A PIS screen control unit and a PIS screen control system

Abstract

The utility model discloses a PIS screen control unit and PIS screen control system belong to PIS screen technical field, include: microprocessor, ethernet communication module, ethernet communication unit configuration is microprocessor passes through ethernet communication unit and receives display data and uploads operation state, font library module, font library unit configuration is for microprocessor provides the dot matrix information of chinese character, clock module is connected with microprocessor, clock unit configuration is provide time information, simulation debugging interface module is connected with microprocessor, simulation debugging interface module configuration is simulation debugging and on -line programming, data interaction module, this PIS screen control unit and PIS screen control system are used for driving LED dot matrix's scanning speed is fast enough, does not exist tailing, flicker, scanning speed is not enough fast etc.

Description

Technical Field

[0001] This utility model belongs to the field of PIS screen technology, specifically relating to a PIS screen control unit and a PIS screen control system. Background Technology

[0002] Currently, in the rail transit industry, the red-green dual-color LED (Light Emitting Diode) displays used in platform PIS (Passenger Information System) systems are mostly custom-made products. Their internal software and protocols are kept confidential. Once damaged, they must either be repurchased and re-customized or a new part designed by the custom manufacturer, making self-repair extremely difficult. The red-green dual-color LED displays used in platform PIS systems mostly use constant voltage scanning in their unit drive circuits, which easily leads to LED aging and dead LEDs. Moreover, their scanning method is mostly 1 / 8 scanning, which is only suitable for use in low-light environments such as semi-indoor spaces. When used in bright semi-outdoor or outdoor environments, the brightness of the displayed characters or images is insufficient. Therefore, it is necessary to develop a new PIS screen control unit and PIS screen control system to solve the existing problems. Utility Model Content

[0003] The purpose of this invention is to provide a PIS screen control unit and a PIS screen control system to solve the above-mentioned problems.

[0004] To achieve the above objectives, this utility model provides the following technical solution: a PIS screen control unit, comprising: Microprocessor U2; Ethernet communication module, wherein the Ethernet communication unit is configured so that the microprocessor U2 receives display data and uploads operational status through the Ethernet communication unit; The font library module is configured to provide dot matrix information of Chinese characters to the microprocessor U2. A clock module is connected to the microprocessor U2, and the clock unit is configured to provide time information; A simulation debugging interface module is connected to the microprocessor U2, and the simulation debugging interface module is configured for simulation debugging and online programming; The data interaction module is connected to the microprocessor U2, and the data interface is configured for interactive data.

[0005] Preferably, the font library module includes: Character chip U1; The F_MOSI pin of the character chip U1 is configured as a data or instruction write pin; The F_MISO pin of the character chip U1 is configured as a data output pin; The F_SCLK pin of the character chip U1 is connected to a first resistor R1; The F_ / CS pin of the character chip U1 is connected to a second resistor R2; The second resistor is also connected to the first capacitor C1, which is configured to absorb interference signals.

[0006] Preferably, the clock module includes: Clock chip U8; The VDD pin of the clock chip U8 is connected to one end of the second capacitor C2; The other end of the second capacitor C2 is connected to the battery BT1; The battery BT1 is connected to one end of the third resistor R3; The other end of the third resistor R3 is connected to the first diode D1; The first diode D1 is also connected to one end of the second diode D2; The other end of the second diode D2 is connected to the third diode D3; The SCL pin of the clock chip U8 is connected to the fourth resistor R4; The SDA pin of the clock chip U8 is connected to the fifth resistor R5.

[0007] Preferably, the data interaction module includes: Level conversion chip U7; The C1+ and C1- pins of the level conversion chip U7 are connected to the third capacitor C4; The C2+ and C2- pins of the level conversion chip U7 are connected to the fourth capacitor C5; The V+ and VCC pins of the level conversion chip U7 are connected to the fifth capacitor C6; The fifth capacitor C6 is also connected to the sixth capacitor C7; The V- and GND pins of the level conversion chip U7 are connected to the seventh capacitor C8; The T1IN pin of the level conversion chip U7 is connected to the first light-emitting diode D4; The R1OUT pin of the level conversion chip U7 is connected to the second light-emitting diode D5; The first light-emitting diode D4 is also connected to the sixth resistor R11; The second light-emitting diode D5 is also connected to the seventh resistor R12.

