CN115129522A - A USB function pin detection system - Google Patents

Abstract

The invention discloses a USB function pin detection system, comprising a power adapter, a USB interface, a voltage detection unit, a CC control unit, a fast charging function unit, an MCU unit, an LDO power supply unit and a test indication unit, a voltage detection unit, a CC control unit The unit, the fast charging function unit, the LDO power supply unit and the test indication unit are all connected to the MCU unit, the voltage detection unit is also connected to a power adapter, the USB interface is connected to the MCU unit, and the power adapter is connected to the USB interface. The embodiment can judge whether the power management function and fast charging function of the power adapter are normal, and can judge the connection status of the Type-C terminal in the USB, and can judge whether the power function of the power adapter is normal through the indicator light, and can test the power management function. In addition to the function, it also has the function of testing fast charging, the circuit structure is simple, and the implementation cost is low.

Description

A USB function pin detection system

technical field

The invention relates to the technical field of USB detection, in particular to a USB function pin detection system.

Background technique

A USB Type-C power supply refers to a device that uses USB Type-C terminals for output and supports DFP functions. A PD power adapter (DFP) is a typical USB Type-C power supply. It generally supports power management functions and fast charging functions, that is, It is the PD function and the QC function. See Figure 1. The output port of the PD power adapter uses the Type-C interface. Combined with Figure 1, the PIN pins actually used by the PD power adapter are A1, A12, B1, B12, A4, A9, B4, B9, A5, B5, A6, A7, B6, B7, that is, the PD power adapter uses GND, VBUS , CC1, CC2, D+, D- transmit signals and energy, where GND is the power supply and signal ground, VBUS is the POWER transmission pin, CC1 and CC2 are the PD signal pins, and D+ and D- are the QC signal pins. During the production process of the PD power adapter (Adapter), it is generally only tested whether the PD function and QC function can be output. Some existing test methods may exist that the CC1 terminal is connected correctly, but the CC2 is open, or the CC2 connection is normal. There is no way to test the phenomenon that CC1 is open. It is also possible that the short circuit between CC1 and CC2 cannot be tested. In addition, there may be a situation when one side D+ and D- (such as A6, A7) are connected to the PCB correctly, but the other side D+ and D- (such as B6, B7) are not connected to the PCB. Although some test schemes can test the above situation, the cost is relatively expensive.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a USB function pin detection system, which has a simple circuit structure and low cost, and can comprehensively detect the functions of each USB pin.

The purpose of the present invention adopts following technical scheme to realize:

The invention provides a USB function pin detection system, including a power adapter, a USB interface, a voltage detection unit, a CC control unit, a fast charging function unit, an MCU unit, an LDO power supply unit and a test indication unit, the voltage detection unit, The CC control unit, the fast charging function unit, the LDO power supply unit and the test indication unit are all connected to the MCU unit, the voltage detection unit is also connected to a power adapter, the USB interface is connected to the MCU unit, and the power adapter is connected to The USB interface, the LDO power supply unit is used to provide DC power to the MCU, the voltage detection unit is used to detect the output voltage of the power adapter, and the CC1V1 pin and the CC2V2 pin are set to the input state, the CC The control unit is used to control the EnCC1 pin and the EnCC2 pin to enable when the MCU is powered on, and the fast charge function unit is used to adjust the DPV1 pin, DPGND pin and DMV1 pin when the power adapter outputs the set voltage , so that the MCU unit reads the VBUS voltage of the USB interface through the voltage detection unit after setting the voltage of the fast charge pin in the USB interface. .

In the present invention, as an optional embodiment, the USB interface includes a power signal ground pin, an energy transmission pin, a power management signal pin, and a fast charge signal pin.

In the present invention, as an optional embodiment, the model of the MCU unit is CS32G02X.

