Three-state input circuit, vehicle signal acquisition system and three-state input acquisition method

Abstract

The present application discloses a three-state input circuit, a vehicle signal acquisition system and a three-state input acquisition method, and belongs to the field of input signal acquisition technology. The three-state input circuit includes a first branch, a second branch, a unidirectional diode, a voltage regulator and a pull-up power supply. The cathode of the voltage regulator is suitable for receiving input signals, the anode of the voltage regulator is connected to the cathode of the unidirectional diode, the anode of the unidirectional diode is connected to the sampling module, the anode of the unidirectional diode is connected to the pull-up power supply through the first branch, and the cathode of the unidirectional diode is grounded through the second branch. The vehicle signal acquisition system includes the above-mentioned three-state input circuit and sampling module. The three-state input acquisition method includes selecting a voltage regulator, building a three-state input circuit, input signal judgment, etc. The present application can form three different loops when the input signal is a high level, a suspended signal, and a low level, can detect three-state inputs, has good versatility, and can judge whether the signal line is broken, so as to timely discover and solve faults.

Description

Technical Field

[0001] The present application relates to the technical field of input signal acquisition, and in particular to a three-state input circuit, a vehicle signal acquisition system and a three-state input acquisition method. Background Art

[0002] There are two common input signals in vehicle-mounted systems, one is a positive control input signal and the other is a negative control input signal. The positive control input signal is a valid signal when a high-level signal is input; the negative control input signal is a valid signal when a low-level signal is valid. Sometimes there is also a third signal, that is, a floating signal, where the signal acquisition end is not connected to the input signal line. The three input states of positive control input, negative control input, and floating signal are collectively referred to as three-state input.

[0003] Figure 1 It is a positive control input circuit in the prior art. When the input signal is high, it is generally the body system power. For example, if the body system power is 24V, the input signal is a high level of 24V. At this time, the collection signal is a high level after the body system power is divided. When the positive control signal is invalid, the collection signal is a low level.

[0004] Figure 2 It is a negative control input circuit in the prior art. When the input signal is valid, the acquisition signal is a low level signal. When the negative control signal is invalid, the acquisition signal is a high level signal after VC level conversion, where VC is generally the body system voltage.

[0005] In order to save hardware resources of input pins and increase the versatility of acquisition modules, it is sometimes necessary to reuse the positive control and negative control input pins. The input signal can be set to be positive control valid or negative control valid. The general method of multiplexing is to add a controllable pull-up control on the basis of the positive control input. The positive and negative control input multiplexing circuit is as follows: Figure 3 As shown, in this multiplexing method, the MCU must first read the positive and negative control configuration each time it is powered on, and then determine whether it is necessary to control CON0 to realize RL pull-up power based on the positive and negative control configuration, and then determine whether the input signal is valid based on the configuration status and the collected input status.

[0006] The signal line of the vehicle body may be broken, causing the input signal to be a floating signal, but none of the three existing input circuits can detect a floating signal, and the broken signal line causes a safety hazard. Summary of the invention

[0007] One purpose of the present application is to provide a three-state input circuit, which can realize the detection of three input modes, namely positive control input, negative control input and floating input, using a common input circuit, and the three-state input circuit has a simple structure, low use cost, and can determine whether the signal line is broken, so as to timely discover and solve the fault.

[0008] Another object of the present application is to provide a vehicle signal acquisition system, which uses the above-mentioned three-state input circuit and also has the advantages of strong versatility, simple structure and low cost.

[0009] Another object of the present application is to provide a three-state input acquisition method, which realizes that three input modes, namely positive control input, negative control input and floating input, share one input circuit for detection, and the three-state input circuit has a simple structure and low use cost.

[0010] To achieve the above objectives, the technical solution adopted in the present application is: a three-state input circuit, which includes a first branch, a second branch, a unidirectional diode, a voltage regulator and a pull-up power supply, the cathode of the voltage regulator is suitable for receiving an input signal, the anode of the voltage regulator is connected to the cathode of the unidirectional diode, the anode of the unidirectional diode is connected to a sampling module, the anode of the unidirectional diode is connected to the pull-up power supply through the first branch, and the cathode of the unidirectional diode is grounded through the second branch, so that three different loops are formed when the input signal is a high level, a floating signal, and a low level.

[0011] Preferably, the first branch is provided with a first resistance value, and the second branch is provided with a second resistance value.