[0008] Preferably, the simulation debugging interface module includes: JTAG emulation and debugging interface J15; The first pin of the JTAG emulation and debugging interface J15 is connected to the eighth resistor R7 and the J-TCK pin of the microprocessor U2. The third pin of the JTAG emulation and debugging interface J15 is connected to the J-TDO pin of the microprocessor U2. The fifth pin of the JTAG emulation and debugging interface J15 is connected to the ninth resistor R8 and the J-TMS pin of the microprocessor U2. The ninth pin of the JTAG emulation and debugging interface J15 is connected to the tenth resistor R9 and the J-TDI pin of the microprocessor U2. The sixth pin of the JTAG emulation and debugging interface J15 is connected to one end of the eleventh resistor R10 and the RESET pin of the microprocessor U2. The other end of the eleventh resistor R10 is connected to the eighth resistor R7, the ninth resistor R8, and the tenth resistor R9; Among them, the eighth resistor R7, the ninth resistor R8, the tenth resistor R9, and the eleventh resistor R10 are all pull-up resistors.

[0009] The present invention also provides a PIS screen control system, comprising: The aforementioned PIS screen control unit; The backend server edits, packages, and sends the display data to the PIS screen control unit; The HUB interface output adapter unit increases the output current of the serial scan character signal generated by the PIS screen control unit. The display unit is connected to the HUB interface output adapter unit; The mains power conversion unit is configured to provide power to the PIS screen control unit, the back-end server, the display unit, and the HUB interface output conversion unit.

[0010] Preferably, the mains power conversion unit includes: A mains power input interface is provided, which is connected to the display screen. AC-DC converter power supply, which converts alternating current into direct current to provide output conversion unit for HUB interface; The DC-DC converter power supply converts the direct current into the operating voltage of the microprocessor U2.

[0011] Preferably, the DC-DC converter power supply includes: The first low-dropout regulator U11 is configured to convert the input power supply to power the microprocessor U2 and peripherals. The peripherals include: a character chip U1, a clock chip U8, a level conversion chip U7, a first bidirectional bus buffer U3, a second bidirectional bus buffer U4, a third bidirectional bus buffer U5, a fourth bidirectional bus buffer U6, a fifth bidirectional bus buffer U9, a sixth bidirectional bus buffer U10, etc. The second low-dropout regulator U12 is configured to convert the input power supply to power supply for the microprocessor U2 core. The Vin pin of the second low-dropout regulator U12 is connected to the eighth capacitor C11; The Vout pin of the second low-dropout regulator U12 is connected to the ninth capacitor C14; The Vin pin of the first low-dropout regulator U11 is connected to the tenth capacitor C12; The Vout pin of the first low-dropout regulator U11 is connected to the eleventh capacitor C13.

[0012] Preferably, the HUB interface output adapter unit includes: Output buffer board and HUB output interface; The HUB output interface includes: The GND pin is configured as a common zero-potential connection terminal in the circuit. The / OE pin is configured as the output enable control line; SER_R1 is configured to display red serial character information on the upper half of the screen; The SER_R2 pin is configured to display red serial character information on the lower half of the screen; SER_G1 is configured to display green serial character information on the upper half of the screen; SER_G2 is configured to display green serial character information in the lower half of the screen; The LA, LB, LC, and LD pins are configured as row scan control lines.

[0013] Preferably, the system further includes a twelfth capacitor C9 and a twelfth resistor R13 connected to the microprocessor U2.

