An apparatus comprising an analogue integrated circuit

Abstract

The present disclosure relates to an apparatus comprising an analogue integrated circuit configured to be controlled, at least in part, by a digital integrated circuit. The analogue integrated circuit comprises a tag interface circuit coupled with at least one tag reader analogue device to wirelessly read an external tag apparatus such as RFID tag. The analogue integrated circuit further comprises a wireless charging circuit configured to regulate charging of an external battery.

Description

[0001] AN APPARATUS COMPRISING AN ANALOGUE INTEGRATED CIRCUIT

[0002] The present disclosure relates to an apparatus comprising an analogue integrated circuit configured to be controlled, at least in part, by a digital integrated circuit. The analogue integrated circuit comprises a tag interface circuit coupled with at least one tag reader analogue device to wirelessly read an external tag apparatus such as RFID tag. The analogue integrated circuit further comprises a wireless charging circuit configured to regulate charging of an external battery.

[0003] BACKGROUND OF THE INVENTION

[0004] Analogue integrated circuits that comprise wireless charging capabilities to energize an external rechargeable battery and one or more sensor and indicator interface circuits are useful in various highly integrated products such as toy devices. In toy devices dimensions of electronic and mechanical components and devices, such as an analogue integrated circuits, is critical. Therefore it is beneficial to minimise dimensions of an analogue integrated circuit for example by minimizing the dimensions of the analogue integrated circuit and / or minimize the number and size of associated external components. The one or more sensor interface circuits and indicator interface circuits may be coupled to various types of external tags, external optical sensors and external audio sensors etc.

[0005] SUMMARY OF THE INVENTION

[0006] A first aspect of the disclosure relates to an apparatus comprising an analogue integrated circuit configured to be controlled, at least in part, by a digital integrated circuit. The analogue integrated circuit comprises a tag interface circuit coupled with at least one tag reader analogue device, such as a coil, and configured to wirelessly read an external tag apparatus such as RFID tag. The analogue integrated circuit comprises a wireless charging circuit configured to regulate charging of an external battery or regulate charging of an external capacitor for example a capacitor with large capacitance e.g. a supercapacitor, wherein the analogue integrated circuit is configured to, during operation, be powered by the external battery.

[0007] The present apparatus may be integrated into various toys and / or educational systems or devices and provide one or more of the application and functions discussed below with reference to the appended drawings. The present apparatus may be utilized as a component of toys intended at educational purposes. The present apparatus may for example be mechanically and electrically connected a carrier substrate, such as a printed circuit board, which is arranged in, or on, the toy and / or educational device.

[0008] The digital integrated circuit may comprise a microcontroller such as an off-the-shelf microcontroller, microprocessor or Digital Signal Processor controlled by software routines or applications.

[0009] According to an embodiment of the apparatus the wireless charging circuit further comprises an energy harvesting circuit coupled to at least one external magnetic field sensing analogue device, such as one or more external coils, picking-up magnetic charging fields. The apparatus may further comprise a charge field detection circuit. The charge field detection circuit may be electrically coupled to an input of the energy harvesting circuit. In an embodiment the analogue integrated circuit further comprises an inactive state or low-power state where only the charge field detection circuit is operative. The analogue integrated circuit may be switched to its inactive state or low- power state in response to a shutdown command from the digital integrated circuit. The charge field detection circuit is configured to respond to a magnetic charging field by switching the analogue integrated circuit from the inactive state into an active state such as an autonomous state or slaved state. The inactive state or low-power state of the analogue integrated circuit may be caused by a depleted rechargeable battery.

[0010] The digital integrated circuit and the analogue integrated circuit may be connected through a data communication interface such as a proprietary data communication interface or an industry-standard data communication interface. The industry-standard data communication interface may be embodied as, or at least be compatible with, the synchronous full duplex master-slave-based interface (SPI) standard. The SPI compatible data communication interface may for example connect the digital integrated circuit and the analogue integrated circuit in embodiments where these are separate physical entities for example provided on separate semiconductor substrates.

[0011] The digital integrated circuit may be configured to control the analogue integrated circuit by generating and transmitting commands to the analogue integrated circuit through the data communication interface. The analogue integrated circuit may comprise a plurality of control registers coupled to the data communication interface. The plurality of control registers at least comprises a control register for the tag interface circuit and a control register for the wireless charging circuit. The digital integrated circuit may be configured to access, read and write data from or to the plurality of control registers by transmitting appropriate commands to analogue integrated circuit through the data communication interface.

