Wireless power system with frequency shift keying communication

Abstract

A wireless power system has a wireless power transmitting device and a wireless power receiving device. The device in the wireless power system may communicate using in-band communications. The wireless power transmitting device may transmit data to the wireless power receiving device using frequency shift keying (FSK) modulation. The receiving device may not know the transmission rate of the FSK data. The FSK decoder may identify an actual transmission rate for the incoming bits and decode the wireless power signal into subsequent bits using the actual transmission rate.

Description

[0001] This application claims priority to U.S. Patent Application No. 17 / 883,401, filed on August 8, 2022, and U.S. Provisional Patent Application No. 63 / 355,046, filed on June 23, 2022, which are hereby incorporated by reference in their entirety. Technical Field

[0002] The present disclosure relates generally to power systems, and more particularly, to wireless power systems for charging electronic devices. Background Art

[0003] In a wireless power system (sometimes referred to as a wireless charging system), a wireless power transmission device (such as a charging pad or charging plate) wirelessly transmits power to a wireless power receiving device such as a portable electronic device. The wireless power receiving device has a coil and a rectifier circuit. The coil receives an AC wireless power signal from the wireless power transmission device. The rectifier circuit converts the received signal into DC power. During wireless power transmission, the wireless power transmission device and the receiving device can pass data packets to each other. Summary of the invention

[0004] An electronic device may include: a wireless power transmission circuit having a coil operable to transmit a wireless power signal with an attached wireless charging device; and a frequency shift keying decoder operable to decode data received from the attached wireless charging device during the wireless power transmission. The data may be represented using a frequency shift keying characteristic encoded into the wireless power signal by the attached wireless charging device, the data may be encoded at an actual transmission rate selected by the attached wireless charging device from a plurality of allowed transmission rates, and the frequency shift keying decoder may be configured to use information in the encoded data to identify the actual transmission rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 is a schematic diagram of an illustrative wireless power system including a wireless power transmitting device and a wireless power receiving device according to some embodiments.

[0006] Figure 2 is a circuit diagram of an illustrative wireless power transmission and reception circuit according to some embodiments.

[0007] Figure 3 is a diagram illustrating an exemplary frequency shift keying (FSK) modulation bit encoding scheme according to some embodiments.

[0008] Figure 4 is a circuit diagram of an illustrative wireless power transmission and reception circuit including a multi-channel frequency shift keying decoder according to some embodiments.

[0009] Figure 5 is a diagram of illustrative bytes with a checksum according to some embodiments.

[0010] Figure 6 is a circuit diagram of an illustrative wireless power transmission and reception circuit including a single-channel frequency shift keying decoder according to some embodiments.

[0011] Figure 7 is a diagram of illustrative bytes with one or more predetermined leading bits according to some embodiments. DETAILED DESCRIPTION

[0012] The wireless power system has a wireless power transmission device that wirelessly transmits power to a wireless power receiving device. For example, the wireless power transmission device can be a device such as a wireless charging pad, a wireless charging plate, a wireless charging stand, a wireless charging station, etc. For example, the wireless power transmission device can be a stand-alone device or built into other electronic devices (such as a laptop, a tablet computer, or a cellular phone). The wireless power transmission device has one or more coils used in transmitting wireless power to one or more wireless power receiving coils of the wireless power receiving device. For example, the wireless power receiving device can be a device such as a cellular phone, a watch, a media player, a tablet computer, a pair of earbuds, a remote control, a laptop computer, an electronic pen, a stylus, or other battery-powered electronic device.

[0013] During wireless power transfer operation, the wireless power transmitting device supplies an AC signal to one or more of its wireless power transmitting coils. This causes the coils to transmit an AC electromagnetic signal (sometimes referred to as a wireless power signal) to one or more corresponding coils in the wireless power receiving device. The rectifier circuit in the wireless power receiving device converts the received wireless power signal into direct current (DC) power for powering the wireless power receiving device.

[0014] Some wireless power transmission devices use frequency shift keying (FSK) modulation to transmit in-band data to wireless power receiving devices. During these FSK transmissions, power is wirelessly transferred from the wireless power transmission device to the wireless power receiving device. In FSK communication, the data transmitter (in some examples, the wireless power transmitter) modulates the power transmission frequency or phase of the wireless power signal. The data receiver (also a wireless power transmission device in some examples) rectifies the incoming signal to produce DC power while monitoring the frequency of the AC signal passing through the coil, and uses FSK demodulation circuitry to decode the transmitted in-band data from the received signal.

