Open leakage control circuit for vehicle emergency call system and vehicle-mounted device

Abstract

The utility model relates to the technical field of line detection, in particular to an open-drain control circuit for a vehicle emergency call system and a vehicle-mounted device. The circuit comprises a first control unit, a sending circuit, a diagnosis circuit and a power supply module, and the first control unit controls the mute state of the vehicle-mounted information entertainment system; the transmitting circuit comprises a mute signal input end, and the mute signal input end is connected with the first control unit. The diagnosis circuit is connected with the mute signal input end and connected with the sampling port of the first control unit. The diagnosis circuit is used for judging one or more of battery short circuit, ground short circuit and open circuit faults. According to the circuit, the accuracy of system mute control is improved, the circuit fault diagnosis capability is enhanced, and the reliability of the vehicle emergency call system during emergency communication is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to line detection technical field, specifically, relate to a kind of open drain control circuit and vehicle-mounted device for vehicle emergency call system. BACKGROUND

[0002] With the continuous development of automobile industry, the safety and emergency response capability of vehicle are paid more and more attention. Vehicle emergency call system as an important emergency communication system can quickly send distress signal to emergency rescue center when vehicle emergency occurs. In the existing emergency call scheme, the circuit for controlling the mute operation of in-vehicle infotainment (IVI) system lacks wire harness diagnosis function. Once the circuit fails, it may cause the emergency call system to fail to correctly control the mute state of IVI, thereby affecting the effect of emergency call. SUMMARY

[0003] The utility model solves the problem that the circuit for controlling the mute operation of in-vehicle infotainment system lacks wire harness diagnosis function in the existing emergency call scheme.

[0004] To solve the above problems, the utility model adopts the following technical scheme: an open drain control circuit for vehicle emergency call system, comprising: a first control unit, a transmitting circuit, a diagnosis circuit and a power module, wherein the first control unit controls the mute state of in-vehicle infotainment system; the transmitting circuit includes a mute signal input end, and the mute signal input end is connected to the first control unit; the diagnosis circuit is connected to the mute signal input end and a sampling port connected to the first control unit, and is used for judging one or more of battery short circuit, ground short circuit and open circuit fault; the diagnosis circuit includes a switch tube and a fifth resistor, the base stage of the switch tube is connected to one end of the fifth resistor, the collector of the switch tube is connected to the power module, the emitter of the switch tube is grounded, and the other end of the fifth resistor is connected to the mute signal input end.

[0005] Compared with the prior art, the technical effects achieved by adopting the technical scheme are: in the hard-wire control signal, the open drain output control can effectively and timely transmit the control signal. This simplified structure helps to reduce signal interference and transmission delay in the circuit, so that the mute signal and fault diagnosis signal can be more efficiently transmitted and processed in the circuit, improving the response speed and stability of the entire open drain control circuit. Comprehensive fault detection is added in the circuit, which can judge one or more of battery short circuit, ground short circuit and open circuit fault. At the same time, the fifth resistor is used to limit the current size of the mute signal input end to correctly transmit the signal.

[0006] Further, the open-drain control circuit further comprises a pull-down resistor, one end of the pull-down resistor is connected to the mute signal input end, and the other end of the pull-down resistor is grounded.

[0007] Compared with the prior art, the technical effects achieved by adopting the technical scheme are as follows: by connecting one end of the pull-down resistor to the mute signal input end and grounding the other end, the potential of the input end can be stabilized at a low level state when there is no input signal. In this way, the signal can be effectively prevented from being mis-triggered, and the circuit can be prevented from being incorrectly operated due to the instability of the input signal. The pull-down resistor can protect other elements in the circuit to a certain extent. When the input signal appears an abnormal high level or a short circuit, the pull-down resistor can limit the size of the current to prevent the subsequent circuit elements from being damaged by excessive current.

[0008] Further, the sending circuit further comprises a voltage dividing circuit connected with the power module, the voltage dividing circuit comprising a second resistor, a third resistor and a fourth resistor connected in series, one end of the second resistor being connected to the power module, and the other end of the second resistor being connected in parallel with the third resistor and the switch tube; wherein the third resistor and the fourth resistor are connected with a sampling port.

[0009] Compared with the prior art, the technical effects achieved by adopting the technical scheme are as follows: the voltage dividing circuit can accurately divide the voltage of the power supply, thereby providing a suitable voltage signal for the sampling port of the first control unit. Specifically, first, the first control unit detects the voltage values of the third resistor and the fourth resistor and the battery voltage to determine whether a battery short circuit occurs; second, when a ground short circuit occurs, the diagnostic signal is a logic level of 0V; third, the first control unit determines whether an open circuit fault occurs according to the second resistor, the third resistor and the fourth resistor.

