An electric vehicle charging pile parking space warning system and method based on an STM32 chip

Abstract

The application discloses an electric vehicle charging pile parking space warning system and method based on an STM32 chip, and belongs to the field of automobile parking safety. In view of the situation that electric vehicle charging pile parking spaces are occupied and thus electric vehicles in need of charging cannot be charged, the application designs an electric vehicle charging pile parking space warning system based on an STM32 chip. When a vehicle drives into a parking space, whether the license plate of the parked vehicle is green is recognized by an OPENMV module, and whether the charging pile is in operation is judged by a current sampling circuit; if any of the two conditions is not met, a buzzer continuously issues an alarm, a corresponding warning slogan appears on a display screen, and a GPS module and an ESP8266 communication module are started at the same time to prompt the owner of the vehicle of corresponding information of the nearest parking lot. The application analyzes the situation of the vehicle entering the charging pile parking space from multiple angles through the license plate recognition function and the charging detection function, and the system issues a warning and guides the vehicle to a parking place at the same time, so that the charging pile parking space is fully ensured not to be occupied.

Description

Technical Field

[0001] This invention relates to an electric vehicle charging station parking space warning system and method based on an STM32 chip, belonging to the field of automobile parking safety. Background Technology

[0002] With the increasing number of electric vehicles, parking spaces equipped with charging stations have been installed in cities. However, these spaces are often occupied by gasoline-powered vehicles that don't need charging, or by electric vehicles that haven't moved out of their charging stations after charging, causing significant inconvenience for electric vehicle owners who need to use these charging stations. Furthermore, the occupation of charging spaces directly leads to a waste of infrastructure investment originally planned and constructed for new energy vehicles, further straining the already relatively insufficient charging facilities and exacerbating the difficulties of parking and charging for new energy vehicles. This, to some extent, hinders the further promotion of new energy vehicles.

[0003] Currently, the solutions for managing electric vehicle charging station parking spaces still have shortcomings. For example, CN201811467555, a method for detecting non-new energy vehicles occupying charging station parking spaces, uses image recognition and data monitoring to trigger an alarm to prevent non-new energy vehicles from parking in the space. However, it does not consider that if an electric vehicle parks in the space but does not charge, or does not leave promptly after charging, it is also a waste and occupation of the charging station's power resources. Another example is CN202210669698, a multi-functional intelligent charging station ground lock device, which restricts the vehicle's departure time by checking whether the charging station in the parking space has generated charging order information. If there is no charging order information, the lock will be engaged for a certain period of time before the vehicle can leave. However, this method prevents vehicles that need to use the charging station from charging immediately, and instead allows vehicles that do not need to charge to continuously occupy the charging station parking space, which to some extent exacerbates the waste of charging stations.

[0004] To address the aforementioned issues and the shortcomings of existing charging station parking space management solutions, this invention designs an electric vehicle charging station parking space warning system and method based on an STM32 chip. The system uses an OPENMV module to identify whether the license plate of a parked vehicle is green, and a current sampling circuit to determine if the charging station is operational. If either condition is not met, a buzzer continuously sounds an alarm, and a corresponding warning message appears on the display screen. Simultaneously, the GPS module and ESP8266 communication module are activated to provide the driver with information about the nearest parking lot. This invention effectively prevents unqualified vehicles from parking in electric vehicle charging spaces from the parking front end. Summary of the Invention

[0005] This invention provides an electric vehicle charging pile parking space warning system and method based on STM32 chip. The entire circuit system is based on STM32F103R6 microcontroller 6, which connects multiple modules.

[0006] The PA2 and PA3 pins of the STM32F103R6 microcontroller are connected to the TXD and RXD pins of the GPS module 5, respectively. The DV5V pin of the GPS module 5 is connected to the 5V power supply, and the GND pin of the GPS module 5 is grounded.