In the present invention, as an optional embodiment, the voltage detection unit includes a resistor R1 and a resistor R2. One end of the resistor R1 is connected to the VBUS pin of the USB interface, and the other end of the resistor R1 is connected to the VBUS pin of the USB interface. The resistor R2 is grounded, one end of the resistor R1 is also connected to a power adapter, and the AINP8 pin of the MCU unit is connected between the resistor R1 and the resistor R2.

In the present invention, as an optional embodiment, the CC control unit includes a resistor R50, a resistor R51, a resistor R3, a resistor R8, a transistor Q4 and a transistor Q5, and one end of the resistor R50 and one end of the resistor R51 are both Connected with the MCU unit, the other end of the resistor R50 and the resistor R51 are connected to the CC1V1 pin of the USB interface, the other end is connected to the USB interface and the CC2V2 pin of the USB interface, and the other end of the resistor R50 is also connected to a triode The collector of Q4, the collector of the transistor Q4 is also connected to the CC1_1 pin of the MCU unit, the emitter of the Q4 is grounded, the base of the transistor Q4 is connected to the EnCC1 pin of the MCU unit through the resistor R3, and the other side of the resistor R51 One end is also connected to the collector of the transistor Q5, the collector of the transistor Q5 is also connected to the CC2_1 pin of the MCU unit, the emitter of the Q5 is grounded, and the base of the transistor Q5 is connected to the MCU unit through the resistor R5 The EnCC2 pin of the unit.

In the present invention, as an optional embodiment, the LD0 power supply unit includes a power chip, a resistor R27, a resistor R28, a resistor R29, a diode D1, a diode D2, a capacitor C32, a capacitor C33, a capacitor C34, and a capacitor C30, The positive terminal of the diode D1 is connected to the CVBUS pin of the USB interface, the positive terminal of the diode D2 is connected to the power input VIN1, the negative terminal of the diode D1 is connected to the input terminal Vin of the power chip through the resistor R27, and the diode D2 The negative terminal of the capacitor C32 is connected to the input terminal Vin of the power chip through the resistor R29, one end of the capacitor C32 is connected to the input terminal Vin of the power chip, and the other end of the capacitor C32 is grounded; one end of the capacitor C33, one end of the capacitor C34 and the resistor R28 One end of the resistor R28 is connected to the output terminal Vout of the power chip, the other end of the capacitor C33 and the other end of the capacitor C34 are both grounded to GND, the other end of the resistor R28 and one end of the capacitor C30 are connected to the MCU_VCC pin of the MCU unit, the capacitor The other end of C30 is grounded.

In the present invention, as an optional embodiment, the model of the power chip is ME6203A33M3G.

In the present invention, as an optional embodiment, the test indication unit includes a light-emitting diode LED1, a light-emitting diode LED2, a light-emitting diode LED3, a resistor R47, a resistor R48, and a resistor R49. The positive terminal of the light-emitting diode LED1, The positive terminal of the light-emitting diode LED2 and the positive terminal of the light-emitting diode LED3 are both connected to the MCU unit, the negative terminal of the light-emitting diode LED1 is grounded through the resistor R49, the negative terminal of the light-emitting diode LED2 is grounded through the resistor R47, and the light-emitting diode LED3 is grounded. Ground through resistor R48.

In the present invention, as an optional embodiment, the fast charging functional unit includes a resistor R4, a resistor R5, a resistor R6, and a resistor R7, and the resistor R4 and the resistor R6 are connected to form a first series branch. The resistor R5 is connected with the resistor R7 to form a second series branch, one end of the first series branch and one end of the second series branch are both connected to the MCU unit, and the other end of the first series branch is also connected to the MCU unit. In the MCU unit, the other end of the second series branch is grounded, and the MCU unit is further connected between the resistor R4 and the resistor R6 and between the resistor R5 and the resistor R7, respectively.

Compared with the prior art, the beneficial effects of the present invention are:

In the USB function pin detection system provided by the present invention, by setting a voltage detection unit, a CC control unit, a fast charge function unit, an MCU unit, an LDO power supply unit and a test indication unit, it can determine whether the power management function and the fast charge function of the power adapter are not It is normal, and can judge the connection of the Type-C terminal in the USB, and can judge whether the power supply function of the power adapter is normal through the indicator light. It can test the fast charging function as well as the power management function. low cost.

