Building block type development board based on ARM platform

Abstract

The utility model discloses a building block type development board based on an ARM (Advanced RISC Machines) platform, which is characterized by comprising a core board and an expansion board electrically connected with the core board, and the core board is provided with a minimum system circuit, a USB (Universal Serial Bus) to serial port circuit, a USB functional port circuit and a serial port one-key downloading circuit, the minimum system circuit is respectively and electrically connected with the USB function port circuit and the serial port one-key downloading circuit, the serial port one-key downloading circuit is electrically connected with the USB to serial port circuit, the expansion board is provided with a power supply switching circuit, a voltage conversion circuit and an expansion circuit, the power supply switching circuit is electrically connected with the voltage conversion circuit, and the voltage conversion circuit is electrically connected with the expansion circuit. The size of the development board is reduced, the customization convenience is improved, the expansibility is enhanced, the cost is reduced, an external USB to serial port line and a downloader downloading program are not needed, and the convenience is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of development boards, in particular to a building block type development board based on an ARM platform. Background Art

[0002] Traditional development boards use single-chip microcomputers. Due to their low configuration and poor functionality, it is difficult to find what you need from the complex and scattered modules when doing design experiments. Another type integrates multiple interfaces and module chips on the development board, resulting in large development boards and high prices. In addition, users in different fields have different requirements for integrated modules. Too many integrated modules and interfaces will not only increase the size of the development board, but also cause some integrated modules to be wasted and the module utilization rate to be low. Customizing interfaces and module chips for users in different fields will lead to low production efficiency and high costs.

[0003] On the other hand, the traditional development board only has one USB function interface, so printing debugging and downloading programs require an external USB to serial port cable and downloader, which is inconvenient to use, so it is necessary to improve it. Utility Model Content

[0004] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a building block development board based on the ARM platform, which reduces the size of the development board, improves the convenience of customization, enhances scalability, reduces costs, and does not require an external USB to serial port cable and downloader to download programs, thereby improving convenience.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a building block development board based on the ARM platform, including a core board and an expansion board electrically connected to the core board, the core board is provided with a minimum system circuit, a USB to serial port circuit, a USB function port circuit and a serial port one-key download circuit, the minimum system circuit is electrically connected to the USB function port circuit and the serial port one-key download circuit respectively, and the serial port one-key download circuit is electrically connected to the USB to serial port circuit,

[0006] The expansion board is provided with a power switching circuit, a voltage conversion circuit and an expansion circuit, the power switching circuit is electrically connected to the voltage conversion circuit, and the voltage conversion circuit is electrically connected to the expansion circuit;

[0007] The minimum system circuit includes the control chip U2, capacitor C5, capacitor C6, capacitor C7, capacitor C8, capacitor C9, capacitor C10, capacitor C11, capacitor C12, capacitor C13, resistor R6, resistor R7, crystal oscillator Y1 and crystal oscillator Y2,

[0008] The third pin of the control chip U2 is connected to the first end of the capacitor C7 and the first end of the crystal oscillator Y2, the fourth pin of the control chip U2 is connected to the first end of the capacitor C8 and the second end of the crystal oscillator Y2, the second ends of the capacitor C7 and the capacitor C8 are respectively connected to the ground end, the fifth pin of the control chip U2 is connected to the first end of the crystal oscillator Y1 and the first end of the capacitor C6, the sixth pin of the control chip U2 is connected to the third end of the crystal oscillator Y1 and the first end of the capacitor C5, the fourth end of the crystal oscillator Y1 is connected to the second end of the capacitor C6 and the ground end, the second end of the crystal oscillator Y1 is connected to the second end of the capacitor C5 and the ground end, the ninth pin of the control chip U2 is connected to the twenty-fourth pin, the thirty-sixth pin, the forty-eighth pin and the 3V3 power supply end, the first pin of the control chip U2 is connected to the VBAT end, and the seventh pin and the forty-fourth pin of the control chip U2 are respectively connected to the serial port one-key download circuit.

[0009] In a further technical solution, the USB to serial port circuit includes a USB interface J6, a chip U3, a resistor R16, a resistor R17, a resistor R19, a capacitor C19, a capacitor C20 and an inductor L3.

[0010] Pin A1 of USB interface J6 is connected to pin A12, pin B12, pin B1 and ground.

[0011] Pin A1 of the USB interface J6 is connected to pin A12, pin B12, pin B1 and the ground terminal, pin A4 of the USB interface J1 is connected to pin A9, pin B9, pin B4, the first end of capacitor C19, the first end of capacitor C20 and the 5V power supply terminal, pin A5 of the USB interface J6 is connected to the first end of resistor R16, pin A6 of the USB interface J6 is connected to pin B6 and the first pin of chip U3, pin A7 of the USB interface J6 is connected to pin B7 and the second pin of chip U3, pin B5 of the USB interface J6 is connected to the first end of resistor R17, pin C4 of the USB interface J6 is connected to pin C3, pin C2, pin C1 and the first end of inductor L3, and the second ends of capacitor C19, capacitor C20, resistor R16, resistor R17 and inductor L3 are respectively connected to the ground terminal.

[0012] The third pin of chip U3 is connected to the ground terminal, the fourth pin of chip U3 is connected to the serial port one-key download circuit, the fifth pin of chip U3 is connected to the first end of resistor 19, the sixth pin of chip U3 is connected to the second end of resistor 19 and the serial port one-key download circuit, the seventh pin of chip U3 is connected to the eighth pin and the 3V3 power supply terminal, the eighth pin of chip U3 is the data sending pin, and the ninth pin of chip U3 is the data receiving pin.

[0013] In a further technical solution, the serial port one-key download circuit includes a chip U5, a resistor R20, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a resistor R25, a resistor R26, a capacitor C25, a diode D1, a diode D2, a transistor Q1 and a transistor Q2.

[0014] The first pin of chip U5 is connected to the first end of resistor R20, the second end of resistor R20 is connected to the seventh pin of control chip U2, the second pin of chip U5 is connected to the anode of diode D1, the cathode of diode D1 is connected to the second end of resistor R21 and the collector of transistor Q1, the first end of resistor R21 is connected to the 3V3 power supply terminal, the collector of transistor Q1 is connected to the second end of resistor R23, the first end of resistor R23 is connected to the sixth pin of chip U3, the emitter of transistor Q1 is connected to the first end of resistor R25 and the fourth pin of chip U3, the second end of resistor R25 is connected to the collector of transistor Q1, and the first end of resistor R23 is connected to the sixth pin of chip U3. The first end of resistor R24 ​​is connected to the collector of transistor Q2, the second end of resistor R24 ​​is connected to the emitter of transistor Q2 and the 3V3 power supply terminal, the collector of transistor Q2 is connected to the first end of resistor R26, the second end of resistor R26 is connected to the forty-fourth pin of control chip U2, the third pin of chip U5 is connected to the ground terminal, the fourth pin of chip U5 is connected to the positive electrode of diode D2, the second end of resistor R22 and the first end of capacitor C25, the second end of capacitor C25 is connected to the ground terminal, and the fifth pin of chip U5 is connected to the 3V3 power supply terminal, the negative electrode of diode D2 and the first end of resistor R22.