[0012] Further preferably, the first branch includes a first resistor, the second branch includes a third resistor, and the first resistor and the third resistor are used to provide the first resistance value and the second resistance value, respectively.

[0013] Preferably, the first resistance value is substantially equal to the second resistance value.

[0014] Preferably, the voltage of the pull-up power supply is lower than the high level of the input signal.

[0015] Preferably, the anode of the unidirectional diode is connected to a protection module, and the protection module is a current limiting resistor.

[0016] The present application further provides a technical solution: a vehicle signal acquisition system, which includes the above-mentioned three-state input circuit, and also includes a sampling module connected to the three-state input circuit, the pull-up power supply is the working voltage of the sampling module, and the sampling module is an MCU.

[0017] Preferably, the vehicle signal acquisition system further includes a multi-way switch, the three-state input circuit is provided with multiple channels, and is connected to the MCU via the multi-way switch.

[0018] The present application also provides a technical solution: a three-state input acquisition method, which comprises the steps of:

[0019] S1. Select a voltage regulator tube. Select a voltage regulator tube based on the high level of the input signal, so that the voltage regulator tube can be broken down when the input signal is at a high level, and the voltage regulator tube is forward-conducted when the input signal is at a low level;

[0020] S2, build a three-state input circuit, connect the anode of the voltage regulator tube to the cathode of the unidirectional diode, and set a first branch with a first resistance between the anode of the unidirectional diode and the pull-up power supply, and set a second branch with a second resistance between the cathode of the unidirectional diode and the ground, so that when the input signal is a floating signal, the first branch, the unidirectional diode, and the second branch constitute a first loop, when the voltage regulator tube breaks down, the unidirectional diode is cut off, and the first branch and the sampling module constitute a second loop, and when the voltage regulator tube is forward-conducted, the first branch, the unidirectional diode, and the voltage regulator tube constitute a third loop;

[0021] S3, judging the input signal, the AD pin of the MCU samples the voltage of the anode of the unidirectional diode, and the MCU judges whether the input signal is a high level, a low level or a floating signal according to the AD value obtained by the sampling.

[0022] As preferably, the step of:

[0023] S4, alarm, when the MCU determines that the input signal is a suspended signal, the alarm device is triggered; and,

[0024] By setting the resistance ratio between the first resistance value and the second resistance value, the sampling voltages in the three circuits are clearly distinguished.

[0025] Compared with the prior art, the beneficial effects of the present application are: (1) the positive control input and the negative control input share the same input circuit for detection, and can detect floating input, with strong versatility; (2) the circuit structure is simple and the cost of use is low; (3) the high level of the input signal at least needs to break through the Zener diode, so by changing the Zener voltage parameters through the selection of the Zener diode, the high level threshold can be set, thereby improving the anti-interference ability of the circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of a positive control input circuit in the prior art;

[0027] Figure 2 It is a schematic diagram of a negative control input circuit in the prior art;

[0028] Figure 3 It is a schematic diagram of a positive and negative control input multiplexing circuit in the prior art;

[0029] Figure 4 A schematic diagram of a modular structure of a three-state input circuit provided in this application;

[0030] Figure 5 A schematic diagram of the specific structure of the three-state input circuit provided in this application;

[0031] In the figure: D1, unidirectional diode; D2, voltage regulator; 10, first branch; 20, second branch; 30, protection module; 40, sampling module; SAD, sampling voltage; INPUT, input signal. DETAILED DESCRIPTION

[0032] Below, the present application is further described in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0033] In the description of the present application, it should be noted that directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating directions and positional relationships are based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of narrating the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as limiting the specific scope of protection of the present application.

[0034] It should be noted that the terms "first", "second", etc. in the description and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0035] The terms "including" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0036] Embodiment 1: The present application provides a three-state input circuit, such as Figure 4As shown, it includes a first branch 10, a second branch 20, a unidirectional diode D1, a voltage regulator D2 and a pull-up power supply. The cathode of the voltage regulator D2 is suitable for receiving an input signal INPUT, the anode of the voltage regulator D2 is connected to the cathode of the unidirectional diode D1, the anode of the unidirectional diode D1 is connected to the sampling module 40, the anode of the unidirectional diode D1 is connected to the pull-up power supply through the first branch 10, and the cathode of the unidirectional diode D1 is grounded through the second branch 20, so that when the input signal INPUT is a high level, a floating signal, and a low level, three different loops are formed, thereby forming different sampling voltages SAD.