[0014] The technical effects and advantages of this utility model are as follows: The PIS screen control unit and PIS screen control system are designed with an ARM (Advanced RISC Microprocessor) processor with an ARM926EJ-S core as the core circuit design. The maximum frequency can reach 300MHz, which is fast enough to drive the LED dot matrix scanning speed, eliminating phenomena such as trailing, flickering, and insufficient scanning speed. It has 8 HUB-12 interfaces and 4 HUB-08 interfaces, supporting 1 / 2, 1 / 4, 1 / 6, 1 / 8, and 1 / 16 scanning modes. The system board has 16M SRAM (Static Random-Access Memory) and 4M... Flash memory chips; employs a constant current / constant voltage compatible scanning drive method, featuring flicker-free operation, good compatibility, and compatibility with various commonly used constant current / constant voltage chips on the market; supports screen combinations up to 128*1280 dot matrix, with a maximum full-dot matrix scanning frequency of 125Hz and a single-dot scanning frequency of 12.5MHz; uses 10 / 100M adaptive Ethernet wired communication, allowing direct modification of display character information and brightness, and updating of the system board's underlying program via backend computer software, avoiding the cumbersome process of disassembling the screen for modification; the system has a built-in Chinese character font library with common characters such as 16*15, 16*24, and 16*8; when sending Chinese characters or numbers from the backend, only the ASCII encoding of the Chinese character or number needs to be sent, thus reducing the amount of data communicated and making it faster. Fast and reliable; the screen scanning mode can be selected from 1 / 2, 1 / 4, 1 / 6, 1 / 8, 1 / 16 scanning modes according to different screens, making it more adaptable; the screen power supply adopts synchronous rectified switching power supply, which has higher conversion efficiency and less heat generation compared with traditional switching power supplies, and is more conducive to long-term uninterrupted operation; the entire LED screen uses 5mm diameter surface-mount high-brightness dual-color 6 48*24 1 / 4 scanning constant current unit screens to form a dot matrix screen with a length of 144 and a width of 72, with good light efficiency, low light decay, clearer light emission, and longer LED lifespan; the HUB output port has a buffer function, which can enhance the load capacity and the 3.3V and 5V level matching function, and also has a regional scanning function; the system control board has JTAG (Joint... The system control board features a Test Action Group (TAG) simulation debugging interface, an RS232 data download interface, and a USB 2.0 interface for data download and update via USB flash drive. It operates on a 5V power supply, which, after surge protection, is fed to a two-stage LDO (Low-dropout regulator) chip to convert the voltage to 3.3V and 1.8V. It also has networking capabilities, allowing multiple system control boards to be connected to a router to form a local area network. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the PIS screen control system of this utility model. Figure 2a Pin diagram of the HUB-08 interface of this utility model; Figure 2b A schematic diagram of the first type of pinout for the HUB-12 interface of the utility model; Figure 2c A schematic diagram of the second pin configuration of the HUB-12 interface of the utility model; Figure 3a This is a circuit diagram of the font module of this utility model; Figure 3b This is a circuit diagram of the clock module of this utility model; Figure 3c This is a circuit diagram of the data interaction module of this utility model; Figure 3d This is a circuit diagram of the network connector of this utility model; Figure 3e This is a circuit diagram of the DC-DC converter power supply of this utility model; Figure 3f This is a circuit diagram of the simulation debugging interface module of this utility model; Figure 3g This is a circuit diagram of the AC-DC converter power input interface of this utility model; Figure 3h This is a circuit diagram of the reset circuit of this utility model; Figure 3i This is a circuit diagram of the microprocessor of this utility model; Figure 4 This is a schematic diagram of the system operation control process of this utility model. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0017] This utility model provides, for example Figures 3a-3i The PIS screen control unit shown, also known as a PIS screen control card, includes: The Ethernet communication module connects the backend server and the PIS screen control card microprocessor via a 10 / 100M adaptive Ethernet connection, enabling data exchange between the two. The PIS screen control card microprocessor receives display data from the backend server and uploads its own operating status to the backend server.

[0018] The character library module uses a large-capacity Flash memory with an SPI (Serial Peripheral Interface) interface to store 16*15, 16*24, and 16*8 dot matrix information of GBK Chinese characters. The microprocessor only needs to use the SPI interface and the ASCII (American Standard Code for Information Interchange) encoding of the characters to calculate the dot matrix information of the Chinese characters (16*15 Chinese characters, 32-byte characters, 16*8 numbers, 16-byte characters, 16*24 Chinese characters, and 48-byte characters). It is also used to store custom-modified dot matrix information of rare Chinese characters.

[0019] LAT is the display data latch control signal line. The PIS screen control card uses this control line to latch the serial red, green, or yellow character information sent through the shift register to the output of the shift register chip, which is used to light up the LED beads. In the unit screen, all shift registers or constant current chips with shift control function are connected to this control signal. SCK is the serial shift synchronization clock. The control card uses this control line to control all shift registers or constant current chips with shift control function. On the rising edge of the synchronization clock, serial data shifting is achieved. The synchronization clock pins of all shift registers or constant current chips in the unit panel are connected together. Through this clock line, the entire cascaded panel can perform shift operations simultaneously. HUB-08 LED dot matrix screens are generally used for indoor or vehicle interior screens with red and green dual-color unit boards, often employing 1 / 16 or 1 / 8 scanning methods, resulting in lower screen brightness; HUB-12 interfaces are generally used for outdoor and semi-outdoor red and green dual-color dot matrix screens, often employing 1 / 8 or 1 / 4 scanning methods, resulting in higher screen brightness.

[0020] The circuit consisting of microprocessor U2 and its peripheral circuits is the core of the entire PIS screen control system. Its function is to receive instructions and data from the backend server. Based on the instructions and data, it calculates and searches for dot matrix information in the character library unit, and generates serial character information through programming. Using a dynamic scanning method of row and column dot matrix, the row and column scanning information, character information, synchronization clock, and latch information are driven through the output buffer unit and data cable to drive the LED dot matrix screen, and finally the information is displayed on the LED screen. Simultaneously, it reads / writes data from the clock unit on the PIS screen control board and compares it with the time information sent from the background to ensure that the clock information of the entire system is always consistent with the background clock; the microprocessor U2 can also use the RS232 interface to exchange data with other devices, PCs, etc., and to update its own software.