[0015] The data transmitter may select one of at least several possible data transmission rates, sometimes referred to as baud rates. The transmission rate selection may depend on the power transmission frequency, communication channel conditions, wireless power transmission protocol requirements, or other system operating conditions. It is worth noting that a data receiver (e.g., a wireless power receiving device) that decodes incoming data may not know in advance the specific transmission rate used by the data transmitter (e.g., a wireless power transmitting device).

[0016] In some embodiments, to account for multiple possible transmission rates, an FSK decoder in a wireless power receiving device performs multiple decoding operations at multiple transmission rates and compares the decoded data with the checksum information contained in the transmitted data to identify the transmission rate currently in use. In some embodiments, the FSK decoder identifies the transmission rate in use by decoding and identifying a known preamble in the incoming signal path. The known preamble can be a preamble agreed upon by a data transmitter and receiver (e.g., a wireless power transmitting and receiving device) during a handshake or according to a protocol such as a published standard specification.

[0017] Figure 1 An exemplary wireless power system is shown in . Wireless power system 8 includes an exemplary wireless power transmission device 12 and an exemplary wireless power receiving device 24. Wireless power transmission device 12 includes control circuit 16. Wireless power receiving device 24 includes control circuit 30. These control circuits control the operation of system 8, and each control circuit may include a microprocessor, a power management circuit, a digital signal processor, a microcontroller, and / or an application-specific integrated circuit that implements the desired wireless power transmission and communication features of devices 12 and 24. For example, the control circuit 16 in the wireless power transmission device 12 can control the inverter and wireless power coil output to provide wireless power and data communication signals, while the control circuit 30 in the wireless power receiving device 24 can control the rectifier and FSK decoder features to obtain incoming power and data.

[0018] The control circuitry in the system 8 may include dedicated hardware (e.g., custom silicon or an application-specific integrated circuit), firmware (e.g., a programmable chip that executes computer executable code), and / or software (e.g., a microprocessor that executes computer executable code). Code and other data for performing operations in the system 8 are stored on a non-transitory computer-readable storage medium (e.g., a tangible computer-readable storage medium) in the control circuitry 8. Code is sometimes referred to as computer-executable program instructions or computer-executable instructions. A non-transitory computer-readable storage medium may include non-volatile memory such as non-volatile random access memory (NVRAM), one or more hard disk drives (e.g., a disk drive or a solid-state drive), one or more removable flash drives, or other removable media, etc. The software stored on the non-transitory computer-readable storage medium may be executed on the processing circuitry of the control circuitry 16 and / or 30. The portion of the control circuitry 16 and 30 for processing code may be an application-specific integrated circuit, a microprocessor, a central processing unit, etc.

[0019] During operation, the controller in the control circuit 16 uses the power transmission circuit 52 to transmit wireless power to the power receiving circuit 54 of the device 24. The power transmission circuit 52 and / or the wireless power receiving circuit 54 may sometimes be referred to as a wireless power transmission circuit. The power transmission circuit 52 may have a switching circuit (e.g., an inverter circuit 61 formed by a transistor or other switch) that is turned on and off based on a control signal provided by the control circuit 16 to form an AC current signal through one or more wireless power transmission coils (e.g., one or more wireless power transmission coils 36). In some arrangements, the device 12 has a single coil. In some arrangements, the device 12 has multiple coils. When driven by the switch of the power transmission circuit 52, the coil 36 generates a wireless power signal 44 in the form of an electromagnetic field. These fields (sometimes referred to as magnetic flux) received by the coil 48 in the power receiving device 24 are rectified using a rectifier circuit 50 to charge the battery 58 and / or power components of the wireless power receiving device 24 (such as the display 32). In some examples, rectifier circuit 50 includes rectifying components, such as synchronous rectifier metal oxide semiconductor transistors arranged in a bridge network.

[0020] The wireless power receiving device 24 may include an input-output device 56. The input-output device may include an input device for collecting user input and / or taking environmental measurements, and may include an output device (e.g., display 32) for providing output to the user (e.g., display content, audio content, tactile output, etc.). The wireless power transmitting device 12 may also optionally have one or more input-output devices.

[0021] The wireless power transmission device 12 and the wireless power reception device 24 communicate wirelessly using in-band or out-of-band communication to maintain wireless power transfer operation, such as for power feedback control. The exemplary data transmission circuit 40 may generate a wireless data transmission signal, and the exemplary data transmission circuit 46 may receive and decode the data transmission signal.

[0022] It should be noted that the exemplary wireless power transmission device 12 includes measurement circuitry 41 for measuring characteristics of the coil 36, such as voltage and current, which facilitates operations such as foreign object detection. The exemplary wireless power receiving device 24 also includes measurement circuitry 43 for making similar measurements that facilitate operations such as measuring the amount of received power.