[0037] This embodiment is suitable for vehicle-mounted signal input. The high level of the input signal INPUT is generally the body system voltage, such as 24V. The pull-up power supply can be set to the working voltage of the body system after voltage reduction, such as the working voltage of the MCU system, which can be 5V or 3.3V.

[0038] When the input signal INPUT is a suspended signal, the first branch 10, the unidirectional diode D1, and the second branch 20 form a first loop. When the voltage regulator D2 breaks down in the reverse direction, the unidirectional diode D1 is cut off, and the first branch 10 and the sampling module 40 form a second loop. When the voltage regulator D2 is forward-conducted, the first branch 10, the unidirectional diode D1, and the voltage regulator D2 form a third loop. Since the input signal INPUT can form three different loops when it is a high level, a suspended signal, and a low level, the sampling voltage SAD of the anode of the unidirectional diode D1 changes, and the sampling module 40 can respectively measure the different The same AD value, the positive control input and the negative control input can share an input circuit for detection, and can detect the floating input, with strong versatility; the unidirectional conduction characteristic of the unidirectional diode D1 and the reverse breakdown characteristic of the voltage regulator D2 are utilized, and three different circuits are formed under different input signals INPUT with a simple structure, and the circuit structure is simple and the use cost is low; and the high level of the input signal INPUT needs to at least break down the voltage regulator D2, so by changing the voltage regulator voltage parameter of the voltage regulator D2 through the selection of the voltage regulator D2, the high level threshold can be set, thereby improving the anti-interference ability of the circuit.

[0039] It is understandable that when the input signal INPUT is measured to be a suspended signal, it indicates that the signal line is broken, and maintenance should be carried out as soon as possible to solve the fault and eliminate safety hazards. Correspondingly, an alarm device is provided in the second branch 20 of the three-state input circuit or in other associated circuits of the three-state input circuit. The alarm device can be specifically an indicator light, a display screen, a buzzer, etc.

[0040] Preferably, the first branch 10 is provided with a first resistance value, and the second branch 20 is provided with a second resistance value, so that the first branch 10 and the second branch 20 can generate a voltage drop, and the voltage drop generated by the first branch 10 and the second branch 20 can be distinguished from the conduction voltage of the unidirectional diode D1 and the Zener diode D2.

[0041] More specifically, when the input signal INPUT is at a high level, the AD value of the sampling module 40 is recorded as FAD. When the input signal INPUT is at a low level, the voltage regulator D2 is forward-conducted, and the voltage across the second branch 20 is the conduction voltage of the voltage regulator D2. The sampling voltage SAD is the conduction voltage of the unidirectional diode D1 plus the forward conduction voltage of the voltage regulator D2, which is about 1V, and the corresponding AD value is FAD / VCC; when the input signal INPUT is a floating signal, the current flows through the first loop. Since the conduction voltage of the unidirectional diode D1 is small, the voltage across its two ends can be ignored compared with the voltage across the first branch 10 and the second branch 20. The pull-up power supply is equivalent to being divided by the first branch 10 and the second branch 20. The size of the sampling voltage SAD is determined by the resistance ratio of the first resistance value to the second resistance value, and the corresponding AD value is (second resistance value*FAD) / (first resistance value+second resistance value); when the input signal INPUT is at a high level, the sampling voltage SAD is close to the pull-up power supply, and the corresponding AD value is FAD. The sampling voltage SAD of the anode of the unidirectional diode D1 can have a large difference under three input conditions, which is convenient for the MCU to judge the input signal INPUT.

[0042] It should be pointed out that the above analysis is based on the case where both the unidirectional diode D1 and the Zener diode D2 are single. Obviously, in other embodiments, more than one unidirectional diode D1 can be connected in series, or replaced with other modules with unidirectional conductivity. In this case, the change in the conduction voltage of the unidirectional diode D1 will inevitably lead to a corresponding change in the sampling voltage SAD, and the internal logic of the MCU for judging the input signal INPUT also needs to be adjusted, and the same applies to the Zener diode D2.

[0043] Specifically, the first branch 10 includes a first resistor R1, and the second branch 20 includes a third resistor R3, the first resistor R1 and the third resistor R3 are used to provide a first resistance value and a second resistance value respectively. The first branch 10 and the second branch 20 have simple structures.

[0044] It can be understood that the first resistor R1 and the third resistor R3 can be fixed resistors or variable resistors. A filter capacitor can also be connected in parallel to the first branch 10, the second branch 20, or other nodes of the three-state input circuit to filter noise.