[0021] The character library module includes: a character library chip U1, which is the character library chip for the PIS screen control card system. U1, along with first resistor R1, first resistor R2, and first capacitor C1, together form the peripheral circuit of the system character library. The character library chip U1 is a large-capacity programmable Flash memory chip with an SPI interface. It can generally perform block erasure, page-by-page, and single-byte programming operations in a sector-by-sector manner. Each byte unit space of this chip corresponds to a different block, page, and unit address, which can conveniently store 16 / 32-byte data information of common Chinese characters and other characters after modulo operations. First resistor R1 and second resistor R2 are the clock signals for the SPI interface. The pull-up resistors for F_SCLK and the chip select signal F_ / CS are used to ensure the load capacity of the clock signal and the accuracy of the chip select signal; F_MOSI is the data or instruction write pin of the character chip, used to receive data or operation instructions output by the microprocessor U2; F_MISO is the data output pin of the character chip, used to output the character information required by the microprocessor U2; at the same time, the chip has reserved storage space for customizable rare characters, and users can store 32 bytes of rare Chinese characters or other sizes of modulo information; the first capacitor C1 is the filter capacitor for its power supply, used to absorb interference signals in the system to ensure the stability of the chip operation.

[0022] The data interaction module includes: a level conversion chip U7, which is a TTL (Transistor-Transistor Logic)-CMOS (Complementary Metal-Oxide-Semiconductor Level) level conversion chip. It, along with external components, forms a circuit to enable data exchange between the PC and the microprocessor U2 via the RS232 communication interface J13; the sixth resistor R11, the seventh resistor R12, the second LED D5, and the first LED D4 are data transmission and reception indicator circuits used to indicate data exchange; these indicator lights flash rapidly when data exchange occurs; the sixth capacitor C7 is the decoupling capacitor for the chip's power supply pin; the fifth capacitor C6 is an external capacitor for the positive charge pump; the seventh capacitor C8 is an external capacitor for the negative charge pump; the fourth capacitor C5 is an external capacitor for the negative charge doubler voltage; and the third capacitor C4 is an external capacitor for the positive charge doubler voltage. The RS232 communication interface J13 circuit can upload the entire PIS screen control card's startup information and can also be used for data communication with external systems to update system firmware.

[0023] The clock module includes: a clock chip U8, which is the RTC (Real-Time Clock) clock chip of the PIS screen control card. It has an I²C (Inter-Integrated Circuit) interface, providing accurate time information to the system and can synchronize with the backend server via the network to ensure clock consistency across all screen units; BT1 is the backup battery for the clock chip U8, ensuring system time accuracy even in the event of power failure or short-term network outages; the fourth resistor R4 and the fifth resistor R5 are pull-up resistors for the IIC interface, improving the bus's load capacity and signal accuracy. Their values ​​vary depending on the data transmission rate, typically ranging from 4.7K to 10K; the first diode D1; and the second diode D2. The third diode, D3, is an isolation diode. Utilizing the diode's unidirectional conductivity, it prevents the 5V power supply from directly connecting to battery BT1. The third resistor, R3, is a current-limiting resistor, and together with the first diode, D1, forms the charging circuit for battery BT1. That is, when the 5V power supply is present, a small current can be used to charge battery BT1 through this branch. Since the voltage of battery BT1 is lower than the 5V power supply, battery BT1 does not provide energy to clock chip U8 when the 5V power supply is present. When the 5V power supply disappears, battery BT1 provides the operating voltage to clock chip U8 through the third diode D3, thus acting as a backup battery. The second capacitor, C2, is the filter capacitor for the clock chip, absorbing high-frequency components in the power supply voltage. IIC_SCL is the clock pin of the I²C bus, and IIC_SDA is the bidirectional data pin of the I²C bus, used for serial writing and reading of time information. The RTC chip of this interface has two data exchange rates: 100Kbps and 400Kbps.

[0024] Network connector J14 is a standard RJ-45-8P network connector with an internal network isolation transformer. It is used to connect the internal network control card unit of the PIS screen to the external network cable, and can easily access a 10 / 100M network. Resistor R6 and capacitor C3 are anti-static and surge protection networks used to improve the anti-interference capability of the network system. In addition to being used for network communication and data transmission, this network interface can also be used to update the underlying software and system firmware of the system board.

