CN114764399A

CN114764399A - Vehicle-mounted display device

Info

Publication number: CN114764399A
Application number: CN202210364672.5A
Authority: CN
Inventors: 张峥; 黄文宇; 王千兴; 李威; 夏冬; 张雪楠; 马常乐
Original assignee: Beijing Hollysys Co Ltd
Current assignee: Beijing Hollysys Co Ltd
Priority date: 2022-04-07
Filing date: 2022-04-07
Publication date: 2022-07-19

Abstract

The application discloses a vehicle-mounted display device, which comprises a main control board card and a communication interface; the main control board card comprises a first MCU, a second MCU and a watchdog circuit; each MCU is set to receive communication data through a communication interface and send the received communication data to the other MCU of the main control board card; comparing the received communication data, and outputting a square wave signal if the communication data are consistent; if not, not outputting the square wave signal; the watchdog circuit is arranged to generate watchdog voltage according to output signals of the two MCUs; the communication interface is set to be powered on or powered off under the action of the voltage of the watchdog. The device can improve the safety of the vehicle-mounted display device.

Description

Vehicle-mounted display device

Technical Field

The application relates to the field of railway train control equipment, in particular to a vehicle-mounted display device.

Background

The DMI (human-computer interface) is mainly used for realizing information interaction between a driver and vehicle-mounted equipment, and informs the driver of various information of a train and the state of the vehicle-mounted equipment through information such as sound, images and the like so as to prompt the driver to execute corresponding operation. The DMI has interface display, driver command input, sound and voice playing, communication acquisition and fault representation functions.

DMI products are particularly important in ATP (automatic train protection) systems, which is the only means for drivers to identify the driving state of trains. The technology currently faces problems: DMI products are monopolized by foreign brands all the time, and no DMI product matched with a train control system exists in products of domestic brands; the current domestic safety level of DMI is defined as SIL0 level, and belongs to non-safety equipment. But the european market has listed DMI as a SIL2 grade safety product; the existing ATP system has more interface protocols, which are commonly PB bus interface, HDLC bus interface and RS485 bus interface, so that the DMI has more hardware versions, is extremely difficult to manage and is not beneficial to cost reduction; in recent years, DMI has been increasingly demanded in the field of ergonomics. DMI needs to meet the requirements of low noise, automatic backlight adjustment, sound adjustment, switching between keys and touch screens, and the like. In the aspects of maintenance and data, the DMI of foreign brands is mostly upgraded and downloaded data through a USB interface, and the DMI is required to be in a power-on state in the process. However, as the application environment becomes more complex and the demand for fast data availability increases, DMI increasingly requires critical data download work with external USB feed.

Disclosure of Invention

The application provides a vehicle-mounted display device, which can improve the safety of the vehicle-mounted display device.

The application provides a vehicle-mounted display device, which comprises a main control board card and a communication interface;

the main control board card comprises a first MCU, a second MCU and a watchdog circuit;

each MCU is set to receive communication data through a communication interface and send the received communication data to the other MCU of the main control board card; comparing the received communication data, and if the communication data are consistent, outputting a square wave signal; if not, not outputting the square wave signal;

the watchdog circuit is arranged to generate watchdog voltage according to output signals of the two MCUs;

the communication interface is set to be powered on or powered off under the action of the voltage of the watchdog.

In an exemplary embodiment, the apparatus further comprises an LED display screen; the main control board card also comprises a video memory;

the first MCU is also set to refresh the video memory when the received communication data are judged to be consistent; and opening or closing communication with the LED display screen under the action of the voltage of the watchdog.