[0012] Each of the plurality of control registers may comprise at least one of

[0013] - sensor signals collected from a sensor interface circuit of the analogue integrated circuit such as tag data collected by the tag interface circuit,

[0014] - indicator signals of an indicator interface circuit such as an optical indicator signal,

[0015] - configuration settings of the sensor interface circuit or of the indicator interface circuit,

[0016] - status information of the sensor interface circuit or of the indicator interface circuit.

[0017] Different types of commands that may be issued by the digital integrated circuit may comprise one or more of reading respective sensor signals from the plurality of control registers, writing respective indicator signals to the plurality of control registers and reading respective status information from the plurality of control registers.

[0018] The analogue integrated circuit may comprises a digital controller or digital state machine connected to the data communication interface for receipt of certain commands from the digital integrated circuit e.g. commands to control the operational state of the analogue integrated circuit for example a command to switch the analogue integrated circuit into a low-power mode or slaved state. The digital controller may be configured to handle various tasks of the analogue integrated circuit when operating in the slaved state. In the slaved state the digital controller may for example be configured to monitor activity on the data communication interface and switch to the autonomous state in response to inactivity, such as absence of incoming data, commands and / or clock signal, on the data communication interface. For example inactivity exceeding a predetermined time period such as 30 s or 1 minute etc. The digital controller may additionally be configured to handle various tasks of the analogue integrated circuit when operating in the autonomous state such as monitoring energy harvesting of the wireless charging circuit, regulate charging of the rechargeable battery or the supercapacitor, and monitor its voltage.

[0019] In one embodiment the analogue integrated circuit comprises at least two operational states

[0020] - an autonomous state wherein the analogue integrated circuit operates independent of the commands from the digital integrated circuit; and

[0021] - a slaved state wherein the analogue integrated circuit receives, and operates in accordance with, the commands from the digital integrated circuit.

[0022] The analogue integrated circuit may in some embodiments further comprise a magnetic field measurement circuit coupled with at least one external magnetic field sensing analogue device such as an external coil. The magnetic field measurement circuit is configured to measure either or both of at least one amplitude of the magnetic field and at least one phase of the magnetic field. The analogue integrated circuit is further configured to transmit the at least one amplitude of the magnetic field and at least one phase of the magnetic field to the digital integrated circuit. The skilled person will understand that the at least one amplitude of the magnetic field and at least one phase of the magnetic field may be stored in a control register of the magnetic field measurement circuit. The control register may be addressed and read by the digital integrated circuit through the data communication interface. In an embodiment the at least one magnetic field sensing analogue device(s) comprises a first magnetic field sensing analogue device arranged to measure a first magnetic field amplitude and phase along a first vector direction and a second magnetic field sensing analogue device arranged to measure a second magnetic field amplitude and phase along a second vector direction. The first and second vector directions are preferably substantially orthogonal. The magnetic field measurement circuit may be configured to receive the first magnetic field amplitude and phase and the second magnetic field amplitude and phase in a sequential fashion.

[0023] The digital integrated circuit may utilize the measured at least one amplitude of the magnetic field and at least one phase of the magnetic field to compute distances and orientations to an associated external toy device for example as discussed below in connection with the appended drawings.

[0024] According to some embodiments of the apparatus the analogue integrated circuit further comprises an audio interface circuit configured to generate an audio signal that controls an audio analogue device. The audio interface circuit may comprise a speaker interface circuit configured to supply a first audio signal to an external speaker and a microphone interface circuit configured to receive a second audio signal from an external microphone.

[0025] According to some embodiments of the apparatus the analogue integrated circuit further comprises an optical interface circuit that controls an optical analogue device such as a photo-diode or LED. The optical interface circuit may in some embodiments comprise

[0026] - an optical transmitter interface configured to control an external light emitter (such as a LED)

[0027] - an optical receiver interface coupled to an external light detector for receipt of an electrical signal representative of received light. The received light may comprise continuous ambient light or data-modulated light of any colour.

[0028] Another aspect of the disclosure relates to an apparatus comprising:

[0029] - a tag interface circuit coupled with at least one tag reader analogue device and configured to wirelessly read an external tag apparatus;

[0030] - a wireless charging circuit configured to regulate charging of an external battery or supercapacitor, wherein the tag interface circuit and the charging circuit are configured to, during operation, be powered by the external battery.

[0031] BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Other and further aspects and features of the invention will be evident from reading the following detailed description of the embodiments. The drawings illustrate the design and utility of embodiments of the apparatus in which similar elements are referred to by common reference numerals. These drawings are not necessarily drawn to scale. These drawings depict only typical embodiments and are therefore not to be considered limiting the scope of the appended patent claims.

