Frequency sweep for detecting attached wireless power transmitter or receiver

Abstract

The invention relates to a frequency sweep for detecting an attached wireless power transmitter or receiver. Detecting an object proximate to an electronic device that is operable in a wireless power receiver (PRx) mode to receive power from a wireless power transmitter (PTx) or in a PTx mode to transmit power to the PRx can include: in response to detecting the object, receiving power from the electronic device; identifying the object as at least one of PRx and PTx by performing one or more frequency sweeps to identify one or more resonant frequencies of the object that characterize the object as PRx or PTx; in response to identifying the object as PRx, activating the PTx mode and transmitting power to an accessory using wireless power transfer circuitry of the electronic device; and in response to identifying the object as PTx, activating the PRx mode and receiving power from the PTx using the wireless power transfer circuitry of the electronic device.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 680,816, filed August 8, 2024, entitled “Detection and Coil Operation in Wireless Power Transfer,” U.S. Provisional Application No. 63 / 802,717, filed May 9, 2025, entitled “Low Power Ping Transition to Wireless Power Receiver Mode,” U.S. Provisional Application No. 63 / 802,722, filed May 9, 2025, entitled “Frequency Sweep to detect Attached Wireless Power Transmitter or Receiver,” and U.S. Provisional Application No. 63 / 802,728, filed May 9, 2025, entitled “Ultra Low Power Object Detection,” all of which are incorporated herein by reference in their entirety. BACKGROUND

[0003] Wireless power transfer is used in a variety of electronic devices. For example, smart phones, tablet computers, smart watches, wireless earphones, styluses, and the like can employ wireless power transfer to facilitate battery charging within the device and / or to power the device during operation. SUMMARY

[0004] Wireless power transmission can use one or more techniques to detect whether a wireless power receiver is inductively coupled and ready for wireless power transfer operation.

[0005] An electronic device that is selectively operable in a wireless power receiver mode to receive power from a wireless power transmitter and in a wireless power transmitter mode to transmit power to an accessory, the electronic device can include: a wireless power transmission coil; a rectifier coupled to the wireless power transmission coil and operable in the wireless power receiver mode to convert an AC voltage induced in the wireless power transmission coil by a wireless power transmitter into a DC voltage for use by the electronic device; an inverter coupled to the wireless power transmission coil and operable in the wireless power transmitter mode to convert a DC voltage into an AC voltage applied to the wireless power transmission coil; and a controller and communication circuit that detects an object proximate to the electronic device; in response to detecting the object, attempts to identify the object as at least one of a wireless power receiver and a wireless power transmitter by performing one or more frequency sweeps to identify one or more resonant frequencies of the object that characterize the object as a wireless power receiver or a wireless power transmitter; in response to identifying the object as a wireless power receiver, activates the wireless power transmitter mode; and in response to identifying the object as a wireless power transmitter, activates the wireless power receiver mode.

[0006] The one or more frequency sweeps can be performed over a frequency range of interest from 600 kHz to 2 MHz. The one or more frequency sweeps can be a continuous frequency sweep over the frequency range of interest. The one or more frequency sweeps can be at a plurality of discrete frequencies over the frequency range of interest. Performing the one or more frequency sweeps to identify one or more resonant frequencies of the object can include driving the wireless power transmission coil with the inverter. Performing the one or more frequency sweeps to identify one or more resonant frequencies of the object can include driving the wireless power transmission coil with the auxiliary circuit.

[0007] The wireless power transmitter can be characterized by a first resonant frequency, where the first frequency is at least one of: a frequency associated with a compatible wireless power transmitter intended for operation with the electronic device; or a frequency different from a resonant frequency of a wireless power receiver intended for operation with the electronic device. The wireless power receiver can be characterized by a second resonant frequency and a third resonant frequency, where a valley is between the second resonant frequency and the third resonant frequency, where the valley is at a higher frequency than the first resonant frequency, where one or more of the second resonant frequency and the third resonant frequency and the valley can be: a frequency associated with a compatible wireless power receiver intended for operation with the electronic device; or a frequency different from a resonant frequency of a wireless power transmitter intended for operation with the electronic device.

[0008] The wireless power transmission coil can be a single coil. The rectifier and the inverter can include the same switching device. Activating at least one of the wireless power transmitter mode and the wireless power receiver mode can include loading additional firmware corresponding to one of the respective modes. Activating the wireless power receiver mode can include transmitting one or more object detection pings, an interval between at least two of the one or more object detection pings being randomized.

[0009] A method performed by a wireless power transmission controller and a communication circuit of an electronic device capable of operating in a wireless power receiver mode to receive power from a wireless power transmitter or in a wireless power transmitter mode to transmit power to a wireless power receiver, the method can include detecting an object proximate to the electronic device; in response to detecting the object, attempting to identify the object as at least one of a wireless power receiver and a wireless power transmitter by performing one or more frequency sweeps to identify one or more resonant frequencies of the object that characterize the object as a wireless power receiver or a wireless power transmitter; in response to identifying the object as a wireless power receiver, activating the wireless power transmitter mode and using wireless power transmission circuitry of the electronic device to transmit power to the accessory; and in response to identifying the object as a wireless power transmitter, activating a wireless power receiver mode and using wireless power transmission circuitry of the electronic device to receive power from a wireless power transmitter.

[0010] The one or more frequency sweeps can be performed over a frequency range of interest from 600 kHz to 2 MHz. The one or more frequency sweeps can be a continuous frequency sweep over the frequency range of interest. The one or more frequency sweeps can be at a plurality of discrete frequencies over the frequency range of interest. Performing the one or more frequency sweeps to identify the one or more resonant frequencies of the object can include driving the wireless power transmission coil with an inverter of the wireless power transmission circuitry of the electronic device. Performing the one or more frequency sweeps to identify the one or more resonant frequencies of the object can include driving the wireless power transmission coil with an auxiliary circuit.

[0011] The wireless power transmitter can be characterized by a first resonant frequency, where the first frequency is at least one of: a frequency associated with a compatible wireless power transmitter intended for operation with the electronic device; or a frequency different from a resonant frequency of a wireless power receiver intended for operation with the electronic device. The wireless power receiver can be characterized by a second resonant frequency and a third resonant frequency, where a valley is between the second resonant frequency and the third resonant frequency, where the valley can be at a higher frequency than the first resonant frequency, where one or more of the second resonant frequency and the third resonant frequency and the valley can be: a frequency associated with a compatible wireless power receiver intended for operation with the electronic device; or a frequency different from a resonant frequency of a wireless power transmitter intended for operation with the electronic device.

[0012] Activating at least one of the wireless power transmitter mode and the wireless power receiver mode can include loading additional firmware corresponding to one of the respective modes. Activating the wireless power transmitter mode can include transmitting one or more object detection pings, an interval between at least two of the one or more object detection pings being randomized.

[0013] A controller and communication circuit of a wireless power transmission system for an electronic device that is selectively capable of operating in a wireless power receiver mode to receive power from a wireless power transmitter and in a wireless power transmitter mode to transmit power to an accessory can be configured to: detect an object in proximity to the electronic device; in response to detecting the object, attempt to identify the object as at least one of a wireless power receiver and a wireless power transmitter by performing one or more frequency sweeps to identify one or more resonant frequencies of the object that characterize the object as a wireless power receiver or a wireless power transmitter; in response to identifying the object as a wireless power receiver, activate the wireless power transmitter mode; and in response to identifying the object as a wireless power transmitter, activate the wireless power receiver mode.

[0014] The controller and communication circuit can be further configured to: activate the wireless power transmitter mode by loading additional firmware corresponding to the wireless power transmitter mode; and activate the wireless power receiver mode by loading additional firmware corresponding to the wireless power receiver mode. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 A simplified block diagram of a wireless power transmission system is illustrated.

[0016] Figures 2A-2B An electronic device capable of wirelessly transmitting power and a wireless power receiver capable of wirelessly receiving power are illustrated.

[0017] Figure 3 A flowchart illustrating an inductive triggering technique for the wireless power transmitter mode of an electronic device is shown.

[0018] Figure 4 A flowchart illustrating a first inductive triggering technique for the wireless power transmitter mode of an electronic device is shown.

[0019] Figure 5 A timing diagram illustrating a first inductive triggering technique for the wireless power transmitter mode of an electronic device is shown.

[0020] Figure 6 A simplified schematic diagram of a wireless power transmission system showing aspects related to a second inductive triggering technique for the wireless power transmitter mode of an electronic device is shown.

[0021] Figure 7 A timing diagram illustrating a second inductive triggering technique for the wireless power transmitter mode of an electronic device is shown.

[0022] Figure 8 A flowchart illustrating an inductive triggering technique for selecting the wireless power transmitter mode or the wireless power receiver mode in an electronic device is shown.

[0023] Figure 9 A simplified schematic diagram of a low power ping detection circuit and an ultra-low power object detection injection and detection circuit for an electronic device is shown.

[0024] Figure 10 A timing diagram illustrating a detection and identification technique for a wireless power receiver in an electronic device is shown.

[0025] Figure 11 A series of identification frequency response curves for detecting and identifying a wireless power receiver or a wireless power transmitter by an electronic device is shown.

[0026] Figures 12A-12C An alternative timing diagram for detecting and identifying a wireless power receiver or a wireless power transmitter in an electronic device is shown. DETAILED DESCRIPTION

[0027] In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed concept. As part of the description, some of the diagrams in the present disclosure are represented in block diagram form to simplify and clarify the exemplary embodiments of the present disclosure. Not all of the features of the actual implementation are described in this disclosure for the sake of brevity. Furthermore, the language used in this disclosure has been principally selected for readability and instructional purposes and it can not have been selected to delineate or circumscribe the disclosed subject matter. Rather, the appended claims are intended to define, in part, the disclosed subject matter. Any trademarks used herein are intended only to identify the examples and are the property of their respective owners.

