Sensing system including sensor chain

Abstract

The present invention relates to a sensing system comprising a sensor chain. A sensor and a sensing system comprising a sensor chain, wherein each sensor comprises an input control port (112), an output control port (113), a power interface (111) and an output interface (114), and is configured such that when the sensor (110) is powered on via the power interface (111), an enable signal at the input control port (112) triggers the sensor (110) to perform a sequence comprising measuring a physical property and subsequently sending an enable signal via the output control port (113). The output control port (113) of an earlier sensor (110) is connected to the input control port (112) of the next sensor (110). The first sensor is configured to repeat the sequence with a predefined period.

Description

Technical Field

[0001] The present invention relates to the field of sensors and sensing systems. More particularly, it relates to a sensing system comprising a sensor chain and thus to a sensor. Background Art

[0002] A sensing system including multiple sensors organized in a chain operating in a sleep / wake-up mode may be affected by power supply issues. For example, in the case of a printed circuit board (PCB) strip application, the resistance of the PCB traces used to power the sensors (e.g., integrated circuits (ICs)) is typically around 1-2Ω per meter. A 5mm sensor spacing results in 200 ICs per meter, each consuming about 2mA. Therefore, the total peak system supply current is about 400mA per meter.

[0003] Therefore, a power supply capable of producing such a total current should be provided, and the supply voltage should be high enough to compensate for the voltage drop on the PCB traces so that the farthest IC still has sufficient supply voltage (for modules several meters long, the voltage drop can exceed 1V). In addition, such peak currents lead to high electromagnetic compatibility (EMC) emissions due to switching relatively high currents on and off in the large module (which acts as an effective antenna).

[0004] In prior art devices, these problems are usually solved by providing sufficiently large filtering capacitors distributed along the PCB strip, by oversizing the power supply, by increasing the supply voltage, and by shielding the sensing system, resulting in increased cost of the entire device. Implementations may also be limited to short PCB strips (e.g. less than 1 m).

[0005] There is therefore a need for an alternative sensing system comprising a sensor chain and a sensor for such a sensing system. Summary of the invention

[0006] It is an object of embodiments of the present invention to provide a good sensor and a sensing system, the sensing system comprising a sensor chain, for measuring a physical property.

[0007] The above objects are achieved by the device and system according to the present invention.

[0008] In a first aspect, embodiments of the invention relate to sensors for use in a sensing system comprising a chain of such sensors. The sensor comprises an input control port, an output control port, a power interface, and an output interface. The sensor is configured such that when the sensor is powered on via the power interface, an enable signal (EN) at the input control port triggers the sensor to perform a sequence comprising measuring a physical property and subsequently sending an enable signal via the output control port, wherein the sensor is configured to output the measurement result via the output interface.

[0009] An advantage of embodiments of the present invention is that a plurality of such sensors can be chained together. The peak supply current of such a chain is reduced compared to a sensing system in which all sensors are continuously activated.

[0010] In an embodiment of the invention, the sensor is configured to repeat the sequence with a predefined period if the duration of the enable signal at its input port is longer than the predefined period.

[0011] An advantage of an embodiment of the invention is that the sensor is arranged for repeating a sequence with a predefined period. When such a sensor is placed as the first sensor in a daisy chain, it will repeatedly start measuring without the need to close the sensor loop or to provide an additional trigger connection or microcontroller for triggering the start of a new sequence.

[0012] In an embodiment of the invention, the sensor is a magnetic field sensor or a capacitive sensor or an optical sensor.

[0013] In an embodiment of the invention, the sensor comprises a comparator for comparing a measured physical property with a threshold, and an output switch, and the output interface comprises a first output node connected to the output switch, and the sensor is configured to switch the output switch when the threshold is crossed.

[0014] In an embodiment of the present invention, the sensor includes a comparator for comparing a measured physical property with a threshold, and an output switch, and the output interface includes a first output node and a second output node, and the output switch is connected between the first output node and the second output node, wherein the sensor is configured to switch the output switch when the threshold is crossed.

[0015] In such embodiments, the sensor's measurement is an open or closed switch.

[0016] In a second aspect, embodiments of the present invention relate to a sensing system for measuring a physical property. The sensing system comprises a plurality of sensors according to embodiments of the present invention. In such a sensor system, an output control port of an earlier sensor is connected to an input control port of a next sensor, thereby forming a sensor chain. The first sensor in the sensor chain is configured to repeat a sequence with a predefined period. In embodiments of the present invention, the predefined period may be longer than or equal to the duration required for the plurality of sensors to continuously perform the sequence. In alternative embodiments of the present invention, the predefined period may be shorter than the duration.