[0023] Figure 2 A circuit diagram of an exemplary wireless power transmission circuit 52 of a wireless power transmission device 12 in system 8 is shown. The wireless power transmission circuit 52 includes one or more inverters 61 that generate wireless power signals that are transmitted through an output circuit including one or more coils 36 and a capacitive element 70. In a multi-coil transmitter, the device 12 may include a single inverter 61 connected to multiple coils, or may include multiple inverters 61, each inverter powering one coil. In the single coil example, the inverter 61 is coupled to the coil 36.

[0024] During operation, the control circuit 16 provides a control signal to the switch of the inverter 61 at the control input 74. Applying the drive signal using the inverter 61 causes the output circuit formed by the selected coil 36 and the capacitive element 70 to generate an AC electromagnetic field 44, which is received by the wireless power receiving circuit 54 using the wireless power receiving circuit formed by one or more coils 48 and one or more capacitive elements 72 in the wireless power receiving device 24. The rectifier circuit 50 is coupled to the one or more coils 48 and converts the received power from AC to DC and provides a corresponding DC output voltage Vrect at the rectifier output terminal 76 for powering a load (such as a battery 58 and / or a display 32).

[0025] The exemplary system 8 utilizes in-band communication with coils 36 and 48 to transmit information between devices 12 and 24. In some embodiments, the wireless power transmission device 12 transmits in-band data from device 12 to the wireless power receiving device 24 using frequency shift keying (FSK) technology, and the wireless power receiving device 24 transmits in-band data from device 24 to device 12 using amplitude shift keying (ASK) technology. During these FSK and ASK transmissions, power is wirelessly transmitted from device 12 to device 24. While the power transmission circuit 52 drives an AC signal into coil 36 at a power transmission frequency to produce signal 44, the wireless transceiver circuit 40 modulates the power transmission frequency driving the AC signal using FSK modulation to pass the FSK communication into signal 44. At the receiving device 24, the FSK decoding circuit 102 (sometimes referred to as FSK decoder 102) monitors the frequency of the AC signal passing through coil 48 and uses FSK demodulation to extract (decode) the transmitted in-band data from signal 44. This method allows data bit packets to be transmitted in-band from device 12 to device 24 using coils 36 and 48 during wireless power transfer using the same coils. In some examples, FSK decoder 102 is Figure 1 Part of the wireless transceiver circuit 46.

[0026] In-band communication in the direction from the wireless power receiving device 24 to the device 12 may use ASK modulation and demodulation techniques. During wireless power transfer, the circuit 46 transmits in-band data to the device 12 by using a switch (e.g., one or more transistors in the transceiver 46 coupled to the coil 48) to modulate the impedance of the power receiving circuit 54 (e.g., coil 48). This in turn modulates the amplitude of the signal 44 and the resulting amplitude of the AC signal through the one or more coils 36. The wireless transceiver circuit 40 monitors the amplitude of the AC signal and extracts the data transmitted by the wireless transceiver circuit 46 using ASK demodulation techniques. This approach allows data bit packets to be transmitted in-band from the device 24 to the device 12 using the coils 48 and 36, while power is wirelessly transmitted from the device 12 to the device 24 using the same coils.

[0027] The foregoing examples of FSK and ASK modulation represent one possible implementation of in-band communication. It should be noted that other permutations are possible and that devices in a system such as the wireless power transfer system 8 may be designed to operate based on either the FSK or ASK principle.

[0028] The preceding discussion of FSK and ASK modulations contemplates the transmission of information useful for controlling wireless power transfer, such as feedback information regarding received power, battery charge status, and the like. Out of an abundance of caution, it is noted that to the extent that any implementation of this communication technology involves the use of device identification information (or more generally, personally identifiable information) for the purpose of wireless charging, implementers should follow privacy policies and practices that are generally considered to meet or exceed industry or government requirements for maintaining user privacy. For example, identification information data should be managed and processed to minimize the risk of unintentional or unauthorized access or use, and the nature of the authorized use should be clearly indicated to the user. Where possible, such identification information may be extracted so that the resulting identification is not globally unique but is still sufficient to facilitate communication in reasonable device usage scenarios.