[0015] In a further technical solution, the USB function port circuit includes a USB interface J1, a resistor R1, a resistor R15, a resistor R18, a capacitor C17, a capacitor C18 and an inductor L2.

[0016] Pin A1 of the USB interface J1 is connected to pin A12, pin B12, pin B1 and the ground terminal, pin A4 of the USB interface J1 is connected to pin A9, pin B9, pin B4, the first end of capacitor C17, the first end of capacitor C18 and the 5V power supply terminal, pin A5 of the USB interface J1 is connected to the first end of resistor R1, pin A6 of the USB interface J1 is connected to pin B6, the second end of resistor R18 and the thirty-third pin of the control chip U2, pin A7 of the USB interface J1 is connected to pin B7 and the thirty-second pin of the control chip U2, pin B5 of the USB interface J1 is connected to the first end of resistor R15, pin C4 of the USB interface J1 is connected to pin C3, pin C2, pin C1 and the first end of inductor L2, the second ends of capacitor C17, capacitor C18, resistor R1, resistor R15 and inductor L2 are respectively connected to the ground terminal, and the first end of resistor R18 is connected to the 3V3 power supply terminal.

[0017] In a further technical solution, the power switching circuit includes an automatic switching circuit and a manual switching circuit.

[0018] The automatic switching circuit includes MOS tube Q91, resistor R92, resistor R93 and voltage regulator diode D94.

[0019] The source of the MOS transistor Q91 is connected to the 5V input terminal, the drain of the MOS transistor Q91 is connected to the 5V output terminal, the gate of the MOS transistor Q91 is connected to the first end of the resistor R93, the second end of the resistor R92, and the cathode of the Zener diode D94, the first end of the resistor R92 is connected to the 12V power supply terminal, and the anode of the Zener diode D94 and the second end of the resistor R93 are respectively connected to the ground terminal;

[0020] The manual switching circuit includes a switch SW92 and a capacitor C923.

[0021] The sixth pin of the switch SW92 is connected to the third pin, the 5V power supply terminal and the first terminal of the capacitor C923. The second terminal of the capacitor C923 is connected to the ground terminal. The fifth pin of the switch SW92 is connected to the second pin and the 5V output terminal.

[0022] In a further technical solution, the voltage conversion circuit includes a 5V conversion circuit and a 3V3 conversion circuit.

[0023] The 5V conversion circuit includes chip U91, inductor L91, diode D91, diode D92, diode D93, resistor R911, resistor R913, capacitor C912, capacitor C917, capacitor C918, capacitor C926, capacitor C924, capacitor C925,

[0024] The seventh pin of chip U1 is connected to the first end of capacitor C924, the first end of capacitor C925, the cathode of diode D93, and the cathode of diode D91. The anode of diode D91 is connected to the 12V input terminal. The second end of capacitor C924, the second end of capacitor C925, and the anode of diode D93 are connected to each other and to the ground terminal. The eighth pin of chip U91 is connected to the second end of capacitor C917, the cathode of diode D92, and the first end of inductor L91. The first pin of chip U91 is connected to the cathode of capacitor C917. The first end, the positive electrode of the diode D92, is connected to the ground terminal. The second end of the inductor L91 is connected to the first end of the capacitor C926, the first end of the capacitor C912, the first end of the capacitor C918, the first end of the resistor R911, and the 5V output terminal. The fourth pin of the chip U91 is connected to the second end of the resistor R911 and the first end of the resistor R913. The sixth pin and the ninth pin of the chip U91 are respectively connected to the ground terminal. The second ends of the capacitors C926, C912, C918, and R913 are respectively connected to the ground terminal.

[0025] The 3V3 conversion circuit includes chip U93, inductor L93, resistor R926, resistor R927, resistor R929, capacitor C919, capacitor C920, capacitor C921, capacitor C922, capacitor C927 and capacitor C930.

[0026] The fourth pin of chip U93 is connected to the first end of resistor R929, the first end of capacitor C922, the first end of capacitor C930 and the 5V input end, the first pin of chip U93 is connected to the second end of resistor R929 and the first end of capacitor C927, the third pin of chip U93 is connected to the first end of inductor L93, the fifth pin of chip U93 is connected to the second end of resistor R926 and the first end of resistor R927, the second end of inductor L93 is connected to the first end of capacitor C919, the first end of capacitor C920, the first end of capacitor C921, the first end of resistor R926 and the 3V3 output end, the second end of capacitor C930, the second end of capacitor C922, the second pin of chip U93, the second end of capacitor C927, the second end of capacitor C919, the second end of capacitor C920, the second end of capacitor C921 and the second end of resistor R927 are respectively connected to the ground end.

[0027] In a further technical solution, the minimum system circuit is further provided with an indicator light circuit and a key circuit, which are respectively connected to the control chip U2.

[0028] The indicator light circuit includes a red light LED1, a green light LED2, a blue light LED3, resistors R2, R3, and R4. The first ends of the red light LED1, green light LED2, and blue light LED3 are connected to each other and to the 3V3 power supply terminal. Resistor R2 is connected in series between the second end of the red light LED1 and the eleventh pin of the control chip U2. Resistor R3 is connected in series between the second end of the green light LED2 and the twelfth pin of the control chip U2. Resistor R4 is connected in series between the second end of the blue light LED3 and the thirteenth pin of the control chip U2.

[0029] The key circuit includes a first key sub-circuit, a second key sub-circuit and a third key sub-circuit.

[0030] The first key sub-circuit includes a key SW1, a resistor R8, a resistor R9 and a capacitor C14.

[0031] The first pin of the button SW1 is connected to the second pin, the second end of the resistor R8, the second end of the resistor R9, and the first end of the capacitor C14. The third pin of the button SW1 is connected to the fourth pin, the 3V3 power supply terminal, and the second end of the capacitor C14. The first end of the resistor R8 is connected to the tenth pin of the control chip U2. The first end of the resistor R9 is connected to the ground terminal.

