Mobile terminals and docking stations with Type-C interfaces

Abstract

This invention provides a mobile terminal and a docking station with a Type-C interface. The mobile terminal includes an access device determination module for identifying the type of access device based on the voltages of the CC1 and CC2 pins of a first Type-C interface, and sending the access device type to a central processing module; a central processing module connected to the access device determination module for issuing a first control signal and a second control signal based on the type of access device; a first analog switch for selectively connecting to either the access device determination module or the central processing module based on the first control signal; a second analog switch for selectively connecting to either the access device determination module or the central processing module based on the second control signal; and a charging module connected to the VBUS pin of the first Type-C interface. This invention's Type-C interface mobile terminal, through circuit improvements, enables the mobile terminal to be used with a customized docking station.

Description

Technical Field

[0001] This invention relates primarily to the field of communication technology, and more particularly to a mobile terminal and docking station with a Type-C interface. Background Technology

[0002] Currently, more and more terminal devices are using Type-C interfaces. Since most devices now only have one Type-C interface, this interface is expected to not only provide charging functionality but also support some peripheral expansion functions. Therefore, the demand for docking stations with Type-C interfaces is increasing.

[0003] Currently, the most common docking station solution on the market is implemented through the PD protocol (Power Delivery). However, this method requires the addition of PD protocol chips that support dual roles on both the mobile terminal and the docking station, which increases hardware and debugging costs. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a mobile terminal and a docking station with a Type-C interface, thereby solving the problem that existing mobile terminals only support docking stations based on the PD protocol, which leads to high costs.

[0005] To address the aforementioned technical problems, this invention provides a mobile terminal with a Type-C interface, including a first Type-C interface, and further comprising: an access device determination module, configured to identify the type of access device based on the voltages of the CC1 and CC2 pins of the first Type-C interface, and send the access device type to a central processing module; a central processing module, connected to the access device determination module, configured to issue a first control signal and a second control signal based on the type of access device; a first analog switch, connected to the CC1 pin of the first Type-C interface, configured to selectively connect to the access device determination module or the central processing module based on the first control signal; a second analog switch, connected to the CC2 pin of the first Type-C interface, configured to selectively connect to the access device determination module or the central processing module based on the second control signal, wherein the default state of the first analog switch and the second analog switch is connected to the access device determination module; and a charging module, connected to the VBUS pin of the first Type-C interface.

[0006] Optionally, the central processing module includes a central processing unit and a pull-up unit. The central processing unit includes an ADC pin, which is connected to the first analog switch and the second analog switch through the ADC pin. The ADC pin is pulled up to a preset voltage by the pull-up unit.

[0007] Optionally, the access device determination module is used to determine the type of the access device according to the following strategy: when the voltages of both the CC1 pin and the CC2 pin are at a first preset value, the type of the access device is determined to be an earphone; when one of the voltages of the CC1 pin and the CC2 pin is at a second preset value, the type of the access device is determined to be a charging cable; when one of the voltages of the CC1 pin and the CC2 pin is at a third preset value, the type of the access device is determined to be an OTG cable or a docking station.

[0008] Optionally, when the central processing module receives a signal indicating that the access device is an earphone or a charging cable, it sends a first control signal and a second control signal as a non-switching instruction; the first analog switch and the second analog switch are used to select to continue connecting with the access device determination module according to the non-switching instruction.

[0009] Optionally, when the type of the access device is an OTG cable or a docking station, the central processing module is used to obtain the voltage of the CC1 pin and the voltage of the CC2 pin from the access device determination module, and determine whether the first control signal and the second control signal are a switching instruction or a non-switching instruction based on the voltage of the CC1 pin and the voltage of the CC2 pin; the first analog switch and the second analog switch are used to select to connect with the access device determination module according to the non-switching instruction, and select to connect with the central processing module according to the switching instruction.