Description of drawings

1 is a schematic diagram of a module structure of a USB function pin detection system according to an embodiment of the present invention;

2 is a circuit structure diagram of an MCU unit according to an embodiment of the present invention;

3 is a circuit structure diagram of a USB interface according to an embodiment of the present invention;

4 is a circuit structure diagram of a voltage detection unit according to an embodiment of the present invention;

5 is a circuit structure diagram of a CC control unit according to an embodiment of the present invention;

6 is a circuit structure diagram of an LDO power supply unit according to an embodiment of the present invention;

7 is a circuit structure diagram of a test indication unit according to an embodiment of the present invention;

8 is a circuit structure diagram of a fast charging functional unit according to an embodiment of the present invention;

FIG. 9 is a corresponding table of voltages of D+ and D- in the QC2.0 handshake protocol applied in the embodiment of the present invention.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that, on the premise of no conflict, the embodiments or technical features described below can be combined arbitrarily to form new embodiments. . Unless otherwise specified, the materials and equipment used in this embodiment can be purchased from the market. Examples of embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, but not to understand the limitations of the present application.

In the description of this application, it should be understood that the terms "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", The orientation or positional relationship indicated by "outside" is based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, It is constructed and operated in a particular orientation and therefore should not be construed as a limitation of the present application. In the description of this application, "plurality" means two or more, unless it is precisely and specifically specified otherwise.

In the description of the present application, it should be noted that, unless otherwise expressly specified and limited, the terms "connected", "connected" and "connected" should be understood in a broad sense, for example, a fixed connection can be made, or an intermediary can be used. The connection between the media can be the internal connection of two elements or the interaction relationship between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific situations.

The terms "first", "second" and the like in the description and claims of the present application and the above drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. Furthermore, the terms "comprising" and "having" and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those expressly listed Rather, those steps or units may include other steps or units not expressly listed or inherent to these processes, methods, products or devices.

The embodiment of the present application provides a USB function pin detection system. By setting a voltage detection unit, a CC control unit, a fast charging function unit, an MCU unit, an LDO power supply unit and a test indication unit, the power management function and fast charging function of the power adapter can be determined. Whether the charging function is normal, and can judge the connection of the Type-C terminal in the USB, through the indicator light can judge whether the power supply function of the power adapter is normal, can test the power management function and also test the fast charging function, circuit structure Simple and low cost to implement.

1 shows a schematic diagram of a module structure of a USB function pin detection system according to an embodiment of the present invention, FIG. 2 shows a circuit structure diagram of an MCU unit according to an embodiment of the present invention, and FIG. 3 shows an embodiment of the present invention. The circuit structure diagram of the USB interface, FIG. 4 shows the circuit structure diagram of the voltage detection unit according to the embodiment of the present invention, FIG. 5 shows the circuit structure diagram of the CC control unit according to the embodiment of the present invention, and FIG. 6 shows the circuit structure diagram of the present invention. The circuit structure diagram of the LD0 power supply unit of the embodiment, FIG. 7 shows the circuit structure diagram of the test indication unit of the embodiment of the present invention, and FIG. 8 shows the circuit structure diagram of the fast charging function unit of the embodiment of the present invention.