[0032] The second key sub-circuit includes a key SW2, a resistor R10, a resistor R11 and a capacitor C15.

[0033] The first pin of the button SW2 is connected to the second pin, the second end of the resistor R10, the second end of the resistor R11, and the first end of the capacitor C15. The third pin of the button SW2 is connected to the fourth pin, the 3V3 power supply terminal, and the second end of the capacitor C15. The first end of the resistor R10 is connected to the second pin of the control chip U2. The first end of the resistor R11 is connected to the ground terminal.

[0034] The third key sub-circuit includes a key SW3, a resistor R12 and a capacitor C16.

[0035] The first pin of the button SW3 is connected to the second pin, the first end of the capacitor C16, the second end of the resistor R12 and the seventh pin of the control chip U2. The third pin of the button SW3 is connected to the fourth pin and the ground end. The first end of the resistor R12 is connected to the 3V3 power supply end, and the second end of the capacitor C16 is connected to the ground end.

[0036] In a further technical solution, the expansion circuit includes a communication interface circuit, a general input and output circuit, a digital analog general interface circuit, an OLED screen interface circuit, an ultrasonic interface circuit, an encoder interface circuit, a servo interface circuit and a motor drive circuit, which are respectively electrically connected to the minimum system circuit.

[0037] In a further technical solution, the model of the control chip U2 is STM32F103C8T6.

[0038] After adopting the above structure, the advantages of the present invention compared with the prior art are: the core board is connected to various module modules through the expansion board, thereby reducing the size of the core board, facilitating customization according to usage requirements, improving customization convenience, and reducing costs; the core board integrates two USB ports, one USB port is directly connected to the control chip U2 through the USB function port circuit, and the other USB port integrates a USB to serial port circuit and a serial port one-key download circuit to realize a one-key download function, which is convenient for users to use quickly without external tools; various modules are classified according to interface type through the expansion board, and the module pins of the same type of signal are designed to be compatible. The core board selects a group of signals to switch and connect different modules, and the combination is more flexible; the expansion board includes an interface compatible with modules of the same signal and an interface for connecting fixed modules. It has a building block design and can freely plug in and select modules without cumbersome wiring; the expansion board switches the 12V DC power supply and the core board 5V power supply through the power switching circuit, so that the expansion board can be independently powered. When connecting modules such as 12V motors, there is no need to independently power the motor, which is more convenient to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0040] Figure 1 This is a circuit block diagram of the core board of the utility model;

[0041] Figure 2 It is a combined block diagram of the core board and expansion board of the utility model;

[0042] Figure 3 It is a circuit diagram of the minimum system circuit of the utility model;

[0043] Figure 4 This is a circuit diagram of the USB to serial port circuit of the utility model;

[0044] Figure 5 It is a circuit diagram of the serial port one-key download circuit of the utility model;

[0045] Figure 6 This is a circuit diagram of the USB function port circuit of the utility model;

[0046] Figure 7 It is a circuit diagram of the power switching circuit of the utility model;

[0047] Figure 8 This is a circuit diagram of a 5V conversion circuit of the present utility model;

[0048] Figure 9 It is a circuit diagram of the 3V3 conversion circuit of the utility model;

[0049] Figure 10 It is a circuit diagram of the indicator light circuit of the utility model;

[0050] Figure 11 It is a circuit diagram of the key circuit of the utility model;

[0051] Figure 12 It is a circuit diagram of the communication interface circuit of the utility model;

[0052] Figure 13 It is a circuit diagram of the universal input and output circuit of the utility model;

[0053] Figure 14 This is a digital analog universal interface circuit of the utility model;

[0054] Figure 15 This is the OLED screen interface circuit of the utility model;

[0055] Figure 16 This is the ultrasonic interface circuit of the utility model;

[0056] Figure 17 This is a circuit diagram of the encoder interface circuit of the utility model;

[0057] Figure 18 This is a circuit diagram of the servo interface circuit of the utility model;

[0058] Figure 19 It is a circuit diagram of the motor drive circuit of the utility model. DETAILED DESCRIPTION

[0059] The following are merely preferred embodiments of the present invention and do not limit the scope of protection of the present invention.

[0060] A building block development board based on the ARM platform, such as Figures 1 to 19 As shown, it includes a core board and an expansion board electrically connected to the core board, the core board is provided with a minimum system circuit, a USB to serial port circuit, a USB function port circuit and a serial port one-key download circuit, the minimum system circuit is electrically connected to the USB function port circuit and the serial port one-key download circuit respectively, the serial port one-key download circuit is electrically connected to the USB to serial port circuit, the expansion board is provided with a power switching circuit, a voltage conversion circuit and an expansion circuit, the power switching circuit is electrically connected to the voltage conversion circuit, and the voltage conversion circuit is electrically connected to the expansion circuit. The traditional development board is an integrated structure, and the expansion circuit is integrated on the core board, resulting in a large size of the core board, high customization difficulty, high cost, and only one USB port. When printing, debugging and downloading programs, an external USB to serial port cable and downloader are required, which is inconvenient to use. The core board of the utility model connects various modules through the expansion board, thereby reducing the size of the core board, facilitating customization according to usage requirements, improving customization convenience and reducing costs; the core board integrates two USB ports, one USB is directly connected to the control chip U2 through the USB function port circuit, and the other USB integrates the USB to serial port circuit and the serial port one-key download The circuit realizes the one-key download function, which is convenient for users to use quickly without external tools; the various modules are classified according to the interface type through the expansion board, and the module pins of the same type of signal are designed to be compatible. The core board can switch to connect different modules by selecting a group of signals, and the combination is more flexible; the expansion board contains interfaces compatible with modules of the same signal and interfaces for connecting fixed modules. The building block design allows free plug-in and selection of modules without cumbersome wiring; the expansion board switches the 12V DC power supply and the core board 5V power supply through the power switching circuit, so that the expansion board can be independently powered. When connecting modules such as 12V motors, there is no need to independently power the motor, which is more convenient to use.