[0029] It has been described that power can be transmitted simultaneously between devices while using in-band communication for data transmission between devices. In other words, in some examples, in-band communication can rely on modulation of the power transmission signal (e.g., modulating the power transmission frequency or modulating the amplitude of the signal at the power transmission frequency). However, it should be noted that in-band communication may occur between devices before the devices agree on the power transfer rate, power transfer frequency, etc. After initial detection and inductive coupling, the device may undergo a handshake process to determine compatibility, negotiate power transfer frequency, negotiate power transfer rate, etc. During this process, in-band communication may involve FSK and / or ASK modulation of the basic signal that provides limited power in a wireless manner. This is advantageous because even if the power receiving device has enough remaining battery power to remain powered on, this allows the device to complete the handshake process. Even if the negotiation between the devices does not ultimately result in the continued transmission of wireless power (e.g., even if the device does not enter a dedicated power transfer phase), this transmission of wireless power during in-band communication may also occur during the handshake process.

[0030] The above-described FSK and ASK modulation and demodulation techniques can be used to transmit data packets between two devices within the system 8. Each data packet can include multiple data bits. These bits can be grouped into bytes.

[0031] The FSK decoder 102 in the power receiving circuit 54 decodes FSK communications received from the wireless power transmitting device 12 at the coil 48 of the wireless power receiving device 24 .

[0032] During FSK modulation, the power transfer device 12 may operate at a first operating frequency (eg, an unmodulated operating frequency f op ) and a second operating frequency (eg, a modulated operating frequency f mod ) to switch its inverter output frequency between the two frequencies. The difference between the two frequencies has a polarity (indicated by f mod and fop The difference between the positive and negative) and the depth (indicates whether f mod and f op The value of the difference between .

[0033] Using an unmodulated operating frequency and a selected modulated operating frequency, the power transmitter can transmit bits using FSK modulation. The power transmitter can use a bit encoding scheme to transmit bits using FSK modulation. In an illustrative example, the power transmitter can use a differential bi-phase encoding scheme to modulate data bits using a power signal. This type of bi-phase encoding scheme is Figure 3 Shown in.

[0034] Figure 3 The power signal frequency is shown as a function of time during FSK modulation. The power signal frequency switches between frequencies f1 and f2 to encode bits. Frequencies f1 and f2 may be equal to f as previously described. op and f mod , where f op or mod is the higher of the two frequencies. Figure 3 In the encoding scheme of , a transition between two frequencies occurs at the beginning of each bit. To encode a "one" bit, there are two transitions in the power signal frequency. To encode a "zero" bit, there is one transition in the power signal frequency.

[0035] For example, at t1, the operating frequency (power signal frequency) is switched from f2 to f1. This indicates the start of encoding a bit. For a given number of power signal cycles (e.g., 256 cycles), the operating frequency may remain at f1 and then switch back to f2 at t2. For a given number of cycles, the operating frequency remains at f2. At t3, the encoding of a bit is completed. At t3, the operating frequency (power signal frequency) is switched from f2 to f1. This indicates the start of encoding a zero bit. For a given number of cycles (e.g., 512 cycles), the operating frequency may remain at f1 and then switch back to f2 at t4. At t4, the encoding of the zero bit is completed.

[0036] In the same number of cycles (e.g. Figure 3 Each bit (either a "one" or a "zero") is transmitted during a duration T2 in the bit period. This number of periods may sometimes be referred to as the bit period. For a zero bit, the operating frequency switches once at the beginning of the bit period and then remains at the same operating frequency throughout the bit period (T2). For a single bit, the operating frequency switches once at the beginning of the bit period and again halfway through the bit transmission. Thus, during the encoding of a single bit, the operating frequency is at both frequencies f1 and f2 for the same number of periods T1, which is half of T2.

[0037] In use Figure 3During the encoding of the bits by the differential biphase encoding scheme, the frequency is kept constant for a number of periods, T2 or T1, before switching to another frequency. T1 is half of T2. These periods of time during which the frequency is constant can be referred to as modulation states. Modulation states are used to transmit bits using a bit encoding scheme.

[0038] The bit period has an associated transmission rate (e.g., the number of bits transmitted per second, sometimes referred to as the bit rate). The FSK communication signals received by the wireless power receiving device 24 may sometimes have different transmission rates. The transmission rate of FSK communication may be affected by the frequency of the carrier signal and the number of cycles per bit period. For example, a first power transmission device may transmit wireless power using a carrier signal of a first frequency, while a second different power transmission device may transmit wireless power using a carrier signal of a second different frequency. In addition, different FSK modulation schemes may use different numbers of power signal cycles during each bit period.

[0039] As an example, the duration of each bit period (e.g., Figure 3 The T2 in ( ) can be 512 cycles in total. Therefore, T1 is 256 cycles. For encoding zero bits, the operating frequency switches and then remains constant for 512 cycles. For encoding one bit, the operating frequency switches, remains constant for 256 cycles, switches again, and then remains constant for 256 cycles again. Therefore, the modulation state (where the operating frequency is constant) is 512 cycles or 256 cycles.