[0028] Various embodiments of the disclosed concept are illustrated by way of example and not by way of limitation in the accompanying drawings, in which like reference numbers indicate similar elements. For simplicity and clarity, the drawing figures have not been drawn to scale, and in some instances, the drawings have been purposefully distorted to illustrate aspects of the present disclosure. Moreover, numerous specific details are set forth in order to provide a thorough understanding of the specific implementations described herein. In other instances, methods, procedures and components are not described in detail so as not to obscure the related relevant function being described. References to "one" or "another" embodiment in the present disclosure are not necessarily to the same or different embodiments, and are intended to mean at least one. A given figure can be used to illustrate more than one embodiment or kind of feature, and not all of the elements illustrated in a given figure can be required for a given embodiment or kind. When provided in a given figure, reference numbers refer to the same element throughout several figures, but they can not be repeated in every figure. The drawings are not to scale, and the proportions of certain components can be exaggerated to better illustrate the details of the present disclosure.

[0029] Figure 1 A simplified block diagram of a wireless power transfer system 100 is illustrated. The wireless power transfer system includes a power transmitter (PTx) 110 that wirelessly transmits power to a power receiver (PRx) 120, such as via an inductive coupling 130. The power transmitter 110 can receive input power that is converted by an inverter 114 into an AC voltage having particular voltage and frequency characteristics. The inverter 114 can be controlled by a controller / communication module 116 that operates as further described below. In various embodiments, the inverter controller and communication module can be implemented in a common system, such as a microprocessor, microcontroller, or the like based system. In other embodiments, the inverter controller can be implemented by separate controller and communication modules with a communication device therebetween. The inverter 114 can be constructed using any suitable circuit topology (e.g., full-bridge, half-bridge, etc.) and can be implemented using any suitable semiconductor switching device technology (e.g., MOSFETs, IGBTs, etc. manufactured using silicon, silicon carbide, or gallium nitride devices).

[0030] Inverter 114 delivers the generated AC voltage to transmitter coil 112. In addition to allowing magnetic coupling to the receiver's wireless coil, Figure 1 The illustrated transmitter coil block 112 may include tuning circuitry (such as additional inductors and capacitors) that facilitates transmitter operation under various conditions, such as different degrees of magnetic coupling to the receiver, different operating frequencies, etc. The wireless coil itself can be constructed in a variety of different ways. In some embodiments, the wireless coil may be formed as a metal wire winding around a suitable spool. In other embodiments, the wireless coil may be formed as a trace on a printed circuit board. Other arrangements are also possible and can be used in conjunction with the various embodiments described herein. The wireless transmitter coil may also include a magnetically permeable material (e.g., ferrite) core configured to influence the flux pattern of the coil in a manner suitable for a particular application. The teachings herein can be applied in conjunction with any of the various transmitter coil arrangements suitable for a given application.

[0031] The PTx controller / communication module 116 can monitor the transmitter coil and use information derived therefrom to control the inverter 114 to suit a given situation. For example, the controller / communication module can be configured to operate the inverter 114 at a given frequency or output voltage depending on the specific application. In some embodiments, the controller / communication module can be configured to receive information from the PRx device and control the inverter 114 accordingly. This information can be received via the power transmission coil (i.e., in-band communication) or via a separate communication channel (not shown, i.e., out-of-band communication). For in-band communication, the controller / communication module 116 can detect and decode signals (such as voltage, frequency, or load changes) applied to the magnetic link by the PRx to receive information, and can command the inverter to modulate the delivered power to transmit information to the PRx by manipulating various parameters of the generated voltage (such as voltage, frequency, etc.). In some embodiments, the controller / communication module can be configured to use Frequency Shift Keying (FSK) communication to transmit data to the PRx, in which the frequency of the inverter signal is modulated. The controller / communication module 116 can be configured to detect amplitude shift keying (ASK) communication or load-modulated communication from the PRx. In either case, the controller / communication module 126 can be configured to change the current drawn on the receiver side to manipulate the waveform seen on the Tx coil, thereby delivering information from the PRx to the PTx. For out-of-band communication, additional modules, such as WiFi, Bluetooth, or other radio links, or any other suitable communication channel, can be provided to allow communication between the PTx and PRx.

[0032] As mentioned above, the controller / communication module 116 can be, for example, a single module disposed on a single integrated circuit, or it can be constructed from multiple modules / devices disposed on different integrated circuits, or a combination of integrated circuits and discrete circuits having both analog and digital components. The teachings herein are not limited to any particular arrangement of the controller / communication circuitry.

[0033] The PTx device 110 may optionally include other systems and components, such as a separate communication module 118. In some embodiments, the communication module 118 may communicate with a corresponding module tag in the PRx via a power delivery coil. In other embodiments, the communication module 118 may communicate with the corresponding module using a separate physical channel 138.

[0034] As mentioned above, the wireless power transmission system also includes a wireless power receiver (PRx) 120. The wireless power receiver may include a receiver coil 122 that is magnetically coupled 130 to the transmitter coil 112. As discussed above, the transmitter coil 112... Figure 1 The illustrated receiver coil block 122 may include tuning circuitry (such as additional inductors and capacitors) that facilitates the operation of the transmitter under various conditions, such as different degrees of magnetic coupling to the receiver, different operating frequencies, etc. The wireless coil itself can be constructed in a variety of different ways. In some embodiments, the wireless coil may be formed as a metal wire winding around a suitable spool. In other embodiments, the wireless coil may be formed as a trace on a printed circuit board. Other arrangements are also possible and can be used in conjunction with the various embodiments described herein. The wireless receiver coil may also include a magnetically permeable material (e.g., ferrite) core configured to influence the flux pattern of the coil in a manner suitable for a particular application. The teachings herein can be applied in conjunction with any of the various receiver coil arrangements suitable for a given application.

[0035] Receiver coil 122 outputs an AC voltage induced therein via magnetic induction from transmitter coil 112. This output AC voltage can be provided to rectifier 124, which provides DC output power to one or more loads associated with the PRx device. Rectifier 124 can be controlled by controller / communication module 126, which operates as further described below. In various embodiments, the rectifier controller and communication module can be implemented in a common system (such as a microprocessor-based, microcontroller-based system). In other embodiments, the rectifier controller can be implemented by a separate controller module and communication module having communication means therebetween. Rectifier 124 can be constructed using any suitable circuit topology (e.g., full-bridge, half-bridge, etc.) and can be implemented using any suitable semiconductor switching device technology (e.g., MOSFETs, IGBTs, etc., made using silicon, silicon carbide, or gallium nitride devices).

[0036] The PRx controller / communication module 126 can monitor the receiver coil and use information derived therefrom to control the rectifier 124 to suit a given situation. For example, the controller / communication module can be configured to cause the rectifier 124 to provide a given output voltage depending on the specific application. In some embodiments, the controller / communication module can be configured to transmit information to the PTx device to effectively control the power delivered to the receiver. This information can be transmitted via the power transmitting coil (i.e., in-band communication) or via a separate communication channel (not shown, i.e., out-of-band communication). For in-band communication, the controller / communication module 126 can, for example, modulate the load current or other electrical parameters of the received power to transmit information to the PTx. In some embodiments, the controller / communication module 126 can be configured to detect and decode signals (such as voltage, frequency, or load changes) applied to the magnetic link by the PTx to receive information from the PTx. In some embodiments, the controller / communication module 126 can be configured to receive frequency shift keying (FSK) communication to convey data to the PRx, in which the frequency of the inverter signal has been modulated. The controller / communication module 126 can be configured to generate amplitude shift keying (ASK) communication or load modulation-based communication from the PRx. In either case, the controller / communication module 126 can be configured to change the current drawn on the receiver side to manipulate the waveform seen on the Tx coil, thereby delivering information from the PRx to the PTx. For out-of-band communication, additional modules, such as WiFi, Bluetooth, or other radio links, or any other suitable communication channel, can be provided to allow communication between the PTx and PRx.

[0037] As mentioned above, the controller / communication module 126 may be a single module disposed on a single integrated circuit, or it may be constructed from multiple modules / devices disposed on different integrated circuits, or a combination of integrated circuits and discrete circuits having both analog and digital components. The teachings herein are not limited to any particular arrangement of the controller / communication circuitry. The PRx device 120 may optionally include other systems and components, such as a communication (“communication”) module 128. In some embodiments, the communication module 128 may communicate with a corresponding module in the PTx via a power delivery coil. In other embodiments, the communication module 128 may communicate with a corresponding module or tag using a separate physical channel 138.

[0038] Many variations and enhancements to the wireless power transmission system 100 described above are possible, and the following teachings apply to any of such variations and enhancements.

[0039] Figures 2A-2BAn electronic device 220 (also described herein as device 220) capable of wirelessly receiving or transmitting power is illustrated, as well as a wireless power receiver (PRx) 230 capable of wirelessly receiving (and optionally also transmitting) power. In some embodiments, device 220 may be a smartphone, but it may be other types of electronic devices, such as tablets, laptops, etc. PRx 230 may be a smartphone, but it may be other types of electronic devices, such as tablets, laptops, etc. PRx 230 also includes accessory devices for use with device 220 or with other electronic devices. In some embodiments, PRx 230 may be an accessory to electronic device 220, such as a smartwatch, wireless earphone charging case, stylus, etc., that is paired with the electronic device in some way. (Such pairing may, but does not necessarily, use...) (Or other protocols.) To facilitate wireless power transfer, the PRx 230 may include wireless power receiver circuitry, such as those described above relative to... Figure 1 The wireless power receiver circuit is described. For the sake of brevity, in Figures 2A-2B Only the wireless power receiving coil 232 is depicted. Similarly, device 220 may include wireless power receiver circuitry as described above, as well as wireless power transmitter circuitry. In some cases, the wireless power receiver circuitry and wireless power transmitter circuitry of device 220 may share one or more components. For example, a single wireless power transmission coil 222 may be used as both a wireless power receiving coil and a wireless power transmitting coil: as a wireless power receiving coil when device 220 operates as a wireless power receiver to receive power from a wireless power transmitter (not shown), and as a wireless power transmitting coil when the device operates as a wireless power transmitter, as described in more detail herein. Other components of the wireless power transmission circuitry of device 220 may also be used in both wireless power receiver mode and wireless power transmitter mode. For example, common control and communication circuitry may be used in both operating modes, and a common switching device may be used as an inverter in wireless power transmitter mode and as a rectifier in wireless power receiver mode.