[0061] Specifically, if Figure 3As shown, the minimum system circuit includes a control chip U2, a capacitor C5, a capacitor C6, a capacitor C7, a capacitor C8, a capacitor C9, a capacitor C10, a capacitor C11, a capacitor C12, a capacitor C13, a resistor R6, a resistor R7, a crystal oscillator Y1 and a crystal oscillator Y2. The third pin of the control chip U2 is connected to the first end of the capacitor C7 and the first end of the crystal oscillator Y2. The fourth pin of the control chip U2 is connected to the first end of the capacitor C8 and the second end of the crystal oscillator Y2. The second ends of the capacitors C7 and C8 are connected to the ground terminal respectively. The fifth pin of the control chip U2 is connected to the crystal oscillator Y1. The first end of the control chip U2 is connected to the first end of the capacitor C6, the sixth pin of the control chip U2 is connected to the third end of the crystal oscillator Y1 and the first end of the capacitor C5, the fourth end of the crystal oscillator Y1 is connected to the second end of the capacitor C6 and the ground end, the second end of the crystal oscillator Y1 is connected to the second end of the capacitor C5 and the ground end, the ninth pin of the control chip U2 is connected to the twenty-fourth pin, the thirty-sixth pin, the forty-eighth pin and the 3V3 power supply end, the first pin of the control chip U2 is connected to the VBAT end, and the seventh pin and the forty-fourth pin of the control chip U2 are respectively connected to the serial port one-key download circuit.

[0062] Specifically, if Figure 4As shown, the USB-to-serial port circuit includes a USB interface J6, a chip U3, a resistor R16, a resistor R17, a resistor R19, a capacitor C19, a capacitor C20, and an inductor L3. Pin A1 of the USB interface J6 is connected to pin A12, pin B12, pin B1, and the ground terminal. Pin A1 of the USB interface J6 is connected to pin A12, pin B12, pin B1, and the ground terminal. Pin A4 of the USB interface J1 is connected to pin A9, pin B9, pin B4, a first end of capacitor C19, a first end of capacitor C20, and a 5V power supply terminal. Pin A5 of the USB interface J6 is connected to the first end of resistor R16. Pin A6 of the USB interface J6 is connected to pin B6 and the first pin of the chip U3. Pin A7 of the USB interface J6 is connected to pin B7. The second pin of chip U3 and pin B5 of USB interface J6 are connected to the first end of resistor R17. Pin C4 of USB interface J6 is connected to pin C3, pin C2, pin C1, and the first end of inductor L3. Capacitor C19, capacitor C20, resistor R16, resistor R17, and the second end of inductor L3 are respectively connected to the ground terminal. The third pin of chip U3 is connected to the ground terminal. The fourth pin of chip U3 is connected to the serial port one-key download circuit. The fifth pin of chip U3 is connected to the first end of resistor 19. The sixth pin of chip U3 is connected to the second end of resistor 19 and the serial port one-key download circuit. The seventh pin of chip U3 is connected to the eighth pin and the 3V3 power supply terminal. The eighth pin of chip U3 is the data transmission pin, and the ninth pin of chip U3 is the data reception pin. The USB-to-serial port circuit can not only be used for power supply, but also realize the USB-to-serial port function through chip U3. As a COM device on a computer, it can conveniently send and receive communications with a group of serial port pins of control chip U2 through serial port debugging software. The core board is connected through the USB to serial port circuit. The serial port burning software directly sets the request sending interface RTS and the data terminal ready interface DTR, which correspond to the control level interface BOOT0 and reset options. The data terminal ready interface DTR request sending interface RTS sends a signal to the chip U3 and its peripheral circuits. The main system reset port NRST and the level interface BOOT0 signal control the core board to start and reset from ROM. The USB to serial port circuit performs serial port burning on the core board. After the burning is completed, the main system reset port NRST and the level interface BOOT0 signal control the microcontroller to start and reset from the internal FLASH.

[0063] Specifically, if Figure 5As shown, the serial port one-key download circuit includes a chip U5, a resistor R20, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a resistor R25, a resistor R26, a capacitor C25, a diode D1, a diode D2, a transistor Q1 and a transistor Q2. The first pin of the chip U5 is connected to the first end of the resistor R20, the second end of the resistor R20 is connected to the seventh pin of the control chip U2, the second pin of the chip U5 is connected to the anode of the diode D1, the cathode of the diode D1 is connected to the second end of the resistor R21 and the collector of the transistor Q1, the first end of the resistor R21 is connected to the 3V3 power supply terminal, the collector of the transistor Q1 is connected to the second end of the resistor R23, and the first end of the resistor R23 is connected to the sixth pin of the chip U3. The emitter of the transistor Q1 is connected to the first end of the resistor R25 and the fourth pin of the chip U3, the second end of the resistor R25 is connected to the first end of the resistor R24 ​​and the collector of the transistor Q2, the second end of the resistor R24 ​​is connected to the emitter of the transistor Q2 and the 3V3 power supply terminal, the collector of the transistor Q2 is connected to the first end of the resistor R26, the second end of the resistor R26 is connected to the forty-fourth pin of the control chip U2, the third pin of the chip U5 is connected to the ground terminal, the fourth pin of the chip U5 is connected to the anode of the diode D2, the second end of the resistor R22 and the first end of the capacitor C25, the second end of the capacitor C25 is connected to the ground terminal, and the fifth pin of the chip U5 is connected to the 3V3 power supply terminal, the cathode of the diode D2 and the first end of the resistor R22. The computer is connected to the USB interface J6 via USB. The upper computer communication control chip U3 makes RTS output a low level, thereby turning on the transistor Q2, and BOOT0 obtains a high level through the pull-up resistor until the capacitor C25 is charged to 1.8V. The fourth pin of the chip U5 is enabled, the first pin and the second pin are turned on, and the DTR is set to a high level through the upper computer, turning on the transistor Q1, forming a path that brings NRST close to a low level. The chip U5 is reset and enters the download mode from the execution mode; when the program download is completed, the upper computer control chip U3's RTS and DTR restore the level state, turn off the transistor Q2 and the transistor Q1, the BOOT0 state is restored, and the chip U5 resumes the execution mode.

[0064] Specifically, if Figure 6As shown, the USB function port circuit includes a USB interface J1, a resistor R1, a resistor R15, a resistor R18, a capacitor C17, a capacitor C18 and an inductor L2, a pin A1 of the USB interface J1 is connected to a pin A12, a pin B12, a pin B1 and a ground terminal, a pin A4 of the USB interface J1 is connected to a pin A9, a pin B9, a pin B4, a first end of a capacitor C17, a first end of a capacitor C18 and a 5V power terminal, a pin A5 of the USB interface J1 is connected to a first end of the resistor R1, and a pin A6 of the USB interface J1 is connected to Pin B6, the second end of resistor R18, and pin 33 of control chip U2 are connected. Pin A7 of USB interface J1 is connected to pin B7 and pin 32 of control chip U2. Pin B5 of USB interface J1 is connected to the first end of resistor R15. Pin C4 of USB interface J1 is connected to pin C3, pin C2, pin C1, and the first end of inductor L2. The second ends of capacitor C17, capacitor C18, resistor R1, resistor R15, and inductor L2 are each connected to ground. The first end of resistor R18 is connected to the 3V3 power supply. The USB function port circuit is directly connected to control chip U2 to enable richer data exchange, increased transmission speed, and richer functionality.