[0010] Further, the sending circuit further comprises a mute signal output end and a second capacitor, wherein the mute signal output end is connected in parallel with the third resistor; one end of the second capacitor is connected to the second resistor, and the other end of the second capacitor is grounded; and / or the sending circuit further comprises a third capacitor, one end of the third capacitor is connected to the third resistor, and the other end of the third capacitor is grounded.

[0011] Compared with the prior art, the technical effects achieved by adopting the technical scheme are as follows: the mute signal output end is connected in parallel with the third resistor, which helps to accurately output the mute signal. Through the association with the third resistor, it can be ensured that the level of the mute signal output meets the design requirements under various circuit states. Capacitors have the characteristics of blocking direct current and passing alternating current. In the circuit, the second capacitor and the third capacitor can filter out high-frequency noise components in the signal, thereby enhancing the anti-interference ability of the circuit and ensuring the stability of the mute signal transmission and the accuracy of the sampling signal.

[0012] Further, the sending circuit further comprises a current limiting circuit, the current limiting circuit comprises a first resistor and a current limiting transistor, a base of the current limiting transistor is arranged between an emitter of the switching transistor and the first resistor, an emitter of the current limiting transistor is grounded, and one end of the first resistor is connected with the switching transistor and the current limiting transistor in parallel, and the other end of the first resistor is grounded.

[0013] Compared with the prior art, the technical effects achieved by the technical scheme are as follows: when an abnormal situation occurs in the circuit, for example, the current suddenly increases due to power fluctuation or external interference, the current limiting circuit can prevent excessive current from passing through the switching transistor and prevent the generation of ground offset and reduce the heat dissipation when the short-circuit power supply.

[0014] Further, the sending circuit further comprises a first anti-reverse diode, and an anode of the first anti-reverse diode is connected to the power supply module.

[0015] Compared with the prior art, the technical effects achieved by the technical scheme are as follows: in the complex environment of the vehicle electrical system, there is a possibility of power supply misconnection. The existence of the first anti-reverse diode can effectively prevent the damage of the open-drain control circuit caused by the reverse connection of the power supply. When the power supply is normally connected, the diode is in a forward conduction state, and the circuit can work normally. If the power supply is reversely connected, the diode is in a reverse blocking state, which prevents the reverse flow of current, thereby protecting the circuit from the impact of reverse current and greatly improving the safety and reliability of the circuit. At the same time, the anti-reverse diode helps to stabilize the power input to the open-drain control circuit. When a momentary reverse peak voltage occurs in the power supply, the reverse blocking characteristic of the diode can prevent these peak voltages from entering the circuit, thereby maintaining the relative stability of the power input of the circuit, and thus facilitating the stable operation of the entire open-drain control circuit and ensuring the stability of signal transmission.

[0016] Further, the sampling port is connected in parallel with a third voltage stabilizing diode, and an anode of the third voltage stabilizing diode is grounded.

[0017] Compared with the prior art, the technical effects achieved by the technical scheme are as follows: the third voltage stabilizing diode provides overvoltage protection for the sampling port. When the voltage of the port exceeds the voltage stabilizing value of the voltage stabilizing diode, the third voltage stabilizing diode will be turned on to release the excess voltage to the ground through the turned-on state, thereby preventing excessive voltage from being applied to the sampling port and avoiding damage to the chip due to overvoltage. The voltage stabilizing diode stabilizes the voltage when overvoltage occurs, provides protection, and ensures that the first control unit sampling port can more accurately measure the voltage parameters in the circuit during fault diagnosis.

[0018] Further, the open-drain control circuit further comprises a receiving circuit connected with the sending circuit, the receiving circuit is used for sending a mute signal to the vehicle information entertainment system, and a power supply pull-up resistor is arranged in the receiving circuit, and the power supply pull-up resistor is used for controlling the current of the switching transistor.

[0019] Compared with the prior art, the technical effects reached by adopting the technical scheme are: the receiving circuit is connected with the mute signal output end, forming a complete link for transmitting the mute signal from the control unit to the vehicle information entertainment system. In the emergency call system, when it is necessary to make the vehicle information entertainment system enter the mute state, the first control unit performs relevant operations through the sending circuit, and then the receiving circuit accurately sends the mute signal to the vehicle information entertainment system. Meanwhile, the collector current of the switch tube in the whole open drain output circuit is mainly determined by the power supply pull-up resistor, and by making the switch tube work in the saturation region and the cutoff region, the current in the circuit can be accurately controlled. In the saturation region, the collector current of the switch tube is large, and the signal can be quickly and effectively transmitted; in the cutoff region, the switch tube is almost not conductive, and the current is extremely small, which helps to reduce power consumption and unnecessary interference.

