CN113708753A - Three-state input interface circuit for detecting switching value of commercial vehicle and vehicle-mounted terminal - Google Patents
Three-state input interface circuit for detecting switching value of commercial vehicle and vehicle-mounted terminal Download PDFInfo
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- H—ELECTRICITY
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Abstract
The application provides a three-state input interface circuit, a vehicle-mounted terminal and a commercial vehicle for detecting the switching value of the commercial vehicle. The tri-state input interface circuit for detecting the switching value of the commercial vehicle comprises: the cathode of the first diode is connected with a signal source; a first resistor connected in parallel with the first diode; and a second resistor connected between the first power source and the anode of the first diode.
Description
Technical Field
The application belongs to the field of commercial vehicles, and particularly relates to a three-state input interface circuit, a vehicle-mounted terminal and a commercial vehicle for detecting the switching value of the commercial vehicle.
Background
At present, there are two kinds of automobile switching value signals, namely a positive input (high level is effective) and a negative input (low level is effective). The existing vehicle-mounted terminal has two corresponding switching value detection circuits, namely a positive input detection circuit and a negative input detection circuit.
As the switching value input end of the vehicle-mounted terminal, three possible states are provided, namely a triggered signal state, a non-triggered signal state and a suspension state.
For example, in the detection of door opening, the low level of the type a indicates the door opening state, and the high level of the type B indicates the door opening state. Because the door opening detection has two states, the vehicle-mounted terminal needs two different products to adapt to the door opening detection, the product model of the vehicle-mounted terminal is increased, and the production and management cost is also increased.
In the prior art, a positive input detection circuit and a negative input detection circuit of a vehicle-mounted terminal are different. The vehicle-mounted terminal needs a plurality of different products to be matched with different types of switching value input applications, so that the product types of the vehicle-mounted terminal are increased, and the production and management costs are also increased.
Disclosure of Invention
The application aims at providing a three-state input interface circuit for detecting the switching value of a commercial vehicle, which can be adapted to various vehicles and can reduce the production management cost and the use management cost of products. The application also provides a vehicle-mounted terminal with the three-state input interface circuit for detecting the switching value of the commercial vehicle and the commercial vehicle.
According to a first aspect of the present application, there is provided a switching value tri-state input interface circuit for a commercial vehicle, comprising: the cathode of the first diode is connected with a signal source; a first resistor connected in parallel with the first diode; and a second resistor connected between the first power source and the anode of the first diode.
Optionally, the tri-state input interface circuit may further include: and a third resistor connected between the second power source and the anode of the first diode.
Optionally, the first power supply may be a dc voltage source; the second power supply may be a signal ground.
Optionally, the anode of the first diode may be connected with an analog quantity acquisition interface.
Optionally, the analog quantity acquisition interface may be built in the processor.
Optionally, the tri-state input interface circuit may further include: and the first filter is cascaded between the anode of the first diode and the analog quantity acquisition interface.
Optionally, the tri-state input interface circuit may further include: and the first voltage clamp protector is cascaded between the anode of the first diode and the analog quantity acquisition interface.
Optionally, when the anode voltage of the first diode is in a first preset range, it may be determined that the signal source outputs a high level at this time; when the anode voltage of the first diode is in a second preset range, the signal source can be judged to be suspended at the moment; when the anode voltage of the first diode is in a third preset range, it can be determined that the signal source outputs a low level at the moment.
According to another aspect of the present application, there is also provided a vehicle-mounted terminal, including any one of the three-state input interface circuits.
According to another aspect of the application, a commercial vehicle is further provided, and the commercial vehicle comprises any one of the three-state input interface circuits and/or any one of the vehicle-mounted terminals.
According to the three-state input interface circuit, the vehicle-mounted terminal and the commercial vehicle, provided by some embodiments of the application, the switching value signal from the target signal source can be identified through the resistance voltage division with the diode and the analog quantity acquisition mode.
The mode has certain anti-interference characteristic for high-level signals and low-level signals. Therefore, the tri-state input interface circuit provided by the application can be adapted to a signal source with effective high level and can also be adapted to a signal source with effective low level. Meanwhile, the tri-state input interface circuit can detect the suspension state at the same time, and fault troubleshooting is facilitated.