In an exemplary embodiment, the apparatus further includes a switching module, an isolation module, a bus mode determination module, an RS 422-to-HDLC processing module, a PB transmission module, an RS485 transmission module, and an ASPC2 chip, which are respectively disposed between the communication interface and the first MCU and between the communication interface and the second MCU;

the switching module is configured to receive a signal of an RS422 protocol or a signal of an RS485 protocol according to a configuration signal of the corresponding MCU, and the configuration signal is generated according to the type of a signal to be received sent by an external program;

the isolation module is arranged between the switching module and the bus mode judging module;

the bus mode judging module is set to identify the protocol type of the communication data according to the digit, the transmission speed and the check bit of the communication data and send the communication data to the corresponding module according to the identified protocol type of the communication data;

the RS 422-to-HDLC processing module is arranged for receiving the communication data which is judged to be sent by the bus mode judging module as the HDLC protocol, converting the communication data into the data of the TTL protocol and sending the data to each MCU respectively;

the RS485 transmission module is arranged to receive the communication data which is judged to be transmitted by the RS485 protocol through the bus mode judgment module and respectively send the communication data to each MCU;

the ASPC2 chip is arranged to receive the communication data sent by the PB protocol judged by the bus mode judging module and convert the received data into asynchronous communication data through an external SRAM chip;

and the PB transmission block is set to receive asynchronous communication data and respectively send the asynchronous communication data to each MCU.

In an exemplary embodiment, the apparatus further comprises an external feeding module; the second MCU comprises a USB interface; the external feed module is connected with a USB interface of the second MCU;

the external feeding module comprises a load switch and an anti-reverse diode;

the external feed module is arranged between the USB interface of the second MCU and the USB interface of the external computer;

the anti-reverse diode is connected with a USB interface of the external computer through the load switch; the anti-reverse diode is connected with the USB interface of the second MCU;

the load switch is set to limit the current between the USB interface of the second MCU and the USB interface of the external computer when the USB interface of the second MCU is communicated with the USB interface of the external computer;

and the anti-reverse diode is arranged to prevent the current flowing to the USB interface of the second MCU from flowing backwards when the USB interface of the second MCU is communicated with the USB interface of an external computer.

In an exemplary embodiment, the external feeding module further includes a shielding unit;

the protection unit is arranged between the USB interface of the second MCU and the USB interface of the external computer and used for avoiding the phenomenon that the USB generates overvoltage in the external computer in the plugging and unplugging process.

In one exemplary embodiment, the apparatus includes an automatic light sensing circuit;

the automatic photosensitive circuit is arranged to acquire external natural light and process the natural light;

and the first MCU is also set as a control signal for carrying out backlight adjustment on the LED display screen according to the processed natural light output.

In an exemplary embodiment, the processing of natural light by the automatic light sensing circuit comprises:

the automatic photosensitive circuit sequentially amplifies and converts the natural light into analog and digital.

In an exemplary embodiment, the backlight adjustment of the LED display screen by the first MCU according to the processed natural light includes:

and the first MCU outputs a control signal for carrying out backlight regulation on the LED display screen according to the processed lumen coefficient of the natural light.

In an exemplary embodiment, the device further comprises a backlight constant current driving circuit;

the backlight constant current driving circuit is arranged for adjusting backlight of the LED display screen according to the control signal for adjusting backlight.

The application includes the following advantages:

at least one embodiment of the present application is capable of implementing a DMI circuit based on a SIL2 rating through hardware design.

In an implementation manner of the embodiment of the application, automatic switching of an HDLC protocol, a PB protocol and an RS485 bus can be realized.

In one implementation of the embodiment of the present application, a circuit based on external feeding and electroless downloading may be designed.

In an implementation manner of the embodiment of the application, a circuit design for automatically adjusting the backlight current of a screen based on an external light source is provided.

Of course, it is not necessary for any product to achieve all of the above-described advantages at the same time for the practice of the present application.

Additional features and advantages of the application will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the application. Other advantages of the present application may be realized and attained by the instrumentalities and combinations particularly pointed out in the specification and the drawings.

Drawings

The accompanying drawings are included to provide an understanding of the present disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the examples serve to explain the principles of the disclosure and not to limit the disclosure.