[0065] Specifically, if Figure 7As shown, the power switching circuit includes an automatic switching circuit and a manual switching circuit. The automatic switching circuit includes a MOS transistor Q91, a resistor R92, a resistor R93, and a Zener diode D94. The source of the MOS transistor Q91 is connected to the 5V input terminal, the drain of the MOS transistor Q91 is connected to the 5V output terminal, the gate of the MOS transistor Q91 is connected to the first end of the resistor R93, the second end of the resistor R92, and the cathode of the Zener diode D94. The first end of the resistor R92 is connected to the 12V power terminal, and the anode of the Zener diode D94 and the second end of the resistor R93 are respectively connected to the ground terminal. The manual switching circuit includes a switch SW92 and a capacitor C923. The sixth pin of the switch SW92 is connected to the third pin, the 5V power terminal, and the first end of the capacitor C923. The second end of the capacitor C923 is connected to the ground terminal. The fifth pin of the switch SW92 is connected to the second pin and the 5V output terminal. When the expansion board is plugged into a DC power supply for 12V power, the voltage regulator diode D94 clamps the voltage at 5.1V, the MOS tube Q91 is turned off, and the core board no longer supplies 5V power to the expansion board. The expansion board switches to the DC power supply for 6-12V power supply, thereby automatically switching the power supply to improve the power supply stability of each module and meet the needs of modules such as motors that require 12V voltage. When the expansion board is unplugged from the DC power supply and stops supplying 6-12V power, the MOS tube Q91 is turned on, and the core board supplies 5V power to the expansion board. The 5V power supply of the expansion board is controlled by manually controlling the switch SW92 to be turned on and off. When the switch SW92 is turned on, the expansion board can output 5V power. When the switch SW92 is turned off, the expansion board does not output 5V power. The switch SW92 is manually controlled to control the expansion board to power each module.

[0066] Specifically, the voltage conversion circuit includes a 5V conversion circuit and a 3V3 conversion circuit, such as Figure 8As shown, the 5V conversion circuit includes a chip U91, an inductor L91, a diode D91, a diode D92, a diode D93, a resistor R911, a resistor R913, a capacitor C912, a capacitor C917, a capacitor C918, a capacitor C926, a capacitor C924, and a capacitor C925. The seventh pin of the chip U1 is connected to the first end of the capacitor C924, the first end of the capacitor C925, the cathode of the diode D93, and the cathode of the diode D91. The anode of the diode D91 is connected to the 12V input terminal. The second end of the capacitor C924, the second end of the capacitor C925, and the anode of the diode D93 are connected to each other and to the ground terminal. The eighth pin of the chip U91 is connected to The second end of capacitor C917, the cathode of diode D92 and the first end of inductor L91, the first pin of chip U91 is connected to the first end of capacitor C917, the anode of diode D92 is connected to the ground end, the second end of inductor L91 is connected to the first end of capacitor C926, the first end of capacitor C912, the first end of capacitor C918, the first end of resistor R911 and the 5V output end, the fourth pin of chip U91 is connected to the second end of resistor R911 and the first end of resistor R913, the sixth pin and the ninth pin of chip U91 are respectively connected to the ground end, and the second ends of capacitor C926, capacitor C912, capacitor C918 and resistor R913 are respectively connected to the ground end; as Figure 9 As shown, the 3V3 conversion circuit includes a chip U93, an inductor L93, a resistor R926, a resistor R927, a resistor R929, a capacitor C919, a capacitor C920, a capacitor C921, a capacitor C922, a capacitor C927 and a capacitor C930. The fourth pin of the chip U93 is connected to the first end of the resistor R929, the first end of the capacitor C922, the first end of the capacitor C930 and the 5V input end. The first pin of the chip U93 is connected to the second end of the resistor R929 and the first end of the capacitor C927. The third pin of the chip U93 is connected to the first end of the inductor L93. The fifth pin of chip U93 is connected to the second end of resistor R926 and the first end of resistor R927. The second end of inductor L93 is connected to the first end of capacitor C919, the first end of capacitor C920, the first end of capacitor C921, the first end of resistor R926 and the 3V3 output end. The second end of capacitor C930, the second end of capacitor C922, the second pin of chip U93, the second end of capacitor C927, the second end of capacitor C919, the second end of capacitor C920, the second end of capacitor C921 and the second end of resistor R927 are respectively connected to the ground end. When the expansion board is connected to a DC power supply for 6-12V power supply, the 6-12V voltage is converted to 5V voltage by chip U91 to realize power supply for 5V powered modules; the 5V voltage output by the 5V conversion circuit is converted to 3.3V voltage by chip U93 to realize power supply for 3.3V powered modules, thereby meeting the power supply requirements of modules with different voltage requirements.

[0067] Specifically, the minimum system circuit is further provided with an indicator light circuit and a key circuit, and the indicator light circuit and the key circuit are respectively connected to the control chip U2. Figure 10 As shown, the indicator light circuit includes a red light LED1, a green light LED2, a blue light LED3, a resistor R2, a resistor R3 and a resistor R4. The first ends of the red light LED1, the green light LED2 and the blue light LED3 are connected to each other and to the 3V3 power supply terminal. The resistor R2 is connected in series between the second end of the red light LED1 and the 11th pin of the control chip U2. The resistor R3 is connected in series between the second end of the green light LED2 and the 12th pin of the control chip U2. The resistor R4 is connected in series between the second end of the blue light LED3 and the 13th pin of the control chip U2. Intuitive status indication and user interaction are provided by the red light LED1, the green light LED2 and the blue light LED3. Indicates the working status, debugging process and error prompts of the core board, allowing users to better understand the operation of the core board and helping developers to debug and interact. When debugging code, LED is used to indicate program status. It has a simple structure and low cost, and can help understand the status of the core board.