[0017] An advantage of embodiments of the present invention is that the peak supply current of the sensing system is reduced compared to a sensing system where all sensors are awake at the same time.

[0018] In an embodiment of the present invention, a single master device (first sensor) and a plurality of slave devices are connected to each other in a daisy chain using two dedicated ports (an input control port and an output control port).

[0019] In an embodiment of the invention, all sensors of the system may be configured to repeat a sequence with a predefined period.

[0020] In an embodiment of the present invention, the sensing system may include a printed circuit board, wherein the sensor is provided on the printed circuit board, and wherein the connection to the power interface, the connection between the input control port and the output control port, and the connection to the output interface are achieved through printed circuit board traces.

[0021] In an embodiment of the present invention, the sensing system comprises one or more AD converters connected to the output interface. In an embodiment of the present invention, the processing unit may be connected to the one or more AD converters.

[0022] The AD converter can be shared between different interfaces, or each interface can have a separate AD converter.

[0023] In an embodiment of the present invention, the sensing system comprises a display device directly connected to the output interface and configured to display the measured physical property.

[0024] In an embodiment of the present invention, the input control port of the first sensor is connected to a fixed potential or is left floating.

[0025] In an embodiment of the present invention, each output control port of a sensor connected to an input control port of another sensor is connected to only one input control port. In an embodiment of the present invention, each input control port is connected to at most one output control port.

[0026] In an embodiment of the invention, at least one of the output control ports is connected to more than one input control port. An advantage of an embodiment of the invention is that multiple sensors can be enabled simultaneously. This allows reducing the processing time of a complete sensor array without increasing power consumption.

[0027] In an embodiment of the present invention, the number of sensors is at least 10, for example, at least 100 or even at least 1000.

[0028] In an embodiment of the present invention, the pitch of one sensor is 5 mm. In a line configuration of sensors with a pitch of 5 mm, 1000 sensors can be used to obtain a sensing range of 5 m.

[0029] Particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. Features from the dependent claims may be combined with features of the independent claims and with features of other dependent claims as appropriate and not just as explicitly set out in a claim.

[0030] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic block diagrams of exemplary sensors and exemplary sensing systems according to exemplary embodiments of the present invention are shown.

[0032] Figure 2 Shown in Figure 1 A timing diagram of signals occurring in an exemplary sensing system is schematically shown in FIG.

[0033] Figure 3 A timing diagram of a prior art sensing system is shown.

[0034] Figure 4 A timing diagram of a sensing system according to an embodiment of the present invention is shown.

[0035] Figure 5 A schematic diagram of a sensing system according to an exemplary embodiment of the present invention is shown, wherein a single sensor is enabled at a time.

[0036] Figure 6 A schematic diagram of a sensing system according to an exemplary embodiment of the present invention is shown, wherein multiple sensors are enabled simultaneously.

[0037] Figure 7 A schematic diagram of a sensor according to an embodiment of the present invention is shown.

[0038] Figure 8 A schematic diagram of a sensor according to an embodiment of the present invention is shown, wherein the power interface and the output interface share terminals.

[0039] Any reference signs in the claims should not be construed as limiting the scope.

[0040] The same reference numbers in different drawings refer to the same or similar elements. DETAILED DESCRIPTION

[0041] The present invention will be described with respect to specific embodiments and with reference to certain drawings, but the invention is not limited thereto but only by the claims. The drawings described are only schematic and non-limiting. In the drawings, for illustrative purposes, the dimensions of some of the elements may be exaggerated and not drawn to scale. The dimensions and relative dimensions do not correspond to actual reductions to the implementation of the invention.

[0042] The terms first, second, etc. in the specification and in the claims are used to distinguish between similar elements and not necessarily to describe a sequence in time, space, level, or in any other manner. It should be understood that the terms so used are interchangeable where appropriate, and that the embodiments of the invention described herein are capable of operating in a different sequence than described or illustrated herein.

[0043] It is to be noted that the term "comprising" used in the claims should not be interpreted as being limited to the means listed thereafter; it does not exclude other elements or steps. Therefore, the term should be interpreted as specifying the presence of the stated features, integers, steps or components as mentioned, but does not exclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Therefore, the scope of the expression "a device comprising means A and B" should not be limited to devices consisting only of components A and B. It means that for the present invention, the only relevant components of the device are A and B.