[0040] Figure 2A Examples of electronic devices 220 and PR x 230 are shown, which are separated from each other in both plan view and cross-sectional view. Figure 2B An example is illustrated where electronic devices 220 and PRx 230 overlap because they will be positioned to facilitate wireless power transfer from device 220 to PRx 230. As illustrated, this overlap allows for the alignment of the corresponding wireless power transfer coils to facilitate wireless power transfer. Finally, as also... Figure 2BAs depicted herein, external power supply 227 can also be connected to electronic device 220. When such external power supply is connected, power from external power supply 227 can be delivered to PRx 230 by electronic device 220 operating in wireless power transmitter mode. Finally, although the description herein refers to electronic devices as capable of operating as wireless power transmitters or wireless power receivers, and PRx 230 as capable of operating as a receiver, the reverse is also possible. For example, PRx 230 may be capable of operating as a wireless power receiver or a wireless power transmitter, wherein electronic device 230 is capable of bidirectional wireless power transmission or acting only as a receiver. Therefore, the principles described herein are equally applicable to any type of electronic device or PRx and should not be limited to any specific example given herein.

[0041] Figure 3 A flowchart 300 illustrates an operating technique for an electronic device capable of wirelessly receiving or transmitting power and a PRx capable of wirelessly receiving power. This process can be performed by any suitable control circuitry and / or processor of the electronic device. This can include, but is not limited to, controllers and communication circuitry of wireless power transmission systems for such devices as described above. For the purposes of the following description, various actions or determinations will be described as being performed by the device, and it should be understood that suitable control circuitry and / or processors of the device (e.g., electronic device 220) are used to perform such actions or determinations. Furthermore, although various actions and determinations are described in a specific order, in some cases, various actions or determinations may be performed in a different order, simultaneously, or even omitted. Therefore, the following description should not be construed as implying any particular order unless such order is expressly or implicitly required by the nature of the particular action or determination.

[0042] The process can begin at the start box 341. Then, in box 342, the device can determine whether the "Wireless Power Transmission (WPTx) Mode" is available. As used herein, "Wireless Power Transmission Mode" can be considered synonymous with a wireless power transmitter operation mode in which the device operates as a wireless power transmitter to deliver power to a PRx device. This power can, but does not necessarily, be used by the PRx device to charge its own battery. In any case, in box 342, various conditions or signals can be used to indicate that the Wireless Power Transmission Mode is available. For example, the device is plugged into an external power source (as described above relative to...). Figure 2BThe described signal can be one such indication. If an external power source is available, the device will have sufficient power to deliver power to the PRx and will not need to wirelessly receive power for its own purposes. Additionally or alternatively, the device's battery charge status can be used to indicate whether the wireless power transmission mode is available. That is, if the device's battery charge is above a certain threshold, it may be able to deliver power to the PRx device. Conversely, if the device's battery charge is below a certain threshold (which may be the same threshold or a different threshold), the device may not have sufficient power reserve to deliver power to the PRx device. Additionally or alternatively, explicit user actions can be used alone or in combination with other conditions or signals to indicate the availability of the wireless power transmission mode. Device orientation can be such a user action. For example, placing a smartphone face down allows the user to place the PRx device on the back of the smartphone, thereby allowing coupling of the corresponding wireless power transmission coil. Other orientations may be suitable for different device types. In some applications, a physical switch or user interface power indicator may be provided to allow the user to indicate that the wireless power transmission mode should be used. Each of the foregoing signals, as well as other signals, can be used alone or in various combinations to indicate the availability of the wireless power transmission mode.

[0043] In box 342, if it is determined that the wireless power transmission mode is unavailable, then in box 344, it can be determined whether a wireless power transmitter device (PTx) has been detected. If not, the process can return to the start box 341. Otherwise, if a wireless power transmitter is detected, then in box 350, electronic device 220 can receive power from the wireless power transmitter device. In box 351, it can be determined whether the charging of the internal battery of electronic device 220 is complete. If not, receiving wireless power from the wireless power transmitter can continue. If yes, the process can end (box 349) and can also optionally return to the start box 341. Additionally or alternatively, receiving wireless power from the wireless power transmitter in box 350 is not necessarily limited to charging the device's internal battery. For example, the received wireless power can also be used to power electronic device 220, and in such cases, it may be desirable to continue receiving wireless power from the wireless power transmitter indefinitely as long as electronic device 220 is consuming power.

[0044] Returning to box 341, if the wireless power transmission mode is determined to be available, then in box 343, the device can determine whether a PRx is detected. This type of PRx is one capable of receiving wireless power from a device operating in wireless power transmitter mode; however, such a PRx may also be capable of operating as a wireless power transmitter itself, as described above. If no PRx is detected in box 343, then the presence of a wireless power transmitter can be determined in box 344, as described above. Otherwise, if a wireless power receiving PRx is detected in box 343, then in box 345, it can be determined whether sufficient power is available to deliver power to the PRx device. This can be determined by factors such as whether an external power supply is connected, the charging status of the device's own battery, etc. Such determinations can be performed as described above relative to box 342, and can be performed in one of the following ways: if they are used to indicate the availability of the wireless power transmission mode, they are performed again; performed independently; or omitted entirely at this stage and a similar determination is made in conjunction with box 342. In the illustrated example, if insufficient power is available, the technique can terminate (box 349) and optionally return to the start box 341. Otherwise, the technique can proceed to PRx authentication in box 346.

[0045] In box 345, PRx authentication can be performed to verify that the device is suitable for wirelessly receiving power from a device operating in wireless power transfer mode. Various authentication schemes and communication modes can be used depending on the requirements of the specific system. In some applications, authentication can be omitted. In any case, authentication can rely on data exchange, i.e., communication between the PRx and the device, where this communication is used by the device to identify the PRx and confirm that it is appropriate for the PRx to wirelessly power the device, optionally even based on authentication to determine appropriate wireless power transfer parameters (e.g., power level, operating frequency, etc.). Communication between PRx devices can be in-band communication achieved by modulating one or more characteristics of the wireless power transfer link (e.g., voltage or current amplitude, frequency, etc.), or out-of-band communication using alternative communication channels, such as... NFC (Near Field Communication), etc. In some cases, the device can use its own resources to authenticate the PRx. In other cases, the device can communicate with a second device via a network to perform or assist authentication. In any case, if the PRx is not authenticated, the process can end (box 349), optionally returning to the start box 341. Otherwise, if the PRx device is authenticated, wireless power transfer to the PRx can begin (box 347).

[0046] In box 347, the device can transfer power to the PRx / accessory. In box 348, it can be determined whether the charging of the PRx's internal battery is complete. If not, wireless power transfer can continue. If yes, the process can end (box 349) and can also optionally return to the start box 341. Additionally or alternatively, the wireless power transfer from the device to the PRx in box 347 is not required to be limited to charging the device's internal battery. For example, the received wireless power can also be used to power an electronic device, and in such cases, it may be desirable to continue receiving wireless power from the wireless power transmitter indefinitely, or to stop such wireless power transfer based on some other condition, such as the availability of an external power connection or sufficient battery power in the electronic device.

[0047] The above references Figure 3 The activation of the described wireless power transmission mode can be based on various triggering techniques. In some cases, this mode can be triggered by inductive detection and at least some in-band communication between the device and the PRx. The following is in contrast to... Figures 4-7 Describe this type of arrangement in more detail.

[0048] Figure 4 A flowchart 500 illustrates a first inductive triggering technique for a wireless power transmitter mode of an electronic device (e.g., electronic device 220) capable of wirelessly receiving or transmitting power. As described above, the flowchart illustrates exemplary steps in a specific order, but some steps may be omitted, other steps may be added, and / or the order of at least some steps may be changed if appropriate for a given implementation. In this case, the triggering of the wireless power transmission mode of device 220 is based on the inductive detection of PRx using a corresponding circuit that detects PRx using the device's wireless power transmission circuitry. Otherwise, flowchart 500 can be considered as above relative to... Figure 3 The flowchart 300 described is a subset, simplification, or variation thereof. As mentioned above, the techniques illustrated in the flowchart can be performed by a device, such as by combining or replacing the device's wireless power transmission controller and communication circuitry and / or any other control circuitry and / or processor of such a device. Figure 3 The process is executed according to the flowchart illustrated.

[0049] Starting at box 561, the process can proceed to box 562, where it is determined whether a PRx device has been inductively detected. This inductive detection can be performed using techniques defined by standards (such as the Qi standard described above) or proprietary techniques. Generally, such techniques may include periodically measuring one or more electrical or magnetic characteristics of the device's magnetic circuitry, such as the quality factor Q of the device's wireless power transmission coil. This Q factor will vary depending on whether it is measured "outdoors," when the PRx is absent, or when the PRx device is present. This difference can be used to determine the presence of the PRx. Additionally, the coupled Q can vary depending on whether the PRx device's wireless power transmission coil is open or short-circuited, as described in more detail below. Other parameters, such as resonant frequency, may be used alternatively or additionally, as many electrical and magnetic characteristics are affected by the presence or absence (i.e., proximity) of the wireless power receiver.