[0025] The simulation debugging interface module, JTAG (Joint Test Action Group) simulation debugging interface J15, is mainly used for chip monitoring, simulation, and debugging. It can also be used for ISP online program programming and updates of the microprocessor U2 chip, as well as programming of the Flash chip. It is mainly used for simulation debugging and online programming of the microprocessor U2 program. The eighth resistor R7, the ninth resistor R8, the tenth resistor R9, and the eleventh resistor R10 are pull-up resistors for the test lines TDI, TMS, and TDO. The pin symbols for JTAG are defined as follows: TCK: Test clock input; TDI: Test data input; data is input to the JTAG port via TDI. TDO: Test data output; data is output from the JTAG port via TDO. TMS: Test Mode Selection. TMS is used to set the JTAG port to a specific test mode. / RESET: Test reset, input pin, active low.

[0026] Resistor R13 and capacitor C9 form a reset circuit. Their main function is to provide a reliable reset action for the chip during the power-on period of the microprocessor U2. As a watchdog function, if the microprocessor U2 chip fails to perform the watchdog operation through the WDI (Watch Dog Input) pin in time, it will trigger the reset action of the microprocessor U2.

[0027] The power input interface J16, diode D6, capacitor C10, eighth capacitor C11, first low-dropout regulator U11, second low-dropout regulator U12, tenth capacitor C12, eleventh capacitor C13, and ninth capacitor C14 form the power supply circuit. Its main function is to connect to an external 5V power supply and convert it to 3.3V after being stepped down by the first low-dropout regulator U11 (LDO), powering the microprocessor U2 and its peripheral chips. The second low-dropout regulator U12 is the LDO that powers the microprocessor U2 core, converting the external 5V power supply to the MPU core's 1.8V power supply. Diode D6 provides reverse connection and overvoltage protection. Eighth capacitor C11 and tenth capacitor C12 are input power filter capacitors, while eleventh capacitor C13 and ninth capacitor C14 are output filter capacitors for the low-dropout regulator U9.

[0028] The microprocessor U2, along with the externally expanded flash memory and RAM chips, constitutes the hardware control part of the entire PIS screen control card. This microprocessor U2 uses an ARM926EJ-S core and can run a 300MHz embedded industrial control system. Its main functions include exchanging data with the backend server, time synchronization, and sending and receiving commands. Based on the ASCII code of the Chinese character or other character sent from the backend server, it calculates the storage address of the character's or other character's modulus information according to the corresponding formula, retrieves it, processes it, and then sends it from SER1-SER8, SEG1-... On the SEG8 pin, serial data is synchronously shifted and serially output on the rising edge of SCK. When sent to a cascaded serial-in parallel-out shift register chip (constant voltage or constant current), the shifted data is parallel latched and output during the high-level pulse output of the LAT pin. Thus, during the 1 / 2, 1 / 4, 1 / 8, 1 / 16 row power supply scan controlled by LA, LB, LC, and LD, the corresponding row power supply switch is turned on, thereby enabling a certain LED in that row to be lit and turned off. After the corresponding number of rows is scanned, the "persistence of vision" of the human eye will form the function of displaying Chinese characters, symbols, or pictures on the LED dot matrix screen.

[0029] The first bidirectional bus buffer U3, the second bidirectional bus buffer U4, the third bidirectional bus buffer U5, the fourth bidirectional bus buffer U6, the fifth bidirectional bus buffer U9, and the sixth bidirectional bus buffer U10 in the system circuit are digital buffer circuits. Their main function in the circuit is to improve the load-carrying capacity of the output pins controlled by the output microprocessor U2 and improve the anti-interference capability of the output signal. J1-J8 are eight HUB-12 interfaces, and J9-J12 are four HUB-08 interfaces. The output signal of the microprocessor U2, whose load-carrying capacity has been increased by the buffer chips, is applied to the HUB interface and can be directly connected to single and dual-color LED unit screens to light up the screen and display corresponding information.