[0007] The TXD and RXD pins of ESP8266 module 3 are also connected to the PA2 and PA3 pins of STM32F103R6 microcontroller 6, respectively. The GPIO2 pin of ESP8266 module 3 is connected to resistor R2 4, and the other end of resistor R2 4 is connected to a 5V power supply. The GND pin of ESP8266 module 3 is grounded. The VCC pin and CH-PD pin of ESP8266 module 3 are both connected to a 5V power supply. One end of resistor R3 1 is connected to the RST pin of ESP8266 module 3, and the other end of resistor R3 1 is connected to a 5V power supply. One end of capacitor C6 2 is connected to the RST pin of ESP8266 module 3, and the other end of capacitor C6 2 is grounded.

[0008] The RS, RW, EN, D0, D1, D2, D3, D4, D5, D6, and D7 pins of the LCD1602 liquid crystal display screen 8 are connected to the PA8, PA9, PA10, PB0, PB1, PB2, PB3, PB4, PB5, PB6, and PB7 pins of the STM32F103R6 microcontroller 6, respectively. The GND pin of the LCD1602 liquid crystal display screen 8 is directly grounded. The VCC pin of the LCD1602 liquid crystal display screen 8 is connected to a 5V power supply. The VL pin of the LCD1602 liquid crystal display screen 8 is connected to the upper sliding arm of the sliding rheostat 7. One end of the sliding rheostat 7 is connected to a 5V power supply, and the other end is grounded.

[0009] The P4 and P5 pins of the OPENMV module 9 are also connected to the PA10 and PA9 pins of the STM32F103R6 microcontroller 6, respectively. The 3.3V pin of the OPENMV module 9 is connected to the 5V power supply. The RST, BOOT and GND pins of the OPENMV module 9 are grounded. The VIN pin of the OPENMV module 9 is connected to the 5V power supply.

[0010] One end of resistor R126 is connected to the NRST pin of STM32F103R6 microcontroller 6, and the other end of resistor R126 is connected to the 5V power supply; one end of capacitor C427 and button 28 are both connected to the NRST pin of STM32F103R6 microcontroller 6, and the other end is grounded.

[0011] One end of resistor R423 is connected to the PC0 pin of the STM32F103R6 microcontroller 6, and the other end of resistor R423 is connected to the base of PNP transistor 24. The collector of PNP transistor 24 is grounded, the emitter of PNP transistor 24 is connected to buzzer 25, and the other end of buzzer 25 is grounded.

[0012] One end of capacitor C5 (14) is connected to pin PC11 of the STM32F103R6 microcontroller 6, and the other end is grounded; one end of resistor R11 (15) is connected to pin PC11 of the STM32F103R6 microcontroller 6, and the other end is connected to the output of amplifier 17. Resistor R10 (16) is connected between the output and inverting input of amplifier 17. The negative power supply side of amplifier 17 is grounded, and the positive power supply side is connected to a 5V power supply; one side of resistor R7 (19) is connected to the inverting input of amplifier 17, and the other end is connected to a 4.5V power supply; one side of resistor R8 (21) is connected between resistor R7 (19) and the 4.5V power supply, and the other side is grounded; one side of resistor R6 (20) is connected to the non-inverting input of amplifier 17, and the other end is connected to a 4.5V power supply; one side of resistor R5 (22) is connected between resistor R7 (19) and the 4.5V power supply, and the other side is connected between resistor R6 (20) and the 4.5V power supply; one side of resistor R9 (18) is connected to the non-inverting input of amplifier 17, and the other end is grounded.

[0013] One side of capacitor C1 (C113) is connected to the OSCIN_PD0 pin of STM32F103R6 microcontroller 6, and the other side is grounded; one side of capacitor C2 (C211) is connected to the OSCOUT_PD1 pin of STM32F103R6 microcontroller 6, and the other side is grounded; one side of crystal oscillator 12 is connected between capacitor C1 (C113) and the OSCIN_PD0 pin of STM32F103R6 microcontroller 6, and the other side is connected between capacitor C2 (C21) and the OSCOUT_PD1 pin of STM32F103R6 microcontroller 6; one side of capacitor C3 (C3103R6) is connected to the VBAT pin of STM32F103R6 microcontroller 6, and the other side is grounded; a 5V power supply is connected between capacitor C3 (C310) and the VBAT pin of STM32F103R6 microcontroller 6, and the BOOT0 pin of STM32F103R6 microcontroller 6 is grounded.