[0033] FIG. 1 shows a block diagram of an exemplary apparatus comprising an analog integrated circuit 5 and a digital integrated circuit in accordance a first embodiment of the invention,

[0034] FIG. 2 shows a block diagram of an exemplary apparatus comprising an analog integrated circuit 5 and a digital integrated circuit in accordance with a second embodiment of the invention,

[0035] FIG. 3 shows an expanded block diagram of the analog integrated circuit according to the first and second exemplary embodiments of the apparatus,

[0036] FIG. 4 shows a detailed block diagram of a wireless charging circuit of the analog integrated circuit according to exemplary embodiments thereof; and FIG. 5 shows a detailed block diagram of a tag interface circuit according to exemplary embodiments thereof.

[0037] DETAILED DESCRIPTION OF THE DRAWINGS

[0038] The skilled person will understand that the accompanying drawings are schematic and simplified for clarity, and may in some instances merely show details which are essential to the understanding of the embodiments of the exemplary apparatus while other details have been left out.

[0039] FIG. 1 shows a block diagram of an apparatus 1 comprising an analogue (“analog”) integrated circuit 5 configured to be controlled, fully or at least in part, by a digital integrated circuit 10. The digital integrated circuit 10 may for example comprise a microcontroller such as an off-the-shelf microcontroller, microprocessor or Digital Signal Processor controlled by software routines or applications that each may comprise a set of executable program instructions. The software routines or applications running on the digital integrated circuit 10 may control various tasks of the digital integrated circuit 10 such as generating and transmitting commands to the analog integrated circuit 5 to control its operation and read data from control registers of the analog integrated circuit 5.

[0040] The analog integrated circuit 5 and the digital integrated circuit 10 are connected through a data communication interface 55. The data communication interface 55 may comprise a proprietary data communication interface or an industry-standard serial data communication interface for transmission of the commands from the digital integrated circuit 10 to the analog integrated circuit 5. The industry-standard serial data communication interface may be embodied as, or at least be compatible with, the synchronous, full duplex master-slave-based interface (SPI) standard.

[0041] The analog integrated circuit 5 and the digital integrated circuit 10 may in some embodiments be integrated on a common semiconductor substrate and interconnected by an on-chip data communication interface 55. Alternatively, the analog integrated circuit 5 and the digital integrated circuit 10 may be separate physical entities such as separate integrated circuits arranged on different semiconductor substrates as schematically illustrated on FIG. 2. In the latter embodiment, the separate analog integrated circuit 5 and digital integrated circuit 10 may be bonded to a common carrier substrate such as a printed circuit board (not shown) and electrically interconnected by respective externally accessible bonding pads and suitable wiring patterns arranged on, or in, the common carrier substrate. The DC power supply Vdd generated on the analog integrated circuit 5 by a wireless charging circuit 25 may be coupled to a DC supply input of the digital integrated circuit 10 via respective bonding pads and PCB wiring.

[0042] The apparatus 1 may comprise a clock generator 15 which is configured to supply a clock signal to the digital integrated circuit 10. The digital integrated circuit 10 may be configured to derive an internal master clock signal from the clock signal and use the internal master clock signal to synchronize digital circuitry of the digital integrated circuit 10. The internal master clock signal may be used to derive a clock signal of a clock line of the data communication interface 55. The clock signal may thereby at least partly synchronize operations of the analog integrated circuit 5 with operations of the digital integrated circuit 10.

[0043] The data communication interface 55 handling of incoming data and outgoing data such as commands and other control data in accordance with a protocol of the data communication interface in question for example the bidirectional SPI data communication interface. The data communication interface 55 may generally be connected to a plurality of control registers of the analogue integrated circuit 5 via a data bus or respective data lines 78. The plurality of control registers may at least comprise a control register 40a of a tag interface circuit 40 and a control register 25a for the wireless charging circuit 25 as schematically indicated on FIG. 1.

[0044] Each of the plurality of control registers may in some embodiments comprise at least one of sensor signals collected from a sensor interface circuit of the analogue integrated circuit 5, such as the tag interface circuit 40, and indicator signals of an indicator interface circuit such as an audio or optical interface circuit (shown on FIG. 3) as discussed in additional detail below. Each of the plurality of control registers may generally comprise one or both of configuration settings of the sensor interface circuit and the indicator interface circuit and / or status information of the sensor interface circuit or of the indicator interface circuit.

[0045] The analog integrated circuit 5 comprises a tag interface portion or circuit 40 coupled with at least one tag reader analog device 35 (such as one or more tag coil(s)). The analog integrated circuit 5 is configured to wirelessly read an external tag apparatus (not shown) such as a passive RFID tag or active RFID tag using the least one tag coil 35. The least one tag coil 35 is configured for receipt of magnetically coupled tag signals or data emitted by an antenna of the external tag apparatus. The external tag apparatus may comprise a toy figure and stored tag data therein may be exploited to influence interactive play involving dynamic interactions between the external tag apparatus and the apparatus 1. In some embodiments, the apparatus 1 comprises an audio toy brick which may be given a particular play identity by the tag data received from the external tag apparatus.

