CN215219505U

CN215219505U - On-vehicle OBD supervisory equipment of multiprotocol extensible interface

Info

Publication number: CN215219505U
Application number: CN202121125450.5U
Authority: CN
Inventors: 郑君瑜; 廖松地; 余飞; 朱曼妮
Original assignee: Jinan University
Current assignee: Jinan University; University of Jinan
Priority date: 2021-05-25
Filing date: 2021-05-25
Publication date: 2021-12-17
Anticipated expiration: 2031-05-25

Abstract

The utility model discloses an on-vehicle OBD supervisory equipment of multiprotocol extensible interface, including on-vehicle mounting box, PCB control circuit board and mobile data communication terminal, PCB control circuit board is equipped with the OBD module, CAN data communication module, TF draw-in groove, SIM card, main control chip that are used for connecting vehicle OBD interface and connects main control chip's remote communication module, two transceivers, GPS orientation module, RS485 module, RS232 module, TTL module, power module and TF card respectively. The remote communication module is connected with the SIM card, the OBD module is connected with the double transceivers through the CAN data communication module, and the GPS positioning module and the remote communication module are connected with the mobile data communication terminal. The utility model discloses on-vehicle OBD supervisory equipment small in size, expanded a plurality of interfaces, the multiprotocol is compatible, and the integrated level is high, can support vehicle supervision and vehicle exhaust emission monitoring.

Description

On-vehicle OBD supervisory equipment of multiprotocol extensible interface

Technical Field

The utility model relates to a motor vehicle OBD diagnostic equipment technical field, especially a multi-protocol extensible interface's on-vehicle OBD supervisory equipment.

Background

The On-Board diagnostics (OBD) can constantly monitor the operating state of the vehicle and the operation of the exhaust gas aftertreatment system. The vehicle-mounted OBD equipment can acquire relevant information of the working state of the vehicle or control the vehicle through an OBD interface of the vehicle.

The pollution of the tail gas of the motor vehicles brings great harm to human life and body health, and along with the rapid increase of the quantity of the motor vehicles kept, the emission of the tail gas of the motor vehicles needs to be limited to reach the national VI standard, so that strict road emission tests need to be carried out on the motor vehicles in China.

However, the road emission test greatly requires the performance requirements of the vehicle-mounted OBD device, because the OBD data interface of the vehicle is the most important physical interface for vehicle monitoring and troubleshooting, most of the vehicle-mounted OBD devices in the current market do not support simultaneous data acquisition of protocols of commercial vehicles and passenger vehicles, and have single function, and one OBD device can only perform OBD communication on one type of protocol vehicles; meanwhile, remote and local real-time processing of data is not supported mostly, mainly because the time resolution of the OBD equipment monitored remotely is low, the second-level data information which cannot be acquired can not be stored, and the data quality lacks backup and reconnection in the remote transmission process of the data; in addition, at present, the on-board OBD equipment cannot expand enough development interfaces to communicate with an external sensor for monitoring tail gas.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to solve prior art's not enough, provide an on-vehicle OBD supervisory equipment of expanded interface of multiprotocol, can the compatible and a plurality of interfaces of extension of multiprotocol, the integrated level is high, and the function is abundanter, can provide effectual technical support for vehicle supervision and vehicle exhaust emission monitoring.

The purpose of the utility model is realized through the following technical scheme: a vehicle-mounted OBD monitoring device with a multi-protocol extensible interface comprises a vehicle-mounted mounting box, a PCB control circuit board and a mobile data communication terminal, wherein the PCB control circuit board is mounted in the vehicle-mounted mounting box and is provided with a main control chip, a remote communication module, a GPS positioning module, an RS485 module with an RS485 communication interface, an RS232 module with an RS232 communication interface, a TTL module with a TTL communication interface, an OBD module with an OBD communication interface, a CAN data communication module, a double transceiver, a power supply module, a TF card slot, a TF card, an SIM card slot and an SIM card;

the remote communication module, the GPS positioning module, the RS485 module, the RS232 module, the TTL module, the OBD module, the double transceivers, the CAN data communication module and the main control chip are respectively connected with the power supply module;

the main control chip, the double transceivers, the CAN data communication module and the OBD module are sequentially connected, the remote communication module is connected with the main control chip and the SIM card, and the GPS positioning module, the RS485 module, the RS232 module, the TTL module and the TF card are respectively connected with the main control chip;

the mobile data communication terminal comprises a GPS external antenna and an LTE external antenna which are arranged on the outer surface of the vehicle-mounted mounting box, the GPS positioning module is connected with the GPS external antenna through a signal line, and the remote communication module is connected with the LTE external antenna through a signal line.

Preferably, the main control chip opens an RS485 communication interface, an RS232 communication interface, a TTL communication interface and an OBD communication interface, and the communication interfaces are respectively exposed on the outer surface of the vehicle-mounted mounting box;

the main control chip is connected with an external vehicle tail gas monitoring sensor through an open RS485/RS232/TTL communication interface, is connected with an upper computer through an open RS232 communication interface, and is connected with an OBD interface of a vehicle through an open OBD communication interface.