[0010] Optionally, the central processing module is configured to: when the voltage of the CC1 pin is the third preset value, issue a first control signal as a no-switching instruction and a second control signal as a switching instruction; when the voltage of the CC2 pin is the third preset value, issue a first control signal as a switching instruction and a second control signal as a no-switching instruction.

[0011] Optionally, the central processing module is further configured to detect the voltage of the ADC pin, determine whether the voltage of the ADC pin is a fourth preset value, and if so, determine that the type of the access device is an OTG line.

[0012] Optionally, the central processing module is further configured to determine whether the voltage of the ADC pin is a fifth preset value; if so, it determines that the type of the access device is an expansion dock with a connected charger.

[0013] Optionally, the central processing module is further configured to determine whether the voltage of the ADC pin is a sixth preset value; if so, it determines that the type of the access device is an expansion dock without a charger connected.

[0014] Optionally, the central processing module is connected to the access device determination module via an I2C interface.

[0015] To address the aforementioned technical problems, this invention provides a docking station, including a second Type-C interface connected to a first Type-C interface of a mobile terminal. The station further includes: a first pull-down circuit comprising a first resistor connected to the CC2 pin of the second Type-C interface, the CC2 pin being pulled down to ground via the first resistor; a second pull-down circuit comprising a second resistor, a third resistor, and a transistor, the second resistor connected to the CC1 pin of the second Type-C interface, the CC1 pin being pulled down to ground via the second resistor, the second resistor also being connected in parallel with the third resistor, and the third resistor and the transistor being connected in series; and a charging interface connected to the VBUS pin of the second Type-C interface and the transistor.

[0016] Optionally, the transistor is an NMOS transistor, and the charging interface is connected to the gate of the NMOS transistor.

[0017] Optionally, the first resistor is 5.1K ohms and the second resistor is 100K ohms.

[0018] Optionally, the device also includes a diode, the anode of which is connected to the charging interface, and the cathode of which is connected to the VBUS pin of the Type-C interface.

[0019] Optionally, it also includes a USB interface, which is connected to the DP and DM pins of the second Type-C interface.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] The mobile terminal with a Type-C interface of the present invention identifies the type of access device through an access device determination module, and the first analog switch and the second analog switch selectively connect to the access device determination module or the central processing module, so that the mobile terminal can identify other general-purpose devices and can also be used with a customized expansion dock; the present invention also provides an expansion dock that does not need to include a PD protocol chip, which can save hardware costs and debugging costs. Attached Figure Description

[0022] The accompanying drawings are included to provide a further understanding of this application; they are incorporated into and constitute a part of this application. The drawings illustrate embodiments of this application and, together with this specification, serve to explain the principles of this application. In the drawings:

[0023] Figure 1 This is a system block diagram of a mobile terminal with a Type-C interface according to an embodiment of the present invention.

[0024] Figure 2 yes Figure 1 A circuit diagram of a mobile terminal with a Type-C interface according to one embodiment.

[0025] Figure 3 This is a circuit diagram of a headset that is the access device connected to a mobile terminal.

[0026] Figure 4 This is a circuit diagram of a mobile terminal connected to a standard charging cable.

[0027] Figure 5 This is a circuit diagram of the access device that the mobile terminal connects to, which is an OTG cable.

[0028] Figure 6 It is an expansion dock according to an embodiment of the present invention.

[0029] Figure 7 This is a circuit diagram of a docking station, which is the access device for mobile terminals. Detailed Implementation

[0030] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some examples or embodiments of this application. For those skilled in the art, these drawings can be applied to other similar scenarios without creative effort. Unless obvious from the context or otherwise specified, the same reference numerals in the drawings represent the same structures or operations.

[0031] More and more mobile terminals (such as mobile phones and handheld POS machines) are adopting Type-C as their charging and communication port. The Type-C interface is a bidirectional interface, functioning as either an upstream facing port (UFP) or a downstream facing port (DFP). When used as a UFP, the Type-C interface provides data transmission and power to external devices. When used as a DFP, it receives data transmission and charging from external devices. In other words, both ends of every USB Type-C cable are completely identical, meaning that the two connected devices must communicate with each other to determine whether they should function as a host or a peripheral.

