Transmission of signals in a control system
Patent Information
- Application Number
- EP2024710384
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-03-09
- Filing Date
- 2024-03-07
- Publication Date
- 2026-01-14
AI Technical Summary
Existing control systems face challenges in efficiently transmitting interrupt requests between control devices, particularly due to delayed data traffic over shared connections, difficulty in determining the origin of requests, and inability to distinguish between priorities and urgency levels.
A control system utilizing a single signal line where each signal is represented by a current multiple of a base current, allowing simultaneous transmission and decoding of multiple signals, with reconfigurable priorities and independent evaluation order, using a single analog-to-digital converter to break down the total current into individual signals.
Enables rapid handling of signaled states, reduces system complexity, supports simultaneous transmission of all signals, and allows for flexible priority management, ensuring reliable and efficient communication between control devices.
Smart Images
Figure EP2024055999_12092024_PF_FP
Abstract
Description
[0001] Transmission of signals in a control system
[0002] The invention relates to a control system comprising a first and a plurality of second control devices. In particular, the invention relates to the transmission of signals in such a control system.
[0003] A household appliance comprises a control system with multiple control devices. A first control device can perform central control tasks, while several second control devices can be assigned to dedicated purposes. One of the second control devices can determine a state or event that should be signaled to the first control device. For example, one of the second control devices can detect an error that it cannot correct itself or that also affects another control device.
[0004] For fast signaling between control devices, an interrupt request can be transmitted. If a data connection between the control devices is used for this purpose, ongoing data traffic can delay the transmission of the interrupt request. Therefore, a dedicated signal line is often used to signal the interrupt request.
[0005] In one embodiment, each second control device is assigned a dedicated signal line. In another embodiment, a common signal line is provided on which a predetermined level is driven to send an interrupt request. Each of the second control devices can cause this level, so that the first control device can determine an interrupt request from any second control device. However, it can be difficult or time-consuming to determine the actual originator of the interrupt request among the second control devices. Furthermore, this approach does not support different priorities, and it is not possible to distinguish between an urgent and a less urgent interrupt request.
[0006] In yet another embodiment, the signal line from the first control device passes through the second control devices sequentially (daisy chain). To generate an interrupt request, a second control device can break the signal line and set it to a predetermined level. The order in which the second control devices are connected to each other determines a priority. However, the priority is hard-wired and cannot be changed by configuration.
[0007] One object underlying the present invention is to provide an improved technique for transmitting a signal from multiple control devices to another control device. The invention achieves this object by means of the subject matter of the independent claims. Subclaims specify preferred embodiments.
[0008] According to a first aspect of the present invention, a control system comprises a first control device, a plurality of second control devices, and a signal line connecting the first and second control devices. The first control device is configured to determine a total current flowing through the signal line. A second control device is configured to transmit a signal by causing a current flowing from the signal line that is a predetermined multiple of a predetermined base current. Different signals are assigned different multiples.
[0009] In the control system, multiple signals can be transmitted simultaneously over a single signal line. Each signal is represented by a current, with multiple individual currents adding up to a total current. The first control device can determine the total current and use this to determine the individual currents. This allows it to be directly determined which combination of multiple signals will be transmitted over the signal line at a predetermined time.
[0010] In this way, a signaled state or event can be handled quickly by the first control device. By requiring only a single signal line, the control system can be designed simply and compactly. Transmission does not use priorities, and all predetermined signals can be transmitted simultaneously. The order in which the first control device evaluates or responds to signals can be determined independently of the system architecture. This also allows for support for reconfigurable priorities.
[0011] The base current can be determined depending on control system parameters. For example, possible interference on the signal line, such as electromagnetic interference, or the stability of the control system's power supply can be taken into account.
[0012] In a first variant of the control system, different multiples are assigned to each of the second control devices. A signal indicates one of the second control devices. Thus, the second control devices can provide signals concurrently to each other, each indicating that a respective second control device requires the attention of the first control device.
[0013] In a second variant, different multiples are assigned to predetermined events or states. A signal can indicate one of the events. In this way, system-wide defined events can be determined and signaled at different second control devices. For example, in a distributed or concurrent system or a system in which a task is executed by distributed second control devices, this assignment can be advantageous. In this variant, it is preferred that disjoint sets of signals are assigned to the second control devices in order to avoid the simultaneous provision of the same signal by different second control devices.
[0014] It is particularly preferred that different multiples be different integer powers of the number two. The multiples can thus be one, two, four, eight, 16, 32, etc. Individual currents can thus be determined more effectively based on the total current. It is generally preferred that all currents have the same sign. The exponent of the integer power is preferably also positive, but negative exponents can optionally also be used. Even more preferably, a series of consecutive integers is used as powers.