Further, external vehicle exhaust monitoring sensors include nitrogen oxide sensors, particulate matter sensors, and oxygen sensors.

Preferably, the OBD communication interface supports a K line, an L line and a CAN bus;

the dual transceivers support a high-speed CAN and a low-speed CAN, wherein the data transmission speed of the high-speed CAN is not less than 500kb/s, and the data transmission speed of the low-speed CAN is not more than 125 kb/s;

the CAN data communication module supports international communication protocols of passenger cars including ISO14230, ISO15765 and ISO9141, and supports international communication protocols of commercial cars including SAEJ 1939.

Preferably, the remote communication module adopts a 4G network communication module, and the main control chip adopts an STM chip.

Preferably, the power module includes a first voltage reducer U2, a second voltage reducer U3, a third voltage reducer N3, a first resistor R86, a second resistor R77, a third resistor R75, a fourth resistor R85, a fifth resistor R83, a first diode D12, a second diode D1, a third diode D11, a first capacitor C41, a second capacitor C42, a third capacitor C45, a fourth capacitor C38, a fifth capacitor C40, a sixth capacitor C43, a seventh capacitor C56, an eighth capacitor C57, a ninth capacitor C59, a tenth capacitor C53, an eleventh capacitor C55, a twelfth capacitor C58, a thirteenth capacitor C60, a fourteenth capacitor C63, a fifteenth capacitor C62, a first inductor L3, and a second inductor L4;

the voltage input pin of the first voltage reducer U2 is connected to the power supply voltage of the OBD interface of the vehicle through a first resistor R86, and the voltage input pin is grounded through a first diode D12, a first capacitor C41 and a second capacitor C42 which are connected in parallel; a starting control pin of the first voltage reducer U2 is connected with a phase voltage pin of the first voltage reducer U2, a cathode of a second diode D1 and one end of a first inductor L3 through a third capacitor C45, and an anode of a second diode D1 is grounded; the other end of the first inductor L3 outputs 3.8V, and is grounded through a fourth capacitor C38, a fifth capacitor C40 and a sixth capacitor C43 which are connected in parallel, and through a second resistor R77 and a third resistor R75 which are connected in series; the second resistor R77 is connected to the voltage detection pin of the first voltage reducer U2;

a voltage input pin of the second voltage reducer U3 is connected to a power supply voltage of an OBD interface of the vehicle, and the voltage input pin is grounded through a seventh capacitor C56 and an eighth capacitor C57 which are connected in parallel; a starting control pin of the second voltage reducer U3 is connected with a phase voltage pin of the second voltage reducer U3, a cathode of a third diode D11 and one end of a second inductor L4 through a ninth capacitor C59, and an anode of a third diode D11 is grounded; the other end of the second inductor L4 outputs 5V voltage, and is grounded through a tenth capacitor C53, an eleventh capacitor C55 and a twelfth capacitor C58 which are connected in parallel, and through a fourth resistor R85 and a fifth resistor R83 which are connected in series; the fourth resistor R85 is connected to the voltage detection pin of the second voltage reducer U3;

the input end of the third voltage reducer N3 is connected with 5V voltage and is grounded through a thirteenth capacitor C60 and a fourteenth capacitor C63 which are connected in parallel, and the output end of the third voltage reducer N3 outputs 3.3V voltage and is grounded through a fifteenth capacitor C62.

Preferably, the RS485 module further includes a gate inverter D4, an RS485 transceiver D2, a sixth resistor R110, a seventh resistor R19, an eighth resistor R20, a ninth resistor R21, a sixteenth capacitor C6, a fourth diode V13, a first bidirectional zener diode V11, a second bidirectional zener diode V10, and a third bidirectional zener diode V12;

the input end of the gate inverter D4 is connected with the main control chip, the power supply end of the gate inverter D4 is connected with the power supply module, the output end of the gate inverter D4 is connected with the enable pin of the RS485 transceiver D2, the data receiving pin of the RS485 transceiver D2 is connected with the cathode of the fourth diode V13, the anode of the fourth diode V13 is connected with the main control chip and is connected with the power supply module through the sixth resistor R110, and the data sending pin of the RS485 transceiver D2 is connected with the main control chip; a power supply pin of the RS485 transceiver D2 is connected with the power supply module and is grounded through a sixteenth capacitor C6;

two RS485 data pins of the RS485 transceiver D2 are connected with an RS485 communication interface to access an RS485 signal, and the two RS485 data pins are connected through an eighth resistor R20 and a second bidirectional voltage stabilizing diode V10; one RS485 data pin is grounded through a seventh resistor R19, grounded through a third bidirectional voltage stabilizing diode V12 and connected with a power supply module through a ninth resistor R21; the other RS485 data pin is connected to ground through a first zener diode V11.