[0032] Currently, the common docking station solution on the market uses the PD (Power Delivery) protocol. The power supply and data transmission directions are determined through a PD protocol handshake between the device and the docking station, enabling simultaneous charging and data transfer. However, this method requires dual-role PD protocol chips on both the device and the docking station, increasing hardware and debugging costs. This invention provides a docking station that does not require a PD protocol chip, saving costs. Furthermore, to ensure compatibility with this docking station, improvements have been made to mobile terminals with Type-C interfaces, enabling them to charge and transfer data with the docking station. Although the mobile terminal design has been modified, it does not affect the recognition of other common Type-C interface peripherals (OTG cables, Type-C analog headphones, ordinary charging cables, etc.).

[0033] Figure 1 This is a system block diagram of a mobile terminal with a Type-C interface according to an embodiment of the present invention. Figure 1 As shown, the mobile terminal 100 includes a first Type-C interface 11, a first analog switch 12, a second analog switch 13, an access device determination module 14, a central processing module 15, and a charging module 16. The first Type-C interface 11 includes, but is not limited to, VBUS pins, CC1 pins, and CC2 pins. The first analog switch 12 is connected to the CC1 pin of the first Type-C interface 11. The first analog switch 12 is used to receive a first control signal from the central processing module 15 and selectively connect to either the access device determination module 14 or the central processing module 15 according to the first control signal. The second analog switch 13 is connected to the CC2 pin of the first Type-C interface 11. The second analog switch 13 is used to receive a second control signal from the central processing module 15 and selectively connect to either the access device determination module 14 or the central processing module 15 according to the second control signal. The default state of the first analog switch 12 and the second analog switch 13 is connection to the access device determination module 14. The access device determination module 14 is used to identify the type of access device based on the voltage of the CC1 and CC2 pins of the first Type-C interface and send the access device type to the central processing module 15. The types of access devices include, but are not limited to, Type-C analog headphones, ordinary charging cables, OTG cables, and docking stations. Preferably, the access device determination module 14 includes a CC logic control chip (Configuration Channel Logic) U1, also known as CCLogic chip U1. A central processing module 15 is connected to the access device determination module 14, and the central processing module 15 is used to issue a first control signal and a second control signal according to the type of access device. The charging module 16 is connected to the VBUS pin of the first Type-C interface 11.

[0034] Figure 2 yes Figure 1 A circuit diagram of a mobile terminal with a Type-C interface according to one embodiment. Figure 2 As shown, the mobile terminal 100 includes a Type-C interface J1, analog switches U3 and U4, a CC Logic chip U1, a central processing module, and a charging module. The central processing module includes a central processing unit (CPU) and a resistor R1. Resistor R1 acts as a pull-up unit, pulling up the CPU's ADC pin to a preset voltage. Optionally, the preset voltage is 1.8V. The charging module includes a charging circuit U2 and a battery.

[0035] The CPU's GPIO1 pin is connected to the control terminal of analog switch U4, and the CPU's GPIO2 pin is connected to the control terminal of analog switch U3. The CC Logic chip U1 identifies the type of access device connected to the Type-C interface J1 through the voltage of its CC1 and CC2 pins and notifies the CPU via the I2C interface. The CPU issues a first control signal and a second control signal based on the type of access device. The first control signal is sent to analog switch U3 via the GPIO2 pin, and the second control signal is sent to analog switch U4 via the GPIO1 pin. Optionally, analog switches U3 and U4 are single-pole double-throw analog switches used to switch the connection positions of the CC1 and CC2 pins of the Type-C interface: one is switched to the CC1 and CC2 pins of the CC Logic chip U1, and the other is switched to the CPU's ADC pin. The default state of analog switches U3 and U4 is switched to the CC1 and CC2 pins of the CC Logic chip U1. Analog switches U3 and U4 switch according to the first and second control signals. The charging circuit U2 can charge the battery via an external VBUS power supply; at the same time, it can also boost the battery voltage to 5V and supply power to external connected devices via VBUS.