[0044] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment, but may refer to the same embodiment. Furthermore, in one or more embodiments, the particular features, structures, or characteristics may be combined in any suitable manner as will be apparent to one of ordinary skill in the art from this disclosure.

[0045] Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, this disclosure method should not be interpreted as reflecting an intention that the claimed invention requires more features than those expressly recited in each claim. On the contrary, as reflected in the appended claims, inventive aspects reside in fewer features than all of the features of a single preceding disclosed embodiment. Therefore, the claims appended after the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim itself representing a separate embodiment of the invention.

[0046] In addition, although some embodiments described herein include some features included in other embodiments but do not include other features included in other embodiments, as will be understood by those skilled in the art, the combination of features of different embodiments is intended to fall within the scope of the present invention and form different embodiments. For example, in the appended claims, any of the claimed embodiments can be used in any combination.

[0047] In the description provided herein, numerous specific details are set forth. However, it should be understood that embodiments of the present invention may be practiced without these specific details. In other examples, well-known methods, structures, and techniques are not shown in detail to avoid confusing the understanding of this description.

[0048] In a first aspect, embodiments of the invention relate to a sensor 110 for a sensing system 100 comprising a chain of such sensors according to embodiments of the invention, and in a second aspect, embodiments of the invention relate to a sensing system 100 for measuring a physical property. Figure 1 Schematic block diagrams of exemplary sensors and exemplary sensing systems according to exemplary embodiments of the present invention are shown in FIG.

[0049] The sensing system 100 according to an embodiment of the present invention includes a plurality of sensors 110 configured to measure a physical property.

[0050] Each sensor includes an input control port 112, an output control port 113, a power interface 111, and an output interface 114. Each sensor 110 is configured such that when the sensor 110 is powered on through the power interface 111, an enable signal at the input control port 112 triggers the sensor 110 to perform a sequence including measuring a physical property and subsequently sending an enable signal through the output control interface 113. Each sensor is configured to output a measurement result through the output interface 114.

[0051] In an embodiment of the invention, the output control port 113 of an earlier sensor 110 is connected to the input control port 112 of the next sensor 110, thereby forming a sensor chain in which the first sensor in the chain is configured to repeat the sequence with a predefined period.

[0052] In an embodiment of the present invention, the predefined period may be shorter than the duration required for multiple sensors to continuously perform a sequence, but large enough so that not all sensors are active at the same time. In this case, multiple but not all sensors are active at the same time. In this case, there will be two or more "waves" of active sensors in the chain. In this case, multiple "sub-chains" of operating sensors are formed in the entire chain. In other words, in this case, multiple sensors operate simultaneously. In this case, the peak power associated with a system in which all sensors operate simultaneously is reduced. For example, if the period is substantially equal to the duration required for 10 sensors to continuously perform a sequence, this means that 10% of the sensors in the chain will operate simultaneously. This is already a 90% peak power reduction. Pushing the reason to the extreme: if the period is equal to the duration required for two sensors to continuously perform a sequence, 50% of the sensors operate simultaneously.

[0053] In an embodiment of the present invention, the predefined sequence may be longer than or equal to the duration required for the plurality of sensors to execute the sequence. In this case, a single sensor operates at a single moment.

[0054] The predefined period may for example be equal to or greater than the duration of one sequence multiplied by the number of sensors in the chain.The duration of one sequence of a sensor is also referred to as the operating period of the sensor.

[0055] In an embodiment of the present invention, the sensor is configured such that after measuring a physical property, the sensor stops measuring until a new enable signal is received. Thus, power consumption is reduced when not measuring.

[0056] Figure 7A schematic diagram of a sensor 110 according to an embodiment of the present invention is shown. The sensor includes a power interface 111 for supplying power to the sensor. In this example, the power interface includes a first terminal for applying a power supply voltage VDD and a second terminal for connecting to a ground GND. The sensor 110 further includes a control circuit 115 connected to an input control port 112 and an output control port 113. The control circuit 115 is configured to trigger a measurement circuit 117 to start measuring a physical property. In addition, the control circuit is configured to subsequently send an enable signal through the output control port 113. In this example, the sensor includes a measurement circuit 117 that uses a sensing element 116 to start measuring a physical property. The sensing element 116 can be, for example, a magnetic sensor, a capacitive sensor, a resistive sensor, or an optical sensor. The measurement circuit 117 can, for example, include a drive circuit for applying a current through the sensing element 116 and a receiving circuit for filtering and / or amplifying an output signal from the sensing element 116. The sensing element can be a Hall plate, or a Wheatstone bridge having four or more terminals (e.g., two bias terminals and two sensing terminals). In this example, the sensor 110 further includes a comparator 118 for comparing the measured physical property with a threshold value and outputting the comparison result through the output interface 114. In an alternative embodiment of the present invention, a direct measurement result of the physical property may be output through the output interface.