[0045] More specifically, the first resistance value is substantially equal to the second resistance value. When the input signal INPUT is a floating signal, the sampling voltage SAD is approximately half of the pull-up power supply voltage, i.e., VCC / 2, and the AD value is FAD / 2. The sampling voltage SAD has a difference of (VCC / 2-1)V from the sampling voltage SAD when the input signal INPUT is at a low level, and has a difference of VCC / 2 from the sampling voltage SAD when the input signal INPUT is at a high level. The three sampling voltages SAD are clearly distinguished from each other. Even in the presence of clutter interference, the MCU can still easily determine the type of the input signal INPUT.

[0046] Furthermore, in order to prevent the sampling module 40 from burning out under abnormal conditions, the anode of the unidirectional diode D1 is connected to a protection module 30, which may be a voltage limiting module or a current limiting module, such as Figure 5 As shown, the protection module 30 may be a current limiting resistor R2. The influence of the current limiting resistor R2 on the sampling voltage SAD can be ignored under normal circumstances, and it can play a certain protective role for the sampling module 40 when an abnormality occurs.

[0047] Embodiment 2: This application provides a vehicle signal acquisition system, such as Figure 4 , Figure 5 As shown, it includes the above-mentioned three-state input circuit and also includes a sampling module 40 connected to the three-state input circuit.

[0048] Specifically, the sampling module 40 is an MCU, which can simultaneously complete sampling and input signal INPUT judgment and execute subsequent logic. There is no need to set up an additional sampling module 40, and the structure of the vehicle signal acquisition system is streamlined.

[0049] The pull-up power supply is the operating voltage of the sampling module 40 , ie, the operating voltage VCC of the MCU.

[0050] When the signal acquisition system is actually used, it is usually necessary to collect multiple input signals INPUT. As an improvement, the vehicle signal acquisition system also includes a multi-way switch, and the three-state input circuit is provided with multiple channels, and is connected to the MCU via the multi-way switch. The signal acquisition system is practical, simple in structure and low in cost.

[0051] Embodiment 3: The present application can also provide a three-state input acquisition method, which includes the steps of:

[0052] S1. Select a Zener diode D2. Select a Zener diode D2 based on the high level of the input signal INPUT so that the Zener diode D2 can be broken down when the input signal INPUT is at a high level, and the Zener diode D2 is forward-conducted when the input signal INPUT is at a low level. The stabilizing voltage parameter of the Zener diode D2 can determine the threshold of the high level of the input signal INPUT. In automotive circuits, a higher high-level threshold can improve the anti-interference ability.

[0053] S2, build a three-state input circuit, connect the anode of the voltage regulator D2 to the cathode of the unidirectional diode D1, and set a first branch 10 with a first resistance between the anode of the unidirectional diode D1 and the pull-up power supply, and set a second branch 20 with a second resistance between the cathode of the unidirectional diode D1 and the ground, so that when the input signal INPUT is a floating signal, the first branch 10, the unidirectional diode D1, and the second branch 20 constitute a first loop, when the voltage regulator D2 breaks down, the unidirectional diode D1 is cut off, and the first branch 10 and the sampling module 40 constitute a second loop, and when the voltage regulator D2 is forward-conducted, the first branch 10, the unidirectional diode D1, and the voltage regulator D2 constitute a third loop;

[0054] S3, input signal INPUT judgment, the AD pin of the MCU samples the voltage of the anode of the unidirectional diode D1, and the MCU judges whether the input signal INPUT is a high level, a low level or a floating signal based on the AD value obtained by the sampling.

[0055] Obviously, in the same application scenario, S1 and S2 can be one-time, and after the three-state input circuit is built, S3 can be repeated.

[0056] Under this method, the positive control input and the negative control input can share an input circuit for detection, and can detect floating input. It has strong versatility, simple circuit structure, low cost of use, and can detect safety hazards of broken signal lines. In addition, through the selection of the voltage regulator D2 and other circuit components, this method can be easily transferred to the input signal INPUT acquisition system outside the automotive circuit.

[0057] Preferably, the three-state input acquisition method further comprises the steps of:

[0058] S4, alarm. When the MCU determines that the input signal INPUT is a suspended signal, the alarm device is triggered. After detecting that the signal line is broken, the alarm device is directly triggered to remind the user to repair the signal line; and

[0059] By setting the resistance ratio of the first resistance value to the second resistance value, the sampling voltages SAD in the three loops are clearly distinguished.