[0040] As another example, the duration of each bit period (e.g., Figure 3 The T2 in ( ) can be 128 cycles in total. Therefore, T1 is 64 cycles. For encoding zero bits, the operating frequency switches and then remains constant for 128 cycles. For encoding one bit, the operating frequency switches, remains constant for 64 cycles, switches again, and then remains constant again for 64 cycles. Therefore, the modulation state (where the operating frequency is constant) is 128 cycles or 64 cycles.

[0041] Thus, the duration of each bit period may vary depending on one or more of the type of power transmission device transmitting the wireless power signal, the communication protocol used by the wireless power transmission device, the negotiated power transmission frequency, etc. It is desirable for the FSK decoder 102 to be able to demodulate FSK communication signals having different bit periods (and corresponding different transmission rates), particularly when the decoder does not know in advance the transmission rate used by the transmitter.

[0042] Figure 4 An exemplary FSK decoder 402 (which may be Figure 2102 in FIG. 10 ). Figure 4 As shown, FSK decoder 402 may include multiple inputs, such as input 106-1 and input 106-2. Common signal 104 (whose frequency is equal to the frequency of the wireless power signal received at coil 48) may be provided to both inputs.

[0043] Input 106-1 may be an input to a first channel 108-1 within FSK decoder 402 that decodes incoming signals using a first transmission rate. Input 106-2 may be an input to a second channel 108-2 within FSK decoder 402 that decodes incoming signals using a second transmission rate. Decoder channels 108 may have duplicate logic / circuitry so that incoming signals are decoded in parallel in each channel. Decoder channels themselves may sometimes be referred to as corresponding FSK decoders.

[0044] like Figure 5 As shown in FIG. 1 , each byte 202 transmitted by the wireless power transmission device 12 may have a header 206, a message (sometimes referred to as a payload) 208, and / or a checksum 210. Each portion of a byte 202 may include any desired number of bits (eg, one or more bits). Figure 4 Each channel in the FSK decoder 402 in the byte can decode the bits in the byte (e.g., from the byte header and / or the payload) and use the decoded bits to perform a checksum operation. The checksum operation can produce an output that is compared with the received value of the checksum 210. If the output of the checksum operation matches the checksum 210, the checksum can be considered valid / true, and the FSK decoder 402 considers that the byte was successfully transmitted without any bit errors. If the output of the checksum operation does not match the checksum 210, the checksum can be considered invalid / false, and the FSK decoder 402 considers that the byte has one or more bit errors.

[0045] Consider an example where the actual transmission rate is equal to the first transmission rate (used by the first channel 108-1, but not by the second channel 108-2). In this case, each byte received by the first channel 108-1 will have a valid checksum indicating that the byte was received without error. Therefore, the data decoded by the first channel 108-1 is output to the downstream circuit as valid in-band communication data. At the same time, the second channel 108-2 will repeatedly have an invalid checksum, which indicates that the byte was received with one or more errors. Therefore, the data decoded by the second channel 108-2 will be discarded.

[0046] Consider an example where the actual transmission rate is equal to the second transmission rate (used by the second channel 108-2, but not by the first channel 108-1). In this case, each byte received by the second channel 108-2 will have a valid checksum indicating that the byte was received without error. Therefore, the data decoded by the second channel 108-2 is output to the downstream circuit as valid in-band communication data. At the same time, the first channel 108-1 will repeatedly have an invalid checksum, which indicates that the byte was received with one or more errors. Therefore, the data decoded by the first channel 108-1 will be discarded.

[0047] Figure 5 The example of the FSK decoder having two inputs for two corresponding decoder channels (operating at two different transmission rates) is merely illustrative. In general, the FSK decoder can have any desired number of inputs. Each input receives a common signal 104 (which has the same frequency as the received wireless power signal). Each input is provided to an associated decoder channel operating at a different transmission rate. If the incoming FSK communication has a transmission rate that matches one of the decoder channels, the FSK decoder 402 will accurately decode the FSK communication using the appropriate decoder channel (while discarding irrelevant results of other decoder channels).

[0048] It should be noted that signal 104 (sometimes referred to as AC signal 104, input signal 104, etc.) can have a frequency equal to the frequency of the wireless power signal received by coil 48. In some cases, signal 104 can come directly from coil 48 (e.g., FSK decoder 402 can be directly coupled to coil 48 and thus receive analog signal 104 from coil 48). As another example, signal 104 can come from rectifier 50 (e.g., signal 104 can be an analog signal from rectifier 50). Signal 104 can sometimes be a digital signal having the same frequency as the wireless power signal received by coil 48. For example, rectifier 50 may include one or more comparators whose digital output changes between two states at the same frequency as the wireless power signal received by coil 48. The signal can be provided to FSK decoder 402 for FSK decoding operations.

