Modulation of power supply current in active antenna systems

Abstract

Disclosed are exemplary embodiments of current control circuits and methods for modulating power supply current from a first device (such as a telematics control unit (TCU) or the like) to one or more second devices (such as one or more compensators or the like). In an exemplary embodiment, a method includes modulating a power supply current from a first device to one or more second devices into different current values for reporting different information from the one or more second devices to the first device. An exemplary embodiment of a current control circuit includes a variable voltage source electrically coupled to a current source and a current sink. The current control circuit is configured to be operable to modulate a power supply current from a first device to one or more second devices into different current values for reporting different information from the one or more second devices to the first device.

Description

[0001] Related applications

[0002] This application claims priority to U.S. Provisional Application US63 / 214994, filed June 25, 2021, which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to the modulation of power supply current in an active antenna system. Background Technology

[0004] As motor vehicles become increasingly data-driven, the need to communicate with the outside world becomes ever more critical. Passengers within vehicles frequently rely on personal mobile devices for streaming music, communicating with others, and even navigation. Motor vehicles themselves can also interact with external systems. Such communication allows for over-the-air updates of vehicle-related external conditions and navigation information via Vehicle-to-Everything (V2X) communication from a central server. If a vehicle possesses autonomous driving capabilities, the ability to provide sensed data to a central server allows for the reception of improved driving algorithms. Therefore, there are numerous reasons for both providing data to and receiving data from a motor vehicle.

[0005] Unfortunately, from a transmitting and receiving point of view, motor vehicles are often less than ideal. The thick metal plates of a vehicle often greatly increase transmission losses, and therefore many vehicles employ externally mounted antennas to avoid these losses. For example, vehicles typically include a small fin antenna (often called a shark fin antenna) mounted on the roof of the vehicle to reduce these losses.

[0006] However, as the number of antennas in a vehicle increases, this creates a more complex system. For example, if both V2X and conventional cellular communication are desired, two antenna systems may be used. These antenna systems will often be installed at spaced locations, and, for example, one antenna system may be installed facing the front of a vehicle while another faces the rear. If a single receiver is used as two antennas, the insertion loss in the cable system between the Network Access Device (NAD) and one or both antennas will necessitate utilizing one or more compensator systems to ensure the desired performance. Because the operation of the communication system is critical to the safety systems within a vehicle, it is often desirable to know how the various systems can operate in a cost-effective manner. As a result, some groups will appreciate further improvements in compensator systems. Summary of the Invention

[0007] This section provides a general overview of this disclosure but is not a complete disclosure of the full scope or all features of this disclosure.

[0008] Several exemplary embodiments of a current control circuit and method for modulating the power supply current from a first device (such as a telematics control unit (TCU)) to one or more second devices (such as one or more compensators) are disclosed. In one exemplary embodiment, a method includes modulating a power supply current from a first device to one or more second devices into different current values ​​for reporting different information from the one or more second devices to the first device.

[0009] An exemplary embodiment of a current control circuit includes a variable voltage source electrically connected to a current source and a current sink. The current control circuit is configured to operate to modulate a power supply current from a first device to one or more second devices to different current values ​​for reporting different information from the one or more second devices to the first device.

[0010] Further areas of application will become clear from the description provided herein. The descriptions and specific examples in this invention are for illustrative purposes only and are not intended to limit the scope of this disclosure. Attached Figure Description

[0011] This application illustrates, but is not limited to, the accompanying drawings by way of example, in which similar reference numerals denote similar parts, in which:

[0012] Figure 1 This is a block diagram of an example vehicle communication system according to an exemplary embodiment of the present disclosure, the example vehicle communication system including a V2X compensator having a current control circuit configured to modulate the power supply current from the TCU to the DC of the V2X compensator.

[0013] Figure 2 This is a circuit diagram illustrating an exemplary embodiment of a current control circuit, which can be used in... Figure 1 In the V2X compensator or other device shown (such as another compensator, an antenna of a distributed antenna system, etc.).

[0014] Figure 3 This is a block diagram of an example implementation of an exemplary embodiment of the present disclosure, in which multiple devices each include a current control circuit and are electrically connected to a voltage power supply that is grounded and electrically connected to a base device.

[0015] Figure 4 It is shown Figure 3A circuit diagram of an example current monitoring circuit for a basic device shown.