Preferably, the RS232 module further includes an RS232 transceiver D3, a seventeenth capacitor C9, an eighteenth capacitor C10, a nineteenth capacitor C12, a twenty-fourth capacitor C8, and a twenty-fifth capacitor C11;

the internal positive and negative power pins of the RS232 transceiver D3 are grounded through a twentieth capacitor C9 and a twenty-first capacitor C10, respectively; the positive terminal pin of the voltage-multiplying charge pump capacitor of the RS232 transceiver D3 is connected with the negative terminal pin of the voltage-multiplying charge pump capacitor through a twenty-fourth capacitor C8, and the positive terminal pin of the reversed-phase charge pump capacitor of the RS232 transceiver D3 is connected with the negative terminal pin of the reversed-phase charge pump capacitor through a twenty-fifth capacitor C11; an RS232 data receiving pin and an RS232 data sending pin of the RS232 transceiver D3 are both connected with an RS232 communication interface so as to access an RS232 signal; an input serial port pin and an output serial port pin of the RS232 transceiver D3 are both connected to the main control chip, and the output serial port pin is also connected with the power supply module through a resistor; an external power pin of the RS232 transceiver D3 is connected to the power supply module and to ground through a nineteenth capacitor C12.

Preferably, the TTL module further includes a TTL communication matching interface circuit, a TTL to K line and an L line interface circuit;

the TTL communication matching interface circuit comprises a first triode V18, a second triode V21, a twelfth resistor R29, a thirteenth resistor R52, a fourteenth resistor R53 and a fifteenth resistor R54;

an emitting electrode of the first triode V18 is connected with the main control chip, a base electrode is connected with voltage through a twelfth resistor R29, and a collector electrode is connected with the voltage of the remote communication module through a fifteenth resistor R54 and is also connected with the remote communication module; the collector of the second triode V21 is connected with the main control chip and is also connected with the power supply module through a fourteenth resistor R53, the base is connected with the voltage carried by the remote communication module through a thirteenth resistor R52, and the emitter is connected with the remote communication module;

the TTL-to-K line and L line interface circuit comprises a NAND gate chip, an MOS (metal oxide semiconductor) tube and a voltage comparator, wherein the input end of the NAND gate chip is respectively connected to a main control chip, the output end of the NAND gate chip is connected to the grid electrode of the MOS tube through a resistor, the source electrode of the MOS tube is grounded, the drain electrode of the MOS tube is connected to the input end of the voltage comparator, and the output end of the voltage comparator is connected to the main control chip.

Preferably, the dual transceiver includes a first CAN bus transceiver chip D13, a second CAN bus transceiver chip D14;

the CAN data input pin of the first CAN bus transceiving chip D13 is connected with the CAN data communication module so as to access the signal converted from the high-speed CAN signal, and is grounded through a capacitor; a serial port communication pin of the first CAN bus transceiver chip D13 is connected to the main control chip; the CAN data input pin of the second CAN bus transceiver chip D14 is connected with the CAN data communication module through a resistor to access the signal converted from the low-speed CAN signal, and the serial port communication pin of the second CAN bus transceiver chip D14 is connected to the main control chip.

The utility model discloses for prior art have following advantage and effect:

the utility model discloses on-vehicle OBD supervisory equipment small in size, the multiprotocol is compatible, the extension has a plurality of interfaces (RS485 RS232 TTL OBD communication interface), can remote communication and real-time location, accomplish efficient data acquisition, can provide more functional customization for future OBD on-vehicle control, can be used to the vehicle inspection center, vehicle enterprise and scientific research institute, can provide the platform for the management and control of vehicle and the exhaust emissions control of vehicle simultaneously, very big market potential and value have.

Drawings

Fig. 1 is a schematic perspective view of an on-board OBD monitoring device with a multi-protocol extensible interface according to embodiment 1 of the present invention.

Fig. 2 is a perspective view of the on-board OBD monitoring device of fig. 1 from another perspective.

Fig. 3 is a schematic diagram of a main control chip in embodiment 1 of the present invention.

Fig. 4 is a circuit diagram of a power module according to embodiment 1 of the present invention.

Fig. 5 is a circuit diagram of an RS485 module in embodiment 1 of the present invention.

Fig. 6 is a circuit diagram of an RS232 module in embodiment 1 of the present invention.

Fig. 7 is a circuit diagram of a TTL module in embodiment 1 of the present invention.

Fig. 8 is a circuit diagram of a dual transceiver in embodiment 1 of the present invention.

Fig. 9 is a circuit diagram of a telecommunications module according to embodiment 1 of the present invention.

Fig. 10 is a schematic diagram of the connection between the main control chip and other components in fig. 3.

Fig. 11 is a topology diagram of the power supply module of fig. 4.

Description of reference numerals:

1-vehicle mounting box; 2-RS485 communication interface; 3-RS232 communication interface; 4-TTL communication interface; 5-OBD communication interface; 6-GPS external antenna; 7-LTE external antenna.