[0057] In an embodiment of the present invention, the output interface and the power interface may share a terminal. Figure 8 An example of this is shown in the schematic diagram in FIG. Except for the output block 119, the schematic diagram is similar to Figure 7 Schematic diagram in. Figure 7 In the example, the output result is transmitted to the output interface 114 having a terminal different from the power interface 111, and in the example Figure 8 In the embodiment, the power interface and the output interface share the same terminals. The sensor can deliver a measurement result (e.g., a value or a data frame or a comparison result) by modulating its supply current. Typically, the additional current is artificially added to the supply current by block 119. A current source can be used. Block 119 can be a voltage-controlled current source or a digitally controlled current source. Block 119 can be controlled by the measurement circuit 117. The change in the supply current can then be detected and decoded downstream of the power supply or by the power supply itself (e.g., a microcontroller).

[0058] In an embodiment of the present invention, the sensor may be implemented as an integrated circuit.

[0059] In an embodiment of the present invention, the sensing system may include an elongated strip module (which may be implemented as a printed circuit board) having traces for connecting input control ports, output control ports, and power interfaces of multiple device sensors. In an embodiment of the present invention, the sensing system 100 may include a printed circuit board. In such a device, the sensor may be provided on a printed circuit board, and the connection to the power interface 111, the connection between the input control port 113 and the output control port 114, and the connection to the output interface 114 are realized through printed circuit board traces.

[0060] The sensor can operate in a sleep mode (i.e., a reduced power mode when not measuring) and in a wake-up mode. The wake-up mode can last for a fixed duration. The sum of the sleep duration and the wake-up duration is also called the operating cycle. The operating cycle can be the same for multiple sensors. As will be discussed later, different types of sensors can be used. The sensor can be used, for example, to detect the presence of a magnet moving along the strip.

[0061] In prior art systems, all sensors may be operated with equal cycles and they are usually synchronized in the application by a supply voltage that supplies power to all sensors simultaneously, so all sensors will start measuring at the same time. Therefore, in such prior art systems, the peak supply current will be equal to the wake-up current of each sensor multiplied by the number of sensors in the strip.

[0062] An advantage of embodiments of the present invention is that the peak device supply current is reduced to the sum of the wake-up current of a single sensor (ie when measuring) and the sleep current of the remaining sensors (ie when not measuring).

[0063] In an embodiment of the present invention, during operation, an enable signal is provided on the input control port of the first sensor, the enable signal duration being longer than a predefined period. This can be obtained, for example, by grounding the input control port or by floating the input control port. However, the present invention is not limited thereto. As will be appreciated by those skilled in the art, the enable signal may also be defined differently. The enable signal may, for example, be a fixed potential (e.g., VDD / 2).

[0064] An advantage of embodiments of the present invention is that longer sensor modules may be produced with reduced requirements on filtering, power supply and design.

[0065] In an embodiment of the invention, the sensors are arranged along a dimension and the physical property is measured along the dimension.

[0066] An advantage of the sensing system according to an embodiment of the invention is that the first sensor is arranged to repeat the sequence with a predefined period. The effect is that the last sensor does not need to be connected to the first sensor (the loop is not closed) and no trigger connection or addressing from the microcontroller is required. Since the first sensor in the chain is configured to repeat the sequence with a predefined period, each new measurement of the first sensor will trigger the measurement chain of subsequent sensors. In this sense, the first sensor is also called the master sensor. However, it is not the master sensor in a conventional communication system, which means that it addresses each of the individual sensors or reads data from each of the individual sensors.

[0067] In an embodiment of the present invention, the sensing system may include a plurality of integrated circuits.

[0068] In an embodiment of the invention, each sensor is configured to repeat the sequence with a predefined period if the duration of the enable signal of the sensor is longer than the predefined period.

[0069] An advantage of embodiments of the invention is therefore that the sensing system is fault tolerant in the event of a chain breaking into sub-chains. If the sensor's enable signal is a floating input control port, braking of the chain will result in one master sensor per sub-chain. This is particularly advantageous because it means that the sensing system can be manufactured in long strips during production and cut into random lengths without the need to manually assign master roles.