Meanwhile, the topological structure of the tri-state input interface circuit is relatively simple, and the tri-state input interface circuit can be realized only by a small number of components. The level shifting chip in the tri-state input interface circuit shown in fig. 1 and 2 may be omitted. The tri-state input interface circuit is simple and reliable, and can effectively reduce the wiring area.
The tri-state input interface circuit provided by the application has lower requirements on a post-stage analog quantity acquisition interface. Many low-end processors on the market today have their own analog acquisition interfaces to meet the requirements. Therefore, the production cost of the tri-state input interface circuit provided by the application is relatively low.
According to other embodiments provided by the application, the vehicle-mounted terminal is internally provided with the tri-state input interface circuit provided by the application. Because the tri-state input interface circuit can be adapted to both high level active signal sources and low level active signal sources. Therefore, the vehicle-mounted terminal can be matched with various vehicles by a single model. Therefore, the production management cost and the use management cost of the product can be reduced.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application and do not limit the present application.
Fig. 1 shows a topological connection diagram of a switching value tri-state input interface circuit for high-level active switching values in the prior art.
Fig. 2 shows a topological connection diagram of a switching value tri-state input interface circuit for low level active in the prior art.
Fig. 3 shows a schematic diagram of a switching value tri-state input interface circuit according to an exemplary embodiment of the present application.
Fig. 4 shows a schematic diagram of a switching value tri-state input interface circuit according to another embodiment of the present application.
Fig. 5 is a schematic diagram showing a composition of a vehicle-mounted terminal according to another embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
At present, when the remote management is carried out on vehicles, particularly effective management is carried out on a fleet formed by a plurality of vehicles, a vehicle-mounted terminal is often needed. The vehicle-mounted terminal can be arranged in the target commercial vehicle and is connected with the target commercial vehicle into a whole. The vehicle-mounted terminal can detect the state of the target commercial vehicle, report the state to the background server and control the target commercial vehicle according to the instruction of the background server.
The target commercial vehicle may be a passenger-purpose commercial vehicle, such as a taxi, a bus, a school bus, or any other passenger vehicle. It may also be a commercial vehicle for freight purposes, such as a slag car, a hazardous material car or other freight car. And the vehicle can also be a special vehicle for engineering application, such as a commercial concrete vehicle.
For the commercial vehicles, government regulatory agencies and fleet themselves have special regulatory requirements. The vehicle-mounted terminal arranged in the target commercial vehicle can detect the running state of the target commercial vehicle at any time and can effectively restrict a driver so that the driving process of the driver meets the requirements. When the driver of the target commercial vehicle seriously violates the relevant regulations, the energy supply of the target commercial vehicle can be cut off, and the target commercial vehicle is forced to stop.
The switching value signal of the target commercial vehicle may include: a door opening signal of a vehicle door, a container door opening signal, a covering signal of tarpaulin of a muck vehicle, and the like.
Fig. 1 shows a topological connection diagram of a prior art switching value interface circuit for high level activity. Fig. 2 shows a topological connection diagram of a switching value interface circuit for low level activity in the prior art.
For the interface circuit shown in fig. 1, a pull-down resistor is provided. For an input disconnection hanging, the interface circuit recognizes a low level. Even if the input signal is doped with interference, it is difficult to recognize the original low-level signal as a high level due to interference because the power of the general interference signal is weak. Therefore, the circuit shown in fig. 1 has strong interference resistance for high level identification. But the low level input of the circuit does not require energy input. Thus, the coupled interference easily interferes with the low state of the interface circuit. The low-level identification of the system has weak anti-interference capability. Therefore, the interface circuit is only suitable for adapting to a signal source with high level efficiency.
For similar reasons, the interface circuit shown in fig. 2 has a strong low-level identification immunity and a weak high-level identification immunity. Only suitable for adapting to signal sources active at low levels.
Because of the difference of various automobiles, the switching value output signals of the built-in sensors are different. For example, for a door open signal, some vehicles may be active high and some vehicles may be active low. That is, some require the interface circuit shown in fig. 1 to be mated, and some require the interface circuit shown in fig. 2 to be mated.