FIG. 1 is a schematic view of an in-vehicle display device according to an embodiment of the present application;

FIG. 2 is a schematic diagram of an in-vehicle display device according to an exemplary embodiment of the present disclosure;

FIG. 3 is a schematic diagram of a secure logic architecture of now 2 taken 2 provided by an example embodiment of the present application;

fig. 4 is a schematic diagram of a dynamic refresh video memory circuit according to an exemplary embodiment of the present application;

fig. 5 is a block diagram illustrating a circuit module in a smart jack according to an exemplary embodiment of the present application;

FIG. 6 is a schematic diagram of an external supply circuit provided in an exemplary embodiment of the present application;

fig. 7 is a schematic diagram of an automatic photosensitive circuit according to an exemplary embodiment of the present application.

Detailed Description

Fig. 1 is a schematic view of a vehicle-mounted display device according to an embodiment of the present application, and as shown in fig. 1, the vehicle-mounted display device according to the embodiment includes a main control board and a communication interface;

In an exemplary embodiment, the watchdog circuit generates a watchdog voltage that is a high level voltage when both MCUs output square wave signals. When only one of the two MCUs outputs the square wave signal or neither of the two MCUs outputs the square wave signal, the watchdog voltage generated by the watchdog circuit is zero.

the first MCU is also configured to refresh the video memory when the received communication data is judged to be consistent; and opening or closing communication with the LED display screen under the action of the watchdog voltage.

the switching module is configured to receive signals of an RS422 protocol or signals of an RS485 protocol according to configuration signals of the corresponding MCU, and the configuration signals are generated according to types of signals to be received and transmitted by an external program;

the RS 422-HDLC conversion processing module is arranged for receiving the communication data which is judged to be sent by the bus mode judging module in an HDLC protocol, converting the communication data into data of a TTL protocol and sending the data to each MCU respectively;

the RS485 transmission module is arranged to receive the communication data which is judged to be transmitted by the RS485 protocol by the bus mode judgment module and respectively send the communication data to each MCU;

the external feeding module comprises a load switch and an anti-reverse diode;

and the backlight constant current driving circuit is used for carrying out backlight adjustment on the LED display screen according to the control signal for carrying out backlight adjustment.

The embodiment of the application has the following advantages:

Fig. 2 is a schematic diagram of an example of a vehicle-mounted display device according to an embodiment of the present application, and as shown in fig. 2, the vehicle-mounted display device includes a power board, a main control board, an LED display module, a power interface, and a communication interface.

1. Implementation of security

SIL2 level security requirements are realized in the main control board card through a secure AND gate circuit and dynamic refresh video memory. The combination of the two functional circuits can ensure the validity, integrity and safety of communication data.

(1) Safety AND gate circuit

The SIL2 grade is usually realized by using two MCUs to process and judge communication data in a circuit respectively and comparing the data to realize a 2-out-of-2 safety logic architecture. The general MCU can use a commonly used embedded microcontroller such as a DSP (digital signal processor) series, an ARM series SOC, a low power consumption ARM series, a PowerPC series, and the like, and the present invention is implemented by using a TMS320F28xx series digital signal processor DSP of TI corporation. The scheme adopts ARM series SOC and low-power ARM.