[0030] The present invention further provides, for example, Figure 1 The PIS screen control system shown is a red and green dual-color LED display screen for rail transit platforms designed based on an ARM926EJ-S core ARM processor. It features high brightness, flicker-free operation, easy installation, and 10 / 100M adaptive Ethernet communication. It consists of a mains power conversion unit, a PIS screen control unit, and a red and green display screen board unit. The AC-DC converter unit consists of three parts: AC power input, AC-DC converter, and DC-DC converter. The mains power input is a unit that supplies power to the screen via an air switch, and also provides power to equipment such as network switches at the site; An AC-DC converter is a power supply device that converts AC220V alternating current into DC5V direct current. It is used to provide power supply voltage to various control units in the entire screen. The output end adopts synchronous rectification technology. Under full load, its conversion efficiency can reach up to about 92%. Compared with diode rectifier circuits, it has the characteristics of better stability, less heat generation, lower power consumption, and smaller size, making it very suitable for installation inside LED screens. DC-DC power supplies are non-isolated voltage conversion components, consisting of LDO chips, used to convert +5V DC voltage into two power supplies, +3.3V and +1.8V, for microprocessor power. The HUB interface output adapter unit consists of two parts: an output buffer board and a HUB output interface. The output buffer unit is used to increase the output current of the scan signal by passing the serial scan character signal generated by the microprocessor through a digital buffer circuit, thereby increasing the signal transmission distance and ensuring the accuracy of the scan information. The HUB output interface includes four HUB-08 interfaces, and each HUB-08 interface is further divided into two HUB-12 interfaces, thus providing eight HUB-12 interfaces.

[0031] The two interfaces are as follows: Figures 2a-2c As shown, the pin definitions are as follows: GND: Common zero potential connection terminal in the circuit; / OE: Output enable control line; the control card uses this line to control all decoders, shift registers or constant current chips on the screen board to start the scanning display action; this signal line has two outputs, high level and low level, which can generally be selected on the control card according to the different chips used in different screen boards; SER_R1: This represents the red serial character information for the upper half of the screen, used to drive the column LEDs to display characters. SER_R2: This represents the red serial character information in the lower half of the screen, used to drive the column LEDs to display characters. SER_G1: This represents the green serial character information for the upper half of the screen, used to drive the column LEDs to display characters. SER_G2: This represents the green serial character information for the lower half of the screen, used to drive the column LEDs to display characters. LA, LB, LC, LD: These are the line scan control lines, connected to the 3-8 decoder (74HC138) or 4-16 decoder (74HC154 / CD4514) on the screen driver board, used to control the line power supply switch and provide power to the LED beads connected to the common anode of the unit screen in one line. If it's a 1 / 16 scan, the combination is as follows: When the outputs of pins LD, LC, LB, and LA are all 0000, the 0th row of the LED display screen is selected. When the outputs of pins LD, LC, LB, and LA are 0001, the first row of the LED display screen is selected. When the outputs of pins LD, LC, LB, and LA are 0010, the second row of the LED display screen is selected. ...... When the outputs of pins LD, LC, LB, and LA are all 1111, the 15th row of the LED display screen is selected. If it's a 1 / 8 scan, the combination is as follows: When the outputs of pins LC, LB, and LA are all 000, the 0th row of the LED display screen is selected. When the outputs of pins LC, LB, and LA are 001, the first row of the LED display screen is selected. When the outputs of pins LC, LB, and LA are 010 respectively, the second row of the LED display screen is selected. ...... When the outputs of pins LC, LB, and LA are all 111, the 7th row of the LED display screen is selected. If it's a 1 / 4 scan, the combination is as follows: When the outputs of pins LB and LA are both 00, the 0th row of the LED display screen is selected. When the outputs of pins LB and LA are 0 and 1 respectively, the first row of the LED display screen is selected. When the outputs of pins LB and LA are both 10, the second row of the LED display screen is selected. When the outputs of pins LB and LA are both 11, the third row of the LED display screen is selected. Because the more lines scanned, the shorter the time spent scanning a single line, and the lower the screen brightness, indoor screens and car interior screens can generally use a 1 / 16 scanning method, semi-outdoor screens can use a 1 / 8 scanning method, and outdoor screens generally use at least a 1 / 4 scanning method. The 72*144 red-green display panel unit is the display unit of the entire PIS information screen. It consists of six commercially available 1 / 8 scan constant voltage or constant current 24*48 dot matrix screens arranged in a 3x2 row configuration. Each unit screen is divided into several parts, including column information display, row power switch, and row scan decoding. The two screens in each row are connected end-to-end by a 16-pin ribbon cable. The input terminal of the HUB signal socket is connected to the three output terminals HUB-12-0, HUB-12-1, and HUB-12-2 on the HUB signal output adapter board.