Detailed Description

The present invention will be described in further detail with reference to the following examples and drawings, but the present invention is not limited thereto.

Example 1

The embodiment provides a vehicle-mounted OBD monitoring device with a multi-protocol extensible interface, which comprises a vehicle-mounted mounting box 1, a PCB control circuit board mounted in the vehicle-mounted mounting box and a mobile data communication terminal.

The PCB control circuit board is provided with a main control chip, a remote communication module, a GPS positioning module, an RS485 module containing an RS485 communication interface 2, an RS232 module containing an RS232 communication interface 3, a TTL module containing a TTL communication interface 4, an OBD module containing an OBD communication interface 5, a CAN data communication module, two transceivers, a power supply module, a TF card slot, a TF card installed in the TF card slot, an SIM card slot and an SIM card installed in the SIM card slot.

The number of the RS485/RS232/TTL/OBD communication interfaces can be multiple, and the communication interfaces are exposed on the surface of the vehicle-mounted mounting box, for example, see FIG. 1, the communication interfaces can be arranged on the front surface, see FIG. 2, and the communication interfaces can be arranged on the rear surface.

The mobile data communication terminal comprises a GPS external antenna 6 and an LTE external antenna 7, which are both arranged on the surface of the vehicle-mounted mounting box, for example, see FIG. 2, and can be arranged on the rear surface.

The main control chip is connected with the RS485/RS232/TTL module, controls the opening of the RS485/RS232/TTL communication interface and performs data conversion processing through the RS485/RS232/TTL module. Wherein, open RS485/RS232/TTL communication interface can be as on-vehicle OBD supervisory equipment and the interface of external circuit connection, for example can be used for connecting outside vehicle exhaust monitoring sensor for example Nitrogen Oxide (NO)_x) Sensor, Particulate Matter (PM) sensor, and oxygen (O)₂) Sensors, etc., thereby realizing multivariate data acquisition. Open RS232 communication interface can be used for being connected with outside host computer, and the host computer can carry out high time resolution's data reception, realizes data acquisition and control to the real-time operating mode of vehicle, knows the running state of vehicle, and the better aassessment vehicle operating mode is with the correlation of exhaust pollutant emission.

The main control chip, the double transceivers, the CAN data communication module and the OBD module are connected in sequence, the main control chip controls the opening of the OBD communication interface through the double transceivers and the CAN data communication module, the open OBD communication interface CAN be used for being connected with the OBD interface of the vehicle, and the main control chip CAN acquire relevant information of the working state of the vehicle and control the vehicle.

Here, the master control chip may employ an STM chip, such as the STM32F103RCT6 shown in fig. 3 and 10, which is an integrated circuit of an embedded-microcontroller, with a core size of 32 bits, a speed of 72MHz, a program memory capacity of 256KB, a program memory type FLASH, and a RAM capacity of 48K.

The OBD communication interface supports a K line (a serial port 1), an L line and a CAN bus. The dual-transceiver supports a high-speed CAN (corresponding to the CAN serial port 1) and a low-speed CAN (corresponding to the CAN serial port 2), wherein the data transmission speed of the high-speed CAN is not less than 500kb/s, and the data transmission speed of the low-speed CAN is not more than 125 kb/s.

The CAN data communication module supports various national standard communication protocols of passenger vehicles such as ISO14230, ISO15765 and ISO9141, supports various national standard communication protocols of commercial vehicles such as SAEJ1939, and CAN automatically realize conversion among different protocols according to the communication protocol types of vehicles after being accessed into the OBD communication interface, thereby carrying out effective data acquisition.

The remote communication module is connected with the main control chip and controlled by the main control chip, and is connected with the SIM card and is accessed into the mobile communication network through the SIM card. The remote communication module is also connected with the LTE external antenna through a signal line. The remote communication module is also connected with an open TTL communication interface, and relevant parameters of the remote communication module can be debugged through the TTL communication interface in actual use.

Here, the remote communication module may be a 4G network communication module, such as an EC20 module (7-mode full network) shown in fig. 9. The 4G network communication module can improve the transmission quality of data by means of an LTE external antenna and through data flow support of a 4G SIM card, so that remote transmission of collected data can be carried out, and interconnection of vehicle-mounted OBD monitoring equipment and a network data platform is realized.

The GPS positioning module is connected with the main control chip and sends the acquired positioning data to the main control chip. The GPS positioning module is also connected with a GPS external antenna through a signal line, in the embodiment, the GPS positioning module is an integrated module, a passive internal antenna is adopted, signals are enhanced by means of the GPS external antenna, and accurate positioning of the vehicle is realized.

The TF card can be connected with the main control chip through the SPI interface. The TF card can store the collected data in real time. In the remote data transmission process, because of the vehicle gets into the tunnel or the not good region of signal causes data loss, perhaps in with host computer communication in-process the accident lead to under the condition that data lost, data can both in time be preserved in the TF card, carry out the replenishment of data again after the signal recovery and upload or can derive data in order to carry out post processing, so can guarantee the quality of data collection.