[0070] In an embodiment of the present invention, the input control port 112 of the first sensor is connected to a fixed potential or remains floating. In the case of a fixed potential, the input control port of the first sensor can be connected to ground GND or a power supply voltage VDD, for example. The signal connected to the first connector should correspond to the enable signal. Therefore, the master role of the first sensor is automatically assigned to the first chip (for example, by floating the input control port of the first sensor or connecting the input control port to a fixed potential). The remaining sensors are slave sensors because the input control port is connected to the output control port of the earlier sensor. Therefore, the enable signal from the earlier sensor triggers the next sensor to execute the sequence. The enable signal has only a limited duration. It should be shorter than a predefined cycle. In some embodiments of the present invention, the enable signal can be a falling edge or a rising edge, or both a falling edge and a rising edge, or a pulse or multiple pulses, a floating signal, a fixed potential, or a logic state.

[0071] In a configuration where the input control port of the first sensor is connected to a fixed potential or left floating, the first sensor will start the read sequence of the chain.

[0072] In an embodiment of the present invention, the output port of the last sensor is not connected.

[0073] In an embodiment of the invention, the sensor is positioned on a line.The sensor may be positioned on a substantially straight line.

[0074] In an embodiment of the invention, the sensor is a magnetic field sensor, a capacitive sensor or an optical sensor. In a wider range, other sensors can also be used, such as temperature sensors, humidity sensors, gas sensors, etc. In the latter case, they prefer to transmit a digital value without comparing the value with a threshold value and only output a binary signal.

[0075] Figure 1 A schematic block diagram of a sensing system 100 according to an embodiment of the present invention is shown. The sensing system includes three sensors. Only the input control port 112, the output control port 113, the power interface 111 and the output interface are shown. For simplicity, other sensor pins and external components are omitted. The purpose of this schematic diagram is to show how the input control port 112 and the output control port 113 should be connected for daisy chain operation mode. As previously described, the effect of the daisy chain operation mode is to reduce the overall peak supply current by ensuring that only one sensor in the chain is awake (i.e., it is measuring).

[0076] Figure 2 Shown in Figure 1 1 . A timing diagram of signals occurring in an exemplary sensing system 100 schematically shown in FIG. 1 . Thus, a daisy chain mode of operation for three sensors is shown. Signals for a first sensor (chip 1), a second sensor (chip 2), and a third sensor (chip 3) are shown. For each sensor, the top graph shows the signal at the input control port 112, the middle graph shows the signal at the output control port 113, and the bottom graph shows the sensor state. In this timing diagram, the input control pin of the first sensor is either floating or connected to GND (the input control pin may, for example, be connected to a pull-down circuit).

[0077] In an embodiment of the present invention, the sensor 110 comprises a control circuit connected to an input control port 112. The control circuit is configured to trigger the sensor for executing a sequence when the enable signal is a floating voltage at the input control port.

[0078] In an embodiment of the present invention, the control circuit is configured to trigger the sensor for executing the sequence when the enable signal is a voltage at the input control port that is higher and / or lower than a predefined threshold, or when the enable signal is a falling edge (i.e., a transition from a high voltage level to a low voltage level at the input control port) or a rising edge (i.e., a transition from a low voltage level to a high voltage level at the input control port). In an embodiment of the present invention, the enable signal is a falling edge and a rising edge (or vice versa). In an embodiment of the present invention, the enable signal is a pulse or multiple pulses. The enable signal can be higher than a first predefined voltage and lower than a second predefined voltage, wherein the first predefined voltage is greater than the second predefined voltage (the latter case corresponds to a window comparator).

[0079] The input control pin can be implemented as a digital input pin. Such a pin can be connected to a circuit that generates a logic state (high or low) based on a comparison of the applied voltage being above or below a threshold (or 2 thresholds). For floating state detection, both the pull-up and the pull-down can be embedded in the chip so that when no voltage is applied, the pin will see VDD / 2. Alternatively, the first sensor can connect its input to an external resistor divider, such as to detect a fixed potential (e.g., VDD / 2) as an enable signal.

