the safety of the connection, modulation techniques may also be used when generating the current pulses. In this way, the current pulses may be encrypted by a modulation technique such that the initiating handshaking circuit receiving the current pulses may know the modulation scheme applied to the current pulses and demodulate the current pulses in order to decrypt the information stored in the current pulses. In this way, handshaking circuits may be provided that communicate using encrypted information communicated over a power supply line.

Fig. 5 illustrates handshaking circuit 500. handshaking circuit 500 may, for example, provide a power supply signal to a device and determine whether such a device includes a handshaking circuit operable to communicate with handshaking circuit 500. More specifically, handshaking circuit 500 may provide a power supply signal at a particular voltage (e.g., low or high) on node 592. Handshaking circuit 500 may also receive, for example, current pulses on node 592 while handshaking circuit 500 is delivering a power supply signal.

Current pulses generated by a handshaking circuit (e.g., handshaking circuit 400 of fig. 4) may be provided to node 592 while handshaking circuit 500 provides a power supply signal on node 592. The current pulse detector 560 may be used, for example, to detect incoming current pulses. Those skilled in the art will recognize that: the current pulse detector may also identify different types of current pulses and may react differently depending on the type of current pulse received. Generally, sense resistor 561 may be used to sense a change in current and may provide a different voltage signal to comparator 562 to determine whether an appropriate current pulse has been received. Handshaking circuit 500 may include any number of comparators to sense any number of different types of current pulses. Similarly, handshaking circuit 500 may include any number of sense resistors to sense any number of different types of current pulses. A current mirror may be used to provide these resistors with the same current as the current on a particular node (e.g., a power supply node).

The output of comparator 562 may provide a logic high signal when an appropriate current pulse is detected. In doing so, pulse stretching circuit 511 may trigger the generation of pulses. Pulse stretching circuit 511 may, for example, generate pulses having a duration longer than those generated by the output of comparator 562. In practice, pulse stretching circuit 511 may, for example, generate pulses having a duration that is multiple times (e.g., twice) the period of the pulses from node 592. Pulse stretching circuit 511 may also be retriggerable in that the circuit may resume generating pulses when enabled. Thus, pulse stretching circuit 511 may not have to wait until the generation of a pulse is completed in order to generate a new pulse. Likewise, pulse stretching circuit 511 may, for example, provide a constant signal to node 593-without interruption-as long as the current pulse is sensed by pulse detector 560.

A delay circuit 520 may be provided to delay the signal generated by pulse stretching circuit 511. For example, the characteristics of resistor 521 and capacitor 522 may be selected to achieve a particular time delay (e.g., 0.5 seconds). For example, the voltage on the capacitor 522 may build up over time and the switching circuit 530 may be enabled at a predetermined time by causing the output of the comparator 531 to go low. In turn, the output of comparator 531 may disable voltage regulation circuit 540 and enable switch 551 such that the voltage of the power supply signal provided onto node 592 is stepped up from a safe, protected voltage (e.g., 2.9 volts) to an initial power supply voltage (e.g., 5.0 volts). More specifically, when power regulation circuit 540 is disabled, switching circuit 550 is turned on and the initial power on node 591 is electrically connected to node 592.

Before the current pulse is received at node 592 and detected by pulse detection circuit 560, voltage regulation circuit 540 may be enabled such that the initial power supply signal on node 591 may be stepped down by voltage regulation circuit 540 to a particular voltage (e.g., 2.9 volts). When device 541 is enabled, switch circuit 550 is turned off so that the power supply signal on node 591 is not directly connected to node 592. Thus, device 541 steps down the voltage of the power supply signal on node 591 and provides this stepped down voltage on node 592 as a result of, for example, the characteristics of switch 542, switch 543, resistor 544, resistor 545, and capacitor 546.

Those skilled in the art will recognize that: the receptacle on the device may be a male connector, a female connector, or may take the form of neither a male connector nor a female connector. Similarly, the plug on the cable may be a male connector, a female connector, or may take the form of neither a male nor a female connector.

Those skilled in the art will recognize that: the current pulses may be generated such that although each current pulse has a relatively high current (e.g., 60 milliamps), the average current of these current pulses is low (e.g., 50 microamps).

From the foregoing description, those skilled in the art will recognize that the present invention provides handshaking between devices. Additionally, one skilled in the art will recognize that: the various configurations described herein may be combined without departing from the invention. It will also be appreciated that the invention may take many forms other than those described in this specification. It is therefore emphasized that the present invention is not limited to the methods, systems, and devices described, but is intended to include variations and modifications thereof within the spirit of the following claims.

Claims (18)

1. A method of using a power supply signal between a first device and a second device, the method comprising:

receiving, by a first handshaking circuit of a first device, a power supply signal, the first device operative to selectively provide the power supply signal having a first characteristic or a second characteristic to a second device depending upon whether a series of predetermined current spikes are detected on the power supply signal, wherein the power of the power supply signal having the first characteristic is lower than the power of the power supply signal having the second characteristic;

providing a power supply signal having a first characteristic, wherein the first characteristic is provided by a first handshaking circuit;

monitoring, by a first handshaking circuit, a power supply signal to determine whether the current spike is being received; and

providing a power supply signal having a second characteristic in response to identifying the current spike, wherein the power supply signal having the second characteristic is provided by a first handshaking circuit.

2. The method of claim 1, wherein the first characteristic of the power supply signal comprises:

the current of the power supply signal is limited and the voltage level is reduced step by step.

3. The method of claim 1, wherein the second characteristic of the power supply signal comprises:

a stepped up power supply signal.

4. The method of claim 1, wherein the first device is a cable coupled to the second device, and the first handshaking circuitry is located within the cable.

5. The method of claim 4, wherein the cable comprises one or more plugs.

6. The method of claim 5, wherein at least one of the plugs is a universal serial bus plug.

7. The method of claim 5, wherein at least one of the plugs is a 30-pin connector plug.

8. The method of claim 1, wherein the first device is a power supply and the first handshaking circuitry is located within the power supply.

9. The method of claim 1, wherein the first device is an accessory device of the second device, and the first handshaking circuit is located within the accessory device.

10. An electronic device, comprising:

a first handshaking circuit, wherein the first handshaking circuit is located in a first device and is configured to: receiving a power supply signal and selectively providing the power supply signal having a first characteristic or a second characteristic based on whether a predetermined series of current spikes are detected on the power supply signal, wherein the power of the power supply signal having the first characteristic is lower than the power of the power supply signal having the second characteristic; and

a current detector, wherein the current detector is located in the first device and is configured to monitor the power supply signal for a current spike, and the first handshaking circuit is configured to provide the power supply signal with the second characteristic in response to the current detector identifying the current spike.

11. The electronic device of claim 10, wherein the first characteristic of the power supply signal comprises a current limited, stepped down voltage level of the power supply signal.

12. The electronic device of claim 10, wherein the second characteristic of the power signal comprises a stepped-up power signal.

13. The electronic device of claim 10, wherein the first device is a cable coupled to the second device, and the first handshaking circuitry is located within the cable.

14. The electronic device of claim 13, wherein the cable comprises one or more plugs.

15. The electronic device of claim 14, wherein at least one of the plugs is a universal serial bus plug.

16. The electronic device of claim 14, wherein at least one of the plugs is a 30-pin connector plug.

17. The electronic device of claim 10, wherein the first device is a power supply and the first handshaking circuitry is located within the power supply.

18. The electronic device of claim 10, wherein the first device is an accessory device of the second device, and the first handshaking circuit is located within the accessory device.