The remote communication module, the GPS positioning module, the RS485 module, the RS232 module, the TTL module, the OBD module, the double transceivers, the CAN data communication module and the main control chip are respectively connected with the power supply module. The power module supplies power to the connected component modules by acquiring the power of the OBD interface of the vehicle and performing voltage stabilization and conversion processing.

In this embodiment, as shown in fig. 4 and fig. 11, the power module includes a first voltage reducer U2, a second voltage reducer U3, a third voltage reducer N3, a first resistor R86, a second resistor R77, a third resistor R75, a fourth resistor R85, a fifth resistor R83, a first diode D12, a second diode D1, a third diode D11, a first capacitor C41, a second capacitor C42, a third capacitor C45, a fourth capacitor C38, a fifth capacitor C40, a sixth capacitor C43, a seventh capacitor C56, an eighth capacitor C57, a ninth capacitor C59, a tenth capacitor C53, an eleventh capacitor C55, a twelfth capacitor C58, a thirteenth capacitor C60, a fourteenth capacitor C63, a fifteenth capacitor C62, a first inductor L3, and a second inductor L4. Here, the first voltage reducer U2 and the second voltage reducer U3 are TPS543X chips such as TPS5430, and the third voltage reducer N3 is ME6206a33XG chips.

The voltage input pin VIN of the first step-down transformer U2 is connected to the power supply voltage of the OBD interface of the vehicle through a first resistor R86, and is grounded through a first diode D12, a first capacitor C41 and a second capacitor C42 which are connected in parallel; a start control pin BOOT of the first voltage reducer U2 is connected to a phase voltage pin PH of the first voltage reducer U2, a cathode of a second diode D1 and one end of a first inductor L3 through a third capacitor C45, and an anode of a second diode D1 is grounded; the other end of the first inductor L3 outputs a 3.8V supply voltage, and is grounded through a fourth capacitor C38, a fifth capacitor C40 and a sixth capacitor C43 which are connected in parallel, and through a second resistor R77 and a third resistor R75 which are connected in series; the second resistor R77 is connected to the voltage detection pin VSNS of the first voltage reducer U2;

a voltage input pin VIN of the second voltage reducer U3 is connected to a power supply voltage of an OBD interface of the vehicle, and the voltage input pin is grounded through a seventh capacitor C56 and an eighth capacitor C57 which are connected in parallel; a start control pin BOOT of the second voltage reducer U3 is connected to a phase voltage pin PH of the second voltage reducer U3, a cathode of a third diode D11 and one end of a second inductor L4 through a ninth capacitor C59, and an anode of the third diode D11 is grounded; the other end of the second inductor L4 outputs a 5V supply voltage, and is grounded through a tenth capacitor C53, an eleventh capacitor C55 and a twelfth capacitor C58 which are connected in parallel, and through a fourth resistor R85 and a fifth resistor R83 which are connected in series; the fourth resistor R85 is connected to the voltage detection pin VSNS of the second voltage reducer U3;

the input end of the third voltage reducer N3 is connected with 5V voltage and is grounded through a thirteenth capacitor C60 and a fourteenth capacitor C63 which are connected in parallel, and the output end of the third voltage reducer N3 outputs 3.3V supply voltage and is grounded through a fifteenth capacitor C62.

Here, the power supply module forms a DC-DC conversion circuit through the TPS543X chip. When the FET switch of the TPS543X chip is in the on state, the voltage across the inductor is Vin-Vout, and the current through the inductor increases at a rate di/dt (Vin-Vout)/L. When the FET switch is turned off, the inductor voltage generates an induced voltage to keep the inductor current flowing continuously. The voltage across the diode is relatively small and the inductor current will drop at a slow rate. In FET switch closure, the steady state load current is often dominated by the inductance; the average inductor current is equal to the load current. The TPS543X chip monitors external voltage through R75 and R77; the calculation formula of the output voltage is that Uo is 1.221(1+ R77/R75), and the output voltage is only related to the resistance values of R75 and R77; when the output voltage is higher than the reference voltage, the output of the comparator in the chip jumps, and the on-off frequency of the FET is controlled through the PWM controller and the gate drive in the chip, so that the purpose of automatically controlling the output voltage is achieved.

In this embodiment, as shown in fig. 5, 10 and 11, the RS485 module specifically includes an RS485 communication port, a gate inverter D4, an RS485 transceiver D2, a sixth resistor R110, a seventh resistor R19, an eighth resistor R20, a ninth resistor R21, a sixteenth capacitor C6, a fourth diode V13, a first bi-directional zener diode V11, a second bi-directional zener diode V10 and a third bi-directional zener diode V12. Here, the gate inverter may use SN74AHC1G04DBV chip, and the RS485 transceiver D2 may use MAX3485 chip.