[0014] The main controller is a 64-pin STM32F103R6 microcontroller.

[0015] The vision module is an integrated OPENMV module 9 with an STM32F427 CPU as its core and an integrated OV7725 camera chip.

[0016] GPS module 5 is an integrated module that uses the MT3318 chip for positioning;

[0017] The communication module is the ESP8266 module 3, which integrates an MCU to enable serial communication between microcontrollers via a WIFI serial port.

[0018] The buzzer is the FMQ-A1 buzzer, which operates at a voltage of 3.3V.

[0019] The crystal oscillator is 8MHz.

[0020] R1 resistor 26 is 10KΩ, R2 resistor 4 is 1KΩ, R3 resistor 1 is 10KΩ, R4 resistor 23 is 10KΩ, R5 resistor 22 is 0.05Ω, R6 resistor 20 is 1KΩ, R7 resistor 19 is 1KΩ, R8 resistor 21 is 100Ω, R9 resistor 18 is 100Ω, R10 resistor 16 is 51KΩ, and R11 resistor 15 is 1KΩ.

[0021] C1 capacitor 13 is 0.1uF, C2 capacitor 11 is 22pF, C3 capacitor 10 is 22pF, C4 capacitor 27 is 100nF, C5 capacitor 14 is 15pF, and C6 capacitor 2 is 0.1uF.

[0022] The electric vehicle charging station parking space warning system based on the STM32 chip includes license plate recognition and charging detection functions.

[0023] The system is installed on a charging station and uses the rectangular contour detection in the OPENMV module 9 to find license plates. It can be set according to the exact size and approximate position of the license plate to further improve accuracy. After locking the area, the color recognition program built into the OPENMV module 9 determines whether the license plate is green, and then transmits data through the IO port and the STM32F103R6 microcontroller.

[0024] C5 capacitor 14, R11 resistor 15, R10 resistor 16, amplifier 17, R9 resistor 18, R7 resistor 19, R6 resistor 20, R8 resistor 21, and R5 resistor 22 together form a current detection circuit.

[0025] In this circuit, resistor R5 (22A) is the sampling resistor, and resistor R9 (18A) represents the load resistor. The load resistor represents the charging pile circuit. When the two ends of the load resistor in this circuit are connected to the charging pile circuit, the current flowing through the charging pile will flow through the sampling resistor. The current flowing through the sampling resistor is then converted into voltage, amplified by amplifier 17, and the voltage value is measured to determine the current magnitude. When the charging pile is not working, the current in the charging pile circuit is 0A. Therefore, the current value flowing through the charging pile when it is working is different from that when it is not working, and the voltage value output to the STM32F103R6 microcontroller is also different, thus determining whether the charging pile is working.

[0026] Resistor R4, PNP transistor 24, and buzzer 25 form a buzzer module. When a license plate is not green or the charging station is not working, the STM32F103R6 microcontroller sets the PC0 port high to make the buzzer work.

[0027] The electric vehicle charging pile parking space warning system based on the STM32 chip has the function of helping vehicles with license plates that are not green or do not need charging to find parking spaces. The program library of parking lot locations in the traffic management system is imported into the STM32F103R6 microcontroller 6. It can obtain its own location data through the GPS module 5. The STM32F103R6 microcontroller 6 sends AT commands to the ESP8266 module 3 through the serial port to control the working mode and data transmission and reception of the ESP8266 module 3, thereby realizing the networking function of the system.

[0028] When the STM32F103R6 microcontroller program determines that the vehicle's license plate is not green or the charging station is not working, the STM32F103R6 microcontroller calls this module. In a WiFi environment, the STM32F103R6 microcontroller calls the parking lot location library in the traffic management system. The GPS module 5 obtains its own location data, and then transmits the location data to the STM32F103R6 microcontroller via the ESP8266 module 3. The STM32F103R6 microcontroller program algorithm is designed to compare the location of the GPS module 5 with the parking lot locations in the traffic management library to find the nearest parking lot. The STM32F103R6 microcontroller outputs the parking lot location information from the PB serial port to the LCD1602 LCD screen 8 serial port to display Chinese characters, thereby reminding car owners who do not need to use the charging station to go to a place where they can park.