[0016] Figure 5A , Figure 5B , Figure 5C and Figure 5D Including targeting Figure 3 The current control circuits for the multiple devices shown are (specifically, the current control circuit for device n+1). Figure 5A ), the current control circuit of device n+2 ( Figure 5B ), the current control circuit of device n+3 ( Figure 5C The total current distribution across a time interval of constant reference current for all three devices ( ) and the total current distribution across a constant reference current for all three devices ( ) Figure 5D Linear graph of current distribution in milliamperes (mA) versus time in seconds (s).

[0017] Figure 6 This is a block diagram of an example implementation of an exemplary embodiment of the present disclosure, in which a single device includes a current control circuit electrically connected to a voltage power supply that is grounded and electrically connected to a base device.

[0018] Figure 7 It is aimed at Figure 6 The diagram shows a linear graph of the total current distribution in milliamperes (mA) and seconds (s) for the current control circuit of a single device under different current states of that single device.

[0019] In several figures that are covered by the accompanying drawings, corresponding reference numerals may indicate corresponding (but not necessarily identical) parts. Detailed Implementation

[0020] The following detailed description illustrates exemplary embodiments and is not intended to limit to the explicitly disclosed combinations. Therefore, unless otherwise stated, the features disclosed herein can be combined to form other combinations not shown for purposes of brevity.

[0021] Today's TCUs can monitor the current of V2X compensators, but current-based implementations may require components capable of handling power dissipation greater than 700 milliwatts (mW). As can be recognized, these higher-power components are expensive and larger in size. Furthermore, existing implementations rely on voltage power supplies and require an additional communication path (e.g., UART / LIN, UART on a pilot tone).

[0022] Having understood the foregoing, this document develops and / or discloses exemplary embodiments of current control circuits and methods configured to modulate a power supply current from a first device (e.g., a TCU, the central unit of a distributed antenna system, etc.) to a second device (e.g., one or more compensators, etc.). In several exemplary embodiments, the current control circuit includes a variable voltage source electrically connected (e.g., via a transistor, etc.) to a current source and a current absorber. The variable voltage source (e.g., a digital-to-analog converter (DAC), an adjustable voltage stabilizer, a programmable voltage stabilizer, a voltage divider, etc.) is operable to adjust or modulate the power supply current to different current values ​​for reporting different information (e.g., error messages, status information, control information, etc.) from the second device (which may be two or more devices) to the first device. The current control circuit may be configured to respond using a predetermined current value that is independent of and does not depend on the power supply voltage from the current source.

[0023] In one exemplary embodiment, the current control circuit is connected to a UART-TX port of a microcontroller (MCU) to modulate a UART frame to a fixed current (e.g., Figure 5A , Figure 5B and 5C (etc.). In this example, the variable voltage source of the current control circuit can be replaced by a diode in the current control circuit of the MCU or used in conjunction with a diode in the current control circuit of the MCU. One or more resistors in the current control circuit of the MCU can be changed depending on the desired / required current intensity.

[0024] In another exemplary embodiment, the current control circuit is connected to a DAC port of a microcontroller, thereby making the timing and current intensity controllable (e.g., Figure 5A , Figure 5B , Figure 5C and Figure 7 (etc.). In this example, the variable voltage source (such as a DAC, etc.) can replace the diode in a current control circuit of the MCU. The variable voltage source can operate to adjust or modulate the power supply current to different values ​​for reporting different information (such as error messages, status information, control information, etc.) from the one or more second devices to the first device.

[0025] The variable voltage source can be a digital-to-analog converter (DAC), an adjustable voltage stabilizer, a programmable voltage stabilizer, a specific voltage divider, etc. For example, for multiple devices with different current values ​​used to report their different statuses, a specific voltage divider can be used at the UART-TX port of a microcontroller. Alternatively, for example, the variable voltage source can be an adjustable voltage stabilizer, and a circuit can be used to control the resistor value at the adjustable voltage stabilizer (and not to control the resistor of the current sink). The resistor at the adjustable voltage stabilizer is not necessarily required to be in a high current / power range.

[0026] Advantageously, the exemplary embodiments disclosed herein can solve or mitigate problems or deficiencies associated with conventional implementations. Compared to conventional systems, the exemplary embodiments disclosed herein can provide one or more (but not necessarily any or all) of the following advantages or characteristics. For example, exemplary embodiments include components with low power performance and avoid the use of more expensive and higher power dissipation components, thereby reducing costs and saving space. In several exemplary embodiments, additional communication paths (such as UART / LIN, UART on a pilot) for reporting information from the V2X compensator to the TCU are not required. Several exemplary embodiments are configured to employ an electrical current draw that is independent of and does not depend on the power supply voltage from the current source.