[0015] The first control device may comprise an analog-to-digital converter configured to provide a binary representation of the determined total current, such that one bit of the binary representation corresponds to a predetermined signal. Such analog-to-digital converters (ADCs) can be inexpensively available and are already integrated into some microprocessors or microcontrollers. The breakdown of the total current into a superposition of signals can thus be performed quickly and easily.
[0016] The analog-to-digital converter can have a resolution in bits that exceeds a number of different multiples, with at least one least significant bit not being evaluated. A measurement uncertainty of the analog-to-digital converter can manifest itself in one or more least significant digits not representing reliable information. Such effects can be filtered out by omitting one or more least significant digits (Least Significant Bits, LSBs). For example, a 12-bit ADC can be used to decode a total stream provided by ten different second control devices. Each control device is assigned one bit of the ADC, with the two least significant bits not being evaluated.
[0017] In one embodiment, the total current includes a predetermined offset corresponding to half the base current. The offset can be permanently applied via the signal line. This allows for improved filtering of both positive and negative deviations of the measured value from the sum of the currents provided by the second control devices. Such a deviation can be caused, for example, by interference or noise.
[0018] In a particularly preferred embodiment, the first control device comprises a voltage source connected to the signal line. The voltage provided by the voltage source can be fixedly predetermined or determined by the first control device, for example, by means of another ADC. In one embodiment, a voltage provided by the voltage source can be controlled by the first control device. At the first control device, the total current preferably flows through a resistor with a predetermined conductance. A voltage drop across the resistor is then proportional to the total current and can be determined with respect to the provided voltage.
[0019] Preferably, one of the second control devices is configured to effect a predetermined minimum current through the signal line. The first control device is configured to determine a fault in the signal line if the total current is below the minimum current. If the minimum current is not maintained, there may be a break in the control line, for example, which could interrupt the transmission of a signal. Preferably, signal currents are generated in addition to the minimum current, and the first control device determines the total current with respect to the minimum current. The minimum current may include the offset or be impressed on the signal line in addition to it. It is further preferred that the second control device furthest away from the first control device with respect to the control line effects the minimum current. By maximizing the distance, any disturbance on the signal line can be detected.This means that an unnoticed disturbance cannot occur.
[0020] The control system comprises a first and a plurality of second control devices, each configured to implement a technique described herein. A first control device comprises a connection for a signal line; a current sensor for determining a current flowing through the signal line; and a processing device configured to decompose the determined current into predetermined summands, each representing a signal; wherein a summand is a predetermined multiple of a predetermined base current, and wherein different signals are assigned different multiples.
[0021] A second control device comprises a terminal for a signal line; a current sink for causing an electrical current through the terminal, wherein the current is a predetermined multiple of a predetermined base current; and a processing device for controlling the current sink depending on a signal to be provided on the signal line. Different signals are assigned different multiples.
[0022] According to a further aspect of the present invention, a household appliance comprises a control system described herein, a first control device described herein, or a second control device described herein. The household appliance may, for example, comprise a kitchen appliance, a laundry care appliance, or a refrigerator. Other appliances, particularly those used in a household, are also possible.
[0023] According to yet another aspect of the present invention, a method for transmitting signals via a signal line connecting a first and a plurality of second control devices comprises the steps of causing currents to flow from the signal line by one of the second control devices; each current being a predetermined multiple of a base current and different multiples being associated with different signals to be transmitted; determining a total current flowing through the signal line by the first control device; and determining signals provided by the second control devices. The method can be carried out by means of a control system described herein. The control system can comprise one or more processing devices that can be involved in carrying out the method.For this purpose, a processing device can be implemented electronically and, for example, comprise a programmable microcomputer or microcontroller. The method can be in the form of a computer program product with program code means. The computer program product can also be stored on a computer-readable data carrier. Features or advantages of the method can be transferred to the device, or vice versa.
[0024] The invention will now be described in more detail with reference to the accompanying figures, in which:
[0025] Figure 1 shows a control system; and
[0026] Figure 2 shows a flow diagram of a process.
[0027] Figure 1 shows a control system 100 that may be included in a household appliance 105. The household appliance 105 is illustrated as a washing machine by way of example; in other embodiments, any other household appliance 105 may also be equipped with a control system 100.
[0028] The control system 100 comprises a first control device 110 and a plurality of second control devices 115. The control devices 110, 115 are preferably each embodied as a microcomputer or microcontroller or comprise such a device. The control system 100 is further preferably configured for distributed information processing and in particular for controlling a household appliance 105. The control system 100 is preferably comprised by a single assembly in the household appliance 105. The assembly may comprise a printed circuit board with multiple components. Particularly preferably, the control system with all control devices 110, 115 is implemented on an integrated circuit. The circuit may represent one of the components of the assembly.