[0032] The entire system's working process is as follows: Figure 4 As shown: After the system is powered on, the AC220V AC power conversion unit first converts the AC power to DC5V DC power to supply power to each unit of the LED screen (IPS screen control card, display unit). After the IPS screen control card is powered on, it first starts the Boot and peripheral parameter initialization unit inside the microprocessor U2, configures its peripheral units, network parameters, external connection interfaces, etc., and then starts its embedded operating system. It caches the system files stored in the external flash memory to the external RAM unit to run the APP program at high speed. Then, it runs the embedded operating system according to the PLL (Phase Locked Loop) system clock frequency set by the system. It reads the IP (Internet Protocol) point number, site number, and other information stored in the EEPROM (Electrically Erasable Programmable Read Only Memory) memory unit. After the entire system is started, it waits for the real information sent by the background server. The backend server processes the clock, station, weather, and Chinese character information (if Chinese characters or numeric characters are to be sent, they will be transmitted in ASCII code rather than character modulo information; this is mainly to improve data transmission speed and reliability), as well as train arrival information, and packages them into a data stream according to a specific format after editing by the host computer software. This data is then transmitted via dedicated fiber optic cable to the switching units at each station. Each station has a switching unit that receives the data from the backend server and forwards it to the upstream and downstream PIS screens. The upstream and downstream screens receive the information from the backend server according to their respective settings and send back "OK" commands to the backend. The backend server uses agreed-upon "heartbeat packets" and "return commands" to determine if the corresponding screen is online. If no return command is detected from the corresponding station's PIS screen control card after N consecutive transmissions (3-5 times), the screen is reported as offline. If the PIS screen control card receives Chinese character information, it will read 32 bytes or 16 bytes of Chinese character encoding information from the corresponding character address of the character library chip according to the encoded numbers, and use this information to control the display. A single PIS screen control card can also be connected to a PC via a network cable. With the host computer open and in administrator mode, the IP address, station number, and other information of the PIS screen card can be set individually, thereby enabling batch numbering of control cards and downloading of display information.

[0033] The PIS screen control card of this application is designed with an ARM (Advanced RISC Microprocessor) processor with an ARM926EJ-S core as the core circuit. Its maximum frequency can reach 300MHz, providing a sufficiently fast scanning speed to drive the LED dot matrix, eliminating issues such as trailing, flickering, and insufficient scanning speed. It has 8 HUB-12 interfaces and 4 HUB-08 interfaces, supporting 1 / 2, 1 / 4, 1 / 6, 1 / 8, and 1 / 16 scanning modes. The system board has 16M SRAM (Static Random-Access Memory) and 4M Flash memory chips built-in. It adopts a constant current / constant voltage compatible scanning driving method, featuring flicker-free operation, good compatibility, and applicability to various commonly used constant current and constant voltage chips on the market. It can support screen combinations with a maximum resolution of 128*1280 dot matrix, with a maximum full-dot matrix scanning frequency of 125Hz and a single-dot scanning frequency of 12.5MHz. Employing 10 / 100M adaptive Ethernet wired communication, the system allows direct modification of displayed character information and brightness, as well as updates to the system board's underlying program, via backend server software, avoiding the cumbersome process of disassembling the screen for modification. The system includes built-in Chinese character libraries for common characters such as 16*15, 16*24, and 16*8. When the backend server sends Chinese characters or numbers, it only needs to send their ASCII codes, thus reducing the amount of data transmitted and making communication faster and more reliable. The screen scanning mode can be selected from 1 / 2, 1 / 4, 1 / 6, 1 / 8, and 1 / 16 scanning modes depending on the screen being used. Its adaptability is wider; the screen power supply adopts synchronous rectification switching power supply, which has higher conversion efficiency and less heat generation compared with traditional switching power supply, and is more conducive to long-term uninterrupted operation; the entire LED screen adopts 6 high-brightness dual-color 48*24 1 / 4 scanning constant current unit screens with a diameter of 5mm to form a dot matrix screen with a length of 144 and a width of 72. The LED beads have good light efficiency, low light decay, clearer light emission, and longer lifespan; the HUB output port has a buffer function, which can enhance the load capacity and the 3.3V and 5V level matching function, and also has a regional scanning function; the system control board has a JTAG (Joint Test Action Group) simulation debugging interface, RS232 data download interface, and USB2.0 interface for USB flash drive data download and update function; the entire system control board uses 5V power supply, which is sent to two-stage LDO (Low-dropout regulator) voltage regulator chips after surge protection absorption, converting to 3.3V and 1.8V two sets of power supply; it has networking function, which can connect several system control boards to a router to set up a local area network.

[0034] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A PIS screen control unit, characterized in that: include: microprocessor; An Ethernet communication module is configured so that the microprocessor receives display data and uploads operational status via the Ethernet communication module. A character library module, configured to provide dot matrix information of Chinese characters to the microprocessor; A clock module, connected to the microprocessor, is configured to provide time information; A simulation debugging interface module is connected to the microprocessor, and the simulation debugging interface module is configured for simulation debugging and online programming; A data interaction module is connected to the microprocessor, and the data interface is configured for interactive data.