[0020] The receiving circuit further comprises a second anti-reverse diode, an anode of the second anti-reverse diode being connected with the power supply pull-up resistor, and a cathode of the second anti-reverse diode being connected with the sending circuit.

[0021] Compared with the prior art, the technical effects reached by adopting the technical scheme are: preventing reverse current flow: the anode of the second anti-reverse diode is connected with the sending circuit, which can effectively prevent reverse current flow. In the vehicle electronic system, reverse current flow may damage circuit components and affect the normal operation of the whole emergency call system. The presence of the second anti-reverse diode can avoid this situation and improve the reliability and stability of the circuit. Meanwhile, when the circuit state is normal, the first control unit obtains the forward voltage drop of the second anti-reverse diode and the power supply pull-up resistor to determine whether the circuit is working normally.

[0022] The utility model also provides a vehicle-mounted device, including above-mentioned for vehicle emergency call system's open drain control circuit, its beneficial effect does not repeat here. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a sending circuit diagram of the open drain control circuit of the utility model embodiment;

[0024] Figure 2 It is a receiving circuit diagram of the open drain control circuit of the utility model embodiment;

[0025] Figure 3 It is a detection flow chart of the open drain control circuit of the utility model embodiment. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned purpose, features and advantages of the utility model more obvious and easy to understand, the specific embodiments of the utility model are explained in detail below with reference to the drawings.

[0027] See Figures 1-3It is a kind of open-circuit control circuit for vehicle emergency call system provided by the utility model embodiment, including: first control unit, sending circuit, diagnostic circuit and power module, wherein, first control unit controls the mute state of vehicle information entertainment system, and first control unit in the embodiment is microcontroller unit (Microcontroller Unit, MCU) 1;Sending circuit includes: mute signal input end, and mute signal in the embodiment is MCU_MUTE_CTRL sent by MCU1;One end of pull-down resistor R6 is connected to mute signal input end, and the other end of pull-down resistor R6 is grounded;Diagnostic circuit connected with mute signal input end, diagnostic circuit is used to judge one or more of battery short circuit, ground short circuit and open-circuit fault, and diagnostic circuit connects the sampling port ADC of first control unit, and MCU1 obtains ECALL_DIAG_AD, i.e. circuit logic level value by ADC port, to judge system state, simultaneously, diagnostic circuit includes switch tube Q1 and fifth resistor R5, the base level of switch tube Q1 is connected with fifth resistor R5, the collector of switch tube Q1 is connected with power module, and the emitter of switch tube Q1 is connected with first resistor R1 ground.

[0028] Fifth resistor R5 is used to limit the current size of mute signal input end, to correctly transmit signal MCU_MUTE_CTRL.Pull-down resistor R6 can pull down MCU1 pin voltage, effectively prevent signal misfire.

[0029] Specifically, sending circuit further includes: voltage dividing circuit, voltage dividing circuit is connected with power module, voltage dividing circuit includes second resistor R2, third resistor R3, fourth resistor R4, switch tube emitter connects first resistor ground, second resistor R2, third resistor R3 and fourth resistor R4 are connected in series, second resistor R2 is connected with power module, and the other end of second resistor R2 is connected with third resistor R3 in parallel with switch tube Q1;Wherein, third resistor R3 and fourth resistor R4 are connected with sampling port ADC.

[0030] Voltage dividing circuit can accurately divide power voltage, to provide suitable voltage signal for the sampling port ADC of first control unit.

[0031] Specifically, as shown in Figure 1 Sending circuit includes mute signal output end, and mute signal output end outputs eCall_MUTE to IVI end in the embodiment, and sending circuit is further provided with second capacitor C2, third capacitor C3, and mute signal output end is connected with third resistor in parallel;One end of second capacitor C2 is connected with second resistor R2, and the other end is grounded;One end of third capacitor C3 is connected with third resistor R3, and the other end is grounded.

[0032] Specifically, the sending circuit further comprises a current limiting circuit, the current limiting circuit is provided with a first resistor R1 and a current limiting tube Q2, a base of the current limiting tube Q2 is arranged between an emitter of the switch tube Q1 and the first resistor R1, an emitter of the current limiting tube Q2 is grounded, the first resistor R1 has the switch tube Q1 and the current limiting tube Q2 in parallel at one end, and the first resistor R1 is grounded at the other end.