[0027] In several exemplary embodiments, the first device may include a telematics control unit (TCU), and the second device may include at least one V2X compensator. The power supply current from the TCU to the V2X compensator may be modulated by a device on or included within the V2X compensator to report information from the V2X compensator to the TCU. The information may include status information, control information, an error message, etc. Using the modulation of the power supply current from the V2X compensator, the information can be transmitted from the V2X compensator to the TCU via the same single coaxial conductor or cable that also supplies the power voltage from the TCU to the V2X compensator. Accordingly, the information can be transmitted from the V2X compensator to the TCU without incurring the additional costs associated with a separate communication path such as UART / LIN or UART on a pilot.

[0028] Now refer to the attached diagram, Figure 1An example of an in-vehicle communication system 100 (generally, a system) according to an exemplary embodiment is shown. This example in-vehicle communication system 100 includes a telematics control unit (TCU) 104 (an example of a first device), an antenna 108, and a V2X compensator 112 (an example of a second device). The V2X compensator 112 is generally positioned between the TCU 104 and the antenna 108. The TCU 104 is electrically connected to the V2X compensator 112 via a single coaxial line or cable 132.

[0029] V2X compensator 112 includes a control unit 116 (such as a microcontroller (MCU)) and a device 120 that communicates with the control unit 116 via a communication path 124. The control unit 116 also communicates with a signal coupler 128 via a communication path 126.

[0030] Device 120 includes a current control circuit 130 configured to modulate the DC power supply current to V2X compensator 112 to different current values ​​for reporting different information (such as status information, control information, an error message, etc.) from V2X compensator 112 to TCU 104. In this exemplary embodiment, the power supply voltage is provided from TCU 104 to V2X compensator 112 via a coaxial conductor or cable 132 connected to signal coupler 128. Accordingly, information can be transmitted from V2X compensator 112 to TCU 104 using the same single coaxial conductor or cable 132 that also provides power supply voltage from TCU 104 to V2X compensator 112.

[0031] DC power supply current is provided from signal coupler 128 to current control circuit 130 via electrical line 140. For example, signal coupler 128 may be a PCB trace RF coupler, a chip-based directional coupler, or a bidirectional coupler, etc.

[0032] A gain modifier 144 of the V2X compensator 112 can be configured to adjust the gain of a signal so that the signal emitted from antenna 108 more closely matches the signal to be transmitted by the receiver. The gain modifier 144 may include a variable gain amplifier, an attenuator, and an amplifier along a Tx (transmit) path between a first switching element 148 and a second switching element 152. Both the first switching element 148 and the second switching element 152 may include an RF switch that selectively activates either the transmit path (Tx path) or the receive path (Rx path). The variable gain amplifier, the attenuator, and the amplifier connected in series to form the attenuator can operate to attenuate a signal received from the variable gain amplifier, which can then be sent from the attenuator to the amplifier for amplification. The attenuator may be a variable attenuator, a step attenuator, or a fixed attenuator. The attenuator may be controlled by voltage, current, digital signals, etc.

[0033] In other exemplary embodiments, the gain modifier 144 may include fewer components, more components, and / or different components. For example, in an alternative embodiment, the gain modifier 144 may include one or more (but not necessarily all) of the variable gain amplifier, the attenuator, the amplifier, or combinations thereof. A gain modifier may also or alternatively be located along the Rx (receive) path 156 between the first switching element 148 and the second switching element 152. Another alternative location for a gain modifier is between the signal coupler 128 and the first switching element 148.

[0034] A filter 158 is located between the second switching element 152 and the antenna 108. In this exemplary embodiment, the V2X compensator 112 integrally includes the antenna 108. In an alternative embodiment, the antenna 108 may be external to the V2X compensator 112. In this case, the V2X compensator 112 may be positioned relatively close to the external antenna 108 and connected to the antenna 108 via a coaxial cable or other suitable link. For the external antenna 108, the current control circuit 130 can be used to confirm whether the external antenna 108 still exists after an accident, and if the external antenna 108 does not exist, this state can be reported by a variable voltage source of the current control circuit 130 using current modulation.