[0080] Since the first sensor is always enabled in this exemplary embodiment of the present invention, the first sensor will repeat the sequence with a predefined period T_OP. The period can be programmed or defined in any other suitable manner. During this period, the first sensor switches between wake-up and sleep states. The duration of the wake-up phase is t_ACT. The duration of the wake-up phase can be, for example, between 100μs and 10ms. At the end of the wake-up phase, the chip generates a pulse of duration t_SYNC on its output control port. This pulse is used to convert the second sensor from the sleep phase to the wake-up phase. The duration of the synchronization (sync) pulse can be, for example, between 10μs and 1ms. The second sensor then activates the third sensor, and so on. The duration of t_ACT plus t_SLEEP (not shown) is the duration of a sequence of sensors and is also referred to as the operating cycle (T_op) of the sensor. The sleep duration t_SLEEP can be, for example, 1ms to 200ms.

[0081] Figure 3 The timing diagram shown in Figure 1 shows how an example system consisting of 3 sensors would behave without chip-to-chip synchronization (daisy chain). The top graph shows the supply voltage versus time. The next three graphs show the sensor current versus time for the first, second, and third sensors, respectively. The bottom graph shows the total current versus time. In this case, the system peak supply current is:

[0082] I SYS_PEAK =N x I DD_AWAKE (I SYS_峰值 =N x I DD_唤醒 )

[0083] in:

[0084] I SYS_PEAK is the system peak supply current.

[0085] N is the number of sensors (eg, ICs) in the chain.

[0086] I DD_AWAKE is the current consumption of a single sensor in awake state.

[0087] Figure 4 The timing diagram in FIG. 1 shows the current through three sensors of an exemplary sensing system according to an embodiment of the present invention. The top graph shows the variation of the supply voltage over time. The next three graphs show the variation of the sensor current over time for the first, second and third sensors, respectively. The bottom graph shows the variation of the total current over time. In this case, the peak supply current of the sensing system is:

[0088] I SYS_PEAK =(N-1)x I DD_SLEEP +I DD_AWAKE (I SYS_峰值 =(N-1)x I DD_睡眠 +I DD_唤醒 )

[0089] in:

[0090] I SYS_PEAK is the sensing system peak supply current.

[0091] N is the number of sensors (eg, ICs) in the chain.

[0092] I DD_AWAKE is the current consumption of a single sensor in awake state.

[0093] I DD_SLEEP is the current consumption of a single sensor in sleep state.

[0094] Because I DD_SLEEP Substantially less than I DD_AWAKE (e.g., 20 or 200 times or something else), so the overall sensing system current consumption is significantly reduced.

[0095] In an embodiment of the present invention, the sensor includes a comparator (the comparator is used to compare the measured physical property with a threshold value) and an output switch. The output interface 114 of the sensor includes a first output node and a second output node, wherein the output switch is connected between the first output node and the second output node. Each sensor 110 is configured to switch the output switch when the threshold value is crossed. The sensing system includes a resistor divider, which includes a plurality of resistors, with a connection node between the resistors, wherein the first output node of the sensor is connected to the corresponding connection node, and wherein the second output node is connected together.

[0096] In an embodiment of the invention, the outer end of the resistor divider may be connected between a supply voltage and ground. An advantage of an embodiment of the invention is that the connected second output node represents the sensing system output.

[0097] The advantage of a voltage divider combined with an input-output enable mechanism is that no ID is required for the sensor circuit.

[0098] Alternatively, the sensor can communicate its measurement output on a digital bus. In this case, an ID will also need to be communicated so that the microcontroller can identify which sensor sent the data.

[0099] In a third aspect, embodiments of the present invention relate to a position sensing device. The position sensing device comprises a sensing system 100 according to an embodiment of the present invention. The sensor is configured to measure a magnetic field. In addition, the position sensing device comprises a magnet and a positioning system configured to guide the magnet along the sensor. An advantage of embodiments of the present invention is that the position of the magnet along the sensing system can be determined from the measurements of the sensors. In fact, it can be determined from the measurements of the sensors which sensor is closest to the magnet.

[0100] Figure 5 and Figure 6 A schematic diagram of a sensing system 100 according to an embodiment of the present invention is shown.