[0049] Figure 6 An exemplary FSK decoder 602 with a single demodulation channel (which may be Figure 2 102 in FIG. 10 ). Figure 6 As shown, FSK decoder 602 may include a single input, such as input 606 - 1 . Input 606 - 1 receives signal 104 (whose frequency is equal to the frequency of the wireless power signal received at coil 48 ).

[0050] The FSK decoder 602 may decode data represented using the FSK characteristic based on a single transmission rate. The data may be encoded with an actual transmission rate (e.g., selected by the wireless power transmission device 12) from among a plurality of allowed transmission rates. The FSK decoder 602 may be configured to use information encoded in the data to identify the actual transmission rate.

[0051] Input 606-1 may be an input to a first channel 608-1 within FSK decoder 602. Channel 608-1 may be decoded using different transmission rates at different times. For example, for received FSK data, there may be a first allowed transmission rate, a second allowed transmission rate, and a third allowed transmission rate. Thus, FSK decoder 602 may be able to decode an incoming signal using a first transmission rate at a first time, decode the incoming signal using a second transmission rate at a second time after the first time, and decode the incoming signal using a third transmission rate at a third time after the second time.

[0052] To allow the FSK decoder 602 to use the information in the encoded data to identify the actual transmission rate, the FSK decoder 602 can synchronize operation with the detected transmission rate based on the known bit patterns in the received FSK bytes. Figure 7 As shown in , each byte 702 transmitted by the wireless power transmission device 12 may have one or more predetermined symbols 204 at the beginning of the byte in addition to the header 206, the message 208, and the checksum 210. Each portion of the byte 702 may include any desired number of bits (e.g., one or more bits).

[0053] The predetermined symbol 204 may sometimes be referred to as a preamble 204 or a predetermined preamble 204. The preamble 204 may be the same bit pattern for each byte. The FSK decoder 602 may know the bit pattern for the preamble 204 (eg, the bit pattern may be stored in a memory of the FSK decoder 102).

[0054] The FSK decoder 602 may periodically scan a predetermined preamble at a first transmission rate (among a plurality of allowed transmission rates). If the first transmission rate is found (e.g., when a predetermined preamble is identified at the first transmission rate), the FSK decoder may decode subsequent data using the first transmission rate. If the first transmission rate is not found (e.g., when a predetermined preamble is not identified at the first transmission rate), the FSK decoder may periodically scan a predetermined preamble at a second transmission rate (among a plurality of allowed transmission rates) different from the first transmission rate. This cycle may be repeated for different allowed transmission rates until an actual transmission rate is identified. Once the actual transmission rate is identified, the FSK decoder 602 performs subsequent decoding using the actual transmission rate.

[0055] Before data transmission occurs, the data transmitter and receiver (e.g., the wireless power transmission device 12 and the wireless power receiving device 24) may know (agree on) a predetermined preamble. The predetermined preamble may be agreed upon according to a protocol such as a published standard specification. Alternatively, the predetermined preamble may be agreed upon during a handshake phase and / or a negotiation phase between the wireless power transmission device 12 and the wireless power receiving device 24.

[0056] The predetermined preamble may be a series of identical bits (e.g., repeated "0" bits or repeated "1" bits). For example, the predetermined preamble may be four "0" bits. As another example, the predetermined preamble may be four "1" bits.

[0057] In some communication protocols, not every FSK byte includes a preamble 204. The FSK decoder 602 can use the first received byte with a known preamble 204 to determine the transmission rate. The FSK decoder can then operate using the determined transmission rate until it is determined that the transmission rate has changed. Therefore, if a subsequent byte is received that does not include a preamble, the FSK decoder 602 will decode the byte that does not include a preamble using the transmission rate determined from the previous byte.

[0058] In another possible arrangement, the FSK decoder 602 may include a single channel that scans multiple allowed transmission rates until a valid checksum is identified. For example, the FSK decoder may first operate using a first transmission rate (one of the multiple allowed transmission rates). If operating at the first transmission rate produces decoded data with a valid checksum, the FSK decoder identifies the first transmission rate as the actual transmission rate and continues to decode the data at the first transmission rate. If operating at the first transmission rate results in decoded data having an invalid checksum, the FSK decoder may switch to a second transmission rate. This cycle may be repeated until the actual transmission rate is identified.