[0036] Figure 3 This is a circuit diagram showing the connection device (headphones) for a mobile terminal. Figure 3As shown, a mobile terminal (referred to as the device in the diagram) is connected to a Type-C analog headset. When the connected device is a Type-C analog headset, the headset connects to the Type-C interface J1 via Type-C interface J2. When a Type-C peripheral is plugged into the device, the CC1 and CC2 pins of the Type-C interface J1 on the device are connected to the CC1 and CC2 pins of the CC Logic chip U1 by default. Therefore, the type of device can be determined by the state of the CC1 or CC2 pins. Since the CC1 pin of the Type-C interface J2 of the Type-C analog headset is pulled down to ground through resistor R3, and the CC2 pin of the Type-C interface J2 is pulled down to ground through resistor R2, the CC Logic chip U1 can detect the voltage of the CC1 and CC2 pins. When the voltage of both the CC1 and CC2 pins is at a first preset value, it determines that the type of connected device is a headset. Optionally, the values ​​of resistors R2 and R3 are less than or equal to 800Ω. In other words, the CC1 and CC2 pins of the Type-C interface J2 are pulled down to ground through resistors of less than 800Ω.

[0037] Figure 4 This is a circuit diagram showing the connection device for a mobile terminal using a standard charging cable. (For example...) Figure 4 As shown, when the connected device is a standard charging cable, the cable connects to the Type-C interface J1 via Type-A. Since pin CC1 of the Type-A cable is pulled up to VBUS through resistor R3 (which can be 56kΩ), the CC Logic chip U1 detects the voltages of pins CC1 and CC2. When either pin's voltage reaches a second preset value, the connected device is determined to be a charging cable. The charging circuit U2 charges the battery via an external VBUS power supply.

[0038] The CC Logic chip U1 can determine the type of the connected device by the voltages of CC1 and CC2 and inform the CPU accordingly. When the CPU receives a connection indicating that the device type is headphones or a charging cable, it issues a first control signal and a second control signal as a no-switching instruction. Analog switches U3 and U4 are used to select whether to continue connecting to the CC1 and CC2 pins of the CC Logic chip U1 according to the no-switching instruction; that is, the states of analog switches U3 and U4 remain unchanged.

[0039] Figure 5 This is a circuit diagram of an OTG cable used to connect a mobile terminal to an access device. (Example:) Figure 5As shown, when the connected device is an OTG cable, the OTG cable is connected to the Type-C interface J1 via Type-C interface J2. One of the CC1 and CC2 pins of the Type-C interface J2 is pulled down to ground via a resistor, while the other is left floating. Taking the CC1 pin being pulled down to ground and the CC2 pin being floating as an example, the CC1 pin of the Type-C interface J2 is pulled down to ground via resistor R3, which can be 5.1K ohms. The CC2 pin of the Type-C interface J2 is left floating. The CC Logic chip U1 can detect the voltage of the CC1 and CC2 pins. When either the CC1 or CC2 pin voltage is at a third preset value, it determines that the connected device is either an OTG cable or a docking station.

[0040] When the CPU receives a connection from an OTG cable or docking station, it obtains the voltages of pins CC1 and CC2 from the CC Logic chip U1. Based on these voltages, it determines whether the first and second control signals are switching instructions or no-switching instructions. Optionally, when the voltage of pin CC1 is a third preset value, the first control signal is a no-switching instruction, and the second control signal is a switching instruction; when the voltage of pin CC2 is the third preset value, the first control signal is a switching instruction, and the second control signal is a no-switching instruction. In this embodiment, since pin CC1 is pulled down to ground through resistor R3, its voltage is the third preset value. The CPU then sends a no-switching instruction to analog switch U3 via GPIO2, and the state of analog switch U3 remains unchanged. The CPU then sends a switching instruction to analog switch U4 via GPIO1. Analog switch U4 switches pin CC2 of the Type-C interface J1 to the ADC pin according to the switching instruction. Since pin CC2 is floating, the voltage detected by the ADC is the preset voltage (e.g., 1.8V). The CPU is also used to detect the voltage of the ADC pin and determine whether the voltage of the ADC pin is the fourth preset value. If so, it determines that the type of the connected device is an OTG cable. The fourth preset value is equal to the preset voltage.