The input end of the gate inverter D4 is connected with the main control chip, the output end of the gate inverter D4 is determined by the TTL output signal received by the input end, when the TTL output signal is '1', the output end outputs '0', and when the TTL output signal is '0', the output end outputs '1'. The power supply end of the gate inverter D4 is connected with the power supply module to be connected with the power supply voltage. The output end is connected to an enabling pin of the RS485 transceiver D2

DE，

Or DE pin is low level, the transmission is forbidden, the receiving is effective,

or DEWhen the pin is at high level, the transmission is effective and the reception is cut off. A data receiving pin RO of the RS485 transceiver D2 is connected with the cathode of a fourth diode V13, the anode of the fourth diode V13 is connected with the main control chip and the power supply module through a sixth resistor R110, and a data sending pin DI of the RS485 transceiver D2 is connected with the main control chip; a power supply pin VCC of the RS485 transceiver D2 is connected with the power supply module and is grounded through a sixteenth capacitor C6;

an RS485 data pin A, B of the RS485 transceiver D2 is connected with an RS485 communication interface so as to access an RS485 signal, and RS485 data pins A, B are connected through an eighth resistor R20 and are connected through a second bidirectional voltage stabilizing diode V10; one RS485 data pin A is grounded through a seventh resistor R19, grounded through a third bidirectional voltage stabilizing diode V12 and connected with a power supply module through a ninth resistor R21; the other RS485 data pin B is connected to ground through a first zener diode V11.

Here, the RS485 module forms a TTL to 485 protocol conversion circuit through a gate level inverter and an RS485 transceiver. When the sending signal of the main control chip is "1", the "not" operation is performed through the gate-level inverter, and "0" is output, so that the receiver in the RS485 transceiver is in an enabled working state, and at this time, the level of the RS485 data pin A, B is the level of the pull-up and pull-down resistor, namely logic "1". When the signal sent by the main control chip is '0', the 'NOT' operation is carried out through the gate-level inverter to output '1', the transmitter in the RS485 transceiver is in an enabled working state, and the output of the RS485 data pin A, B is logic '0'.

In this embodiment, as shown in fig. 6, 10 and 11, the RS232 module specifically includes an RS232 communication port, an RS232 transceiver D3, a seventeenth capacitor C9, an eighteenth capacitor C10, a nineteenth capacitor C12, a twenty-fourth capacitor C8, a twenty-fifth capacitor C11, a tenth resistor R120, and an eleventh resistor R121. Here, the RS232 transceiver may employ a MAX3232 chip.

The internal positive and negative power supply pins V + and V-of the RS232 transceiver D3 are grounded through a twentieth capacitor C9 and a twenty-first capacitor C10 respectively; the positive terminal pin C1+ of the voltage-multiplying charge pump capacitor of the RS232 transceiver D3 is connected with the negative terminal pin C1-of the voltage-multiplying charge pump capacitor through a twenty-fourth capacitor C8, and the positive terminal pin C2+ of the reversed-phase charge pump capacitor of the RS232 transceiver D3 is connected with the negative terminal pin C2-of the reversed-phase charge pump capacitor through a twenty-fifth capacitor C11; the RS232 data receiving pins R1IN and R2IN of the RS232 transceiver D3 and the RS232 data transmitting pins T1OUT and T2OUT are connected with an RS232 communication interface so as to access RS232 signals; the input serial port pins T1IN and T2IN and the output serial port pins R1OUT and R2 OUT of the RS232 transceiver D3 are connected to the main control chip, and the output serial port pins R1OUT and R2 OUT are also connected with the power supply module through a tenth resistor R120 and an eleventh resistor R121 respectively; the external power pin VCC of the RS232 transceiver D3 is connected to the power supply module and to ground through the nineteenth capacitor C12.

Here, the RS232 module forms an interface conversion circuit for converting TTL to RS-232 protocol through an RS232 transceiver. Pins 1-6 of the MAX3232 chip and 4 capacitors form a charge pump circuit, internal positive and negative power supply pins V + and V-are respectively used as +5.5V ends and-5.5V ends generated by the charge pump, and the capacitors C9 and C10 are used for stabilizing the voltage output by the charge pump. The C8 and the C11 generate two power supplies of +5.5V and-5.5V by voltage doubling by utilizing the principle that the voltage of a capacitor cannot change suddenly, and provide the power supplies for the serial port level required by the RS232 communication port. The method comprises the following steps that 8 pipelining teachings of 7-14 MAX3232 chips form two data channels, TTL/CMOS data are input from input serial port pins T1IN and T2IN, converted into RS-232 data, and then sent to external equipment from RS232 data sending pins T1OUT and T2 OUT; RS-232 data of external equipment is input from RS232 data receiving pins R1IN and R2IN, converted into TTL/CMOS data through a MAX3232 converter, and output from output serial port pins R1OUT and R2 OUT.