[0046] The analog integrated circuit 5 may additionally comprise a wireless charging circuit 25 configured to regulate charging of a battery 20 that may be external to the apparatus 1 such as an external rechargeable battery cell(s). The analog integrated circuit 5 is configured to be powered or energized at least partly by the external battery 20 during operation. The wireless charging portion or circuit 25 may be connected to the external battery 20 by conductive wires or traces 45 coupled to one or more externally accessible pads of the analog integrated circuit 5. A battery voltage derived from the wireless charging circuit 25 may serve as a DC supply voltage, Vdd, of analog and digital circuitry of the analog integrated circuit 5 for example the tag interface circuit 40. The DC supply voltage may further be configured to supply power to the digital integrated circuit 10 for example using electrical traces or wires 45. The wireless charging circuit 25 may comprise an energy harvesting circuit coupled to at least one external magnetic field sensing analogue device 30 such as one or more charge coil(s) configured to pick-up magnetic charging fields generated by an external wireless charger (not shown). The least one external tag reader analog device 35 and the at least one external magnetic field sensing analogue device 30 may be embodied as one or more shared tag and charge coil(s) so as to reduce the number of external components of the apparatus 1.

[0047] FIG. 3 shows an expanded block diagram of the analog integrated circuit 5 according to an exemplary embodiment thereof. The analog integrated circuit 5 may comprise a digital controller 50 such a digital state machine or digital processor that is integrally formed with the analog integrated circuit 5 for example on a common semiconductor substrate. The digital controller 50 is connected to the data communication interface 55 for receipt of commands from the digital integrated circuit 10 e.g. commands that control an operational state of the analogue integrated circuit 5. The digital controller 50 comprises a control register or register stack 76 which inter alia comprises a plurality of control registers that generally comprises various configuration settings of the analogue integrated circuit 5 such as the operational state, clock signal frequency, clock distribution, interrupt masks etc. The digital controller 50 may comprise a hardware timing interface 80 that controls various timing patterns of operations by circuit blocks, such as the wireless charging circuit 25, of the analogue integrated circuit 5. The hardware timing interface 80 may be clocked by the master clock signal CLK supplied by the digital integrated circuit 10. The hardware timing interface 80 may comprise dedicated control register in which configuration settings of the analog integrated circuit 5 can be written by the digital integrated circuit 10 or read by the digital integrated circuit 10. The digital controller 50 may be configured to reset all hardware timing signals of the analogue integrated circuit 5 to default values to achieve a low-power operating state thereof upon entry into an autonomous state of operation of the analogue integrated circuit 5 as discussed below.

[0048] The digital integrated circuit 10 is configured to read tag data or tag messages from a dedicated tag signal portion or segment of the control register 40a of the tag interface circuit 40. The tag messages are transmitted from the external tag apparatus (not shown) and temporarily stored in the tag signal segment. The tag interface circuit 40 may additionally be configured to transmit tag messages, generated and supplied by the digital integrated circuit 10, to the external tag apparatus. The control register 40a of the tag interface circuit 40 may comprise various configuration settings of the tag interface circuit 40 such as transmission frequency, data rate, input sensitivity etc.

[0049] The wireless charging circuit 25 may comprise the control register 25a. The control register 25a may comprise various configuration settings of the wireless charging circuit 25 such as switching frequency, operational mode, supply current limits etc. The digital integrated circuit 10 is configured to control operations of the wireless charging circuit 25 by reading and / or writing the tag messages and / or configuration settings to the control register 25a.

[0050] The digital controller 50 may be configured to switch the analogue integrated circuit 5 between at least two operational states comprising an autonomous state wherein the analogue integrated circuit 5 operates independent of the commands from the digital integrated circuit 10 and a slaved state wherein the analogue integrated circuit 5 receives, and operates in accordance with, the commands from the digital integrated circuit 10. In the latter embodiment, the analog integrated circuit 5 is fully or partly controlled by the digital integrated circuit 10 and predominantly functions a slave of the digital integrated circuit 10 by receiving and operating in accordance with commands from the latter. The digital integrated circuit 10 may be configured to place the analog integrated circuit 5 in the slaved state by writing an appropriate command to the configuration settings of the control register 76 of the digital controller 50.