[0035] In several exemplary embodiments, Figure 1The various components shown can all be integrated or contained in a single integrated component or module. For example, the V2X compensator 112, control unit 116, device 120 including current control circuitry 130, signal coupler 128, gain modifier 144, switching elements 148 and 152, filter 158, and antenna 108 can all be integrated or contained in a single integrated component or module. Alternatively, Figure 1 One or more of these various components shown (such as antenna 108, etc.) may be discrete, independent components that are not integrated into or are not an integral part of V2X compensator 112.

[0036] Figure 2 The illustration shows an exemplary embodiment of the present disclosure that may be included in Figure 1 The example current control circuit 130 within the V2X compensator 112 is shown. However, the V2X compensator 112 is only... Figure 2 The illustrated current control circuit 130 is an example of a device that can be included therein, as the current control device 130 can be included in or used with a variety of other devices. For example, the current control circuit 130 (and other current control circuits disclosed herein) can be used in other compensators, antennas of a distributed antenna system, etc.

[0037] Continue to refer to Figure 2 The current control circuit 130 includes a variable voltage source 160 and a transistor 134 electrically connecting the variable voltage source 160 to a current source 162 and a current sink 164.

[0038] The variable voltage source 160 can operate to adjust or modulate a power supply current from a first device (e.g., TCU 104, other TCUs, the central unit of a distributed antenna system (DAS), other devices, etc.) to one or more second devices (e.g., V2X compensator 112, another compensator, DAS antenna, other devices, etc.) to different current values ​​for reporting different information from the one or more second devices to the first device. The current control circuit 130 can be configured to send information from the first device (e.g., error messages, control information, status information, etc.) using current draw.

[0039] By way of example only, transistor 134 may include an NPN bipolar transistor (BJT), a PNP transistor, a metal-oxide-semiconductor field-effect transistor (MOFSET), or other suitable current-driven or voltage-driven devices. Variable voltage source 160 may be a digital-to-analog converter (DAC), an adjustable voltage regulator, a programmable voltage regulator, a specific voltage divider, etc.

[0040] In the case of the constant current source 162 in this exemplary embodiment, a constant current can be provided that is independent of the power supply voltage from the current source, depending on a control unit (such as the control unit 116 of the V2X compensator 112). Figure 1 The status to be reported to the first device (e.g., TCU 104) is also required. Additionally, transistor 134 is capable of handling the largest portion of the power dissipation, so the resistor in current sink 164 will only need to handle a relatively small portion of the power dissipation (e.g., less than 150mW in the case of 200mA). Alternative embodiments may depend on power dissipation requirements differing from... Figure 2 The configuration shown is as described. For example, other exemplary embodiments may include or require resistors for power dissipation above 700mW.

[0041] By employing a variable voltage source 160 (such as a digital-to-analog converter (DAC), the current from the current source 162 can be modulated into more different values ​​to report different information. For example, this information may include status information, control information, error messages (such as errors on the transmit path (TX path), errors on the receive path (RX path), antenna missing, overheating, execution of a watchdog timer, etc.), periodic reports of OK or error-free status, reports of significant changes in cable loss, etc.

[0042] Figure 3 An example implementation is shown in which a plurality of second devices 182 (e.g., a plurality of compensators, a plurality of DAS antennas, etc.) include a current control circuit 130. The plurality of second devices 182 are electrically connected to a voltage supply source that is grounded and electrically connected to a base device or a first device 184 (e.g., a TCU, a DAS central unit, etc.).

[0043] In this example, the base device 184 includes current monitoring. For example, the base device 184 may include, for example, current monitoring. Figure 4The diagram shows a current monitoring circuit 186. In this example, the current monitoring circuit 186 includes a resistor 188 connected in series with a DC voltage source 190. The total current is determined by dividing the voltage drop across resistor 188 (UP1–UP2) by the resistance (Rmeas) of resistor 188.

[0044] In other exemplary embodiments, the plurality of second devices 182 may include current monitoring other than or alternative to the current monitoring provided by the base device 184. In such alternative embodiments, the plurality of second devices 182 may be configured to monitor and control the current. Additionally, the plurality of second devices 182 may be configured to monitor or listen to other second devices 182.

[0045] Figure 5A , Figure 5B , Figure 5C and Figure 5D Including targeting Figure 4 The diagram shows a line graph of the current distribution in milliamperes (mA) versus seconds (s) for the current control circuit 130 of the multiple devices 182. More specifically, Figure 5A It is a linear diagram of the current distribution in the current control circuit of device n+1. Figure 5B It is a linear diagram of the current distribution in the current control circuit of device n+2. Figure 5C This is a linear graph of the current distribution in the current control circuit of device n+3. For example... Figure 5C As shown, the first time interval is shorter than the other time intervals. Figure 5D It is a linear graph showing the total current distribution of all three devices 182 across a time interval of constant base current.