[0068] like Figure 11As shown, the key circuit includes a first key sub-circuit, a second key sub-circuit and a third key sub-circuit. The first key sub-circuit includes a key SW1, a resistor R8, a resistor R9 and a capacitor C14. The first pin of the key SW1 is connected to the second pin, the second end of the resistor R8, the second end of the resistor R9, and the first end of the capacitor C14. The third pin of the key SW1 is connected to the fourth pin, the 3V3 power supply end and the second end of the capacitor C14. The first end of the resistor R8 is connected to the tenth pin of the control chip U2, and the first end of the resistor R9 is connected to the ground end; the second key sub-circuit includes a key SW2, a resistor R10, a resistor R11 and a capacitor C15. The first pin of the key SW2 is connected to the second pin, the resistor R11 and the capacitor C15. The second end of R10, the second end of resistor R11, the first end of capacitor C15, the third pin of button SW2 connects the fourth pin, 3V3 power supply terminal and the second end of capacitor C15, the first end of resistor R10 connects the second pin of control chip U2, and the first end of resistor R11 is connected to ground terminal;The third button sub-circuit includes button SW3, resistor R12 and capacitor C16, the first pin of button SW3 connects the second pin, the first end of capacitor C16, the second end of resistor R12 and the seventh pin of control chip U2, the third pin of button SW3 connects the fourth pin and ground terminal, the first end of resistor R12 is connected to 3V3 power supply terminal, and the second end of capacitor C16 is connected to ground terminal.Button SW1 and button SW2 are used for the operation button of human-computer interaction, and button SW3 is used for the reset button that core board is reset, and pressing button SW3 can restart core board and module, solve the situation that core board and module have problems or collapse.Particularly in the process of development and debugging, the behavior of core board and module in reset state can be tested, core board and module security are provided, and for recovering the normal operation of core board and module.

[0069] Specifically, if Figures 12 to 19 As shown, the expansion circuit includes a communication interface circuit, a general input and output circuit, a digital analog general interface circuit, an OLED screen interface circuit, an ultrasonic interface circuit, an encoder interface circuit, a servo interface circuit and a motor drive circuit, which are respectively electrically connected to the minimum system circuit.

[0070] like Figure 12As shown, the communication interface circuit is provided with communication interface 1, communication interface 2, communication interface 3 and communication interface 4. Communication interface 1 is VCC3, GND, B11, B10, B9, B8, and communication interface 2 is VCC4, GND, B11, B10, B8, B9. The only difference between the two is the order of B8 and B9. The line sequence is selected as needed. Since the lead pins are the same, the two cannot be used at the same time, and only one of them can be selected for use; both have straight plug and bent plug, and the module can be placed horizontally or vertically according to actual needs; both have level switching, and can choose to supply 3.3V or 5V to the module, which is determined by the module operating voltage; B10 and B11 pins can be reused as I2C2 or USART3, which is suitable for I2C communication modules and serial communication modules, and can adapt to heart rate and blood oxygen detection modules, BMP280 barometer modules, laser ranging modules, MPU6050 six-axis attitude modules, WIFI_ESP8266-12F modules and Bluetooth modules;

[0071] Communication interface 3 is VCC5, GND, A10, A9, A12, and A11. It has straight and angled plugs, allowing the module to be placed horizontally or vertically as needed. It has a level switch, allowing you to choose whether to supply 3.3V or 5V to the module, depending on the module's operating voltage. The A10 and A9 pins can be reused as USART1 for DEBUG printing of debugging information and serial communication modules, and are compatible with the WIFI_ESP8266-12F module and Bluetooth module.

[0072] Communication interface 4 is VCC6, GND, B7, B6, A7, and A8. It has straight and angled plugs, allowing the module to be placed horizontally or vertically as needed. It has a level switch, and can choose to supply 3.3V or 5V to the module, depending on the module's operating voltage. The B7 and B6 pins can be reused as I2C1, suitable for I2C communication modules, and can adapt to heart rate and blood oxygen detection modules, BMP280 barometer modules, laser ranging modules, and MPU6050 six-axis attitude modules.

[0073] like Figure 13 As shown, the general input and output circuit directly leads to two rows of pins of the control chip U2. When the module has no interface for direct plug-in, the module is directly connected to the required IO port through the DuPont line.

[0074] like Figure 14As shown, the digital analog universal interface circuit is equipped with Universal IO Interface 1, Universal IO Interface 2, Universal IO Interface 3, and Universal IO Interface 4. Universal IO Interface 1 is connected to A5, A12, GND, and VCC0, while Universal IO Interface 2 is connected to VCC1, GND, A11, and A4. Both have level switches, which can select whether to supply 3.3V or 5V to the module, depending on the module's operating voltage. These interfaces can accommodate photoresistor modules, thermistor modules, tracking modules, air detection modules, smoke detection modules, and flame detection modules. Universal IO Interface 3 is connected to 3V3, GND, NC, and B12, while Universal IO Interface 4 is connected to 3V3, GND, NC, and A6. NC is a floating pin, and these interfaces can accommodate active buzzers, potentiometers, and DHT11 temperature and humidity modules. Since the sensors and sliding rheostats on different modules are not fixed in position, they can be connected to expansion boards as needed. When multiple modules need to be connected and the interfaces are insufficient, the modules are connected to the two rows of IO ports on the expansion board via DuPont cables.

[0075] like Figure 15 As shown, the OLED screen interface circuit, the OLED screen interface is 3V3, GND, B6, B7, and can be directly plugged into the IIC_OLED module;

[0076] like Figure 16 As shown, the ultrasonic interface circuit, the ultrasonic interface is GND, B3, A15, 3V3, and can be directly plugged into the ultrasonic ranging module;

[0077] like Figure 17 As shown in the figure, the encoder interface circuit has VCC2, GND, A8, A6, GND, and A7 as the rotary encoder interface, which can be directly plugged into the EC11 encoder module; VCC2, GND, A4, A6, A7, and A5 as the SPI1 interface, of which the A4, A5, A6, and A7 pins can be reused as SPI1, which is suitable for SPI communication modules and can be directly plugged into the W25Q64 memory module; there is a level switch, which can select 3.3V or 5V to supply the module, which is determined by the module operating voltage; since the lead pins have the same part, the two cannot be used at the same time, and only one of them can be selected for use.

[0078] like Figure 18 As shown in the figure, the servo interface circuit, servo interface 1 is PWM1, 5V, GND, servo interface 2 is PWM2, 5V, GND, PWM1 is controlled by the core board PB0 pin, PWM2 is controlled by the core board PB1 pin, and can be directly plugged into the SG90 servo;

[0079] like Figure 19As shown in the figure, the motor drive circuit consists of three parts: 5V / 12V level switching, DC motor drive module interface, and wiring terminals: 5V / 12V level switching can choose to supply 5V or 12V to the module, which is determined by the motor operating voltage. When using 12V, a DC power supply interface must be used for power supply; the DC motor drive module interface can be directly plugged into the WildFire Xiaozhi TB6612FNG motor driver module; the wiring terminals are lead-out AO1, AO2, BO1, and BO2, which can drive two DC motors.