[0051] The analog integrated circuit 5 may comprise the above-mentioned wireless charging circuit 25 and the tag interface circuit 40. The analog integrated circuit 5 additionally comprises an optional magnetic field measurement circuit 65 coupled with at least one external magnetic field sensing analogue device such as at least one external, to the apparatus 1 , coil. In the present embodiment, the magnetic field measurement circuit 65 interfaces to three external coils In-x, In-y and In-z. The magnetic field measurement circuit 65 is configured to measure either or both of at least one amplitude of a magnetic field and at least one phase of the magnetic field. In the present embodiment the magnetic field measurement circuit 65 is configured to measure respective amplitudes and phases (“field signals”) of magnetic fields picked- up by the three external coils In-x, In-y and In-z. The three external coils In-x, In-y and In-z may be arranged orthogonally to each other for example attached on orthogonal surfaces of an external toy device like a toy brick. The magnetic field signals of the three external coils In-x, In-y and In-z allow the digital integrated circuit 10, such as the microcontroller of microprocessor, to compute distances and orientations to an associated external toy device. The associated toy device includes a receipt / transmit coil that transmit the magnetic field signal(s) to the three external coils In-x, In-y and In- z in response to receipt of the carrier emission from the external coils In-x, In-y and In- z. The magnetic field measurement circuit 65 may be configured to receive the field signals from the magnetic field sensing analogue devices, e.g. three external coils In-x, In-y and In-z, in a sequential fashion. The respective field amplitudes and field phases of the magnetic field signals may be written by magnetic field measurement circuit 65 to the control register 65a. The digital integrated circuit 10 may read the relevant register locations or cells of the control register 65a through the data communication interface 55 using appropriate commands. The magnetic field signals picked-up by the external coils In-x, In-y and In-z may be inputted to a combine and multiplex circuit 84 that is controlled by the digital integrated circuit 10. The digital integrated circuit 10 may be configured to sequentially route the output of the combine and multiplex circuit 84 to the input of the magnetic field measurement circuit 65.

[0052] The analog integrated circuit 5 may comprise an optional audio interface circuit 70, 72 that is configured to generate at least one audio signal that controls an audio analogue device. In the present embodiment the audio interface circuit comprises a speaker interface circuit 70 and a microphone interface circuit 72. An output of the speaker interface circuit 70 is connectable to an external loudspeaker 205 such as miniature electrodynamic speaker. The speaker interface circuit 70 may comprise a power amplifier such as a pulse-modulated power amplifier that transmits amplified audio signals to the external loudspeaker 205. The speaker interface circuit 70 comprises a control register 70a in which configuration settings, such as amplification, output signal limiting etc., are stored. The configuration settings may be accessed e.g. written to and / or read by the digital integrated circuit 10 using appropriate commands. The control register 70a may be configured for temporary storage a digital audio signal or audio segment to be reproduced as sound by the external loudspeaker 205. The digital audio signal or audio segment may be generated by the digital integrated circuit 10 and transmitted to the control register 70a. The digital integrated circuit 10 may control the timing of the transmission of the digital audio signal.

[0053] The microphone interface circuit 72 comprises a control register 72a in which configuration settings, such as preamplifier amplification, bias current, input signal limiting etc., of the microphone interface circuit 72, may controlled by the digital integrated circuit 10 by reading and writing the control register 72a. The control register 72a may temporary store a digital audio signal, or an audio signal segment, representative of incoming sound at the external microphone 210. The digital integrated circuit 10 may read the audio signal segment by transmitting an appropriate command to the control register 72a. The digital audio signal or audio segment of the control register 72a may represent incoming microphone sound captured by the microphone interface circuit 72 in accordance with a command from the digital integrated circuit 10. In this fashion the digital integrated circuit 10 may control the timing of the capture of the digital audio signal.

[0054] The analog integrated circuit 5 additionally comprises an optional optical interface circuit 74. The optical interface circuit 74 may comprise an optical transmitter interface or circuit configured to control an external light emitter 215 such as a LED coupled to the optical transmitter interface and / or an optical receiver interface or circuit configured to receive an electrical signal representative of light received by an external light receiver 220 such as a photo-diode coupled to the optical receiver interface 74. The optical interface circuit 74 may be used as part of a toy for light signalling to a user. The optical interface circuit 74 may also be used to detect external toy objects by emitting light through the external light emitter 215 and detect reflected light through the external light receiver 220. The optical interface circuit 74 may comprise a control register 74a in which respective configuration settings of the optical transmitter circuit and optical receiver circuit may be stored. The respective configuration settings may be written to, or read by the digital integrated circuit 10 using appropriate commands. The control register 74a may be configured for temporary storage of an optical data signal or signal segment to be emitted by the optical transmitter circuit. The control register 74a may be configured for temporary storage of an optical signal segment that is received by the optical receiver circuit in response to light impinging on the external light receiver 220.