Referring to FIG. 1 , the USB function pin detection system provided by this embodiment includes a power adapter, a USB interface, a voltage detection unit, a CC control unit, a fast charging function unit, an MCU unit, an LDO power supply unit, and a test indication unit. The voltage detection unit, CC control unit, fast charging function unit, LDO power supply unit and test indication unit are all connected to the MCU unit, the voltage detection unit is also connected to a power adapter, and the USB interface is connected to the MCU unit , the power adapter is connected to the USB interface, the LDO power supply unit is used to provide DC power to the MCU, the voltage detection unit is used to detect the output voltage of the power adapter, and the CC1V1 pin and the CC2V2 pin are set to Input state, the CC control unit is used to control the EnCC1 pin and the EnCC2 pin to enable when the MCU is powered on, and the fast charge function unit is used to adjust the DPV1 pin, DPGND when the power adapter outputs the set voltage pin and the voltage of the DMV1 pin, so that the MCU unit reads the VBUS voltage of the USB interface through the voltage detection unit after setting the voltage of the fast charge pin in the USB interface. The power adapter is connected with the USB interface, the power adapter is a USB power adapter, and the USB interface is equivalent to providing the power adapter with an interface to connect with the outside world. Please refer to FIG. 3 , the USB interface includes a PIN pin, a signal transmission pin, a power signal ground pin, and an energy transmission pin. Power management signal pin, fast charge signal pin. Specifically, the USB interfaces include A1, A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, B12, B11, B10, B9, B8, B7, B6, B5, B4 in FIG. 2 , B3, B2, B1 correspond to the interface pins, among which, the PIN pins used by the power adapter include A1, A12, B1, B12, A4, A9, B4, B9, A5, B5, A6, A7, B6, B7, that is, the power adapter uses GND, VBUS, CC1, CC2, D+, D- to transmit signals and energy, where GND is the power signal ground pin, VBUS is the energy transmission pin, and CC1 and CC2 are the power management signal pins. D+ and D- are fast charge signal pins. In the embodiment, by adjusting the voltages of the DPV1 pin, DPGND pin and DMV1 pin, the MCU unit reads the voltage difference of DP1, DM1, DP2 and DM2 to obtain the connection of the two groups of D+ and D- of the power adapter.

Referring to FIG. 2 to FIG. 4 , in the embodiment, the model of the MCU unit is CS32G02X. The voltage detection unit includes a resistor R1 and a resistor R2. One end of the resistor R1 is connected to the VBUS pin of the USB interface, the other end of the resistor R1 is grounded through the resistor R2, and one end of the resistor R1 is also connected to the power adapter. The MCU unit is connected between the resistor R1 and the resistor R2.

5-8, the CC control unit of the embodiment includes a resistor R50, a resistor R51, a resistor R3, a resistor R8, a transistor Q4 and a transistor Q5, and one end of the resistor R50 and one end of the resistor R51 are both connected to the MCU unit, so The other end of the resistance R50 and the other end of the resistance R51 are connected with the USB interface, the other end of the resistance R50 is also connected to the collector of the transistor Q4, the collector of the transistor Q4 is also connected to the MCU unit, and the emitter of the Q4 is grounded , the base of the transistor Q4 is connected to the MCU unit through the resistor R3, the other end of the resistor R51 is also connected to the collector of the transistor Q5, the collector of the transistor Q5 is also connected to the MCU unit, the emitter of the Q5 is grounded, the The base of the transistor Q5 is connected to the MCU unit through the resistor R3.

Further, the LDO power supply unit includes a power chip, a resistor R27, a resistor R28, a resistor R29, a diode D1, a diode D2, a capacitor C32, a capacitor C33, a capacitor C34 and a capacitor C30, and the positive terminal of the diode D1 is connected to the USB interface, and the The positive terminal of the diode D2 is connected to the power supply input, the negative terminal of the diode D1 is connected to the input terminal of the power supply chip through the resistor R27, the positive terminal of the diode D2 is connected to the input terminal of the power supply chip through the resistor R29, and the The negative terminal is connected to the input terminal of the power chip through the resistor R29, one end of the capacitor C32 is connected to the input terminal of the power chip, and the other end of the capacitor C32 is grounded; one end of the capacitor C33, one end of the capacitor C34 and one end of the resistor R28 are all connected to the ground. Connected to the output end of the power chip, the other end of the capacitor C33 and the other end of the capacitor C34 are both grounded, the other end of the resistor R28 and one end of the capacitor C30 are connected to the MCU unit, and the other end of the capacitor C30 is grounded. In the embodiment, the model of the power chip is ME6203A33M3G. The LDO power supply unit provides a voltage of 3.3V for the MCU unit to work.