As shown in fig. 3, the two MCUs respectively compare and verify the communication data, and output square waves to the two flyback power supplies. The flyback switching power supply is realized by an MOS (metal oxide semiconductor) switching tube and an isolation transformer, meets the requirements of power supply isolation and insulation voltage resistance, and outputs two paths of direct current power supplies to a multivibrator for power supply by a first-stage power supply. The flyback power supply is selected and designed mainly in consideration of the aspects of simple circuit structure and low power consumption. When the two paths of power supply of the multivibrator are normal and the time of reaching the multivibrator is less than 1ms, the multivibrator circuit can start oscillation to output high-frequency pulses, the frequency is 25kHz-60kHz square wave signals, when any path of power supply fails, the multivibrator immediately stops oscillation, and the high-frequency pulse output is cut off. The multivibrator designed by the application has the output frequency of 40 kHz. The input signal of the multivibrator is the output of two reverse excitation power supplies, and the output signal is a square wave signal. And the power consumption is very low because of the adoption of low-power devices such as a double triode, a capacitor and the like. The last stage of switch power supply can select a topological structure of a non-isolated switch power supply, such as a BOOST, BUCK and CUK circuit model, and can also select an isolated switch power supply, such as a forward circuit, a flyback circuit, a push-pull circuit, an LLC circuit and the like. In the application, a flyback power supply is adopted, and the flyback power supply mainly serves to output a direct-current voltage power signal. The output power supply voltage is 12VDC and the current is 350 mA. The voltage power signal directly powers the communication interface circuit. When the two MCUs compare and verify the communication data and the comparison is inconsistent, the output of one or two paths of square waves is stopped. When no receiving wave exists, the flyback circuit stops outputting, then the multivibrator and a rear-stage switching power supply circuit stop working, a direct-current voltage power signal becomes 0V, and then the communication control circuit is directly powered off, and stops interacting with ATP communication, so that the safety function of the system is realized. When the output voltage is greater than 12.5V or the output current exceeds the rated current 350mA, the protection circuit acts to directly change the output square wave of the multivibrator into 0V level, so that the switching power supply does not output a direct current power signal, the communication control circuit is directly powered off, and the communication with ATP is stopped to realize the safety function.

(2) Dynamic refreshing video memory circuit

As shown in fig. 4, the display picture of the DMI is stored in the display memory of the SOC, and is dynamically refreshed by using the logic module. And the communication data are subjected to CRC data check on the two MCUs respectively, and the CRC data check result is informed to the comparison logic module whether to close the communication with the LED display screen. Thereby realizing the function of mutual data comparison control and external display of the two CPUs.

2. Multi-communication protocol implementation and identification

The DMI communication protocol is commonly an MVB protocol, a PB protocol and an HDLC protocol. The design is compatible with a PB protocol and an HDLC protocol.

The 2 × RS422 and 2 × RS485 switching module (i.e., the above switching module) in fig. 5 is implemented by using an LTM2881 chip of ADI corporation, and switching between the two systems is implemented by short-circuiting a control line through software.

The isolation module is used as a sub-module of safety design for cutting off the influence caused by external communication interference.

The communication protocol identification module can judge the external bus mode so as to identify the effective information and carry out classification control. The bus mode identification is mainly carried out by the digit number, the transmission speed and the CRC of data. If the data is identified as RS485 data, the information is transmitted to an RS485 transmission module, if the data is identified as HDLC protocol, the data is transmitted to an RS 422-to-HDLC processing module, and if the data is identified as PB bus protocol, the data is transmitted to an ASPC2 chip outside the module for conversion.

The ASPC2 chip is a PB communication module developed by Siemens, converts communication data into asynchronous communication data in a memory sharing mode with an external SRAM chip, and can transmit the asynchronous communication data to the PB transmission module for processing.

3. Implementation of an external feed circuit

The USB interface of the auxiliary computer is a four-wire system, DP and DM are differential data buses, and the voltage of the USB interface is generally 5V dc voltage. During plugging, the auxiliary computer is prone to overvoltage conditions, and therefore a protection circuit is added to a data information transmission path (as shown in fig. 6). A load switch is used at a 5V USB voltage interface, TPS25200 of TI company is used in the design, and an anti-reverse diode is used for preventing the backward flow phenomenon of current.

When 5V power supply reaches the MCU with low power consumption, the MCU works to acquire data from a storage medium outside the eMMC and transmits the data to the auxiliary computer through a USB port of the MCU.

4. Automatic photosensitive circuit implementation

As shown in fig. 7, the natural light sensing circuit can obtain external natural light, and the external natural light is amplified and collected by the ADC, converted into a digital signal, and transmitted to the SOC chip through the I2C interface. The SOC outputs dynamic PWM waveforms to control the backlight constant current driving circuit according to the lumen coefficient of the external light source reflected by the electric signal.