[0050] If no PRx device is detected inductively, the process can return to the start box 561 to periodically check for the presence of the PRx (or a potential wireless power transmitter, as described in more detail below). Otherwise, if a potential PRx is detected in box 562, the device can send a wireless power receiver query to the PRx in box 563. That is, the device can transmit an in-band signal by modulating a signal delivered to the wireless power transmission coil. This query can be based on a standard (such as the Qi standard described above) or on a proprietary protocol. In either case, the intention is to establish communication with the potential PRx by sending a message that will cause the PRx to respond in a known manner that allows its identification. Therefore, in box 564, the device can listen for the response of the wireless power receiver. This response can be based on expectations corresponding to the standards and / or proprietary protocols in use. In some embodiments, the device can be configured to attempt to establish communication according to multiple protocols (such as one or more standardized protocols and / or one or more proprietary protocols) to allow interoperability with various wireless power receiver devices.

[0051] It may be desirable to have a time limit on the time the device spends waiting for a response from a PRx. Therefore, in box 565, the device can determine whether a timeout interval has elapsed. If the timeout in box 565 has expired, the device can infer that the potential PRx detected in box 562 is indeed a wireless power transmitter. Therefore, in box 566, the device can send the expected PRx response to the (inferred) wireless power transmitter. As mentioned above, this response can be based on one or more standard protocols (e.g., those specified by the Qi standard) and / or on one or more proprietary protocols. In either case, this can result in the device operating as a wireless power receiver and thus receiving power from such a wireless power transmitter (box 567). The timeout interval can be selected to allow error-free establishment of communication and power transfer with a wireless power transmitter operating according to a standard or proprietary scheme. For example, according to at least some embodiments of the Qi standard, a 19 ms timeout interval can allow the device to establish communication with a wireless power transmitter operating according to such a Qi standard. In other words, if PRx begins transmitting a wireless power receiver response to the device 19 ms after the initial sensing detection in box 562, the necessary requisite negotiation between the device and PRx can continue if the device is operating in wireless power transmitter mode. Otherwise, if receiving a wireless power receiver response has not begun before the timeout interval (e.g., 19 ms), the device can switch to wireless power receiver mode and establish communication with the wireless power transmitter before the normalized timeout / communication failure interval expected by the wireless power transmitter. The following is relative to... Figure 5 Other aspects of the timing of such signals will be discussed in more detail.

[0052] Otherwise, if the device determines in box 565 that the timeout has not yet expired, then in box 568 the device can determine whether it has received the expected wireless power receiver response. As mentioned above, such a response can be specified by a standard or proprietary communication scheme, such as: a ping or other message according to the Qi protocol; or by the modulation of the wireless power transmission signal by the PRx (which is interpreted by the device as identifying the PRx device). In either case, if an appropriate response is received, the device can operate in wireless power transmission mode, thereby transmitting power to the PRx (box 569). Otherwise, the device can continue listening for responses until the timeout expires, thereby operating the device in wireless power receiver mode as described above.

[0053] Figure 5A timing sequence 600 for a first inductively triggered technique for a wireless power transmitter mode of an electronic device (e.g., electronic device 220) capable of wirelessly receiving or transmitting power is illustrated. The timing sequence includes an upper device sequence and a lower PRx sequence. Timing sequence 600 depicts a series of operations or events 671 to 680b occurring over specific time intervals (e.g., T1, T3, ..., T15) indicated by an uppercase letter “T” followed by an odd number, where each timer interval has a corresponding start or end time (e.g., t0, t2, ..., t14) indicated by a lowercase letter “t” followed by an even number. Additionally, the time and time interval of PRx are indicated by a “-1” suffix. Starting from the device, an initialization period 671 may exist during interval T1, which begins at time t0 and ends at time t2.

[0054] After initialization, there may be a function designed to query whether the detected device is a wireless power receiver transmitter. Figure 5 This is referred to as FSK transmission 672 because, according to the Qi standard (and in at least some proprietary wireless power transmission schemes), the wireless power transmitter communicates with the wireless power receiver in-band via Frequency Shift Keying (FSK). That is, the wireless power transmitter (in this case, the device operating in wireless power transmitter mode) communicates with the receiver by modulating the frequency of a signal applied to the wireless power transmitting coil and detectable on the wireless power receiving coil to encode the message to be transmitted. However, in some implementations, any suitable query on the detected potential PRx can be used. Figure 5 As illustrated, FSK transmission 672 occurs during interval T3, starting at time t2 and ending at time t4. However, FSK transmission 672 or other comparable receiver queries do not necessarily occur immediately after initialization, as other intermediate activities may exist. In any case, after FSK transmission 672, the device may enter an ASK listening period 673, which may occur during a time period T5, starting at time t4 (i.e., at the end of FSK transmission 672 or other comparable queries) and ending at time t6, which may be the timeout interval described above. Again, this is designated as ASK listening because, according to the Qi standard and at least some proprietary wireless power transmission schemes, the wireless power receiver communicates with the wireless power transmitter via amplitude shift keying (ASK), where the amount of power or current drawn by the wireless power receiver is modulated to encode the information transmitted from the wireless power receiver to the wireless power transmitter.

[0055] At time t6, corresponding to the timeout period described above, device operation is dispersed depending on whether the device has received a proper wireless power receiver response from the potential PRx. If no response is received, the upper branch is followed, where the device begins operation in wireless power receiver mode by participating in ASK transmission 674. This is also referred to as ASK transmission because at least some standard and proprietary wireless power transmission schemes allow the wireless power receiver to participate in in-band communication with the wireless power transmitter via amplitude shift keying. However, depending on the wireless power transmission scheme employed, other suitable wireless power receivers may be used to initiate communication. This communication may occur during the interval T7, which begins at time t6 (i.e., the expiration of the timeout interval) and continues until time t8. Then, during the interval T9, which begins at time t8 and continues until time t10, the device may enter negotiation 675, during which a wireless power transmission contract may be negotiated and agreed upon. Thereafter, starting at time t10, during the interval T11, the device can wirelessly receive power from the wireless power transmitter. As described, this reception of wireless power transmission can continue until the device's battery is fully charged, or even after that (if the device is powering other systems from the received wireless power).

[0056] Otherwise, if the device receives an appropriate wireless power receiver response from the PRx, the device can... Figure 5 The device operates in the wireless power transmitter mode described in the lower branch of the device section. That is, negotiation 679a can occur during interval T13, which begins at or before time t6 and ends at time t12. Thereafter, the device can transmit power 680a during interval T15, which begins at time t12 and continues until time t14. Time t14 can be associated with the PRx's battery being fully charged, the PRx being removed from the device's vicinity, or the PRx otherwise no longer needing to receive wireless power from the device. These operations can also correspond to the PRx operations described in the lower PRx path of timing 600.

[0057] More specifically, the PRx may begin with initialization 677 during an interval T3-1, starting at time t0-1 and ending at time t4-1. The precise timing of this initialization interval relative to the PRx device operation is not critical, but it is expected to occur and complete early enough for the PRx to receive the FSK transmission 672 described above. This prompts the PRx to return an ASK transmission 678 to the device, which occurs during an interval T5-1, exemplified as starting at time t4-1 and ending before time t6 (i.e., the timeout described above). As mentioned above, this communication is described as ASK communication because such communication is used in at least some standardized and proprietary wireless power transmission and in-band communication schemes; however, other communication modes may be employed if desired. Otherwise, the precise timing of ASK transmission 678 (or other comparable communication) is not critical, except that the message must be transmitted within a sufficient time before the device returns to the wireless power receiver mode as described above so that the device can detect the message and continue operating in the wireless power transmitter mode. Therefore, it is possible that the ASK transmission 678 communication is completed before timeout T6, or if partial communication has already been received, the device can extend the ASK listening 673 interval to allow the device to enter wireless power transmitter mode and establish wireless power transmission to PRx. In either case, starting from time t6, PRx can participate in negotiation 679b corresponding to negotiation 679a discussed above with respect to the device. These will occur during the same interval T13 discussed above. Once the negotiation is complete, PRx can receive power 680b during interval T15, which corresponds to the transmitted power 680a discussed above and also occurring during the same interval.

[0058] The timing discussed above is merely an example, and in some cases, the described basic principles can be implemented with slightly different timing. It may be desirable to choose timing with certain objectives in mind, such as allowing the device to revert to wireless power receiver mode before the wireless power transmitter determines a communication failure has occurred and / or allowing the device to enter wireless power transmit mode and establish wireless power transfer with the PRx as quickly as possible to provide a better user experience. Otherwise, specific timing requirements can be defined by the particular wireless power transfer scheme employed, potentially including any in-band communication timing associated with such scheme, whether defined by a standard (such as the Qi standard) or one or more proprietary schemes.

[0059] The above references Figure 4 and Figure 5A first inductive triggering scheme for a device's wireless power transmitter mode is described. This first inductive triggering scheme employs specific timing of communications transmitted and received by the device to allow the device to infer whether it should enter wireless power transmitter mode and deliver power to the PRx, or enter wireless power receiver mode in which the device receives power from the wireless power transmitter. Figure 6 and Figure 7 A second inductive triggering scheme, which may also be used or alternatively, is illustrated. This alternative can be considered a "handshake" alternative because it relies on special signaling that does not interfere with, but is not necessarily specified by, the standardized timing arrangement described above.