[0080] Specifically, the model of the control chip U2 is STM32F103C8T6, the model of the chip U3 is CH340X, the model of the chip U5 is 74HC1G66GW, the model of the chip U91 is TPS5430DDAR, and the signal of the chip U93 is MT3520B.

[0081] The above contents are only preferred embodiments of the present invention. For ordinary technicians in this field, according to the concept of the present invention, there may be changes in the specific implementation methods and application scope. The content of this specification should not be understood as limiting the present invention.

Claims

1. A building block development board based on the ARM platform, characterized by: The system comprises a core board and an expansion board electrically connected to the core board. The core board is provided with a minimum system circuit, a USB to serial port circuit, a USB function port circuit and a serial port one-key download circuit. The minimum system circuit is electrically connected to the USB function port circuit and the serial port one-key download circuit respectively. The serial port one-key download circuit is electrically connected to the USB to serial port circuit. The expansion board is provided with a power switching circuit, a voltage conversion circuit and an expansion circuit, the power switching circuit is electrically connected to the voltage conversion circuit, and the voltage conversion circuit is electrically connected to the expansion circuit; The minimum system circuit includes the control chip U2, capacitor C5, capacitor C6, capacitor C7, capacitor C8, capacitor C9, capacitor C10, capacitor C11, capacitor C12, capacitor C13, resistor R6, resistor R7, crystal oscillator Y1 and crystal oscillator Y2, The third pin of the control chip U2 is connected to the first end of the capacitor C7 and the first end of the crystal oscillator Y2, the fourth pin of the control chip U2 is connected to the first end of the capacitor C8 and the second end of the crystal oscillator Y2, the second ends of the capacitor C7 and the capacitor C8 are respectively connected to the ground end, the fifth pin of the control chip U2 is connected to the first end of the crystal oscillator Y1 and the first end of the capacitor C6, the sixth pin of the control chip U2 is connected to the third end of the crystal oscillator Y1 and the first end of the capacitor C5, the fourth end of the crystal oscillator Y1 is connected to the second end of the capacitor C6 and the ground end, the second end of the crystal oscillator Y1 is connected to the second end of the capacitor C5 and the ground end, the ninth pin of the control chip U2 is connected to the twenty-fourth pin, the thirty-sixth pin, the forty-eighth pin and the 3V3 power supply end, the first pin of the control chip U2 is connected to the VBAT end, and the seventh pin and the forty-fourth pin of the control chip U2 are respectively connected to the serial port one-key download circuit.

2. The building block development board based on the ARM platform according to claim 1, characterized in that: The USB to serial port circuit includes a USB interface J6, a chip U3, a resistor R16, a resistor R17, a resistor R19, a capacitor C19, a capacitor C20 and an inductor L3. Pin A1 of USB interface J6 is connected to pin A12, pin B12, pin B1 and ground. Pin A1 of the USB interface J6 is connected to pin A12, pin B12, pin B1 and the ground terminal, pin A4 of the USB interface J1 is connected to pin A9, pin B9, pin B4, the first end of capacitor C19, the first end of capacitor C20 and the 5V power supply terminal, pin A5 of the USB interface J6 is connected to the first end of resistor R16, pin A6 of the USB interface J6 is connected to pin B6 and the first pin of chip U3, pin A7 of the USB interface J6 is connected to pin B7 and the second pin of chip U3, pin B5 of the USB interface J6 is connected to the first end of resistor R17, pin C4 of the USB interface J6 is connected to pin C3, pin C2, pin C1 and the first end of inductor L3, and the second ends of capacitor C19, capacitor C20, resistor R16, resistor R17 and inductor L3 are respectively connected to the ground terminal. The third pin of chip U3 is connected to the ground terminal, the fourth pin of chip U3 is connected to the serial port one-key download circuit, the fifth pin of chip U3 is connected to the first end of resistor 19, the sixth pin of chip U3 is connected to the second end of resistor 19 and the serial port one-key download circuit, the seventh pin of chip U3 is connected to the eighth pin and the 3V3 power supply terminal, the eighth pin of chip U3 is the data sending pin, and the ninth pin of chip U3 is the data receiving pin.

3. The building block development board based on the ARM platform according to claim 2, characterized in that: The serial port one-key download circuit includes a chip U5, a resistor R20, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a resistor R25, a resistor R26, a capacitor C25, a diode D1, a diode D2, a transistor Q1 and a transistor Q2. The first pin of the chip U5 is connected to the first end of the resistor R20, the second end of the resistor R20 is connected to the seventh pin of the control chip U2, the second pin of the chip U5 is connected to the anode of the diode D1, the cathode of the diode D1 is connected to the second end of the resistor R21 and the collector of the transistor Q1, the first end of the resistor R21 is connected to the 3V3 power supply terminal, the collector of the transistor Q1 is connected to the second end of the resistor R23, the first end of the resistor R23 is connected to the sixth pin of the chip U3, the emitter of the transistor Q1 is connected to the first end of the resistor R25 and the fourth pin of the chip U3, the second end of the resistor R25 is connected The first end of the resistor R24 ​​is connected to the collector of the transistor Q2, the second end of the resistor R24 ​​is connected to the emitter of the transistor Q2 and the 3V3 power supply terminal, the collector of the transistor Q2 is connected to the first end of the resistor R26, the second end of the resistor R26 is connected to the forty-fourth pin of the control chip U2, the third pin of the chip U5 is connected to the ground terminal, the fourth pin of the chip U5 is connected to the positive electrode of the diode D2, the second end of the resistor R22 and the first end of the capacitor C25, the second end of the capacitor C25 is connected to the ground terminal, and the fifth pin of the chip U5 is connected to the 3V3 power supply terminal, the negative electrode of the diode D2 and the first end of the resistor R22.

4. The building block development board based on the ARM platform according to claim 1, characterized in that: The USB function port circuit includes a USB interface J1, a resistor R1, a resistor R15, a resistor R18, a capacitor C17, a capacitor C18 and an inductor L2. Pin A1 of the USB interface J1 is connected to pin A12, pin B12, pin B1 and the ground terminal, pin A4 of the USB interface J1 is connected to pin A9, pin B9, pin B4, the first end of capacitor C17, the first end of capacitor C18 and the 5V power supply terminal, pin A5 of the USB interface J1 is connected to the first end of resistor R1, pin A6 of the USB interface J1 is connected to pin B6, the second end of resistor R18 and the thirty-third pin of the control chip U2, pin A7 of the USB interface J1 is connected to pin B7 and the thirty-second pin of the control chip U2, pin B5 of the USB interface J1 is connected to the first end of resistor R15, pin C4 of the USB interface J1 is connected to pin C3, pin C2, pin C1 and the first end of inductor L2, the second ends of capacitor C17, capacitor C18, resistor R1, resistor R15 and inductor L2 are respectively connected to the ground terminal, and the first end of resistor R18 is connected to the 3V3 power supply terminal.