In order to solve the above problems, the existing manufacturers generally produce different models of vehicle-mounted terminals to respectively adapt to various types of commercial vehicles. Therefore, the number of the product models of the vehicle-mounted terminal is increased, and the management cost is increased.
Fig. 3 shows a schematic diagram of a switching value tri-state input interface circuit according to an embodiment of the present application.
The tri-state input interface circuit 1000 may be used to identify three-state switching values including low, high, and floating. Thus, it is possible to match a signal source active at a low level and a signal source active at a high level at the same time.
The tri-state input interface circuit 1000 may be used to identify various switching values in a commercial vehicle. Generally, the switching value of the existing automobile comprises two signal states: respectively a low level (0-1.1V) and a high level (> 6V).
As shown in fig. 3, the tri-state input interface circuit 1000 may include: resistors R1, R2, and diode D1. Wherein the cathode of the diode D1 may be connected to the signal source Vi. A resistor R1 may be connected in parallel with diode D1. One end of the resistor R2 may be connected with the resistor R1 and the diode D1 in parallel. The resistor R2 may be connected to the anode of the diode D1. The other end of the resistor R1 is connected to the power supply VDD. The power supply VDD may be a reference power supply of the analog circuit, a power supply of the processor CPU, or other power supplies.
The tri-state input interface circuit 1000 as shown in fig. 3 may also include a resistor R3. One end of the resistor R3 may be connected to the anode of the diode D1, and the other end may be connected to the second power source. The second power supply may be another power supply different from power supply VDD. Such as the negative reference supply of an analog circuit. As shown in the exemplary embodiment, the second power supply may also be signal ground.
Alternatively, the anode of the diode D1 may be used as the output terminal Vout of the tri-state input interface circuit 1000, and connected to the analog acquisition interface. As shown in the example embodiment, the analog acquisition interface may be an analog acquisition interface built into the processor CPU. And may be connected directly to the output terminal Vout of the circuit 1000 via the analog pin of the processor CPU.
The tri-state input interface circuit 1000 can be used to convert the switching value from the signal source Vi into the voltage state that the analog acquisition interface of the later stage can acquire. After each signal state of the signal source Vi is converted by the tri-state input interface circuit 1000, a different voltage range can be formed at the output terminal Vout.
For example, when the signal source Vi outputs a high level, the voltage Vout at the output terminal may be in a first preset range after being converted by the tri-state input interface circuit 1000. When the signal source Vi is suspended, the voltage at the output terminal Vout may be in a second predetermined range after being converted by the tri-state input interface circuit 1000. When the signal source Vi outputs a low level, the voltage Vout at the output terminal may be in a third preset range after being converted by the tri-state input interface circuit 1000.
Therefore, the voltage of the output end Vout is acquired by using the analog quantity acquisition interface. When Vout is in the first preset range, it can be determined that the signal source Vi is outputting a high level. When Vout is in the second preset range, it may be determined that the signal source Vi is disconnected from the tri-state input interface circuit 1000, or in a failed state. When Vout is in the third preset range, it may be determined that the signal source Vi is outputting a low level.
Optionally, a filter 11 may also be included between the analog acquisition interface and the anode of diode D1. Alternatively, the filter 11 may be a low-pass filter. As shown in the exemplary embodiment, the filter 11 may include a capacitor C1. One terminal of the capacitor C1 may be connected to the anode of the diode D1, and the other terminal may be connected to signal ground.
As shown in fig. 3, a resistor R1 may be used to limit the current. The post-stage circuits of the tri-state input interface circuit 1000, particularly the post-stage processor, are protected. The resistor R1 can be used to block harmful electric signals such as surge, electrostatic shock, etc. from the signal source from being transmitted to the subsequent stage. Alternatively, the value of the resistor R1 may be relatively large, for example, the resistor R1 may be larger than 50K Ω.