2. The PIS screen control unit according to claim 1, characterized in that: The font library module includes: Character chip; The F_MOSI pin of the character chip is configured as a data or instruction write pin; The F_MISO pin of the character chip is configured as a data output pin; The F_SCLK pin of the character chip is connected to a first resistor; The F_ / CS pin of the character chip is connected to a second resistor; The second resistor is also connected to the first capacitor, which is configured to absorb interference signals.

3. A PIS screen control unit according to claim 1, characterized in that: The clock module includes: Clock chip; The VDD pin of the clock chip is connected to one end of the second capacitor; The other end of the second capacitor is connected to the battery; The battery is connected to one end of the third resistor; The other end of the third resistor is connected to the first diode; The first diode is also connected to one end of the second diode; The other end of the second diode is connected to the third diode; The SCL pin of the clock chip is connected to the fourth resistor; The SDA pin of the clock chip is connected to the fifth resistor.

4. A PIS screen control unit according to claim 1, characterized in that: The data interaction module includes: Level conversion chip; The C1+ and C1- pins of the level conversion chip are connected to a third capacitor; The C2+ and C2- pins of the level conversion chip are connected to a fourth capacitor; The V+ and VCC pins of the level conversion chip are connected to the fifth capacitor; The fifth capacitor is also connected to the sixth capacitor; The V- and GND pins of the level conversion chip are connected to the seventh capacitor; The T1IN pin of the level conversion chip is connected to the first light-emitting diode; The R1OUT pin of the level conversion chip is connected to the second light-emitting diode; The first light-emitting diode is also connected to the sixth resistor; The second light-emitting diode is also connected to the seventh resistor.

5. A PIS screen control unit according to claim 1, characterized in that: The simulation debugging interface module includes: JTAG emulation and debugging interface; The first pin of the JTAG emulation and debugging interface is connected to the eighth resistor and the J-TCK pin of the microprocessor. The third pin of the JTAG emulation and debugging interface is connected to the J-TDO pin of the microprocessor. The fifth pin of the JTAG emulation and debugging interface is connected to the ninth resistor and the J-TMS pin of the microprocessor. The ninth pin of the JTAG emulation and debugging interface is connected to the tenth resistor and the J-TDI pin of the microprocessor. The sixth pin of the JTAG emulation and debugging interface is connected to one end of the eleventh resistor and the RESET pin of the microprocessor. The other end of the eleventh resistor is connected to the eighth, ninth, and tenth resistors; Among them, the eighth, ninth, tenth, and eleventh resistors are all pull-up resistors.

6. A PIS screen control system, characterized in that: include: The PIS screen control unit according to any one of claims 1-5; The backend server edits, packages, and sends the display data to the PIS screen control unit; The HUB interface output adapter unit increases the output current of the serial scan character signal generated by the PIS screen control unit. The display unit is connected to the HUB interface output adapter unit; The mains power conversion unit is configured to provide power to the PIS screen control unit, the back-end server, the display unit, and the HUB interface output conversion unit.

7. The PIS screen control system according to claim 6, characterized in that: The mains power conversion unit includes: A mains power input interface, which is connected to the display screen; AC-DC converter power supply, which converts alternating current into direct current to provide output conversion unit for HUB interface; A DC-DC converter power supply that converts direct current into the operating voltage of a microprocessor.

8. The PIS screen control system according to claim 7, characterized in that: The DC-DC converter power supply includes: A first low-dropout regulator is configured to convert the input power supply into the operating voltage of the microprocessor and its peripherals. A second low-dropout regulator is configured to convert the input power supply to the operating voltage of the microprocessor core. The Vin pin of the second low-dropout regulator is connected to an eighth capacitor; The Vout pin of the second low-dropout regulator is connected to a ninth capacitor; The Vin pin of the first low-dropout regulator is connected to a tenth capacitor; The Vout pin of the first low-dropout regulator is connected to an eleventh capacitor.

9. The PIS screen control system according to claim 6, characterized in that: The HUB interface output adapter unit includes: Output buffer board and HUB output interface; The HUB output interface includes: The GND pin is configured as a common zero-potential connection terminal in the circuit. The / OE pin is configured as the output enable control line; SER_R1 is configured to display red serial character information on the upper half of the screen; The SER_R2 pin is configured to display red serial character information on the lower half of the screen; SER_G1 is configured to display green serial character information on the upper half of the screen; SER_G2 is configured to display green serial character information in the lower half of the screen; The LA, LB, LC, and LD pins are configured as row scan control lines.

10. The PIS screen control system according to claim 6, characterized in that: The system also includes a twelfth capacitor and a twelfth resistor connected to the microprocessor.

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