The test indication unit includes a light-emitting diode LED1, a light-emitting diode LED2, a light-emitting diode LED3, a resistor R47, a resistor R48, and a resistor R49. The positive terminal of the light-emitting diode LED1, the positive terminal of the light-emitting diode LED2, and the positive terminal of the light-emitting diode LED3 are all connected with the MCU. The units are connected, the negative terminal of the light emitting diode LED1 is grounded through the resistor R49, the negative terminal of the light emitting diode LED2 is grounded through the resistor R47, and the light emitting diode LED3 is grounded through the resistor R48.

The fast charging functional unit of the present application includes a resistor R4, a resistor R5, a resistor R6, and a resistor R7. The resistor R4 and the resistor R6 are connected to form a first series branch, and the resistor R5 and the resistor R7 are connected to form a second series branch. One end of the first series branch and one end of the second series branch are both connected to the MCU unit, the other end of the first series branch is also connected to the MCU unit, and the other end of the second series branch is connected to the MCU unit. Grounding, the MCU unit is also connected between resistor R4 and resistor R6 and between R5 and resistor R7, respectively.

Based on the above, in order to overcome the problems existing in the prior art, CC1 and CC2 are respectively tested for the power management function of the power adapter. When testing one of CC1 or CC2, the other is pulled down to the GND ground. If CC1 and CC2 Short circuit, the test has no output. When the CC1 (or CC2) channel is tested, the voltage of the CC1 (or CC2) port is controlled according to whether the UPF (power receiving end) is connected to the CC port voltage, so that the power adapter thinks that the UPF (power receiving end) has moved. to stop the output voltage. When testing the QC function, according to the QC2.0 protocol, D+ and D- set different voltages through the voltage divider to induce the power adapter to output the corresponding voltage; when D+ is set to 3.3V and D- is set to 0.6V, the MCU unit collects all The voltages of DP and DP determine the connection of the Type-C terminals D+ and D- of the power adapter. This application can judge whether the power management function and fast charging function of the power adapter are normal, and can judge the connection status of CC1, CC2, D+ and D- of the USB interface Type-C terminal of the power adapter, and encapsulate the test steps in the test program, After the tester puts the test product into the test switch, press the test switch, and use the indicator light to determine whether the power supply function of the adapter and the Type-C power supply function pin are normal. The test device uses an MCU, resistors, transistors, etc. Lower cost devices, which can not only improve the quality of production products, but also take into account the benefits of production.

In the embodiment, a separate 5V power supply is used to supply power to the power supply board. When the MCU unit is powered on and initialized, it is necessary to enable EnCC1 and EnCC2 of the CC control unit first, and set CC1V1 and CC2V2 to the input state, so that CC1 and CC2 are connected to each other. pulled low. Connect the power adapter to be tested to the AC socket, and connect the power adapter to the test circuit of the test system with a TYPE-C full-function cable. When the button is pressed, the MCU unit first shields its own PD function, and sets EnCC1 low to Enable CC1, when the power adapter detects that there is a UFP inserted through the CC line, it will output 5V voltage. However, if CC1 and CC2 are short-circuited, since CC2 is set low at this time, CC1 will also be set low, and the power adapter will not output 5V if it cannot detect that the test circuit is connected. The MCU unit determines whether the power adapter has 5V output through the voltage detection unit. If there is an output, the CC1 terminal of the power adapter is connected to OK, and it is not connected to CC2 or other terminals that cause CC1 to be pulled down.