[0029] Resistor R1, capacitor C4, and button 28 form a reset module. When the system output is incorrect, button 28 can be pressed. When the button is pressed, the NRST pin goes high, and the system is reset. When the button is released, the NRST pin goes low, and the system runs normally. Attached Figure Description

[0030] Figure 1 This is the circuit schematic diagram of the present invention.

[0031] Figure 1The following are the label names: 1. Resistor R3, 2. Capacitor C6, 3. ESP8266 module, 4. Resistor R2, 5. GPS module, 6. STM32F103R6 microcontroller, 7. Sliding rheostat, 8. LCD1602 liquid crystal display, 9. OPENMV module, 10. Capacitor C3, 11. Capacitor C2, 12. Crystal oscillator, 13. Capacitor C1, 14. Capacitor C5, 15. Resistor R11, 16. Resistor R10, 17. Amplifier, 18. Resistor R9, 19. Resistor R7, 20. Resistor R6, 21. Resistor R8, 22. Resistor R5, 23. Resistor R4, 24. PNP transistor, 25. Buzzer, 26. Resistor R1, 27. Capacitor C4, 28. Button.

[0032] Figure 2 This is a flowchart illustrating the operation of the present invention. Detailed Implementation

[0033] This invention comprises a resistor R3 (1), a capacitor C6 (2), an ESP8266 module (3), a resistor R2 (4), a GPS module (5), an STM32F103R6, a microcontroller (6), a sliding rheostat (7), an LCD1602 liquid crystal display (8), an OPENMV module (9), a capacitor C3 (10), a capacitor C2 (11), a crystal oscillator (12), a capacitor C1 (13), a capacitor C5 (14), a resistor R11 (15), a resistor R10 (16), an amplifier (17), a resistor R9 (18), a resistor R7 (19), a resistor R6 (20), a resistor R8 (21), a resistor R5 (22), a resistor R4 (23), a PNP transistor (24), a buzzer (25), a resistor R1 (26), a capacitor C4 (27), and a button (28). Figure 1 As shown. The flowchart of the operation of this invention is as follows. Figure 2 As shown.

[0034] This invention has three implementation methods based on whether the license plate is green and whether the vehicle is charging. Implementation method one is as follows:

[0035] When a vehicle enters the parking space, the OPENMV module 9 first locates the license plate position. Through the built-in color recognition program, it determines whether the license plate is green. At the same time, the data is transmitted through the IO port to the STM32F103R6 microcontroller 6. If the license plate is not green, the STM32F103R6 microcontroller 6 sets the PC0 port high according to the program, so that the buzzer works and the alarm sounds. At the same time, the D0 to D7 ports of the LCD1602 display receive the result signal of the STM32 display program execution and display the words "Non-electric vehicles please do not park".

[0036] The system's networking function is implemented through ESP8266 module 3. In Wi-Fi mode, STM32F103R6 microcontroller 6 calls the parking lot location program library in the traffic management system. Through ESP8266 module 3, the system transmits its own location data obtained by GPS module 5 to STM32F103R6 microcontroller 6. The program algorithm in STM32F103R6 microcontroller 6 is designed to compare the location of GPS module 5 with the parking lot locations in the traffic management program library to find the nearest parking lot. STM32F103R6 microcontroller 6 outputs the parking lot location information from PB serial port to LCD1602 LCD screen 8 serial port to realize Chinese character display. The parking lot related information is displayed on the screen, which can remind car owners who do not need to use charging piles to go to a place where they can park.

[0037] Implementation method two is as follows:

[0038] If the license plate detection is green, the current sampling circuit starts after a two-minute wait. R5 (22µA) is the sampling resistor, and R9 (18µA) represents the load resistor, which is the charging pile circuit. Connecting the load resistor to the charging pile circuit causes the current flowing through the charging pile to pass through the sampling resistor. This current is then converted into voltage, amplified by amplifier 17, and the voltage value is measured to determine the current magnitude. When the charging pile is not working, the current flow in the charging pile circuit is 0A. The analog voltage is then converted to digital voltage by the AD converter. Since the charging pile is not working, the output level is low. The STM32F103R6 microcontroller, based on the program's judgment, sets port PC0 high, activating the buzzer and sounding an alarm. Simultaneously, ports D0 to D7 of the LCD1602 display receive the result signal from the STM32's display program, displaying the message "Do not stop without charging."