In this embodiment, the OBD module and the CAN data communication module may be commercially available modules. In addition to the TTL communication port, as shown in fig. 7, 10 and 11, the TTL module further includes a TTL communication matching interface circuit formed by a first transistor V18, a second transistor V21, a twelfth resistor R29, a thirteenth resistor R52, a fourteenth resistor R53 and a fifteenth resistor R54. Here, the two transistors may employ an NPN transistor S8050.

An emitter of the first triode V18 is connected to a TTL signal sending pin of the main control chip (in this embodiment, TXD2 of the serial port 2 of the main control chip), a base is connected to a voltage through a twelfth resistor R29, and a collector is connected to a voltage through a fifteenth resistor R54, and is also connected to a signal receiving port of the remote communication module; a collector of the second triode V21 is connected to a TTL signal receiving pin of the main control chip (in this embodiment, RXD2 of the serial port 2 of the main control chip), and is connected to the power module through a fourteenth resistor R53 to access 3.3V voltage, a base is connected to voltage through a thirteenth resistor R52, and an emitter is connected to a signal sending port of the remote communication module; here, to simplify the power module circuit, the twelfth resistor R29, the fifteenth resistor R54 and the thirteenth resistor R52 are connected to the telecommunication module to receive the voltage of 1.8V carried by the telecommunication module itself.

Here, the TTL module forms a level matching circuit through two NPN transistors, and controls whether an emitter and a collector of the transistor are turned on or off by controlling a voltage difference between a base and an emitter of the transistor to generate a current. When the TTL signal transmitting pin of the main control chip is at a low level, that is, the signal logic is "0", the base and the emitter of the first triode V18 have conduction current, and at this time, the collector and the emitter are conducted, and the signal logics received by the signal receiving port of the remote communication module and the TTL signal receiving pin of the main control chip are both "0". When the TTL signal transmitting pin of the main control chip is logic "1" (3.3V voltage), the base and emitter of the first triode V18 have no conduction current, and at this time, the collector and emitter are not conductive, and the signal logic received by the TTL signal receiving pin of the main control chip and the signal transmitting port of the remote communication module is "1". Therefore, the master control chip can control the remote communication module to receive and transmit data through the TTL communication matching interface circuit.

In addition, the TTL module further comprises a NAND gate chip, an MOS tube and a voltage comparator, wherein the input end of the NAND gate chip is respectively connected to the main control chip, the output end of the NAND gate chip is connected to the grid electrode of the MOS tube through a resistor, the source electrode of the MOS tube is grounded, the drain electrode of the MOS tube is connected to the input end of the voltage comparator, and the output end of the voltage comparator is connected to the main control chip. The NAND gate chip can adopt a 74HC02 chip, the MOS tube can adopt IRF7313, and the voltage comparator can adopt an LM393 chip.

Here, the TTL module forms a TTL to K line and L line interface circuit of one serial port (serial port 1in this embodiment) of the main control chip through the nand gate chip, the MOS transistor, and the voltage comparator. Specifically, as shown in fig. 7, 10 and 11, when TTL signals are sent, 74HC02 is a mature 4-way nand gate chip, the TXD1 signal of the serial port 1 of the master chip is directly connected to pin 3B of 74HC02, the CKLINE pin of the master chip is connected to pin 2A of 74HC02, the CLLINE pin of the master chip is connected to pin 5 2A of 74HC02, and two

output terminals

1Y and 2Y of 74HC02 are grounded through resistors R91 and R92, respectively, so as to ensure stable signals and fast switching change. 1Y is in turn connected to the 4-pin G2 of IRF7343 through an R90 resistor, and 2Y is in turn connected to the 2-pin G1 of IRF7343 through an R89 resistor. When 1A and 1B are both low level, i.e. the transmission signal is "0", the 1 pin 1Y output signal is "1", and at this time, because IRF7343 is turned on, the 6 pin D22 level K _ LINE signal changes from "1" to "0", and similarly, the signal of L _ LINE changes according to this process.

When the TTL signal is received, the K _ LINE signal is connected with the 3-pin INA + of the LM393 through the R95 resistor, when the K _ LINE signal is 0, the INA-is connected to 5V through the R96 resistor, 0 < "5V", so that the 1-pin OUTA of the LM393 outputs 0 at the moment, and the RXD1 receives the signal 0 because the 1 pin is connected with the RXD1 of the serial port 1. Similarly, when the K _ LINE signal is "1", the RXD1 receives the signal "1".

In this embodiment, as shown in fig. 8, 10 and 11, the dual transceiver includes a first CAN bus transceiver chip D13, a second CAN bus transceiver chip D14, a twentieth capacitor C64, a twenty-first capacitor C65, a twenty-second capacitor C66, a twenty-third capacitor C67, a sixteenth resistor R87 and a seventeenth resistor R88. Here, the first CAN bus transceiver chip and the second CAN bus transceiver chip may both adopt TJA 1050.