As shown in fig. 3, diode D1 may be used to increase the sensitivity of the tri-state input interface circuit 1000 to low level inputs. Since the resistance value of the resistor R1 is relatively large. The larger resistor R1 reduces the voltage variation amplitude of the output terminal Vout and reduces the sensitivity of the tri-state input interface circuit. The diode D1 connected in parallel with the resistor R1 can clamp the voltage across the resistor R1 at a PN junction during low level output, thereby effectively increasing the sensitivity of low level input signals and increasing the variation amplitude of the voltage at the output terminal Vout.
As shown in fig. 3, when the signal source Vi outputs a high level, the diode D1 blocks. From kirchhoff's current law, the following equation can be obtained:
after finishing, the following can be obtained:
as shown in fig. 3, when the signal source Vi is suspended, the current flowing through the resistor R1 and the diode D1 is zero. At this time, the following formula can be obtained according to the resistance voltage division rule:
as shown in fig. 3, when the signal source Vi outputs a low level, the diode D1 is turned on. At this time, the output voltage Vout of the tri-state input interface circuit may satisfy the following relationship:
Vout＝Vi+VD1 (4)
wherein VD1Is the voltage across the diode.
Alternatively, the resistor R1 may be 120K Ω, the resistor R2 may be 10K Ω, and the resistor R3 may be 12K Ω. At least one of the resistors R1, R2, and R3 may be a 1% precision resistor. Diode D1 may be a low power rectifier diode, such as 1n 4148. VDD may be the supply voltage 3.3V for the CPU.
Taking the values of resistors R1, R2, R3, and VDD into equation (1) can yield:
since Vi >6, Vout > 1.98V. I.e., when the signal source Vi outputs a high level, Vout > 1.98V.
When Vi is 36V, Vout ≈ 3.287V < VDD. Therefore, the higher signal source Vi level is converted by the tri-state input interface circuit 1000 without causing damage to the processor CPU.
Taking the values of resistors R1, R2, R3, and VDD into equation (2) can yield:
Vout＝1.8V (6)
that is, when the signal source Vi is suspended, Vout becomes 1.8V.
For a typical diode, the conduction voltage drop is around 0.7V. Since the resistance values of the respective resistors are relatively large in the present exemplary embodiment, the current flowing through the diode D1 is small. So that the voltage V across the diodeD1And is also relatively small, about 0.4V. Handle VD1When the voltage is approximately equal to 0.4V, Vi is 0-1.1V, the band formula (3) can obtain:
Vout≈0.4～1.5V (7)
i.e., when the signal source Vi outputs a low level, Vout < 1.5V.
The first preset range may be set as: 1.9V-3.3V, a second preset range of 1.7-1.9V and a third preset range of 0-1.7V. When the analog quantity acquisition error is less than or equal to 0.5V, the error does not affect the identification accuracy of the tri-state input interface circuit 1000 on the tri-state switching quantity from the signal source Vi.
Obviously, the error requirement can be met only by the 8-bit sampling precision of the later-stage analog quantity acquisition interface. The tri-state input interface circuit 1000 can be used to accurately resolve the three signal states of the signal source Vi. For existing processors, the accuracy requirements can be met even with very inexpensive processor-integrated analog acquisition interfaces.
For example, the conversion accuracy at the analog acquisition interface is 12. The sampled value is:
vout is 1.9V, and AD is 2358. Vout is 1.7V and band (8) AD 2110. Therefore, the analog quantity sampling value corresponding to the first preset range can be 2358-4095, the analog quantity sampling value corresponding to the second preset range can be 2110-2358, and the analog quantity sampling value corresponding to the third preset range can be 0-2110.
As for the tri-state input interface circuit shown in fig. 3, both the high level input and the low level input require a certain amount of energy to drive so as to cause the state of the tri-state input interface circuit to change. Therefore, the tri-state input interface circuit has certain interference resistance for both a high level state and a low level state. Therefore, the method can be suitable for a high-level effective signal source and can also be suitable for a low-level effective signal source.
Fig. 4 shows a schematic diagram of a switching value tri-state input interface circuit according to another embodiment of the present application.
The tri-state input interface circuit 2000 as shown in fig. 4 may include resistors R1, R2, R3, and a diode D1. The resistors R1, R2, R3 and the diode D1 in fig. 4 are similar to the resistors R1, R2, R3 and the diode D1 in fig. 3, and are not described herein again.