[0039] The system's networking function is implemented through ESP8266 module 3. In Wi-Fi mode, STM32F103R6 microcontroller 6 calls the parking lot location program library in the traffic management system. Through ESP8266 module 3, the system transmits its own location data obtained by GPS module 5 to STM32F103R6 microcontroller 6. The program algorithm in STM32F103R6 microcontroller 6 is designed to compare the location of GPS module 5 with the parking lot locations in the traffic management program library to find the nearest parking lot. STM32F103R6 microcontroller 6 outputs the parking lot location information from PB serial port to LCD1602 LCD screen 8 serial port to realize Chinese character display. The parking lot related information is displayed on the screen, which can remind car owners who do not need to use charging piles to go to a place where they can park.

[0040] Implementation method three is as follows:

[0041] If the license plate detection is green, wait two minutes. If the current sampling circuit detects the current flowing in the charging pile, that is, if the charging pile is working, the output level will be high, allowing the vehicle to stop normally. Every 10 minutes, the charging pile will be checked again to see if it is working. If the charging pile is not working after it is fully charged, the STM32F103R6 microcontroller will set the PC0 port high through the program to make the buzzer work and the alarm sound. At the same time, the D0 to D7 ports of the LCD1602 display receive the result signal of the STM32 display program execution and display the words "Do not stop if not charging".

[0042] The system's networking function is implemented through ESP8266 module 3. In Wi-Fi mode, STM32F103R6 microcontroller 6 calls the parking lot location program library in the traffic management system. Through ESP8266 module 3, the system transmits its own location data obtained by GPS module 5 to STM32F103R6 microcontroller 6. The program algorithm in STM32F103R6 microcontroller 6 is designed to compare the location of GPS module 5 with the parking lot locations in the traffic management program library to find the nearest parking lot. STM32F103R6 microcontroller 6 outputs the parking lot location information from PB serial port to LCD1602 LCD screen 8 serial port to realize Chinese character display. The parking lot related information is displayed on the screen, which can remind car owners who do not need to use charging piles to go to a place where they can park.