[0029] The control devices 110, 115 are connected to one another via a common signal line 120. Additional connecting lines, for example, for transmitting data, a common supply line, or a common ground line between the control devices 110, 115, are not shown in Figure 1. The following explains a technique for simultaneously transmitting multiple signals from one or more of the second control devices 115 to the first control device 110 via the single signal line 120. The first control device 110 can decode the individual signals and preferably assign each to a source.
[0030] The first control device 110 comprises a processing device 125. A voltage source 130 is configured to apply a predetermined voltage to the signal line 120. A resistor 135 with a predetermined conductance is provided to determine the total current flowing through the signal line 120. A voltage drop across the resistor 135 can be determined by an analog-to-digital converter 140 and forwarded in digital form to the processing device 125. However, the current flowing through the signal line 120 can also be determined differently, for example, inductively or based on a magnetic field around the signal line 120.
[0031] In some embodiments, the processing device 125 is configured to control the magnitude of the voltage provided by the voltage source 130. For this purpose, a digital-to-analog converter (DAC) may be included.
[0032] A second control device 115 comprises a processing device 145 and a current sink 150. The current sink 150 is configured to cause a predetermined electrical current to flow from the signal line 120. The processing device 145 is configured to activate or deactivate the current sink 150. In some embodiments, the processing device 145 can control the magnitude of a current caused by the current sink 150.
[0033] In the illustrated embodiment, each second control device 115 is assigned an integer number, indicated by a hash symbol. The numbers begin with zero and follow one another immediately. These numbers can be used to identify different second control devices 115.
[0034] Each second control device 115 is assigned a factor or multiple, which here is a power of two with the assigned number as the exponent. The second control device 115 shown above is therefore assigned the factor 2°=1, and a subsequent second control device 115 is assigned the factor 2 1 =2, a further following 2 2 =4 etc. up to 2 N for the second control device 115 shown below. Each second control device 115 can generate an individual signal via the signal line 120 by controlling its respective current sink 150 to draw a current from the signal line 120 that corresponds to a product of the predetermined factor and a predetermined base current. A total current then flows through the signal line 120, which is composed of individual, each characteristic current. Each individual current is twice as large as the next smallest individual current.
[0035] The total current flowing through signal line 120 can be determined by first control device 110 by determining the voltage drop across resistor 135. The determined value indicative of the total current can then be broken down into binary summands, each binary summand corresponding to an individual current that can be caused by one of second control devices 115. This operation essentially corresponds to converting the determined current into a binary value, with the value of the least significant bit corresponding to the base current. Processing device 125 can then identify which of second control devices 115 has transmitted a signal.
[0036] For example, if it is determined that a single base current is flowing, the multiple is one, and it can be determined that the second control device 115 with the number zero has transmitted a signal. For a double base current, the multiple is two, so the second control device 115 with the number one can be determined as the originator. If both second control devices 115 in this example transmit a signal simultaneously, a single and a double base current add up to a total current that corresponds to three times the base current. The first control device 110 can then identify both second control devices 115 as simultaneous transmitters.
[0037] By representing it as a binary number, each bit of the binary representation can be directly assigned to one of the second control devices 115. The least significant bit can be assigned to the second control device 115 with the number zero, the next most significant bit to the second control device 115 with the number one, and so on. The signals of the second control device 115, which are superimposed on the signal line 120 and each represented by individual currents, can thus be directly reconstructed as individual signals within the first control device 110. To prevent a measurement inaccuracy from leading to an incorrect result when determining the total current flowing through the control line 120, the analog-to-digital converter 140 can resolve the flowing current more precisely than is necessary to determine the signals.In other words, it is preferred that a smallest resolvable difference of the analog-to-digital converter 140 is smaller than the magnitude of the base current.
[0038] For example, if four second control devices 115 are provided, the ADC 140 can have a resolution of six bits instead of four. The two least significant bits can be ignored. Optionally, an additional current sink, preferably in the area of the first control device 110, can be used to generate an offset current through the signal line 120 that is half as large as that represented by the least significant evaluated bit of the ADC 140. This prevents interference such as noise from rendering one or more bits of the determined representation of the total current unreliable.
[0039] It should be noted that in another embodiment, different signals that can be transmitted via signal line 120 are not assigned to the individual second control devices 115, but rather to predetermined events or states. In such an embodiment, an event or state can be determined by each of the second control devices 115 and signaled on signal line 120. To ensure that the same signal is not sent multiple times, so that a breakdown of the overall stream is no longer unambiguous, different second control devices 115 can be assigned different signals that they can each send. The sets of the respectively available signals can be disjoint.
[0040] Figure 2 shows a flowchart of a method 200, which can be executed in particular by means of a control system 100. In several independent steps 205, individual currents can be caused through the signal line 120 by different second control devices 115.