[0060] Figure 6 A simplified schematic diagram 700 of a wireless power transmission system is illustrated, showing aspects related to a second inductive triggering technique for a wireless power transmitter mode of an electronic device (e.g., electronic device 220) capable of wirelessly receiving or transmitting power. In the simplified diagram, the wireless power transmitter (i.e., the device) is represented by an inverter 714 and a wireless power transmitting coil 712. For simplicity, other components such as controllers and communication circuits, wireless power receiving circuits, and omitted wireless power transmitting circuits have been omitted, but these components may be included as described above. The remaining components of the simplified schematic diagram 700 are simplified representations of PRx, represented by a wireless power receiving coil 722 and a rectifier 724. For simplicity, other components such as controllers and communication circuits, additional wireless power receiver circuits, etc., have been omitted, but these components may be included as described above.

[0061] The PRx circuit also includes switches 782a and 782b, and a rectifier short-circuit control and switching node voltage detection circuit 781. The latter can be part of the PRx circuit as described above and can be constructed using any suitable combination of analog, digital, and / or programmable circuitry and / or logic components, operating as described in more detail below. The rectifier short-circuit control and switching node voltage detection circuit 781 can monitor the voltage at the switching nodes (represented by points A and B) of the rectifier 724 to detect whether the inverter 714 of the device is operating. The rectifier short-circuit control and switching node voltage detection circuit 781 can also control switches 782a and 782b to selectively short-circuit (or open-circuit) the PRx's wireless power receiving coil 722 to alter the visible circuit or magnetic characteristics of the device via coupling to the wireless power transmitting coil 712. (See below for more details.) Figure 7 As described, this configuration and its controlled operation allow sensing and triggering of the wireless power transmitter mode in the device when a suitable PRx is brought into the range of the device.

[0062] Figure 7Timing 800 of a second inductive triggering technique for a wireless power transmitter mode of an electronic device (e.g., electronic device 220) capable of wirelessly receiving or transmitting power is illustrated. Figure 7 The left side depicts operations that can be performed by the device (e.g., by wireless power transfer control and communication circuitry as described above). Figure 7 The right side depicts operations that can be performed by the PRx (e.g., by the wireless power transmission control and communication circuitry as described above). Corresponding operations are labeled with reference numerals, ending with "a" for devices / wireless power transmitters and "b" for PRx devices.

[0063] Beginning at box 891a, the device can periodically transmit a “low-power ping” to detect when a potential wireless power receiver (PRx) is brought into close range. This low-power ping can be based on a standardized wireless power transfer protocol, such as the Qi standard described above, or on a proprietary wireless power transfer protocol. As an example, a low-power ping is an electrical pulse supplied with power below the typical voltage and / or wattage level used for wireless power transfer. Once a potential PRx is detected, in box 892, the device can briefly enable the inverter for a short period (e.g., approximately tens of milliseconds), which allows a small amount of power to be delivered to the potential PRx, thereby allowing the potential PRx to perform the operations described below, even if the potential PRx has a depleted battery or other lack of internal power. After this short period, the device can stop inverter operation and measure one or more electrical or magnetic characteristics of the circuitry, such as quality factor (Q), resonant frequency, inductance, etc., which will be affected in a known manner based on the presence of the PRx, and can be further used to identify the PRx or obtain other information about the PRx and / or the wireless power link, as further described below.

[0064] In response to a low-power ping 891a and / or brief operation of the inverter of the device as described above, the PRx can wake up (box 891b) and detect that the inverter has stopped (box 893b). For example, the control circuitry of the PRx may include the circuitry described above. Figure 6 The rectifier short-circuit control and switching node voltage detection circuit 781 is described. In response to the device deactivating its inverter, PRx can, for example, be activated by closing the circuit relative to the above... Figure 6 The described switches 782a and 782b short-circuit its wireless power receiving coil (box 894b), which can also be accomplished under the guidance of the rectifier short-circuit control and switching node voltage detection circuit 781. This short circuit of the PRx's wireless power receiving coil can be achieved by measuring the quality factor Q and resonant frequency f in box 894a. resAnd / or other suitable electrical or magnetic parameters of the wireless power transmission circuitry for detection. By comparing the quality factor Q and / or other parameters measured from block 893a with the corresponding measurements performed in block 894a, the device can detect that the PRx has short-circuited its wireless power receiving coil (in block 894b), and thus can infer the presence of a potential PRx, and can take further steps to identify or characterize such a PRx device.

[0065] More specifically, operations 895a and 896a can be repeated multiple times. Operation 895a involves starting the inverter and stopping it again after a short period of time. As an example, as described above, this time could be approximately tens of milliseconds. This start-up and stop of the inverter can have at least two functions. One is to provide a signal and associated timing for communication with the potential PRx, which can be detected by voltage fluctuations at the switching nodes of the rectifier, as described above. The other is to provide a small amount of power transfer to power the PRx's wireless power receiving circuitry, even if the PRx's own battery or other internal power source does not have sufficient power to power the PRx's wireless power receiving circuitry. After each inverter start / stop cycle, the device can measure the quality factor Q and / or other parameters to detect a corresponding short circuit or open circuit in the PRx's wireless power receiving coil via the PRx device's control circuitry. This corresponding short circuit or open circuit can be used to encode identification information, as described below.

[0066] Corresponding to device operations 895a and 896a, the PRx can perform operations 895b and 896b, which can be repeated multiple times. In operation 895b, the PRx device (using its controller circuitry) can detect the cessation of inverter operation, and in response, can either short-circuit its wireless power receiving coil (e.g., by closing switches 782a and 782b) or not short-circuit the coil (e.g., by opening switches 782a and 782b) in operation 896b. This allows the device to detect different quality factor Q and / or other parameter values ​​in operation 896a. Therefore, the PRx can transmit data, such as data encoded using 1s and 0s, which correspond to whether the PRx short-circuits or does not short-circuit its wireless power receiving coil in response to the inverter start / stop operation performed by the device. Thus, each start / stop cycle can allow a single bit of data (e.g.) to be transmitted from the PRx to the device. If the cycle is repeated 32 times (e.g.), 32 bits of data can be transmitted. This can include a digital identifier for the PRx, allowing the device to determine whether the PRx is a device to which it can appropriately provide wireless power by activating the device's wireless power transmitter operating mode (Operation 897a). This exchange of information from the PRx to the device via a selective short circuit of the PRx wireless power transmission coil can be considered a "handshake".

[0067] In some cases, Operation 897a may include further verification or authentication of the PRx device before initiating wireless power transmission. For example, some wireless power receivers may be able to transmit power via other channels such as... NFC and other communication methods are used with the device. In some cases, this auxiliary channel can also be used alone or in conjunction with the "handshake" for PRx authentication. That is, the PRx can transmit its identification information via one of the other channels, and this identification information can be used by the device to authenticate the wireless power receiver independently of or in conjunction with the handshake data. In any case, if authentication is successful, wireless power transfer can be initiated in Operation 897a; otherwise, the device can return to... Figure 7 The operation described herein begins, for example, with periodic low-power pings to detect the presence of the PRx. Correspondingly, if authentication is successful, the PRx device can cooperate with the initiation of wireless power transfer (operation 897b), wherein the resulting initiation of wireless power transfer is performed according to a standard or proprietary protocol, as described elsewhere herein.

[0068] Figure 8A flowchart illustrating an inductive triggering technique 801 for selecting a wireless power transmitter mode or a wireless power receiver mode in an electronic device capable of operating as a wireless power transmitter or a wireless power receiver as described above is provided. In some applications, the electronic device may have firmware, such as firmware stored in and / or executed by the control and communication circuitry as described above. In some cases, such firmware may be able to operate the wireless power transmission circuitry to function as both a wireless power receiver and a wireless power transmitter, in which case... Figure 8 The triggering technique 801 can be mode selection for combined firmware. In other applications, there may be separate firmware modules related to wireless power transmitter operation and wireless power receiver operation. In this case, mode selection may also include loading appropriate firmware once the electronic device (e.g., through its wireless power transmission system control and communication circuitry) determines the desired operating mode. In either case, the technique can begin at block 841, where the electronic device is operating in a hybrid mode that allows the device to detect when a wireless power receiver or wireless power transmitter is placed near the electronic device. If the wireless power receiver is placed within range, the electronic device can operate in wireless power transmitter mode. Alternatively, if the wireless power transmitter is placed within range, the electronic device can operate in wireless power receiver mode.

[0069] In box 842, the electronic device can perform the ultra-low power object detection or uLP OD described herein. The following will refer to... Figure 9 and Figure 10 This uLPOD operation will be described in more detail. For the purposes of this discussion, the uLPOD mode can be considered a very low-power technique for detecting the presence of objects approaching electronic devices. In some prior art wireless power transmission systems, object detection is performed using low-power pings (LPPs), which supply intermittent pulses to the wireless power transmission coil using a wireless power transmission circuit (such as an inverter in a wireless power transmitter). The presence of an object (such as a foreign object or a corresponding wireless power transmission device) can alter the magnetic and / or electrical characteristics of the wireless power transmission circuit, and thus allow for the detection of such objects by measuring the response to such intermittent pulses / low-power pings. However, in at least some cases, using a wireless power transmission circuit for this purpose may result in higher power consumption, which may be undesirable in some specific implementations. Therefore, the following discussion, relative to... Figure 9As described, alternative circuitry can be provided to excite the wireless power transmission coil of an electronic device using periodic pulses with a smaller magnitude and lower frequency than conventional LPP or other similar pulses, thereby allowing object detection with lower power consumption. As an example, uLPOD pulses can be provided to the wireless power transmission coil at a frequency of 10 Hz by auxiliary circuitry. If no change in circuit parameters corresponding to the presence of an object is detected within a specific time period T1 (e.g., approximately several hundred milliseconds), the operation in block 842 can continue until such an object is detected.