Combined with the voltage correspondence table of D+ and D- in the QC2.0 handshake protocol shown in Figure 9, since the power adapter has output 5V, it is necessary to set the D+ voltage to 0.6V and D- to 0V. For the charging function unit, set DPV1 to high (3.3V) and DPGND to low (0V). According to Ohm's law, the voltage of DP1 (D+) is V=3.3V/(4.2KΩ+1KΩ)*1KΩ≈0.6V; MCU The unit sets the DM1 pin to low, then D- is 0V. After a certain delay, set D+ to 3.3V, D- to 0.6V, that is, DPV1 output is high, DPGND is set as input, DP1 is set to ADC mode, DMV1 output is high, DM1 is set to ADC mode, DP2 and DM2 Also set to ADC mode. The MCU unit uses the internal ADC module to first read whether the voltage of DP1 and DP2 is greater than 3V and close, and then read whether the voltage of DM1 and DM2 is greater than 0.5V and less than 0.7V. If the above two conditions are not satisfied, it is possible that the power adapter One way D+ and D- of the output terminal of the device is abnormally connected, or D+ and D- are short-circuited; if the above two conditions are met, the MCU unit reads whether the VBUS voltage is 9V through the voltage detection unit, and if so, the QC9V gear test passes . Similarly, you can set D+ to 0.6V and D- to 0.6V to see if the VBUS voltage is 12V. After the 5V, 9V, and 12V tests are all OK, the basic test of QC2.0 function is OK, which also proves that the D+ and D- functions of the power adapter are normal. It can be indirectly confirmed that if the power adapter protocol chip supports the QC3.0 function, then the power adapter QC3.0 can work normally. The MCU unit opens its own PD protocol, and through negotiation with the power adapter, the power adapter can output different voltages of 5V, 9V, 12V, 15V, 20V (different output voltages need to be requested according to different adapter protocol chips). After sending the application, The MCU unit confirms whether the output voltage is normal through the voltage detection unit, and if it is normal, confirms that the CC1 channel is normal.

In order to test CC2, CC1 needs to be disconnected first, and the voltage of CC line needs to be greater than the voltage in Figure 6 when disconnected, so the MCU unit outputs CC1V1 high, thereby pulling the level of CC line high, so that the power adapter thinks that the device It has been disconnected from it, and the power adapter has no output. Then enable CC2 by setting EnCC2 low. The MCU unit negotiates with the power adapter to allow the power adapter to output different voltages of 5V, 9V, 12V, 15V, and 20V (different output voltages need to be requested according to different adapter protocol chips). If the MCU unit detects that the corresponding voltage is output, it is considered that the CC2 channel is normal and the PD function of the adapter is normal, and then the CC2V2 is set to output high to stop the output of the power adapter. After the above tests are normal, the MCU unit sets the green indicator light to be on, otherwise the red indicator light is set to be on.

While only certain components and embodiments of the present application have been illustrated and described, many modifications and changes will occur to those skilled in the art without actually departing from the scope and spirit of the claims, such as: Variations in size, dimensions, configuration, shape and proportions, mounting arrangements, material usage, color, orientation, etc. of individual elements.

The above embodiments are only preferred embodiments of the embodiments of the present invention, and cannot be used to limit the protection scope of the embodiments of the present invention, and any insubstantial changes made by those skilled in the art on the basis of the embodiments of the present invention and replacement all belong to the scope of protection required by the embodiments of the present invention.

Claims (9)