The output port Vout of the tri-state input interface circuit 2000 may be connected to the analog acquisition interface ADC. A filter 21 and a voltage clamp protector 22 may be cascaded between the analog acquisition interface ADC and the anode of the diode D1.
As shown in fig. 4, the filter 21 may be a low pass filter composed of a resistor R4 and a capacitor C1. Alternatively, the filter 21 may have other topologies.
As shown in fig. 4, voltage-clamp protector 22 may include diodes D2 and D3. Wherein the anode of the diode D2 may be connected to the output terminal Vout and the cathode may be connected to the power supply VDD. The cathode of the diode D3 may be connected to the output terminal Vout and the anode may be connected to signal ground. Alternatively, voltage clamp protector 22 may take other topologies. The voltage clamp protector 22 may also include protection components such as TVS diodes, air discharge tubes, etc. Optionally, the voltage clamp protectors 22 are disposed adjacent to pins of the processor CPU.
Fig. 5 shows a schematic composition diagram of a vehicle-mounted terminal according to another embodiment of the present application.
As shown in fig. 5, the in-vehicle terminal 3000 may include a processor 31. Wherein the processor 31 may have at least one AD sampling channel integrated therein.
The in-vehicle terminal 3000 may further include a three-state input interface circuit 32. The tri-state input interface circuit 32 may be any of the tri-state input interface circuits described above. The tri-state input interface circuit 32 may be connected to a signal source 33 on the vehicle and may be used to collect the switching value signal from the signal source 33.
Optionally, the in-vehicle terminal 3000 may include one tri-state input interface circuit as shown in fig. 4, or may include two or more tri-state input interface circuits as shown in fig. 4, which are respectively connected to two or more signal sources and may be configured to collect switching value signals output by the two or more signal sources. The signal source can comprise a vehicle door opening signal, a container door opening signal, a residue soil vehicle tarpaulin covering signal and the like.
The in-vehicle terminal 3000 may be built in the target commercial vehicle. The vehicle-mounted terminal 3000 may dynamically detect at least one switching value and/or at least one analog value in the target commercial vehicle, and monitor the running state of the target commercial vehicle. And judging whether the driving process of the driver meets the requirements or not. And whether the target commercial vehicle is controlled by a gangster or not can be monitored. And can cut off the energy supply of the target commercial vehicle to force the target commercial vehicle to stop when necessary.
Any one of the three-state input interface circuits in the vehicle-mounted terminal 3000 can be adapted to both a high-level effective signal source and a low-level effective signal source. Therefore, the vehicle-mounted terminal is more adaptive and can be adapted to more vehicles.
The application further provides an embodiment, and the commercial vehicle comprises any one of the vehicle-mounted terminals and/or at least one of the three-state input interface circuits.
Alternatively, the commercial vehicle may be a fuel-powered vehicle, a hybrid fuel-electric vehicle, or an electric vehicle. Optionally, the commercial vehicle may be a passenger vehicle, a freight vehicle, or a special vehicle for engineering applications.
Optionally, the commercial vehicle may detect its own switching value signal by using any one of the built-in vehicle-mounted terminals or any one of the three-state input interface circuits. And can communicate with the background server through the aerial, report the running state of the commercial vehicle at any time.
According to the three-state input interface circuit, the vehicle-mounted terminal and the commercial vehicle, provided by some embodiments of the application, the switching value signal from the target signal source can be identified through the resistance voltage division with the diode and the analog quantity acquisition mode.
The mode has certain anti-interference characteristic for high-level signals and low-level signals. Therefore, the tri-state input interface circuit provided by the application can be adapted to a signal source with effective high level and can also be adapted to a signal source with effective low level. Meanwhile, the tri-state input interface circuit can detect the suspension state at the same time, and fault troubleshooting is facilitated.
Meanwhile, the topological structure of the tri-state input interface circuit is relatively simple, and the tri-state input interface circuit can be realized only by a small number of components. The level shifting chip in the tri-state input interface circuit shown in fig. 1 and 2 may be omitted. The tri-state input interface circuit is simple and reliable, and can effectively reduce the wiring area.