[0070] Otherwise, if the presence of an object is detected in box 842 in response to a uLPOD pulse, then in box 843, further identification steps can be performed to identify the object that has been placed within the proximity range. The following is in contrast to... Figure 10 and Figure 11 These techniques, described in more detail below, can be used to characterize an object as either a wireless power receiver device or a wireless power transmitter device. In some implementations, this may include a frequency sweep signal applied to the wireless power transmission coil, where the frequency response is used to characterize the object as a wireless power transmitter, wireless power receiver, foreign object, free air, etc. If the detected object is identified as a wireless power transmitter, the process proceeds to block 851, where a path toward operating the electronic device in wireless power receiver mode can be selected, as described in more detail below. Otherwise, if the detected object is characterized as a wireless power receiver at block 843, the electronic device may proceed to block 844 and operate in wireless power transmitter mode. In some specific implementations, if the detected object is characterized as not a wireless power transmitter, the process defaults from block 843 to block 844. As described in more detail below, the identification process may take approximately tens of milliseconds.

[0071] Continuing toward operating the electronic device in wireless power transmitter mode, in block 844, the electronic device (e.g., using its wireless power transmission system control and communication circuitry) can provide a low-power pin g (LPP) to determine whether the assumed wireless power receiver device is in a stable position suitable for initiating wireless power transmission. In some embodiments, this may include operation conforming to one or more industry-standard protocols for wireless power transmission, such as the Qi series wireless power transmission standards issued by the Wireless Power Consortium, including but not limited to the Magnetic Power Division (MPP) standard. In some embodiments, the operation of block 844 may also, or alternatively, include one or more proprietary protocols for detecting the presence of the wireless power receiver device in a stable position to establish wireless power transmission. The operation of block 844 may continue until the wireless power receiver is stabilized in a position suitable for initiating wireless power transmission.

[0072] Then, in block 845, the electronic device can initiate a digital ping and FSK handshake to initiate wireless power transfer with the wireless power receiving device. In some embodiments, this can be done according to an industry-standard wireless power transfer protocol, such as the Qi protocol described above. In other embodiments, this can be done alternatively or additionally according to a proprietary wireless power transfer protocol. In many cases, such as wireless power transfer devices operating according to the Qi protocol, the wireless power transmitter can use in-band communication to communicate with the wireless power receiver, which is achieved by using frequency shift keying modulation of the wireless power signal, wherein data is encoded by perturbation of the frequency of the wireless power transfer signal (e.g., by the wireless power transmitter modulating the switching frequency of its inverter). Similarly, the wireless power receiver can use in-band communication to communicate with the wireless power transmitter, which is achieved by using amplitude shift keying (ASK) modulation of the wireless power signal, wherein data is encoded by perturbation of the amplitude of the wireless power transfer signal (e.g., by the wireless power receiver modulating its load).

[0073] Therefore, after initiating the FSK handshake in box 845, the electronic device may wait for an ASK acknowledgment from the wireless power receiving device in box 846. In some cases, a timeout may occur (e.g., a first threshold T3). If no ASK acknowledgment is received within this time frame (which may but does not need to be specified by the standard or proprietary protocol in use), the digital ping may be stopped in box 849, and the electronic device may transition to the receiver mode path, as described in more detail below. Otherwise, if an ASK acknowledgment is received from the device, the digital ping process may be extended in box 847, wherein the electronic device transitions to the wireless power transmitter operating mode in box 848, which may include loading the complete wireless power transmitter firmware (if required).

[0074] A portion of the hybrid operation mode of block 841 may also include observing object detection signals, such as low-power pings or ultra-low-power object detection (uLPOD) pulses associated with a wireless power transmitter, in block 850. This operation may be continuous or intermittent and may be performed in parallel with the object detection operation described above. If an electronic device is placed near a wireless power transmitter, the wireless power transmitter will emit object detection signals, for example, according to one or more of the techniques described above and / or the Qi standard. If these object detection signals are detected, the electronic device can infer its proximity to the wireless power transmitter and thus activate the wireless power receiver operation mode. In some cases, the presence of a wireless power transmitter near the electronic device can also be detected by the presence of the rectifier output voltage (Vrect) caused by a low-power ping or other comparable operation in the wireless power transmission system of the electronic device.

[0075] In any case, if an object detection ping or rectifier output voltage Vrect is detected, in box 851, the electronic device can determine whether its rectifier output voltage Vrect has reached a predetermined threshold within a second time threshold T4. This is also the point the process will reach if no ASK acknowledgment is received in box 846 discussed above. In either case, if Vrect has not reached the programmed threshold within time threshold T4, the process can return to box 841, and the detection mode described above can continue. Otherwise, if so, the electronic device can operate in wireless power receiver mode (box 852), which may include loading a wireless power receiver firmware module if necessary.

[0076] Figure 9 A simplified schematic diagram 900 illustrates an ultra-low power object detection (uLPOD) pulse injection circuit 955a and a uLPOD and low power ping (LPP) detection circuit 955b for an electronic device. As described above, a wireless power transmitter may include an inverter 114 driving a wireless power transmitting coil 112. Similarly, a wireless power receiver may include a rectifier 124 driven by a wireless power receiving coil 122. For electronic devices capable of operating as either a wireless power transmitter or a wireless power receiver, the coil can be generally categorized as a wireless power transmission coil 952, which may be coupled to an inverter and / or rectifier represented by an inverter / rectifier 954 (which may use the same switching devices or separate switching devices as needed). As described above, it may be advantageous to provide uLPOD pulses that excite the wireless power transmission coil 952 to detect the presence of objects (such as foreign objects, wireless power transmitters, or wireless power receivers) near the electronic device while using less power than would be consumed by using an inverter / rectifier 954 to provide these signals.

[0077] For this purpose, a uLPOD injection circuit 955a can be provided for coupling to the wireless power transmission coil 952. The uLPOD injection circuit 955a can be part of the controller and communication circuitry of the wireless power transmission system of an electronic device, or it can be a separate circuit suitable for a given embodiment. Therefore, the uLPOD injection circuit 955a can include generating the above-referenced... Figure 8 See below for reference Figure 10The described uLPOD pulse is an injection circuit for a uLPOD pulse. For example, these pulses can be provided at a relatively low rate (e.g., 10 Hz) and can have relatively small values ​​(e.g., 1.2 V). In some embodiments, a 1.2 V rectangular wave generator can be provided to generate such pulses. However, this is merely an example, and other waveforms of other amplitudes and / or frequencies can be appropriately used to achieve the desired uLPOD pulse, which can consume less power than object detection techniques that rely on inverter / rectifier 954 to generate LPP or similar pulses. The system may also include a uLPOD / LPP detection circuit 955b that can monitor the wireless power transmission coil 952 to measure the response to uLPOD. Depending on the measurement technique to be used, such circuitry may include voltage and / or current sensors, amplifiers, sample-and-hold circuits, comparators, analog-to-digital converters, mixers, etc. The uLPOD injection circuit 955a and the uLPOD / LPP detection circuit 955b can be selectively and alternately coupled to the wireless power transmission coil via suitable switching circuitry, etc. Additional protection circuitry can also be provided to selectively disable the uLPOD circuitry in response to a received wireless power signal, since the wireless power signal may be large enough to damage the uLPOD circuitry configured to operate at a much lower amplitude and power level.

[0078] In some implementations, the uLPOD / LPP detection circuit 955b may include additional circuitry for detecting low-power pings (LPPs) such as those provided by a wireless power transmitter operating according to one or more of the Qi standards described above. Depending on the specific system, this may be the same circuitry as the uLPOD detection circuitry described above, or it may be separate circuitry adapted to a given implementation and the corresponding characteristics of the uLPOD and LPP signals.

[0079] Figure 10 The timing sequence of a detection and identification technique 1000 for a wireless power receiver in an electronic device is illustrated. The timing sequence 1000 may include an object detection segment 1061, which may correspond to the above reference. Figure 8 Box 842 is for discussion. Timing 1000 may also include an identifier segment 1064, which may correspond to the reference above. Figure 8 Box 843 is discussed. Timing 1000 may also include a low-power ping (LPP) segment 1067, which may correspond to the above reference. Figure 8 Box 844 is discussed. Timing 1000 may also include digital ping and FSK / ASK handshake means 1068, which can correspond to the above reference. Figure 8Discuss boxes 845 to 848.

[0080] More specifically, the object detection segment 1061 may include transmitting a plurality of uLPOD pulses 1062. As described above, these pulses may be transmitted at a relatively low rate (e.g., 10 Hz) and may have a relatively low amplitude (e.g., 1.2 V), but other pulse rates and amplitudes may be used. During this time, the electronic device can monitor the response of its wireless power transmission coil, because the presence of an object such as a foreign object, wireless power receiver, or wireless power transmitter can load the wireless power transmission coil in such a way that, for example, the above reference can be used. Figure 9 The described circuitry detects the response to a uLPOD pulse. In some cases, during the object detection phase, if the response indicates the possible presence of a device, the electronic equipment can increase the pulse rate of the uLPOD pulse. For example, the uLPOD pulse 1063 can be transmitted at shorter intervals (e.g., 50 ms) to confirm that the device has been placed within range, where more frequent measurements or observations can provide a more reliable indication.

[0081] The identifier segment 1064 can be executed in various ways. In some implementations, one or more frequency scans or sweeps 1065, 1066 can be performed. See below for reference. Figure 11 In more detail, the various objects detected by object detection segment 1061 can respond differently at different frequencies. That is, the effects of these various objects on the electrical and magnetic characteristics of circuitry, including the wireless power transmission coil of an electronic device, can cause different responses, as described below. Figure 11 As described. Therefore, by performing one or more frequency scans 1065, 1066, the type of object brought into the range of the electronic device can be characterized as a wireless power receiver (causing activation of the wireless power transmitter mode of the electronic device), a wireless power transmitter (causing activation of the wireless power receiver mode of the electronic device), or a foreign object (e.g., causing reduction and / or suppression of wireless power transmission).