[0033] When an abnormal situation occurs in the circuit, for example, the current suddenly increases due to power fluctuations or external interference, the current limiting circuit can prevent excessive current from passing through the switch tube Q1, prevent the generation of ground offset, and reduce the heat dissipation when the power supply is short-circuited.

[0034] Meanwhile, the switch tube Q1 adopts a Negative-Positive-Negative (NPN) triode.

[0035] The NPN triode can efficiently realize the switching of signals. In the process of controlling the IVI mute state, when it is necessary to process and transmit the signal at the mute signal input end, the NPN triode can quickly switch between the on and off states according to the base input signal. At the same time, it is beneficial for fault detection, because the working state of the NPN triode is closely related to the voltage and current in the circuit. When a fault occurs in the circuit, for example, a short circuit of the battery can cause the voltage of the base, collector or emitter of the NPN triode to be abnormal. By sampling the voltage of the circuit node related to the NPN triode through the sampling port ADC of the first control unit, the fault type can be judged according to the different voltage characteristics of the NPN triode in normal and fault states. For the emergency call system in the vehicle, the power supply is usually provided by the vehicle battery. This low-power consumption feature helps to save power and prolong the service life of the battery.

[0036] Specifically, as shown in Figure 1 the sending circuit further comprises a first anti-reverse diode D1, an anode of the first anti-reverse diode D1 is connected to the power supply module 5VS_TBOX.

[0037] For example, D1 adopts a Schottky diode.

[0038] In the complex environment of vehicle electrical system, there is a possibility of power misconnection. The presence of the first anti-reverse diode D1 can effectively prevent the damage of the open-drain control circuit caused by reverse connection of the power supply. When the power supply is normally connected, the diode is in forward conduction state, and the circuit can work normally. If the power supply is connected in reverse, the diode is in reverse blocking state, which prevents the reverse flow of current, thereby protecting the circuit from the impact of reverse current, greatly improving the safety and reliability of the circuit. At the same time, the first anti-reverse diode D1 helps to stabilize the power input to the open-drain control circuit. When a momentary reverse peak voltage occurs in the power supply, the reverse blocking characteristic of the diode can prevent these peak voltages from entering the circuit, maintaining the relative stability of the circuit power input, thereby facilitating the stable operation of the entire open-drain control circuit and ensuring the stability of signal transmission.

[0039] Specifically, the sampling port ADC is connected in parallel with a third voltage stabilizing diode D3, and the anode of the third voltage stabilizing diode D3 is connected to ground.

[0040] At the same time, referring to Figure 2 , the open-drain control circuit further comprises a receiving circuit connected with the sending circuit, the receiving circuit being configured to send a mute signal to the IVI end, and the receiving circuit being provided with a power supply pull-up resistor R9 for controlling the current of the switch tube Q1.

[0041] Specifically, the receiving circuit further comprises a second anti-reverse diode D2, the anode of the second anti-reverse diode D2 being connected to the power supply pull-up resistor R9, and the cathode of the second anti-reverse diode D2 being connected to the sending circuit.

[0042] The receiving circuit is connected with the mute signal output end, forming a complete link for the transmission of the mute signal from the control unit to the IVI. In the emergency call system, when it is necessary to make the IVI enter the mute state, the first control unit performs relevant operations through the sending circuit, and then the receiving circuit accurately sends the mute signal to the IVI.

[0043] Based on Figure 1 , Figure 2 and Figure 3 , the vehicle system is diagnosed according to the following table.

[0044]

[0045] Wherein, H represents the first logic level, L represents the second logic level, VBATT represents the power supply voltage, VF(D2) represents the forward voltage drop of the second anti-reverse diode D2, VBE(Q2) represents the base-emitter voltage of the current limiting tube Q2, VCES(Q1) represents the collector-emitter saturation voltage of the switch tube Q1, and VF(D1) represents the forward voltage drop of the diode D1.

[0046] For example, H is 3.3V, when MCU_MUTE_CTRL is L, the switch tube Q1 is cut off, eCall_MUTE is high at this time, Q3 is cut off, eCall_INT_MCU is low. When MCU_MUTE_CTRL is H, the switch tube Q1 is turned on to GND (ground), eCall_MUTE is low at this time, Q3 is turned on, eCall_INT_MCU is high. Among them, as shown in Figure 1 The diagnostic process is as follows: the vehicle-mounted remote terminal (Telematics BOX, TBOX) and IVI are started, and the system is diagnosed and detected. By reading the eCall_DIAG_AD diagnostic state, the system determines the current wire harness state according to the above table.