[0041] If a signal is to be transmitted from an individual second control device 115 to the first control device 110, it can cause a predetermined current associated with it through the control line 120, and otherwise leave a current flowing through the control line 120 unaffected. Individual currents of the second control devices 115 add up to a total current. In a step 210, the total current can be determined by the first control device 110. For this purpose, a voltage drop across a resistor through which the current flows can be determined. A voltage across the signal line 120 can be kept constant at a predetermined value.
[0042] In a step 215, it can now be determined whether the total current is greater than zero. If this is not the case, no signal is present on control line 120. Otherwise, in a step 220, the determined current can be broken down into binary summands. This can be done simply by expressing the determined current as a binary number, with the least significant bit corresponding to the base current. Each bit can be assigned a predetermined signal. If a bit value is one, the respective signal is present; otherwise, it is not present.
[0043] In a first embodiment, each signal is assigned a different second control device 115. In a step 225, it can be determined based on the set bits which of the second control devices 115 send a signal to the first control device 110.
[0044] In an alternative second embodiment, the signals are assigned to individual events or states. In this case, in a step 230, it can be determined based on the active bits which events or states are signaled simultaneously.
[0045] In both cases, a response to the respective signal, event, or state can occur in a step 235. For this purpose, further communication can occur between the control devices 110, 115, which typically occurs via a method other than signal line 120.
[0046] Reference symbol
[0047] 100 Tax system
[0048] 105 household appliances
[0049] 110 first control device
[0050] 115 second control device
[0051] 120 signal line
[0052] 125 processing facility
[0053] 130 Voltage source
[0054] 135 Resistance
[0055] 140 analog-to-digital converters
[0056] 145 Processing facility
[0057] 150 current sink
[0058] 200 procedures
[0059] 205 electricity causes
[0060] 210 Determine total current
[0061] 215 Total current > 0?
[0062] 220 Decompose current value into binary summands
[0063] 225 participants determine
[0064] Determine 230 signals
[0065] 235 Treat the situation
Claims
PATENT CLAIMS 1. Tax system (100), comprising: - a first control device (110); - a plurality of second control devices (115); - a signal line (120) connecting the first and second control devices (115) to each other; - wherein the first control device (110) is configured to determine a total current flowing through the signal line (120); - wherein a second control device (115) is configured to cause a current flowing from the signal line (120) to transmit a signal, which current is a predetermined multiple of a predetermined base current, - where different signals are assigned different multiples.
2. The control system (100) of claim 1, wherein different multiples are assigned to each of the second control devices (115); and a signal indicates one of the second control devices (115).
3. The control system (100) of claim 1, wherein predetermined events are assigned different multiples; and a signal indicates one of the events.
4. Control system (100) according to one of the preceding claims, wherein different multiples are different integer powers of two.
5. The control system (100) of claim 4, wherein the first control device (110) comprises an analog-to-digital converter (140) for providing a binary representation of the determined total current such that one bit of the binary representation corresponds to a predetermined signal.
6. The control system (100) of claim 5, wherein the analog-to-digital converter (140) has a resolution in bits that is greater than a number of different multiples; wherein at least one least significant bit is not evaluated.
7. Control system (100) according to one of the preceding claims, wherein the first control device (110) comprises a voltage source (130) connected to the signal line (120).
8. The control system (100) according to any one of the preceding claims, wherein one of the second control devices (115) is configured to effect a predetermined minimum current through the signal line (120); wherein the first control device (110) is configured to determine a fault in the signal line (120) if the total current is below the minimum current.
9. Control system (100) according to claim 8, wherein the second control device (115) furthest away from the first control device (110) with respect to the control line (120) effects the minimum current.
10. First control device (110), comprising: - a connection for a signal line (120); - a current sensor (135) for determining a current flowing through the signal line (120); and - a processing device (125) which is arranged to decompose the determined current into predetermined summands, each of which represents a signal; - wherein a summand is a predetermined multiple of a predetermined base current and wherein different signals are assigned different multiples.
11. Second control device (115), comprising: - a connection for a signal line (120); - a current sink (150) for causing an electrical current through the terminal; - wherein the current is a predetermined multiple of a predetermined base current; and - a processing device (145) for controlling the current sink in dependence on a signal to be provided on the signal line (120); - where different signals are assigned different multiples.
12. Household appliance (105) comprising a control system (100) according to one of claims 1 to 9 or a control device (110) according to claim 10 or a control device (115) according to claim 11.
13. Method (200) for transmitting signals via a signal line (120) connecting a first (110) and a plurality of second control devices (115), the method comprising the following steps: - causing (205) currents from the signal line (120) by one of the second control devices (115); - wherein each current is a predetermined multiple of a base current and different multiples are assigned to different signals to be transmitted; - determining (210) a total current flowing through the signal line (120) by the first control device (110); and - determining (225, 230) signals generated by the second control devices (115) are provided.