The light-sensitive integrated chip is OPA3001 of TI company, and the backlight constant-current driving circuit is LT3599 chip of ADI company.

The example of the in-vehicle display device of the present application has the following advantages:

DMI unit based on localization independent research and development;

by designing a DMI circuit based on SIL2 grade through hardware, the development cost of DMI safety grade product series and non-safety product series has no difference;

automatic switching of an HDLC (high-level data link control) protocol, a PB (link partner) protocol and an RS485 bus;

the non-power downloading can be realized based on external feeding;

the backlight automatic adjustment can be realized based on the automatic screen backlight current adjusting circuit of the external light source.

The present application describes embodiments, but the description is illustrative rather than limiting and it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the embodiments described herein. Although many possible combinations of features are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are possible. Any feature or element of any embodiment may be used in combination with or instead of any other feature or element in any other embodiment, unless expressly limited otherwise.

Any features shown and/or discussed in this application may be implemented separately or in any suitable combination.

Further, in describing representative embodiments, the specification may have presented the method and/or process as a particular sequence of steps. However, to the extent that the method or process does not rely on the particular order of steps set forth herein, the method or process should not be limited to the particular sequence of steps described. Other orders of steps are possible as will be understood by those of ordinary skill in the art.

It will be understood by those of ordinary skill in the art that all or some of the steps of the methods, systems, functional modules/units in the devices disclosed above may be implemented as software, firmware, hardware, and suitable combinations thereof. In a hardware implementation, the division between functional modules/units mentioned in the above description does not necessarily correspond to the division of physical components; for example, one physical component may have multiple functions, or one function or step may be performed by several physical components in cooperation. Some or all of the components may be implemented as software executed by a processor, such as a digital signal processor or microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit. Such software may be distributed on computer readable media, which may include computer storage media (or non-transitory media) and communication media (or transitory media). The term computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data, as is well known to those of ordinary skill in the art. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, Digital Versatile Disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the desired information and which can accessed by a computer. In addition, communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media as known to those skilled in the art.

Claims

1. A vehicle-mounted display device is characterized in that,

the device comprises a main control board card and a communication interface;

2. The apparatus of claim 1,

the device also comprises an LED display screen; the main control board card also comprises a video memory;

the first MCU is also set to refresh the video memory when the received communication data are judged to be consistent; and opening or closing communication with the LED display screen under the action of the watchdog voltage.

3. The apparatus of claim 1,

the device also comprises a switching module, an isolation module, a bus mode judging module, an RS 422-to-HDLC processing module, a PB transmission module, an RS485 transmission module and an ASPC2 chip which are respectively arranged between the communication interface and the first MCU and between the communication interface and the second MCU;

the bus mode judging module is set to identify the protocol type of the communication data according to the digit, the transmission speed and the check digit of the communication data and send the communication data to the corresponding module according to the identified protocol type of the communication data;

4. The apparatus of claim 1,

the device further comprises an external feeding module; the second MCU comprises a USB interface; the external feeding module is connected with a USB interface of the second MCU;

the external feeding module comprises a load switch and an anti-reverse diode;

5. The apparatus of claim 4,

the external feeding module further comprises a protection unit;

the protection unit is arranged between the USB interface of the second MCU and the USB interface of the external computer and is used for avoiding the overvoltage phenomenon of the USB generated by the external computer in the plugging and unplugging process.

6. The apparatus of claim 2,

the device comprises an automatic photosensitive circuit;

7. The apparatus of claim 6,

the automatic photosensitive circuit processes natural light and comprises:

8. The apparatus of claim 6,

the first MCU adjusts the LED display screen to be shaded according to the natural light after the processing, and the method comprises the following steps:

9. The apparatus of claim 8,

the device also comprises a backlight constant current driving circuit;