[0047] When MCU_MUTE_CTRL is H and a battery short circuit fault occurs, the switch tube Q1 is turned on, and if the current flowing through the resistor R1 is greater than VBE(Q2) / R1, the final current is limited to VBE(Q2) / R1. When the current ICE(Q2) is less than VBE(Q2) / R1, ICE(Q2) refers to the collector current of the current limiting tube, and the current limiting circuit does not work. MCU_MUTE_CTRL can control the switch tube Q1 to be turned off or turned on.

[0048] Furthermore, when MCU_MUTE_CTRL is L and ECALL_INT_MCU is L, if ECALL_DIAG_AD is (5V-VF(D2))*R4 / (R9+R3+R4) corresponding voltage value, it means that the system is normal, OK2 state is the same.

[0049] Meanwhile, the embodiment also provides a vehicle-mounted device, which comprises the open drain control circuit for the vehicle emergency call system, and has all the advantages of the open drain control circuit, which will not be repeated here.

[0050] Although the utility model discloses as above, the utility model is not limited to this. Any person skilled in the art, without departing from the spirit and scope of the utility model, can make various changes and modifications, therefore the protection scope of the utility model should be limited to the range defined by the claims.

Claims

1. An open-drain control circuit for a vehicle emergency call system, characterized in that: include: A first control unit, a sending circuit, a diagnostic circuit and a power supply module, wherein: The first control unit controls the mute state of the in-vehicle infotainment system; The sending circuit includes a mute signal input terminal, and the mute signal input terminal is connected to the first control unit; The diagnostic circuit is connected to the mute signal input terminal and the sampling port of the first control unit. The diagnostic circuit is used to determine one or more of a battery short circuit, a ground short circuit, and an open circuit fault. The diagnostic circuit includes a switching tube and a fifth resistor. The base of the switching tube is connected to one end of the fifth resistor, the collector of the switching tube is connected to the power module, the emitter of the switching tube is grounded, and the other end of the fifth resistor is connected to the mute signal input terminal.

2. The open-drain control circuit according to claim 1, wherein: The open-drain control circuit further includes: A pull-down resistor, one end of the pull-down resistor is connected to the mute signal input terminal, and the other end of the pull-down resistor is grounded.

3. The open-drain control circuit according to claim 2, wherein: The diagnostic circuit further includes: A voltage divider circuit is connected to the power module, and includes a second resistor, a third resistor, and a fourth resistor. The second resistor, the third resistor, and the fourth resistor are connected in series. One end of the second resistor is connected to the power module, and the other end of the second resistor is connected in parallel with the switching tube and the third resistor. The sampling port is connected between the third resistor and the fourth resistor.

4. The open-drain control circuit according to claim 3, wherein: The transmitting circuit further includes a mute signal output terminal and a second capacitor, wherein the mute signal output terminal is connected in parallel with the third resistor; one end of the second capacitor is connected to the second resistor, and the other end of the second capacitor is grounded; And / or, the transmitting circuit further includes a third capacitor, one end of the third capacitor is connected to the third resistor, and the other end of the third capacitor is grounded.

5. The open-drain control circuit according to claim 3, wherein: The transmitting circuit also includes a current limiting circuit, which includes a first resistor and a current limiting tube. The base of the current limiting tube is arranged between the emitter of the switching tube and the first resistor, and the emitter of the current limiting tube is grounded. One end of the first resistor is connected in parallel with the switching tube and the current limiting tube, and the other end of the first resistor is grounded.

6. The open-drain control circuit according to claim 1, wherein: The transmitting circuit further includes a first anti-reverse diode, and the anode of the first anti-reverse diode is connected to the power supply module. 7 . The open-drain control circuit according to claim 1 , wherein a third voltage-stabilizing diode is connected in parallel to the sampling port, and an anode of the third voltage-stabilizing diode is grounded.

8. The open-drain control circuit according to claim 1, wherein: The open-drain control circuit further includes: A receiving circuit is connected to the transmitting circuit, and the receiving circuit is used to send a mute signal to the in-vehicle infotainment system. The receiving circuit is provided with a power pull-up resistor, and the power pull-up resistor is used to control the current of the switching tube.

9. The open-drain control circuit according to claim 8, wherein: The receiving circuit further includes a second anti-reverse diode, wherein the anode of the second anti-reverse diode is connected to the power pull-up resistor, and the cathode of the second anti-reverse diode is connected to the sending circuit.

10. A vehicle-mounted device, characterized in that: The method comprises the open-drain control circuit for a vehicle emergency call system according to any one of claims 1 to 9.

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