[0055] In some embodiments of the analog integrated circuit 5, the optical transmitter circuit is configured to transmit optical data stored in the sensor and indicator configuration register 74a. The optical data held in the control register 74a may be a simple on-off control of the external light emitter 215 to emit visible light signals to a user. Alternatively, or additionally, the optical data may comprise various types of data to provide an optical wireless data communication interface that are accessible to the digital integrated circuit 10. The digital integrated circuit 10 may control the timing of the emission and capture of the optical signals from the control register 74a using appropriate commands.

[0056] The wireless charging circuit 25 comprises the previously discussed energy harvesting circuit which is electrically coupled to the three external coils In-x, In-y and In-z that may be arranged orthogonally to each other as discussed above. The three external coils In-x, In-y and In-z are configured to pick-up the magnetic charging field provided by the external wireless charger (not shown). The respective energy or power contributions by the three external coils In-x, In-y and In-z are summed by the combine and multiplex circuit 84. The skilled person will understand that use of two, three or more orthogonally arranged external coils provides efficient energy harvesting and less dependency on the actual orientation of the apparatus 1 relative to the external wireless charger.

[0057] The tag interface circuit 40 may share the three external coils In-x, In-y and In-z with the wireless charging circuit 25 in some embodiments of the apparatus 1 to reduce the number of external components, size of the apparatus and its manufacturing costs. The coil sharing is preferably controlled by the digital integrated circuit 10 by operating the combine and multiplex circuit 84 in a sequential fashion where a first time slot is allocated to energy harvesting from the magnetic charging field by the wireless charging circuit 25. A second, and non-overlapping, time slot is allocated to operate the tag interface circuit 40 so as to transmit tag messages and / or receive tag messages. The digital integrated circuit 10 may be configured to make a sequential activation of the wireless charging circuit 25 and tag interface circuit 40 by controlling the combine and multiplex circuit 84 via its select input 85.

[0058] In one embodiment of the apparatus 1 the analogue integrated circuit 5 comprises at least the autonomous state and the slaved state. In the slaved state the digital integrated circuit 10 may be configured to control operational states, control register data of one or more of the audio interface circuit 70, 72, the wireless charging circuit 25, the tag interface circuit 40 and optical interface circuit 74 etc. by appropriate commands. In the slaved state the digital integrated circuit 10 may be configured to control hardware timing of the interface circuits. The analogue integrated circuit 5 is configured to operate independently of commands from the digital integrated circuit 10 in the autonomous state. In the autonomous state the digital controller 50 of the analogue integrated circuit 5 may carry out a number of basic tasks to ensure that the apparatus 1 can recover from a situation where the digital integrated circuit 10, e.g. the microprocessor, is disabled or non-operational. The digital integrated circuit 10 may for example be disabled or non-operational because its DC supply voltage is too low for proper operation. The too low DC supply voltage may be caused by a depleted rechargeable battery 20. Under the latter circumstance the digital integrated circuit 10 is unable to generate and transmit the commands that control the analogue integrated circuit 5. The analogue integrated circuit 5 may in the slaved state be configured to detect the disabled or non-operational state of the digital integrated circuit 10 in various ways to make a decision to switch to the autonomous state. According to one embodiment, the digital controller 50 is configured to monitor activity on the data communication interface 55 while operating in the slaved state and switch to the autonomous state in response to inactivity on the data communication interface 55 longer than a predetermined time limit for example 30 s or 1 minute etc. The detection of inactivity may involve lack of commands and / or absence of a clock signal on communication interface 55 for more than the predetermined time period.

[0059] FIG. 4 shows a detailed block diagram of the wireless charging circuit 25 of the analog integrated circuit 5 according to an exemplary embodiment of the wireless charging circuit 25. As mentioned above the three external coils In-x, In-y and In-z are configured to pick-up the magnetic charging field provided by the external wireless charger (not shown). The external coils In-x, In-y and In-z output corresponding charging signals to a charge coil matching circuit 302 arranged on the analog integrated circuit 5. The charge coil matching circuit 302 is configured to optimize the coupling, and hence energy transfer of, the external coils In-x, In-y and In-z for example by tuning resonance frequencies of the coils In-x, In-y and In-z to an emission frequency of the charging field. The frequency of the magnetic charging field may for example lie between 10 MHz and 40 MHz for example about 27.12 MHz. The tuning or adjustment of the respective resonance frequencies of the external coils In-x, In-y and In-z is carried out by a tuning circuit 304 that may be controlled by the digital integrated circuit 10 by writing configuration register settings into the control register 25a of wireless charging circuit 25 as generally discussed above. The tuning circuit 304 is configured to switch one or more external capacitors (not shown) into the matching circuit 302 in parallel with the respective coils to adjust the respective resonance frequencies.