[0059] According to one embodiment, an electronic device is provided, the electronic device including: a wireless power transmission circuit having a coil operable to transmit a wireless power signal with an attached wireless charging device and a frequency shift keying decoder operable to decode data received from the attached wireless charging device during the wireless power transmission, the data being represented using a frequency shift keying characteristic encoded into the wireless power signal by the attached wireless charging device, the data being encoded at an actual transmission rate selected by the attached wireless charging device from a plurality of allowed transmission rates, and the frequency shift keying decoder being configured to use information in the encoded data to identify the actual transmission rate.

[0060] According to another embodiment, a frequency shift keying decoder includes a plurality of channels, each channel operating at a respective fixed transmission rate.

[0061] According to another embodiment, a frequency shift keying decoder includes a single decoder channel operating at different transmission rates at different times.

[0062] According to another embodiment, the frequency shift keying decoder is configured to decode data at a first transmission rate using a first decoder channel, compare the data decoded at the first transmission rate with a checksum, and output the data decoded at the first transmission rate if the checksum is valid.

[0063] According to another embodiment, the frequency shift keying decoder is configured to discard data decoded at the first transmission rate if the checksum is invalid.

[0064] According to another embodiment, the frequency shift keying decoder is configured to use the first decoder channel and, if the checksum is invalid, decode data at a second transmission rate, compare the data decoded at the second transmission rate with the additional checksum, and, if the additional checksum is valid, output the data decoded at the second transmission rate.

[0065] According to another embodiment, the frequency shift keying decoder is configured to decode data at a second transmission rate using a second decoder channel, compare the data decoded at the second transmission rate with the additional checksum, and output the data decoded at the second transmission rate if the additional checksum is valid.

[0066] According to another embodiment, a frequency shift keying decoder is configured to periodically scan a decoder channel at a first transmission rate for a predetermined preamble, and decode subsequently received data using the first transmission rate based on identifying the predetermined preamble in the data.

[0067] According to another embodiment, the frequency shift keying decoder is configured to periodically scan the decoder channel for a predetermined preamble at a second transmission rate different from the first transmission rate.

[0068] According to another embodiment, before data transmission begins, the electronic device and the attached wireless charging device know a predetermined preamble code.

[0069] According to another embodiment, the predetermined preamble is a series of identical bits.

[0070] According to another embodiment, the predetermined preamble is a series of 1 bits.

[0071] According to another embodiment, the predetermined preamble is a series of 0 bits.

[0072] According to one embodiment, a method of operating an electronic device is provided, the electronic device including a wireless power transmission circuit having a coil and a frequency shift keying decoder, the method including: using the coil, transmitting a wireless power signal using an attached wireless charging device, and using the frequency shift keying decoder to decode data received from the attached wireless charging device during the wireless power transmission, the data being represented using a frequency shift keying characteristic encoded into the wireless power signal by the attached wireless charging device, the data being encoded at an actual transmission rate selected by the attached wireless charging device from a plurality of allowed transmission rates; and using information in the encoded data to identify the actual transmission rate.

[0073] According to another embodiment, the method includes: decoding data at a first transmission rate using a first decoder channel in a frequency shift keying decoder, comparing the data decoded at the first transmission rate with a checksum, and if the checksum is valid, outputting the data decoded at the first transmission rate.

[0074] According to another embodiment, the method includes periodically scanning a decoder channel at a first transmission rate using a frequency shift keying decoder for a predetermined preamble, and decoding subsequently received data using the first transmission rate based on identifying the predetermined preamble in the data.

[0075] According to another embodiment, the predetermined preamble is a series of identical bits.

[0076] According to one embodiment, a method of operating a frequency shift keying decoder in an electronic device is provided, the method comprising: decoding data received from an attached wireless charging device during wireless power transmission, the data being represented using a frequency shift keying characteristic encoded into a wireless power signal by the attached wireless charging device, and the data being encoded at an actual transmission rate selected by the attached wireless charging device from among a plurality of permitted transmission rates; and identifying the actual transmission rate using information in the encoded data.

[0077] According to another embodiment, the method includes: decoding data at a first transmission rate using a first decoder channel in a frequency shift keying decoder, comparing the data decoded at the first transmission rate with a checksum, and if the checksum is valid, outputting the data decoded at the first transmission rate.

[0078] According to another embodiment, the method includes periodically scanning a decoder channel at a first transmission rate for a predetermined preamble, and decoding subsequently received data using the first transmission rate based on identifying the predetermined preamble in the data.

[0079] The foregoing is merely illustrative and various modifications may be made to the embodiments described. The foregoing embodiments may be implemented independently or in any combination.