[0046] Three different devices 182 share the same voltage power supply from the base device 184. Furthermore, each device 182 has a different current value (e.g., 20mA) for reporting its own information than the other devices 182. Figure 5A ), 30mA Figure 5B ), 40mA Figure 5C(etc.). By using a different current value for each device 182, the base device 184 (or other devices connected to the power supply) can distinguish the different devices 182 from each other and determine which device 182 sends which information. The current control circuit 130 of the plurality of devices 182 is configured to modulate the power supply current so that the sum of any two or more of the different current values ​​is unique and not equal to any one of the different current values. In this example, any sum of 20mA, 30mA, and 40mA will not be equal to a current value of any one of the three devices 182. If a fourth device is added, the fourth device will not have a current value of 50mA (the sum of devices 1 and 2, i.e., 20mA + 30mA = 50mA), 60mA (the sum of devices 1 and 3, i.e., 20mA + 40mA = 60mA), 70mA (the sum of devices 2 and 3, i.e., 30mA + 40mA = 70mA), or 90mA (the sum of devices 1, 2, and 3, i.e., 20mA + 30mA + 40mA = 90mA). Therefore, the fourth device will have a current value of 80mA, 100mA, or more than 100mA. If a fifth device is added, the fifth device will have a unique current value that must be adopted in the same way as the fourth device.

[0047] Figure 6 An example implementation is shown in which a single device 182 (e.g., a compensator) includes a current control circuit 130. Device 182 is electrically connected to ground and to a voltage power supply of a base device or a first device 184 (e.g., a TCU).

[0048] The infrastructure 184 includes current monitoring. For example, the infrastructure 184 may include, for instance, current monitoring. Figure 4 The current monitoring circuit 186 is shown.

[0049] Figure 7 It is aimed at Figure 6The diagram shows a line graph of the total current distribution in milliamperes (mA) versus seconds (s) for a single device 182 of the current control circuit 130 under different current states. In this example, the single device 182 uses different current values ​​to report different states, such as 90mA for state 1, 40mA for state 2, 30mA for state 3, etc. Alternatively, different states can be separated by the duration of the current without using different current values. Moreover, different current states and different time periods can be used for more complex information sharing scenarios if needed. However, for less complex scenarios, different current values ​​are preferred because they may be easier to detect, for example, by a TCU or other first device.

[0050] Figure 1 The vehicle communication system 100, TCU 104, and V2X compensator 112 shown are merely one exemplary embodiment of a current control circuit (e.g., current control circuit 130). Figure 2 Examples of systems and devices in which current control circuits may be used, such as those disclosed herein. Exemplary embodiments of the current control circuits disclosed herein may be included in or used with a variety of other devices.

[0051] For example, another exemplary embodiment includes a distributed antenna system (broadly, a system) comprising multiple antennas (broadly, a second device) connected to a central unit or modem (broadly, a first device). In this example, the central unit or modem may include a voltage supply that provides a power supply voltage to the multiple antennas. Each antenna includes a current control circuit that includes (e.g., via a transistor) a variable voltage source electrically connected to a current source and a current absorber.

[0052] The current control circuitry of the plurality of antennas is configured to operate to modulate the power supply current from the central unit to the plurality of antennas into multiple different current values, so that each antenna has a unique current value for reporting information (such as status information, control information, an error message, etc.) to the central unit. This enables the central unit to distinguish the plurality of antennas from one another and thereby determine which antenna reports which information.

[0053] The current control circuitry of the plurality of antennas is configured to modulate the power supply current into the plurality of different current values, such that the sum of any two or more of the different current values ​​is unique and not equal to any one of the different current values. The current control circuitry of the plurality of antennas is configured to operate to modulate the power supply current from the central unit, independent of the power supply voltage from the central unit to the plurality of antennas.

[0054] The distributed antenna system can be installed in a vehicle, with the multiple antennas spaced apart from each other and distributed around the vehicle. For example, a first antenna may be positioned towards the front of the vehicle, such as on the hood. A second antenna may be positioned towards the rear of the vehicle, such as on the trunk. A third antenna may be positioned on the top of the vehicle, such as on the roof. A fourth and fifth antenna may be positioned along the passenger side and driver side of the vehicle, respectively, such as on the side mirrors. By distributing the multiple antennas around the vehicle, the in-vehicle distributed antenna system can operate to provide 180 / 360-degree hemispherical coverage.