[0082] Frequency sweeps 1065 and 1066 can be performed using the wireless power transmission circuitry itself (e.g., inverter 114 of the wireless power transmission circuitry in an electronic device), or by auxiliary circuitry (e.g., uLPOD injection and detection and LPP detection circuitry 955). In either case, the circuitry can be operated to provide a signal sweeping a desired frequency range, and the response can be measured at various frequencies. By detecting one or more peaks (corresponding to resonant frequencies, as discussed below), objects approaching the electronic device can be characterized as wireless power receivers, wireless power transmitters, foreign objects, etc. In some embodiments, the frequency range can be from about 600 kHz to about 2 MHz, but the specific range of interest can correspond to the designed wireless power transmission frequency, the characteristics of the corresponding device, etc. Frequency sweeping can be achieved by providing a continuous sweep of the range of interest, or in some embodiments, by providing discrete signals at fixed intervals over the range. For example, the frequency range of interest can be decomposed into intervals from 25 kHz to 100 kHz. In the latter case, each frequency step can operate within a given time period (e.g., about 0.5 ms), but other times can also be used. This can lead to several to dozens of measurements at different frequencies being used to generate response curves, as shown in the reference below. Figure 11 Those described. Therefore, the characterization of this curve, as described in more detail below, can identify objects near electronic devices.

[0083] Assuming that identification segment 1064 (e.g., associated frequency scans 1065, 1066) determines that the object detected during object detection segment 1061 is a wireless power receiver, the electronic device can begin low-power pinging 1067, as described above relative to... Figure 8 As described in box 844. Thereafter, the wireless power transmitter mode operation of the electronic device can continue with digital ping (DP) in digital ping and FSK / ASK handshake means 1068. These can be followed by FSK handshake initiation (1069a) and ASK handshake response 1069b from the wireless power receiver. As described above, the result can be the establishment of wireless power transmission from the electronic device to the wireless power receiver according to an industry-standard wireless power transmission protocol or a proprietary wireless power transmission protocol. In either case, the establishment of the wireless power transmission can be indicated to the user via a bell or other audible, visual, or other feedback mechanism after the negotiation and establishment of the wireless power transmission.

[0084] Figure 11A graph 1100 illustrates a series of identification frequency response curves 1171 to 1174 for detection and identification of a wireless power receiver or wireless power transmitter by an electronic device. These response curves 1171 to 1174 may correspond to exemplary responses to frequency sweeps or scans as described above. Curve 1171 may correspond to free air, meaning the resonant peak is simply the resonant peak of the wireless power transmission circuitry of the electronic device itself, unaffected by external components. In some embodiments, this curve may correspond to a single peak at approximately 800 kHz, but this can vary depending on the construction of the electronic device itself, its wireless power transmission circuitry (including the designed operating frequency), etc. Curve 1172 may correspond to a wireless power transmitter device. In at least some embodiments, such a device may be characterized by a single peak (e.g., a single peak at approximately 600 kHz), but this can also vary depending on the construction of the electronic device, the wireless power transmitter, their respective wireless power transmission circuitry (including the designed operating frequency), etc. The transmitter peak frequency or resonant frequency may be a known frequency associated with a wireless power transmitter intended for operation with the device. The transmitter peak or resonant frequency can also be any frequency known to differ from the receiver resonant frequency associated with a wireless power receiver intended for use with the device. Curve 1173 can correspond to a wireless power receiver device. In at least some embodiments, such a device can be characterized by a double peak with a valley (e.g., an illustrative valley at 850 kHz), but this can also vary depending on the construction of the electronic device, the wireless power receiver, their respective wireless power transmission circuitry (including the designed operating frequency), etc. These receiver peak frequencies or resonant frequencies and / or corresponding valley frequencies can be known frequencies associated with a wireless power receiver intended for use with the device. These receiver peak frequencies or resonant frequencies and / or corresponding valley frequencies can also be any frequency known to differ from the transmitter resonant frequency associated with a wireless power receiver intended for use with the device. Finally, a foreign object (i.e., an object that is neither a wireless power transmitter nor a wireless power receiver) may be characterized by an illustrative peak at 1 MHz, such as curve 1174, in some other mode.

[0085] When implementing a given electronic device and its wireless power transmission system, the known characteristics of such a device, as well as the expected characteristics of the wireless power transmitter and / or receiver intended to operate with the device, allow designers to set appropriate thresholds or other criteria for resonant peak and / or valley frequencies and / or magnitudes to identify objects as needed. Therefore, the control and communication circuitry of the electronic device's wireless power transmission system can perform one or more frequency sweeps or scans as described above, and use signal processing circuitry such as voltage and / or current sensors, sample-and-hold circuits, analog-to-digital converters, envelope detectors, comparators, etc., to monitor and characterize the responses as described above to determine whether the object detected by the uLPOD detection sequence is a wireless power transmitter or a wireless power receiver, thereby enabling the electronic device to select an appropriate operating mode for its wireless power transmission circuitry.

[0086] Figures 12A-12C Alternative timing schemes for detecting and identifying wireless power receivers or wireless power transmitters in electronic devices are illustrated. Figure 12A Examples similar to the above are shown. Figure 10 Example 1201 shows an electronic device detecting a wireless power receiving device and operating as a wireless power transmitter to power the wireless power receiver. Operation in this mode has been described above and will therefore not be repeated in detail here. Generally, detection segment 1261 corresponds to detection segment 1061 with an associated uLPOD pulse. Similarly, identification segment 1264 corresponds to identification segment 1064, including the frequency scan described above. These are followed by LPP segment 1267 corresponding to LPP segment 1067, and then digital ping / holding means 1268 corresponding to digital ping and FSK / ASK hold means 1068. The frequencies, timings, etc., illustrated in the examples are merely examples, and other timing intervals may be provided. Generally, it may be desirable to provide relatively short intervals, such as the exemplified t2 between initial device detection and the establishment of operation of the electronic device as a wireless power transmitter (or receiver), to provide a suitable user experience. In some implementations, interval t2 may be approximately 700 ms. To achieve this, the subsequent uLPOD pulse may have a total duration t3, which may be approximately 300 ms. Frequency scan 1264 can be completed within a certain time interval t4, which can be approximately 20ms. Finally, the digital ping and FSK / ASK handshake interval t5 can be approximately 200ms. Again, these values ​​are just examples and can vary depending on specific applications, etc.

[0087] Figure 12BExample 1202 is illustrated, in which an electronic device detects a wireless power transmitter device and operates as a wireless power receiver to receive power from the wireless power receiver. The previous sequence illustrates the operation of the wireless power transmitter (PTx), while the following sequence illustrates the operation of the electronic device. Initially, the wireless power transmitter can operate in LPP mode (e.g., as defined by one or more Qi standards discussed above). Simultaneously, the electronic device can operate in detection mode 1261 involving a uLPOD signal as described above. At time 1271, the electronic device can detect the LPP signal from the wireless power transmitter, thereby initiating the wireless power receiver operation mode for the electronic device, as referenced above. Figure 8 Box 850 and subsequent boxes describe this. Therefore, the wireless power transmitter PTx can continue its LPP operation and initiate the digital ping phase EP68 according to the operating protocol. Correspondingly, the electronic device can enter wireless power receiver mode when transitioning to wireless power receiver operation mode, and begin monitoring its rectifier output voltage Vrect at 1272 and establish wireless power transmission (reception) according to the relevant protocol. As described in... Figure 12A In the example shown, the timing is merely exemplary. For example, the interval t3 for more frequent uLPOD pulses could be approximately 185 ms. If, upon entering receiver mode, the device does not detect a low-power ping from the transmitter within interval t6 (e.g., approximately 1 s), the device can resume transmitting uLPOD pulse 1273, which can continue for interval t7 (e.g., up to a few seconds). In other words, as indicated by uLPOD signal 1273, if the electronic device cannot establish wireless power transmission (reception) from the wireless power transmitter PTx, it can resume searching for either the wireless power transmitter object or the wireless power receiver object, as referenced above. Figure 8 As described.

[0088] Figure 12C Example 1203 is illustrated, in which two electronic devices, each capable of bidirectional wireless power transfer operation (i.e., as a wireless power transmitter and as a wireless power receiver), are placed within close range. The preceding sequence illustrates the operation of a first type of device (device 1), while the following sequence illustrates the operation of a second type of device (device 2). Initially, each device can be referenced as above. Figure 12A and Figure 12BIn the detection segments 1261a / 1261b described above, in some cases, one device or another device (in this case, the second device) may have different time intervals T_uLP_spa (i.e., uLPOD signal intervals) to prevent race conditions associated with both devices simultaneously transmitting and receiving uLPOD signals. In any case, when each device detects another device using the uLPOD operation described above, each device may independently transition to its corresponding identification interval 1264a / 1264b. Thus, each device may perform one or more frequency sweeps or scans as described above. Similarly, one device or another device (in this case, the second device) may have a scan offset interval T_scan_spa such that its scan occurs after the scan of the first device. Thus, the first device will detect the second device as a wireless power receiver and begin its LPP operation 1267. If the first device is understood to be a wireless power transmitter, the second device may detect the LPP signal from the first device and thus continue operating as a wireless power receiver. The timing of the various operations and intervals may be generally similar to those described above.