Claims

1. An electronic device, comprising: a wireless power transmission circuit having a coil operable to transmit a wireless power signal with an attached wireless charging device; and a frequency shift keying decoder operable to decode data received from the attached wireless charging device during wireless power transfer, wherein: The data is represented using a frequency shift keying characteristic encoded into the wireless power signal by the attached wireless charging device; The data is encoded at an actual transmission rate selected by the attached wireless charging device from among a plurality of allowed transmission rates; and The frequency shift keying decoder is configured to use information in the encoded data to identify the actual transmission rate.

2. The electronic device of claim 1, wherein the FSK decoder comprises a plurality of channels, each channel operating at a respective fixed transmission rate.

3. The electronic device of claim 1, wherein the frequency shift keying decoder comprises a single decoder channel operating at different transmission rates at different times.

4. The electronic device of claim 1 , wherein the frequency shift keying decoder is configured to use a first decoder channel: decoding the data at a first transmission rate; comparing the data decoded at the first transmission rate with a checksum; and In case the checksum is valid, the data decoded at the first transmission rate is output. 5 . The electronic device of claim 4 , wherein the FSK decoder is configured to discard the data decoded at the first transmission rate if the checksum is invalid.

6. The electronic device of claim 4, wherein the frequency shift keying decoder is configured to, using the first decoder channel and in the event that the checksum is invalid: decoding the data at a second transmission rate; comparing the data decoded at the second transmission rate with an additional checksum; as well as In the case where the additional checksum is valid, the data decoded at the second transmission rate is output.

7. The electronic device of claim 4, wherein the frequency shift keying decoder is configured to use a second decoder channel: decoding the data at a second transmission rate; comparing the data decoded at the second transmission rate with an additional checksum; and In the case where the additional checksum is valid, the data decoded at the second transmission rate is output.

8. The electronic device of claim 1, wherein the frequency shift keying decoder is configured to: periodically scanning a decoder channel at a first transmission rate for a predetermined preamble; and Based on identifying the predetermined preamble in the data, subsequently received data is decoded using the first transmission rate.

9. The electronic device of claim 8, wherein the frequency shift keying decoder is configured to: The decoder channel is periodically scanned for the predetermined preamble at a second transmission rate different from the first transmission rate.

10. The electronic device of claim 8, wherein the predetermined preamble is known to the electronic device and the attached wireless charging device before data transmission begins. The electronic device of claim 8 , wherein the predetermined preamble is a series of identical bits.

12. The electronic device of claim 8, wherein the predetermined preamble is a series of 1 bits.

13. The electronic device of claim 8, wherein the predetermined preamble is a series of 0 bits.

14. A method of operating an electronic device, the electronic device comprising a wireless power transfer circuit having a coil and a frequency shift keying decoder, the method comprising: Using the coil, transmitting a wireless power signal with an attached wireless charging device; as well as Using the FSK decoder: decoding data received from the attached wireless charging device during wireless power transfer, wherein: The data is represented using a frequency shift keying characteristic encoded into the wireless power signal by the attached wireless charging device; and The data is encoded at an actual transmission rate selected by the attached wireless charging device from among a plurality of allowed transmission rates; as well as The actual transmission rate is identified using information in the encoded data.

15. The method according to claim 14, further comprising: Using the first decoder channel in the FSK decoder: decoding the data at a first transmission rate; comparing the data decoded at the first transmission rate with a checksum; as well as In case the checksum is valid, the data decoded at the first transmission rate is output.

16. The method according to claim 14, further comprising: Using the FSK decoder: periodically scanning a decoder channel at a first transmission rate for a predetermined preamble; as well as Based on identifying the predetermined preamble in the data, subsequently received data is decoded using the first transmission rate. The method of claim 16 , wherein the predetermined preamble is a series of identical bits.

18. A method of operating a frequency shift keying decoder in an electronic device, the method comprising: Decoding data received from an attached wireless charging device during wireless power transfer, wherein: The data is represented using a frequency shift keying characteristic encoded into a wireless power signal by the attached wireless charging device; and The data is encoded at an actual transmission rate selected by the attached wireless charging device from among a plurality of allowed transmission rates; and The actual transmission rate is identified using information in the encoded data.

19. The method according to claim 18, further comprising: Using the first decoder channel in the FSK decoder: decoding the data at a first transmission rate; comparing the data decoded at the first transmission rate with a checksum; as well as In case the checksum is valid, the data decoded at the first transmission rate is output.

20. The method according to claim 18, further comprising: periodically scanning a decoder channel at a first transmission rate for a predetermined preamble; as well as Based on identifying the predetermined preamble in the data, subsequently received data is decoded using the first transmission rate.

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