1. a USB function pin detection system, is characterized in that, comprises power adapter, USB interface, voltage detection unit, CC control unit, fast charge function unit, MCU unit, LDO power supply unit and test indication unit, described voltage detection The unit, CC control unit, fast charging function unit, LDO power supply unit and test indication unit are all connected to the MCU unit, the voltage detection unit is also connected to a power adapter, the USB interface is connected to the MCU unit, the power supply The adapter is connected to the USB interface, the LDO power supply unit is used to provide DC power to the MCU, and the voltage detection unit is used to detect the output voltage of the power adapter, and set the CC1V1 pin and the CC2V2 pin to the input state, so The CC control unit is used to control the EnCC1 pin and the EnCC2 pin to enable when the MCU is powered on, and the fast charge function unit is used to adjust the DPV1 pin, DPGND pin and DMV1 when the power adapter outputs the set voltage The voltage of the pin, so that the MCU unit reads the VBUS voltage of the USB interface through the voltage detection unit after setting the voltage of the fast charge pin in the USB interface. 2 . The USB function pin detection system according to claim 1 , wherein the USB interface comprises a power signal ground pin, an energy transmission pin, a power management signal pin, and a fast charge signal pin. 3 . 3. The USB function pin detection system according to claim 1, wherein the model of the MCU unit is CS32G02X. 4. The USB function pin detection system according to claim 3, wherein the voltage detection unit comprises a resistor R1 and a resistor R2, and one end of the resistor R1 is connected to the VBUS pin of the USB interface, and the The other end of the resistor R1 is grounded through the resistor R2, one end of the resistor R1 is also connected to a power adapter, and the MCU unit is connected between the resistor R1 and the resistor R2. 5. USB function pin detection system according to claim 4, is characterized in that, described CC control unit comprises resistor R50, resistor R51, resistor R3, resistor R8, triode Q4 and triode Q5, one end of described resistor R50 One end of the resistor R51 is connected to the MCU unit, the other end of the resistor R50 and the other end of the resistor R51 are connected to the USB interface, and the other end of the resistor R50 is also connected to the collector of the transistor Q4, the collector of the transistor Q4 Also connected to the MCU unit, the emitter of the Q4 is grounded, the base of the transistor Q4 is connected to the MCU unit through the resistor R3, the other end of the resistor R51 is also connected to the collector of the transistor Q5, and the collector of the transistor Q5 is also connected to the MCU unit, the emitter of the Q5 is grounded, and the base of the transistor Q5 is connected to the MCU unit through the resistor R3. 6. The USB function pin detection system according to claim 5, wherein the LD0 power supply unit comprises a power chip, a resistor R27, a resistor R28, a resistor R29, a diode D1, a diode D2, a capacitor C32, a capacitor C33, Capacitor C34 and capacitor C30, the positive terminal of the diode D1 is connected to the USB interface, the positive terminal of the diode D2 is connected to the power input, the negative terminal of the diode D1 is connected to the input terminal of the power chip through the resistor R27, the diode D2 The negative end of the capacitor C32 is connected to the input end of the power chip through the resistor R29, one end of the capacitor C32 is connected to the input end of the power chip, and the other end of the capacitor C32 is grounded; one end of the capacitor C33, one end of the capacitor C34 and one end of the resistor R28 Both are connected to the output end of the power chip, the other end of the capacitor C33 and the other end of the capacitor C34 are both grounded, the other end of the resistor R28 and one end of the capacitor C30 are connected to the MCU unit, and the other end of the capacitor C30 is grounded. 7 . The USB function pin detection system according to claim 6 , wherein the model of the power chip is ME6203A33M3G. 8 . 8. The USB function pin detection system according to claim 1 or 7, wherein the test indication unit comprises a light-emitting diode LED1, a light-emitting diode LED2, a light-emitting diode LED3, a resistor R47, a resistor R48, and a resistor R49. The positive terminal of the light-emitting diode LED1, the positive terminal of the light-emitting diode LED2, and the positive terminal of the light-emitting diode LED3 are all connected to the MCU unit, the negative terminal of the light-emitting diode LED1 is grounded through the resistor R49, and the negative terminal of the light-emitting diode LED2 is connected to the ground through the resistor R49. R47 is grounded, and the light-emitting diode LED3 is grounded through a resistor R48. 9. The USB function pin detection system according to claim 8, wherein the fast charging function unit comprises a resistor R4, a resistor R5, a resistor R6, and a resistor R7, and the resistor R4 and the resistor R6 are connected to form a first A series branch, the resistor R5 and the resistor R7 are connected to form a second series branch, one end of the first series branch and one end of the second series branch are both connected to the MCU unit, and the first series branch The other end of the MCU is also connected to the MCU unit, the other end of the second series branch is grounded, and the MCU unit is also connected between the resistor R4 and the resistor R6 and between the resistor R5 and the resistor R7, respectively.

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