[0055] Exemplary embodiments of the current control circuits and methods disclosed herein can be used with a wide range of platforms, including automobiles, buses, trains, motorcycles, and ships, in addition to mobile platforms. Accordingly, the vehicle referred to herein should not be construed as limiting the scope of this disclosure to any particular type of platform.

[0056] The disclosure provided herein illustrates features through preferred and exemplary embodiments. Upon reading this disclosure, those skilled in the art will conceive of many other embodiments, modifications, and variations within the scope and concept of the appended claims.

Claims

1. A method for modulating current in an active antenna system, the method comprising: A power supply current from a first device to a second device is modulated into multiple current values ​​for reporting different information from the second device to the first device. The second device includes at least one compensator. The step of modulating the power supply current is performed by a current control circuit in the at least one compensator. Modulating the power supply current includes using a variable voltage source electrically connected to a current source and a current absorber. Modulating the power supply current includes modulating the power supply current from the first device to the second device, independently of the power supply voltage from the first device to the second device.

2. The method as described in claim 1, wherein, The first device includes a remote information processing control unit.

3. The method as described in claim 2, wherein, Modulating the power supply current includes: modulating the power supply current from the telematics control unit to the at least one compensator, independently of the power supply voltage from the telematics control unit to the at least one compensator.

4. The method of claim 3, wherein, The method includes: using a single coaxial wire that also provides the power supply voltage from the at least one compensator to the remote information processing control unit.

5. The method of claim 1, wherein, The first device includes a central unit of a distributed antenna system, while the second device includes a plurality of antennas of the distributed antenna system connected to the central unit.

6. The method of claim 1, wherein, The at least one compensator is a V2X compensator.

7. The method of claim 1, wherein, Modulating the power supply current includes using the variable voltage source to modulate the power supply current into different current values ​​for reporting different information from the second device to the first device.

8. The method of claim 1, wherein, The variable voltage source includes a digital-to-analog converter electrically connected to the current source and the current sink via a transistor.

9. The method of claim 1, wherein, The different information includes one or more of a status information, a control information, and an error message.

10. The method of claim 9, wherein, The different information includes an error message that reports one or more errors, such as an error in the transmit path, an error in the receive path, a lost antenna, overheating, and changes in cable loss.

11. The method of claim 1, wherein, The second device is a plurality of second devices, and the first device includes a voltage supply that provides the power supply voltage to the plurality of second devices, and the modulation of the power supply current includes: modulating the power supply current from the first device to the plurality of second devices into a plurality of different current values, such that each second device has a unique current value for reporting information to the first device, which enables the first device to distinguish the plurality of second devices from each other and thereby determine which second device reports which information.

12. The method of claim 1, wherein, The second device is a plurality of second devices, and also includes communication between one of the plurality of second devices and another of the plurality of second devices.

13. The method of claim 1, wherein, The modulation of the power supply current modulates the current into multiple different current values, such that the sum of any two or more of the different current values ​​is unique and not equal to any one of the different current values.

14. A current control circuit for a first device and a second device, the second device including at least one compensator, the current control circuit comprising: A variable voltage source electrically connected to a current source and a current absorber, wherein the current control circuit is configured to modulate a power supply current from the first device to the second device in at least one compensator into different current values, the different current values ​​being used to report different information from the second device to the first device, and to modulate the power supply current from the first device to the second device independently of the power supply voltage from the first device to the second device.

15. The current control circuit as described in claim 14, wherein, The current control circuit includes a transistor electrically connecting the variable voltage source to the current source and the current absorber, and the variable voltage source includes a digital-to-analog converter electrically connected to the current source and the current absorber.

16. The current control circuit as described in claim 14, wherein: The second device is a plurality of second devices; The first device includes a voltage power supply that provides the power supply voltage to the plurality of second devices; and The current control circuit is configured such that the power supply current from the first device to the plurality of second devices is modulated into a plurality of different current values, such that each second device has a unique current value for reporting information to the first device, which enables the first device to distinguish the plurality of second devices from one another and thereby determine which second device reports which information.

17. The current control circuit as described in claim 14, wherein, The current control circuit is configured to modulate the power supply current into multiple different current values, such that the sum of any two or more of the different current values ​​is unique and not equal to any one of the different current values.

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