The CAN data input pins CANH and CANL of the first CAN bus transceiver chip D13 are connected with a CAN data communication module to access signals converted by high-speed CAN signals, and the serial port communication pins TXD and RXD of the first CAN bus transceiver chip D13 are connected to the main control chip; the CAN data input pins CANH and CANL of the second CAN bus transceiving chip D14 are respectively connected with the CAN data communication module through a sixteenth resistor R87 and a seventeenth resistor R88 to access signals converted from low-speed CAN signals, meanwhile, the CAN data input pins CANH and CANL of the second CAN bus transceiving chip D14 are also respectively grounded through a twelfth capacitor C66 and a twenty-third capacitor C67, and serial port communication pins TXD and RXD of the second CAN bus transceiving chip D14 are connected to the master control chip.

Here, the dual transceiver forms a TTL to CAN bus interface circuit through the TJA 1050. To prevent an overcurrent surge, TJA1050 may be connected to the CAN bus of the vehicle at CAN data input pins CANH, CANL via resistors R87 and R88, respectively. 2 capacitors C64 and C65(C66 and C67) are connected in parallel between CANH and CANL, and high-frequency interference on the bus can be filtered. The RS pin of TJA1050 is connected to one pin of the main control chip for mode selection. TJA1050 has two modes of operation: a high speed mode and a silent mode. TJA1050 operates normally in a high-speed mode, while in a silent mode, the transmitter of TJA1050 is disabled, performing a listen-only function, which may be used to prevent network congestion due to out-of-control of the CAN controller. The design of the dual transceiver of the present embodiment adopts advanced silicon-on-insulator SOI technology for processing and the latest EMC technology, so that the dual transceiver has excellent EMC performance.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and should not be taken as limiting the invention, and all modifications, equivalents, improvements and the like that are made within the spirit and principles of the present invention should be included in the scope of the present invention.

Claims

1. A vehicle-mounted OBD monitoring device with a multi-protocol extensible interface is characterized by comprising a vehicle-mounted mounting box, a PCB control circuit board and a mobile data communication terminal, wherein the PCB control circuit board is mounted in the vehicle-mounted mounting box and is provided with a main control chip, a remote communication module, a GPS positioning module, an RS485 module with an RS485 communication interface, an RS232 module with an RS232 communication interface, a TTL module with a TTL communication interface, an OBD module with an OBD communication interface, a CAN data communication module, a double transceiver, a power supply module, a TF card slot, a TF card, an SIM card slot and an SIM card;

2. The vehicle-mounted OBD monitoring device according to claim 1, wherein the main control chip opens an RS485 communication interface, an RS232 communication interface, a TTL communication interface and an OBD communication interface, and the communication interfaces are respectively exposed on the outer surface of the vehicle-mounted mounting box;

3. The on-board OBD monitoring device of claim 2, wherein the external vehicle exhaust monitoring sensors include a nitrogen oxide sensor, a particulate matter sensor, and an oxygen sensor.

4. The on-board OBD monitoring device of claim 1, wherein the OBD communication interface supports K-line, L-line and CAN bus;

5. The vehicle-mounted OBD monitoring device according to claim 1, wherein the remote communication module is a 4G network communication module, and the main control chip is an STM chip.

6. The on-board OBD monitoring device of claim 1, wherein the power module comprises a first voltage reducer U2, a second voltage reducer U3, a third voltage reducer N3, a first resistor R86, a second resistor R77, a third resistor R75, a fourth resistor R85, a fifth resistor R83, a first diode D12, a second diode D1, a third diode D11, a first capacitor C41, a second capacitor C42, a third capacitor C45, a fourth capacitor C38, a fifth capacitor C40, a sixth capacitor C43, a seventh capacitor C56, an eighth capacitor C57, a ninth capacitor C59, a tenth capacitor C53, an eleventh capacitor C55, a twelfth capacitor C58, a thirteenth capacitor C60, a fourteenth capacitor C63, a fifteenth capacitor C62, a first inductor L3, a second inductor L4;

7. The on-board OBD monitoring device of claim 1, wherein the RS485 module further comprises a gate inverter D4, an RS485 transceiver D2, a sixth resistor R110, a seventh resistor R19, an eighth resistor R20, a ninth resistor R21, a sixteenth capacitor C6, a fourth diode V13, a first bi-directional zener diode V11, a second bi-directional zener diode V10, a third bi-directional zener diode V12;

8. The on-board OBD monitoring device of claim 1, wherein the RS232 module further comprises an RS232 transceiver D3, a seventeenth capacitor C9, an eighteenth capacitor C10, a nineteenth capacitor C12, a twenty-fourth capacitor C8, a twenty-fifth capacitor C11;

9. The on-board OBD monitoring device of claim 1, wherein the TTL module further includes a TTL communication matching interface circuit, a TTL to K line and L line interface circuit;

10. The on-board OBD monitoring device of claim 1, wherein the dual transceiver comprises a first CAN bus transceiver chip D13, a second CAN bus transceiver chip D14;