[0101] The sensor 110 is arranged to sense a physical quantity (e.g., a magnetic field). The sensor may include a comparison device and an output switch 121 connected to two output nodes. When the physical quantity is above or below a threshold, the output switch is closed and the output nodes are electrically connected. Each first sensor output (output A in this example) is connected to a corresponding node of a resistor divider R1, R2, R3 (the first node can be connected to VDD and the last node is connected to GND, but this is not required). Each second sensor output (output B) is connected together and represents the sensing system output. It can be connected to an electronic control unit (ECU) and digitized using an analog-to-digital converter (ADC), or it can be directly connected to a display device, such as a gage. In this exemplary embodiment of the present invention, when the physical quantity is detected to be above a threshold, the output switch 121 is closed and the output node V 出 will be connected to the corresponding voltage of the voltage divider (in this example, 2VDD / 3). In other embodiments of the present invention, only one output node may be connected to the gate of the external transistor.

[0102] Output Node V 出 may be connected to an additional pull-up or pull-down resistor (not shown), typically with a value higher than the total resistance of the resistor ladder, such as to pull V 出 Set to VDD or GND. Output node V 出 It can be connected to a filter capacitor (not shown), such as to a low pass filter, and maintain the output voltage while the chain is processed. In some embodiments, the chip supply voltage VDD and the resistor ladder (as shown) are the same, but can also be different. In particular, the supply voltage of the resistor ladder can be higher than the chip power supply. Figure 5 and Figure 6 In the example shown, the sensor chip 110 and the resistor ladder R1 , R2 , R3 are connected to the same voltage source VDD and a common ground.

[0103] In this case, the output switch 121 can be a floating switch. In an embodiment of the present invention, reference is made to a floating switch, and reference is made to a switch that is galvanically isolated from a control input (i.e., the input of the switch). Such a floating switch may include a floating power supply in a floating domain (which is galvanically isolated from the rest of the sensor), and a modulator for modulating the input signal of the switch to obtain a differential signal (in an embodiment of the present invention, a measurement of a physical property) and a demodulator for demodulating the differential signal in a floating domain, wherein the modulator and the demodulator are galvanically isolated. An example of such a floating switch is given in patent application EP20472004 "Floating switch for signal transmission" filed by Melexis on April 15, 2020, which is incorporated herein by reference. When a floating switch is used, the sensor chip and the resistor ladder do not necessarily need to be connected to the same voltage source VDD and a common ground. The sensor and the resistor ladder can be connected to different voltage domains, such as different VDDs and / or different grounds. The power supplies can float relative to each other. For example, the sensor and the resistor ladder can be connected to different grounds, and the voltage source of the resistor divider can be higher than the sensor's supply voltage (e.g., the sensor's voltage source VDD_ 传感器 =1.8V, or 3.3V or 5V, and the resistor divider voltage source VDD_ 梯 higher than 5V, or higher than 10V or higher than 50V).

[0104] In an exemplary position sensing device according to an embodiment of the present invention, the physical quantity may be, for example, a magnetic field generated by a magnet and may be used for level sensing. The magnet may be coupled to a float that is arranged to move with the top surface of the liquid in the tank. When moving up or down, the magnet changes position (e.g., Figure 5 or Figure 6 In this position sensing device, the (analog) output voltage V 出 Indicates the liquid level in the tank.

[0105] Such a system may include a few magnetic switches, or up to 100, or even over 1000 sensors (e.g., for 5 meter sensing with 5 mm spacing, 1000 sensors are required).

[0106] According to an embodiment of the present invention, the advantages of this readout combined with the cascaded enable pulse are:

[0107] Only a subset of the sensor(s) are enabled at a given time; this reduces the overall power / current consumption and supply voltage drop along the sensor array;

[0108] No ID is required in the sensor (as in prior art digital communication protocols, where an ID is required in order to individually address the sensor);

[0109] No electrical connections / communication interfaces / control signals from the ECU are required other than the analog output voltage; this reduces the wiring harness.

[0110] exist Figure 6 The schematic diagram shown in FIG. 1 shows that the present invention is not limited to a single sensor enabled at a time. Multiple sensors can be enabled at the same time, such as Figure 6 (two central sensors are enabled simultaneously). In this example, at least one output control port is connected to more than one input control port. This allows reducing the processing time of the complete sensor array without increasing the power consumption. When using a large number of sensors, a balance between processing time and current consumption can be found.

[0111] In a fourth aspect, embodiments of the present invention relate to a kit of parts, wherein the kit of parts comprises a plurality of sensors according to embodiments of the present invention, and is used to construct a sensor system according to embodiments of the present invention.

Claims

1. A sensor for a sensing system, the sensing system comprising a chain of these sensors, the sensor comprising an input control port, an output control port, a power interface and an output interface, wherein the sensor is configured so that when the sensor is powered on through the power interface, an enable signal at the input control port triggers the sensor to perform a sequence, the sequence comprising measuring a physical property and subsequently sending an enable signal through the output control port, wherein the sensor is configured to output the result of the measurement through the output interface.