[0060] Combined with the three-state input circuit in the above embodiment, as shown in FIG. Figure 5As shown, a first resistor R1 can be set in the first branch 10, and a third resistor R3 can be set in the second branch 20. The first resistor R1 and the third resistor R3 provide a first resistance value and a second resistance value respectively. Here, "setting the resistance value ratio of the first resistance value to the second resistance value" is equivalent to adjusting the resistance values ​​of the first resistor R1 and the third resistor R3, so that the first resistor R1 and the third resistor R3 can produce different voltage dividing effects, thereby adjusting the value of the sampling voltage SAD when the input signal INPUT is a floating signal, so that the AD value obtained by sampling is clearly distinguished from the AD values ​​in the other two cases.

[0061] Preferably, the resistance ratio of the first resistance value to the second resistance value is set to 1:1, that is, the resistance values ​​of the first resistor R1 and the third resistor R3 are equal, and the sampling voltage SAD is approximately half of the pull-up power supply voltage, that is, VCC / 2.

[0062] The above describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited by the above embodiments, and the above embodiments and the specification only describe the principles of the present application. The present application may have various changes and improvements without departing from the spirit and scope of the present application, and these changes and improvements fall within the scope of the present application for which protection is sought. The scope of protection claimed by the present application is defined by the attached claims and their equivalents.

Claims

1. A three-state input circuit, characterized in that: It includes a first branch, a second branch, a unidirectional diode, a voltage regulator and a pull-up power supply, wherein the cathode of the voltage regulator is suitable for receiving an input signal, the anode of the voltage regulator is connected to the cathode of the unidirectional diode, the anode of the unidirectional diode is connected to a sampling module, the anode of the unidirectional diode is connected to the pull-up power supply through the first branch, and the cathode of the unidirectional diode is grounded through the second branch, so that when the input signal is a high level, a floating signal, and a low level, three different loops are formed, wherein the first branch is provided with a first resistance value, the second branch is provided with a second resistance value, the first branch includes a first resistor, the second branch includes a third resistor, and the first resistor and the third resistor are used to provide the first resistance value and the second resistance value, respectively.

2. The tri-state input circuit according to claim 1, wherein: The first resistance value is equal to the second resistance value.

3. The tri-state input circuit according to claim 1, wherein: The voltage of the pull-up power supply is lower than the high level of the input signal.

4. The tri-state input circuit according to claim 1, wherein: The anode of the unidirectional diode is connected to a protection module, and the protection module is a current limiting resistor.

5. A vehicle signal acquisition system, characterized in that: It comprises the three-state input circuit as described in any one of claims 1-4, and also comprises a sampling module connected to the three-state input circuit, the pull-up power supply is the working voltage of the sampling module, and the sampling module is an MCU.

6. The vehicle signal acquisition system as claimed in claim 5, characterized in that: It also includes a multi-way switch. The three-state input circuit is provided with multiple paths and is connected to the MCU via the multi-way switch.

7. A three-state input acquisition method, characterized in that: Includes steps: S1. Select a voltage regulator tube. Select a voltage regulator tube based on the high level of the input signal, so that the voltage regulator tube can be broken down when the input signal is at a high level, and the voltage regulator tube is forward-conducted when the input signal is at a low level; S2, build a three-state input circuit, connect the anode of the voltage regulator tube to the cathode of the unidirectional diode, and set a first branch with a first resistance between the anode of the unidirectional diode and the pull-up power supply, and set a second branch with a second resistance between the cathode of the unidirectional diode and the ground, so that when the input signal is a floating signal, the first branch, the unidirectional diode, and the second branch constitute a first loop, when the voltage regulator tube breaks down, the unidirectional diode is cut off, and the first branch and the sampling module constitute a second loop, when the voltage regulator tube is forward-conducted, the first branch, the unidirectional diode, and the voltage regulator tube constitute a third loop, wherein the first resistance is provided by the first resistor, and the second resistance is provided by the third resistor; S3, judging the input signal, the AD pin of the MCU samples the voltage of the anode of the unidirectional diode, and the MCU judges whether the input signal is a high level, a low level or a floating signal according to the AD value obtained by the sampling.

8. The three-state input acquisition method according to claim 7, characterized in that: Also includes the steps: S4, alarm, when the MCU determines that the input signal is a suspended signal, the alarm device is triggered; and, By setting the resistance ratio between the first resistance value and the second resistance value, the sampling voltages in the three circuits are clearly distinguished.

Images