The tri-state input interface circuit provided by the application has lower requirements on a post-stage analog quantity acquisition interface. Many low-end processors on the market today have their own analog acquisition interfaces to meet the requirements. Therefore, the production cost of the tri-state input interface circuit provided by the application is relatively low.
According to other embodiments provided by the application, the vehicle-mounted terminal is internally provided with the tri-state input interface circuit provided by the application. Because the tri-state input interface circuit can be adapted to both high level active signal sources and low level active signal sources. Therefore, the vehicle-mounted terminal can be adapted to various vehicles by one model, so that the production management cost and the use management cost of products can be reduced.
The foregoing detailed description of the embodiments of the present application has been presented to illustrate the principles and implementations of the present application, and the description of the embodiments is only intended to facilitate the understanding of the methods and their core concepts of the present application. Meanwhile, a person skilled in the art should, according to the idea of the present application, change or modify the embodiments and applications of the present application based on the scope of the present application. In view of the above, the description should not be taken as limiting the application.
Claims (10)
1. A three-state input interface circuit for commercial vehicle switching value detection, comprising:
the cathode of the first diode is connected with a signal source;
a first resistor connected in parallel with the first diode;
and a second resistor connected between the first power source and the anode of the first diode.
2. The tri-state input interface circuit of claim 1, further comprising:
and a third resistor connected between the second power source and the anode of the first diode.
3. The tri-state input interface circuit of claim 2,
the first power supply is a direct current voltage source;
the second power supply is signal ground.
4. The tri-state input interface circuit of claim 1,
and the anode of the first diode is connected with the analog quantity acquisition interface.
5. The tri-state input interface circuit of claim 4, wherein the analog acquisition interface is built into the processor.
6. The tri-state input interface circuit of claim 4, further comprising:
and the first filter is cascaded between the anode of the first diode and the analog quantity acquisition interface.
7. The tri-state input interface circuit of claim 4, further comprising:
and the first voltage clamp protector is cascaded between the anode of the first diode and the analog quantity acquisition interface.
8. The tri-state input interface circuit of claim 5,
when the anode voltage of the first diode is in a first preset range, the processor judges that the signal source outputs a high level at the moment;
when the anode voltage of the first diode is in a second preset range, the processor judges that the signal source is suspended at the moment;
and when the anode voltage of the first diode is in a third preset range, the processor judges that the signal source outputs a low level at the moment.
9. A vehicle mounted terminal comprising the tri-state input interface circuit of any of claims 1-8.
10. A commercial vehicle comprising a tri-state input interface circuit as claimed in any one of claims 1 to 8.
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| CN202110799000.2A CN113708753A (en) | 2021-07-15 | 2021-07-15 | Three-state input interface circuit for detecting switching value of commercial vehicle and vehicle-mounted terminal |
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| CN202110799000.2A CN113708753A (en) | 2021-07-15 | 2021-07-15 | Three-state input interface circuit for detecting switching value of commercial vehicle and vehicle-mounted terminal |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203554407U (en) * | 2013-10-31 | 2014-04-16 | 贵阳永青仪电科技有限公司 | Switching value sampling circuit |
| CN107031409A (en) * | 2017-02-23 | 2017-08-11 | 扬子江汽车集团有限公司 | A kind of high voltage distribution box of the electric automobile controlled based on CAN |
| CN108107357A (en) * | 2017-12-27 | 2018-06-01 | 金卡智能集团股份有限公司 | Switching signal detection circuit with self-diagnostic function |
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2021
- 2021-07-15 CN CN202110799000.2A patent/CN113708753A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN203554407U (en) * | 2013-10-31 | 2014-04-16 | 贵阳永青仪电科技有限公司 | Switching value sampling circuit |
| CN107031409A (en) * | 2017-02-23 | 2017-08-11 | 扬子江汽车集团有限公司 | A kind of high voltage distribution box of the electric automobile controlled based on CAN |
| CN108107357A (en) * | 2017-12-27 | 2018-06-01 | 金卡智能集团股份有限公司 | Switching signal detection circuit with self-diagnostic function |
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Application publication date: 20211126 |