Claims

1. A parking space warning system for electric vehicle charging stations based on an STM32 chip, characterized in that: The entire circuit system is based on the STM32F103R6 microcontroller (6), which connects multiple modules; The PA2 and PA3 pins of the STM32F103R6 microcontroller (6) are connected to the TXD and RXD pins of the GPS module (5) respectively. The DV5V pin of the GPS module (5) is connected to the 5V power supply, and the GND pin of the GPS module (5) is grounded. The TXD and RXD pins of the ESP8266 module (3) are also connected to the PA2 and PA3 pins of the STM32F103R6 microcontroller (6) respectively. The GPIO2 pin of the ESP8266 module (3) is connected to the R2 resistor (4). The other end of the R2 resistor (4) is connected to the 5V power supply. The GND pin of the ESP8266 module (3) is grounded. The VCC pin and CH-PD pin of the ESP8266 module (3) are both connected to the 5V power supply. One end of the R3 resistor (1) is connected to the RST pin of the ESP8266 module (3). The other end of the R3 resistor (1) is connected to the 5V power supply. One end of the C6 capacitor (2) is connected to the RST pin of the ESP8266 module (3). The other end of the C6 capacitor (2) is grounded. The RS, RW, EN, D0, D1, D2, D3, D4, D5, D6, and D7 pins of the LCD1602 liquid crystal display (8) are connected to the PA8, PA9, PA10, PB0, PB1, PB2, PB3, PB4, PB5, PB6, and PB7 pins of the STM32F103R6 microcontroller (6), respectively. The GND pin of the LCD1602 liquid crystal display (8) is directly grounded. The VCC pin of the LCD1602 liquid crystal display (8) is connected to a 5V power supply. The VL pin of the LCD1602 liquid crystal display (8) is connected to the upper sliding arm of the sliding rheostat (7). One end of the sliding rheostat (7) is connected to a 5V power supply, and the other end is grounded. The P4 and P5 pins of the OPENMV module (9) are also connected to the PA10 and PA9 pins of the STM32F103R6 microcontroller (6) respectively. The 3.3V pin of the OPENMV module (9) is connected to the 5V power supply. The RST, BOOT and GND pins of the OPENMV module (9) are grounded. The VIN pin of the OPENMV module (9) is connected to the 5V power supply. One end of resistor R1 (26) is connected to the NRST pin of the STM32F103R6 microcontroller (6), and the other end of resistor R1 (26) is connected to the 5V power supply; one end of capacitor C4 (27) and button (28) are both connected to the NRST pin of the STM32F103R6 microcontroller (6), and the other end is grounded. One end of resistor R4 (23) is connected to the PC0 pin of the STM32F103R6 microcontroller (6), the other end of resistor R4 (23) is connected to the base of PNP transistor (24), the collector of PNP transistor (24) is grounded, the emitter of PNP transistor (24) is connected to buzzer (25), and the other end of buzzer (25) is connected to 5V power supply. One end of capacitor C5 (14) is connected to pin PC11 of the STM32F103R6 microcontroller (6), and the other end is grounded; one end of resistor R11 (15) is connected to pin PC11 of the STM32F103R6 microcontroller (6), and the other end is connected to the output of amplifier (17). Resistor R10 (16) is connected between the output of amplifier (17) and the inverting input. The negative power supply side of amplifier (17) is grounded, and the positive power supply side is connected to a 5V power supply; one side of resistor R7 (19) is connected to the output of amplifier (17). The inverting input terminal is connected to the other end of a 4.5V power supply; one side of resistor R8 (21) is connected between resistor R7 (19) and the 4.5V power supply, and the other side is grounded; one side of resistor R6 (20) is connected to the non-inverting input terminal of amplifier (17), and the other end is connected to a 4.5V power supply; one side of resistor R5 (22) is connected between resistor R7 (19) and the 4.5V power supply, and the other side is connected between resistor R6 (20) and the 4.5V power supply; one side of resistor R9 (18) is connected to the non-inverting input terminal of amplifier (17), and the other end is grounded; One side of capacitor C1 (13) is connected to the OSCIN_PD0 pin of the STM32F103R6 microcontroller (6), and the other side is grounded; one side of capacitor C2 (11) is connected to the OSCOUT_PD1 pin of the STM32F103R6 microcontroller (6), and the other side is grounded; one side of crystal oscillator (12) is connected between capacitor C1 (13) and the OSCIN_PD0 pin of the STM32F103R6 microcontroller (6), and the other side is grounded. Connect capacitor C2 (11) between the STM32F103R6 microcontroller (6) and the OSCOUT_PD1 pin; connect one side of capacitor C3 (10) to the VBAT pin of the STM32F103R6 microcontroller (6) and the other side to ground; connect the 5V power supply between capacitor C3 (10) and the VBAT pin of the STM32F103R6 microcontroller (6), and ground the BOOT0 pin of the STM32F103R6 microcontroller (6).

2. The electric vehicle charging station parking space warning system based on STM32 chip according to claim 1, characterized in that: The main controller is an STM32F103R6 microcontroller with 64 pins (6); The vision module is an integrated OPENMV module (9) with an STM32F427 CPU as its core and an integrated OV7725 camera chip. The GPS module (5) is an integrated module that uses the MT3318 chip for positioning; The communication module is the ESP8266 module (3), which integrates an MCU to realize serial communication between microcontrollers via a WIFI serial port.

3. The electric vehicle charging station parking space warning system based on STM32 chip according to claim 1, characterized in that: The buzzer is the FMQ-A1 buzzer, which operates at a voltage of 3.3V.

4. The electric vehicle charging station parking space warning system based on STM32 chip according to claim 1, characterized in that: The crystal oscillator (12) is 8MHz.