2. The sensor according to claim 1, characterized in that The sensor comprises a control circuit connected to the input control port, the control circuit being configured to trigger the sensor for executing the sequence when the enable signal at the input control port is a fixed potential or a floating voltage.

3. The sensor according to claim 1, characterized in that The sensor includes a control circuit connected to the input control port, and the control circuit is configured to trigger the sensor to execute the sequence when the enable signal at the input control port is a voltage higher than or lower than a predefined threshold, or when the enable signal at the input control port is higher than a first predefined voltage, and to trigger the sensor to execute the sequence when the enable signal at the input control port is lower than a second predefined voltage, or when the enable signal at the input control port is a rising edge or a falling edge, or when the enable signal is a pulse or multiple pulses of the voltage at the input control port, wherein the first predefined voltage is greater than the second predefined voltage.

4. The sensor according to claim 1, characterized in that The sensor is configured to repeat the sequence with a predefined period if the duration of the enable signal at the input control port is longer than a predefined period.

5. The sensor according to claim 4, characterized in that The sensor comprises a comparator and an output switch, wherein the comparator is used to compare the measured physical property with a threshold value, and wherein the output interface comprises a first output node and a second output node, wherein the output switch is connected between the first output node and the second output node, and wherein the sensor is configured to switch the output switch when the threshold value is crossed.

6. The sensor according to claim 1, characterized in that The sensor is a magnetic field sensor, a capacitive sensor, an optical sensor, or an inductive sensor.

7. The sensor according to claim 1, characterized in that The sensor comprises a comparator for comparing the measured physical property with a threshold value and an output switch, wherein the output interface comprises a first output node connected to the output switch, wherein the sensor is configured to switch the output switch when the threshold value is crossed.

8. A sensing system for measuring a physical property, the sensing system comprising a plurality of sensors according to claim 1, in, An output control port of an earlier sensor is connected to an input control port of a next sensor, thereby forming a sensor chain, wherein a first sensor of the sensors in the chain is configured to repeat the sequence with a predefined period if the duration of the enable signal at the input control port is longer than the predefined period.

9. The sensing system according to claim 8, characterized in that Each sensor comprises a comparator for comparing the measured physical property with a threshold value, and an output switch, wherein the output interface of each sensor comprises a first output node and a second output node, wherein the output switch is connected between the first output node and the second output node, wherein each sensor is configured to switch the output switch when the threshold value is crossed, The sensing system comprises a resistive voltage divider comprising a plurality of resistors having connection nodes between the resistors, wherein the first output nodes of the sensors are connected to corresponding connection nodes, and wherein the second output nodes are connected together.

10. The sensing system according to claim 8, characterized in that All sensors are configured to repeat the sequence with a predefined period if the duration of the enable signal at the input control port is longer than the predefined period.

11. The sensing system of claim 8, wherein the sensing system comprises one or more AD converters connected to the output interface, or the sensing system comprises a display device directly connected to the output interface and configured to display the measured physical properties.

12. The sensing system according to claim 8, wherein: The first sensor comprises a control circuit connected to the input control port, the control circuit being configured to trigger the sensor for executing the sequence when the enable signal at the input control port is a voltage above or below a predefined threshold, or when the enable signal at the input control port is above a first predefined voltage, and to trigger the first sensor for executing the sequence when the enable signal at the input control port is below a second predefined voltage, or when the enable signal at the input control port is a rising edge or a falling edge, or when the enable signal is a pulse or multiple pulses of the voltage at the input control port, wherein the first predefined voltage is greater than the second predefined voltage, and The input control port of the first sensor is connected to a fixed potential.

13. The sensing system according to claim 8, wherein: The first sensor comprises a control circuit connected to the input control port, the control circuit being configured to trigger the first sensor for executing the sequence when the enable signal at the input control port is a floating voltage, and wherein the input control port of the first sensor remains floating.

14. The sensing system according to claim 8, wherein: Each output control port of one sensor that is connected to an input control port of another sensor is connected to only one input control port.

15. The sensing system according to claim 8, wherein: At least one of the output control ports is connected to more than one input control port.

16. A position sensing device comprising the sensing system of claim 8, wherein the sensor is configured to measure a magnetic field, the position sensing device further comprising a magnet and a positioning system configured to guide the magnet along the sensor.

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