5. The building block development board based on the ARM platform according to claim 1, characterized in that: The power switching circuit includes an automatic switching circuit and a manual switching circuit. The automatic switching circuit includes MOS tube Q91, resistor R92, resistor R93 and voltage regulator diode D94. The source of the MOS transistor Q91 is connected to the 5V input terminal, the drain of the MOS transistor Q91 is connected to the 5V output terminal, the gate of the MOS transistor Q91 is connected to the first end of the resistor R93, the second end of the resistor R92, and the cathode of the Zener diode D94, the first end of the resistor R92 is connected to the 12V power supply terminal, and the anode of the Zener diode D94 and the second end of the resistor R93 are respectively connected to the ground terminal; The manual switching circuit includes a switch SW92 and a capacitor C923. The sixth pin of the switch SW92 is connected to the third pin, the 5V power supply terminal and the first terminal of the capacitor C923. The second terminal of the capacitor C923 is connected to the ground terminal. The fifth pin of the switch SW92 is connected to the second pin and the 5V output terminal.

6. The building block development board based on the ARM platform according to claim 5, characterized in that: The voltage conversion circuit includes a 5V conversion circuit and a 3V3 conversion circuit. The 5V conversion circuit includes chip U91, inductor L91, diode D91, diode D92, diode D93, resistor R911, resistor R913, capacitor C912, capacitor C917, capacitor C918, capacitor C926, capacitor C924, capacitor C925, The seventh pin of chip U1 is connected to the first end of capacitor C924, the first end of capacitor C925, the cathode of diode D93, and the cathode of diode D91. The anode of diode D91 is connected to the 12V input terminal. The second end of capacitor C924, the second end of capacitor C925, and the anode of diode D93 are connected to each other and to the ground terminal. The eighth pin of chip U91 is connected to the second end of capacitor C917, the cathode of diode D92, and the first end of inductor L91. The first pin of chip U91 is connected to the cathode of capacitor C917. The first end, the positive electrode of the diode D92, is connected to the ground terminal. The second end of the inductor L91 is connected to the first end of the capacitor C926, the first end of the capacitor C912, the first end of the capacitor C918, the first end of the resistor R911, and the 5V output terminal. The fourth pin of the chip U91 is connected to the second end of the resistor R911 and the first end of the resistor R913. The sixth pin and the ninth pin of the chip U91 are respectively connected to the ground terminal. The second ends of the capacitors C926, C912, C918, and R913 are respectively connected to the ground terminal. The 3V3 conversion circuit includes chip U93, inductor L93, resistor R926, resistor R927, resistor R929, capacitor C919, capacitor C920, capacitor C921, capacitor C922, capacitor C927 and capacitor C930. The fourth pin of chip U93 is connected to the first end of resistor R929, the first end of capacitor C922, the first end of capacitor C930 and the 5V input end, the first pin of chip U93 is connected to the second end of resistor R929 and the first end of capacitor C927, the third pin of chip U93 is connected to the first end of inductor L93, the fifth pin of chip U93 is connected to the second end of resistor R926 and the first end of resistor R927, the second end of inductor L93 is connected to the first end of capacitor C919, the first end of capacitor C920, the first end of capacitor C921, the first end of resistor R926 and the 3V3 output end, the second end of capacitor C930, the second end of capacitor C922, the second pin of chip U93, the second end of capacitor C927, the second end of capacitor C919, the second end of capacitor C920, the second end of capacitor C921 and the second end of resistor R927 are respectively connected to the ground end.

7. The building block development board based on the ARM platform according to claim 1, characterized in that: The minimum system circuit is also provided with an indicator light circuit and a key circuit, which are respectively connected to the control chip U2. The indicator light circuit includes a red light LED1, a green light LED2, a blue light LED3, resistors R2, R3, and R4. The first ends of the red light LED1, green light LED2, and blue light LED3 are connected to each other and to the 3V3 power supply terminal. Resistor R2 is connected in series between the second end of the red light LED1 and the eleventh pin of the control chip U2. Resistor R3 is connected in series between the second end of the green light LED2 and the twelfth pin of the control chip U2. Resistor R4 is connected in series between the second end of the blue light LED3 and the thirteenth pin of the control chip U2. The key circuit includes a first key sub-circuit, a second key sub-circuit and a third key sub-circuit. The first key sub-circuit includes a key SW1, a resistor R8, a resistor R9 and a capacitor C14. The first pin of the button SW1 is connected to the second pin, the second end of the resistor R8, the second end of the resistor R9, and the first end of the capacitor C14. The third pin of the button SW1 is connected to the fourth pin, the 3V3 power supply terminal, and the second end of the capacitor C14. The first end of the resistor R8 is connected to the tenth pin of the control chip U2. The first end of the resistor R9 is connected to the ground terminal. The second key sub-circuit includes a key SW2, a resistor R10, a resistor R11 and a capacitor C15. The first pin of the button SW2 is connected to the second pin, the second end of the resistor R10, the second end of the resistor R11, and the first end of the capacitor C15. The third pin of the button SW2 is connected to the fourth pin, the 3V3 power supply terminal, and the second end of the capacitor C15. The first end of the resistor R10 is connected to the second pin of the control chip U2. The first end of the resistor R11 is connected to the ground terminal. The third key sub-circuit includes a key SW3, a resistor R12 and a capacitor C16. The first pin of the button SW3 is connected to the second pin, the first end of the capacitor C16, the second end of the resistor R12 and the seventh pin of the control chip U2. The third pin of the button SW3 is connected to the fourth pin and the ground end. The first end of the resistor R12 is connected to the 3V3 power supply end, and the second end of the capacitor C16 is connected to the ground end.

8. The building block development board based on the ARM platform according to any one of claims 1 to 7, characterized in that: The expansion circuit includes a communication interface circuit, a general input and output circuit, a digital analog general interface circuit, an OLED screen interface circuit, an ultrasonic interface circuit, an encoder interface circuit, a servo interface circuit and a motor drive circuit, which are respectively electrically connected to the minimum system circuit.

9. The building block development board based on the ARM platform according to claim 8, characterized in that: The model of the control chip U2 is STM32F103C8T6.

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