[0060] The wireless charging circuit 25 comprises three auto limiter circuits 306 coupled to the respective output signals of the charge coil matching circuit 302. These auto limiter circuits 306 are configured to protect downstream circuitry of the of the wireless charging circuit 25 from damage by over-voltage spikes or events. The over-voltage spikes or events may be caused by close proximity of the charging coils to the external charger and / or EMI induced. Voltage limited charge signals outputted by the auto limiter circuits 306 are combined and rectified by the energy harvesting circuit 308 to deliver to energize the previously discussed DC supply voltage on supply line or wire 45. The skilled person will appreciate that the energy harvesting circuit 308 may comprise various types of supply voltage conditioning circuits such as DC-DC boost and / or DC-DC buck converters, voltage regulators etc. to provide the DC supply voltage on wire 45. The supply voltage conditioning circuits may comprise an external smoothing capacitor 312.

[0061] The wireless charging circuit 25 may comprise a charge field detection circuit 310 which e.g. is coupled to input of the energy harvesting circuit 308. In the autonomous state of the analogue integrated circuit 5 the charge field detection circuit 310 may be utilized to wake-up the analogue integrated circuit 5 from a deactivated state, off-state or a low-power state. The analogue integrated circuit 5 may reside in the deactivated state, off-state or low-power state if the external rechargeable battery is depleted and there is no useful magnetic charging field available. In the deactivated state of the analogue integrated circuit 5 only the charge field detection circuit 310 may be operative so as to minimize power consumption of the circuit 5. The charge field detection circuit 310 may be configured to respond to the presence of a useful magnetic charging field by switching the analogue integrated circuit 5 into an active state where the wireless charging circuit 25 in response starts to generate the DC supply voltage. The digital integrated circuit 10 may in response detect the presence of an appropriate DC supply voltage, reboot its processing circuitry, load the software applications and commence normal operation. Once normal operation is resumed by the digital integrated circuit 10 the latter may be configured to transmit a command to the analog integrated circuit 5 to switch the analog integrated circuit 5 to its slaved state. The charge field detection circuit 310 may be configured to repeatedly detect various magnetic field variables and energy harvesting variables and write these to the control register 25a for example in appropriate storage cells or memory.

[0062] In the slaved state of the analogue integrated circuit 5, where the digital integrated circuit 10 normally operates as a master device, the latter may be configured to read stored magnetic field variables and energy harvesting variables from the control register 25a. The digital integrated circuit 10 may adapt its processing based on values of the field variables and energy harvesting variables. In one embodiment, the digital integrated circuit 10 is configured to dynamically allocate the amount of time for energy harvesting relative to the amount of time spent for handling of the available sensor and indictor interface circuits based on values of the energy harvesting variables.

[0063] FIG. 5 shows a block diagram of the tag interface circuit 25 according to exemplary embodiment. The tag interface circuit 25 may be configured to operate in a receive mode where the tag interface circuit 25 receives a response message from the external tag device (not shown). The tag interface circuit 25 may be compatible with the RFID standard ISO15693 to energize and activate an external tag device and read-back tag messages transmitted by the external tag device. At the same time the tag reader may be configured to measure and report derived signal properties such as received signal strength and phase by writing these signal variables to the control register 25a of the tag interface circuit 25. During operation the tag interface circuit 25 may be configured to transmit and receive tag data at the same time on a 13.56 MHz carrier. During operation of the tag interface circuit 25 it may be configured to load-modulate a 13.56MHz carrier signal transmission resulting in a smaller signal imposed of a reader carrier. The tag interface circuit 25 may includes an AGC system 503 that selects an optimal gain of a front-end amplifier 501. The tag interface circuit 25 may use a digital back-end processor 505 to receive the output signal of the AGC system 503. The settled-AGC value of a receive gain is useful as the equivalent received signal strength (RSSI) at the input terminal 509 connected to the external tag reader analog device 35. The digital receiver signal strength (“digital rssi”) may optionally repeatedly be measured by the tag interface circuit 25 and written back-end processor 505 into the control register 25a as well as the settled AGC gain. The digital integrated circuit 10 may be configured to read digital rssi and settled AGC gain through the data communication interface and calculate the equivalent RSSI at the at the input terminal 509. Received tag data or messages are likewise stored in the control register 25a for each tag message receipt event.