5. The electric vehicle charging station parking space warning system based on STM32 chip according to claim 1, characterized in that: R1 resistor (26) is 10KΩ, R2 resistor (4) is 1KΩ, R3 resistor (1) is 10KΩ, R4 resistor (23) is 10KΩ, R5 resistor (22) is 0.05Ω, R6 resistor (20) is 1KΩ, R7 resistor (19) is 1KΩ, R8 resistor (21) is 100Ω, R9 resistor (18) is 100Ω, R10 resistor (16) is 51KΩ, and R11 resistor (15) is 1KΩ. C1 capacitor (13) is 0.1uF, C2 capacitor (11) is 22pF, C3 capacitor (10) is 22pF, C4 capacitor (27) is 100nF, C5 capacitor (14) is 15pF, and C6 capacitor (2) is 0.1uF.

6. The method for a parking space warning system for electric vehicle charging piles based on an STM32 chip according to claim 1, characterized in that: The electric vehicle charging station parking space warning system based on the STM32 chip includes license plate recognition and charging detection functions. The system is installed on the charging pile and uses the outline detection of the rectangle in the OPENMV module (9) to find the license plate; and can be set according to the exact size and approximate position of the license plate to further improve accuracy; after locking the area, the color recognition program built into the OPENMV module (9) is used to determine whether the license plate is green, and then data is transmitted through the IO port and the STM32F103R6 microcontroller (6); The current detection circuit is composed of capacitor C5 (14), resistor R11 (15), resistor R10 (16), amplifier (17), resistor R9 (18), resistor R7 (19), resistor R6 (20), resistor R8 (21), and resistor R5 (22). Among them, resistor R5 (22) is the sampling resistor, resistor R9 (18) represents the load resistor, and the load resistor represents the charging pile circuit. When the two ends of the load resistor in this circuit are connected to the circuit of the charging pile, the current flowing through the charging pile will flow through the sampling resistor. The current flowing through the sampling resistor is then converted into voltage, amplified by amplifier (17), and the voltage value is measured to determine the current magnitude. When the charging pile is not working, the current flow in the circuit of the charging pile is 0A. Therefore, the current value flowing through the charging pile when it is working is different from that of the charging pile when it is not working, and the voltage value output to the STM32F103R6 microcontroller (6) is also different, so as to determine whether the charging pile is working. The R4 resistor (23), PNP transistor (24), and buzzer (25) form a buzzer module. When the license plate is not green or the charging pile is not working, the STM32F103R6 microcontroller (6) sets the PC0 port high through the program to make the buzzer work.

7. The method according to claim 6, characterized in that: The electric vehicle charging pile parking space warning system based on STM32 chip has the function of helping vehicles with license plates that are not green or do not need charging to find parking spaces. The program library of parking lot locations in the traffic management system is imported into the STM32F103R6 microcontroller (6). It can obtain its own location data through the GPS module (5). The STM32F103R6 microcontroller (6) sends AT commands to the ESP8266 module (3) through the serial port to control the working mode and data transmission and reception of the ESP8266 module (3), thereby realizing the network function of the system. When the STM32F103R6 microcontroller (6) program determines that the vehicle license plate is not green or the charging pile is not working, the STM32F103R6 microcontroller (6) calls this module; in the WiFi environment, the STM32F103R6 microcontroller (6) calls the parking lot location program library in the traffic management system, the GPS module (5) obtains its own location data, and then transmits the location data to the STM32F103R6 microcontroller (6) through the ESP8266 module (3); the STM32F103R6 microcontroller (6) program algorithm is designed to compare the location of the GPS module (5) with the parking lot location in the traffic management program library to find the nearest parking lot location. The STM32F103R6 microcontroller (6) outputs the parking lot location information from the PB serial port to the LCD1602 liquid crystal display screen (8) serial port to realize Chinese character display, so as to remind car owners who do not need to use the charging pile to go to a place where they can park.

8. The method according to claim 6, characterized in that: The R1 resistor (26), C4 capacitor (27), and button (28) form a reset module. When the system output is incorrect, the button (28) can be pressed. When the button is pressed, the NRST pin is set high, and the system is reset. When the button is released, the NRST pin is at a low level, and the system runs normally.

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