[0089] In some implementations, one or two devices may randomize the time interval between the end of a frequency sweep or scan used to identify another device and a subsequent LPP pulse. In another implementation, one or two devices may randomize the time interval between a first LPP pulse and a subsequent LPP pulse. This can accommodate the scenario where two devices step through the sequence substantially simultaneously, preventing the two devices from detecting each other's LPP pulses, as the corresponding LPP pulse sent by each device can "flood" the signal associated with the LPP from the corresponding device, thus effectively preventing the devices from detecting each other's LPPping. By randomizing the intervals between LPP pulses (e.g., between the first and second pulses and between the second and subsequent pulses), problems associated with such conflicts can be mitigated.

[0090] Therefore, the second device can switch to wireless power receiver operation mode. Thus, the first device can enter digital ping phase 1268, which may include an FSK handshake. Correspondingly, the second device, already in wireless power receiver mode, can begin monitoring its rectifier output voltage Vrect at 1272 and establish wireless power transfer according to a relevant protocol (such as the industry-standard Qi protocol or a proprietary protocol). This may include the ASK portion of the handshake. Once the devices have established wireless power transfer, they can apply device-to-device power transfer strategies to determine which devices may include different transmit and receive roles than those initially negotiated according to the above operation. For example, even if the second device detects another device later and therefore needs to receive LPP signals from the first device operating in wireless power transmitter mode, if conditions indicate that the second device should power the first device, then in this case, the devices can renegotiate their transmitter / receiver relationship according to an appropriate strategy. Details of such strategies are beyond the scope of this application, but they may be based on the relative state of charge of the respective devices' batteries, the total battery capacity of the respective devices, etc.

[0091] The foregoing describes various features and embodiments relating to wireless power transmission devices capable of operating in either a wireless power transmitter mode or a wireless power receiver mode, and techniques for switching between such modes. Such arrangements can be used in a variety of applications, but are particularly advantageous when used in combination with electronic devices (such as mobile phones, tablets, laptops, or notebook computers) and wireless power receivers including accessories (such as wireless headsets, styluses, etc.). Furthermore, although many specific features and various embodiments have been described, it should be understood that, unless otherwise stated to be mutually exclusive, various combinations of features and embodiments can be made in particular specific implementations. Therefore, the various embodiments described above are provided merely by way of illustration and should not be construed as limiting the scope of this disclosure. Various modifications and changes may be made to the principles and embodiments herein without departing from the scope of this disclosure and the claims.

[0092] The foregoing describes an exemplary implementation of a wireless power transmission system capable of sending certain information between PTx and PRx within the system. This disclosure anticipates that this information transmission improves the ability of devices to efficiently provide wireless power signals to each other to facilitate battery charging, such as by sharing the power handling capabilities of the devices. Entities implementing this technology should take care to ensure compliance with established privacy policies and / or privacy practices to the extent that any sensitive information is used in a particular specific implementation. Specifically, such entities will be expected to implement and consistently apply privacy practices generally recognized as meeting or exceeding industry or governmental requirements for maintaining user privacy. Implementers should inform users where personally identifiable information is expected to be sent in the wireless power transmission system and allow users to "optionally join" or "optionally leave" participation. For example, if the power transmitter is configured to poll for sensitive information from the power receiver, such information may be presented to the user when the user places a device on the power transmitter.

Claims

1. An electronic device selectively operable in a wireless power receiver mode to receive power from a wireless power transmitter and in a wireless power transmitter mode to transmit power to an accessory, the electronic device comprising: Wireless power transfer coil; A rectifier coupled to the wireless power transmission coil and capable of operating in the wireless power receiver mode to convert an AC voltage induced by the wireless power transmitter in the wireless power transmission coil into a DC voltage for use by the electronic device. An inverter coupled to the wireless power transmission coil and capable of operating in the wireless power transmitter mode to convert a DC voltage into an AC voltage applied to the wireless power transmission coil; as well as The controller and communication circuit: Detecting objects approaching the electronic device; In response to the detection of the object, an attempt is made to identify the object as at least one of a wireless power receiver and a wireless power transmitter by performing one or more frequency sweeps to identify one or more resonant frequencies that characterize the object as a wireless power receiver or a wireless power transmitter. In response to identifying the object as a wireless power receiver, the wireless power transmitter mode is activated; as well as In response to identifying the object as a wireless power transmitter, the wireless power receiver mode is activated.

2. The electronic device of claim 1, wherein the one or more frequency sweeps are performed over a frequency range of interest from 600 kHz to 2 MHz.

3. The electronic device of claim 1, wherein the one or more frequency sweeps are continuous frequency sweeps over a frequency range of interest.

4. The electronic device of claim 1, wherein the one or more frequencies sweep across a plurality of discrete frequencies within a frequency range of interest.

5. The electronic device of claim 1, wherein performing one or more frequency sweeps to identify one or more resonant frequencies of the object comprises driving the wireless power transmission coil with the inverter.

6. The electronic device of claim 1, wherein performing one or more frequency sweeps to identify one or more resonant frequencies of the object includes driving the wireless power transmission coil with auxiliary circuitry.

7. The electronic device of claim 1, wherein the wireless power transmitter is characterized by a first resonant frequency, wherein the first resonant frequency is at least one of the following: The frequency associated with a compatible wireless power transmitter designed for use with the electronic device; or A frequency different from the resonant frequency of a wireless power receiver designed to operate with the electronic device.

8. The electronic device of claim 7, wherein the wireless power receiver is characterized by a second resonant frequency and a third resonant frequency, wherein a valley is located between the second resonant frequency and the third resonant frequency, wherein the valley is at a frequency higher than the first resonant frequency, and wherein one or more of the second resonant frequency, the third resonant frequency, and the valley are: The frequency associated with a compatible wireless power receiver designed for use with the electronic device; or A frequency different from the resonant frequency of a wireless power transmitter designed to operate with the electronic device.

9. The electronic device of claim 1, wherein the wireless power transmission coil is a single coil.

10. The electronic device of claim 1, wherein the rectifier and the inverter comprise the same switching device.

11. The electronic device of claim 1, wherein activating at least one of the wireless power transmitter mode and activating the wireless power receiver mode comprises loading additional firmware corresponding to one of the respective modes.

12. The electronic device of claim 1, wherein activating the wireless power receiver mode includes transmitting one or more object detection pings, wherein the interval between at least two of the one or more object detection pings is randomized.

13. A method performed by a wireless power transmission controller and communication circuitry of an electronic device, the electronic device being operable in a wireless power receiver mode to receive power from a wireless power transmitter, or in a wireless power transmitter mode to transmit power to a wireless power receiver, the method comprising: Detecting objects approaching the electronic device; In response to the detection of the object, an attempt is made to identify the object as at least one of a wireless power receiver and a wireless power transmitter by performing one or more frequency sweeps to identify one or more resonant frequencies that characterize the object as a wireless power receiver or a wireless power transmitter. In response to identifying the object as a wireless power receiver, the wireless power transmitter mode is activated and the wireless power transmission circuitry of the electronic device is used to transmit power to the wireless power receiver; as well as In response to identifying the object as a wireless power transmitter, the wireless power receiver mode is activated and the wireless power transmission circuitry of the electronic device is used to receive power from the wireless power transmitter.

14. The method of claim 13, wherein the one or more frequency sweeps are performed over a frequency range of interest from 600 kHz to 2 MHz.

15. The method of claim 13, wherein the one or more frequency sweeps are continuous frequency sweeps over a frequency range of interest.

16. The method of claim 13, wherein the one or more frequencies are swept at a plurality of discrete frequencies within a frequency range of interest.

17. The method of claim 13, wherein performing one or more frequency sweeps to identify one or more resonant frequencies of the object comprises driving a wireless power transmission coil with an inverter of the wireless power transmission circuit of the electronic device.

18. The method of claim 13, wherein performing one or more frequency sweeps to identify one or more resonant frequencies of the object comprises driving a wireless power transmission coil with auxiliary circuitry.

19. The method of claim 13, wherein the wireless power transmitter is characterized by a first resonant frequency, wherein the first resonant frequency is at least one of the following: The frequency associated with a compatible wireless power transmitter designed for use with the electronic device; or A frequency different from the resonant frequency of a wireless power receiver designed to operate with the electronic device.

20. The method of claim 19, wherein the wireless power receiver is characterized by a second resonant frequency and a third resonant frequency, wherein a valley is located between the second resonant frequency and the third resonant frequency, wherein the valley is at a frequency higher than the first resonant frequency, and wherein one or more of the second resonant frequency, the third resonant frequency, and the valley are: The frequency associated with a compatible wireless power receiver designed for use with the electronic device; or A frequency different from the resonant frequency of a wireless power transmitter designed to operate with the electronic device.

21. The method of claim 13, wherein activating at least one of the wireless power transmitter mode and activating the wireless power receiver mode comprises loading additional firmware corresponding to one of the respective modes.

22. The method of claim 13, wherein activating the wireless power transmitter mode comprises transmitting one or more object detection pings, wherein the interval between at least two of the one or more object detection pings is randomized.

23. A controller and communication circuit for a wireless power transmission system for an electronic device, wherein the electronic device is selectively operable in a wireless power receiver mode to receive power from a wireless power transmitter and in a wireless power transmitter mode to transmit power to an accessory, the controller and communication circuit being configured to: Detecting objects approaching the electronic device; In response to the detection of the object, an attempt is made to identify the object as at least one of a wireless power receiver and a wireless power transmitter by performing one or more frequency sweeps to identify one or more resonant frequencies that characterize the object as a wireless power receiver or a wireless power transmitter. In response to identifying the object as a wireless power receiver, the wireless power transmitter mode is activated; as well as In response to identifying the object as a wireless power transmitter, the wireless power receiver mode is activated.

24. The controller and communication circuit of claim 23, wherein the controller and communication circuit are further configured to: The wireless power transmitter mode is activated by loading additional firmware corresponding to the wireless power transmitter mode; and The wireless power receiver mode is activated by loading additional firmware corresponding to the wireless power receiver mode.

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