Claims

CLAIMS1. An apparatus comprising- an analogue integrated circuit configured to be controlled, at least in part, by a digital integrated circuit, the analogue integrated circuit comprising- a tag interface circuit coupled with at least one tag reader analogue device and configured to wirelessly read an external tag apparatus,- a wireless charging circuit configured to regulate charging of an external battery, wherein the analogue integrated circuit is configured to, during operation, be powered by the external battery.

2. The apparatus according to claim 1 , wherein the wireless charging circuit further comprises- an energy harvesting circuit coupled to at least one external magnetic field sensing analogue device,- a charge field detection circuit.

3. The apparatus according to claim 2, wherein the analogue integrated circuit further comprises- an inactive state where only the charge field detection circuit is operative, wherein the charge field detection circuit is configured to respond to a magnetic charging field by switching the analogue integrated circuit into an active state.

4. The apparatus according to any of the preceding claims, wherein the digital integrated circuit and the analogue integrated circuit are connected through a data communication interface.

5. The apparatus according to claim 4, wherein the digital integrated circuit is configured to control the analogue integrated circuit by generating and transmitting commands to the analogue integrated circuit through the data communication interface.

6. The apparatus according to any of the preceding claims, wherein the analogue integrated circuit comprises a plurality of control registers coupled to the data communication interface, wherein the plurality of control registers at least comprises- a control register for the tag interface circuit and a control register for the wireless charging circuit.

7. The apparatus according to claim 6, wherein each of the plurality of control registers comprises at least one of- sensor signals collected from a sensor interface circuit of the analogue integrated circuit,- indicator signals of an indicator interface circuit,- configuration settings of the sensor interface circuit or of the indicator interface circuit,- status information of the sensor interface circuit or of the indicator interface circuit.

8. The apparatus according to claim 7, wherein the commands from the digital integrated circuit comprise one or more of- reading respective sensor signals from the plurality of control registers,- writing respective indicator signals to the plurality of control registers,- reading respective status information from the plurality of control registers.

9. The apparatus according to any of the preceding claims, wherein the analogue integrated circuit comprises a digital controller connected to the data communication interface for receipt of commands from the digital integrated circuit.

10. The apparatus according to any of the preceding claims, wherein the analogue integrated circuit comprises at least two operational states- an autonomous state wherein the analogue integrated circuit operates independent of the commands from the digital integrated circuit; and- a slaved state wherein the analogue integrated circuit receives, and operates in accordance with, the commands from the digital integrated circuit.

11. The apparatus according to claim 10, wherein the analogue integrated circuit comprises a digital controller configured to:- monitor activity on the data communication interface in the slaved state; and- switch to the autonomous state in response to inactivity.

12. The apparatus according to any of the preceding claims, wherein the analogue integrated circuit further comprises- a magnetic field measurement circuit coupled with at least one external magnetic field sensing analogue device such as an external coil; and- wherein the magnetic field measurement circuit is configured to measure either or both of at least one amplitude of the magnetic field and at least one phase of the magnetic field, and wherein the analogue integrated circuit is configured to transmit the at least one amplitude of the magnetic field and at least one phase of the magnetic field to the digital integrated circuit.

13. The apparatus according to claim 12, wherein the at least one magnetic field sensing analogue device(s) comprises- a first magnetic field sensing analogue device arranged to measure a first magnetic field amplitude and phase along a first vector direction,- a second magnetic field sensing analogue device arranged to measure a second magnetic field amplitude and phase along a second vector direction, wherein the first and second vector directions are substantially orthogonal; and wherein- the magnetic field measurement circuit is configured to receive the first magnetic field amplitude and phase and the second magnetic field amplitude and phase in a sequential fashion.

14. The apparatus according to any of the preceding claims, wherein the analogue integrated circuit further comprises- an audio interface circuit configured to generate an audio signal that controls an audio analogue device.

15. The apparatus according to claim 14, wherein the audio interface circuit comprises:- a speaker interface circuit configured to supply a first audio signal to an external speaker,- a microphone interface circuit configured to receive a second audio signal from an external microphone.

16. The apparatus according to any of the preceding claims, further comprising- an optical interface circuit that controls an external optical analogue device.

17. The apparatus according to claim 16, wherein the optical interface circuit comprises- an optical transmitter interface configured to control an external light emitter,- an optical receiver interface coupled to an external light detector for receipt of an electrical signal representative of received light such as continuous ambient light or data-modulated light of any colour.

18. An apparatus comprising:- a tag interface circuit coupled with at least one tag reader analogue device and configured to wirelessly read an external tag apparatus;- a wireless charging circuit configured to regulate charging of an external battery, wherein the tag interface circuit and the wireless charging circuit are configured to, during operation, be powered by the external battery.

19. A toy or educational device comprising an apparatus according to any of the preceding claims.

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