[0041] Figure 6 This is an expansion dock according to an embodiment of the present invention, which does not require a PD protocol chip, thus saving costs. Figure 6As shown, the docking station 600 includes a Type-C interface J2, a charging interface J3, a first pull-down circuit, and a second pull-down circuit. The first pull-down circuit includes resistor R2, which is connected to the CC2 pin of the Type-C interface J2. The CC2 pin is pulled down to ground through resistor R2, which can be 5.1K ohms. The second pull-down circuit includes resistors R3 and R4, and transistor Q1. Resistor R3 is connected to the CC1 pin of the second Type-C interface J2, and the CC1 pin is pulled down to ground through resistor R3, which can be 100K ohms. Resistor R3 is also connected in parallel with resistor R4, and resistor R4 is connected in series with transistor Q1. The charging interface J3 is connected to the VBUS pin of the second Type-C interface J2 and to transistor Q1.

[0042] Optionally, transistor Q1 is an NMOS transistor, and charging interface J3 is connected to the gate of the NMOS transistor. The NMOS transistor is turned on by the power supply of charging interface J3; the NMOS transistor will only turn on when power is plugged into charging interface J3.

[0043] Optionally, the docking station 600 also includes a diode Q2. The anode of diode Q2 is connected to the charging interface J3, and the cathode of diode Q2 is connected to the VBUS pin of the Type-C interface J2. Diode Q2 is a switch to prevent reverse power flow and is unidirectional. That is, when no power is plugged into the charging interface J3, the voltage output from the device will not flow back to the charging interface J3.

[0044] Optionally, the docking station 600 also includes a USB Type-A interface, which is connected to the DP and DM pins of the second Type-C interface J2. DP and DM are USB 2.0 signals. When the device enters HOST mode, the docking station can connect an external USB device via Type-A. There is at least one USB interface. The docking station of this invention does not need to include a PD protocol chip and can utilize the Type-C interface to achieve simultaneous charging and peripheral device use.

[0045] Figure 7 This is a circuit diagram of a docking station, the access device to which a mobile terminal connects. For example... Figure 7 As shown, at the docking station end, pin CC2 is directly pulled down to ground through resistor R2, which is 5.1K ohms. (See reference...) Figure 5As shown, when the connected device is an OTG cable, the CC1 pin of the Type-C interface J2 is pulled down to ground through resistor R3, which can be 5.1K ohms. Therefore, the CC Logic chip U1 can detect the voltages of the CC1 and CC2 pins. When either the CC1 or CC2 pin's voltage reaches a third preset value, it determines that the connected device is either an OTG cable or a docking station. In other words, when the inserted device causes either the CC1 or CC2 pin of the CC Logic chip U1 to be pulled down to ground through the 5.1KΩ resistor, it indicates that an external OTG cable or docking station is connected.

[0046] The specially designed expansion dock described in this invention has its CC2 pin pulled down to ground via a 5.1K resistor (resistor R2). The CPU sends a switching command to the analog switch U3 via GPIO2. The analog switch U3, based on the switching command, switches the CC1 pin of the Type-C interface J1 to connect to the ADC pin. For an expansion dock with a charger plugged into the charging interface J3, the ADC detects a voltage of 0.6V; for an expansion dock without a charger connected, the ADC detects a voltage of 0.9V. The voltage magnitude is used to determine whether the device is supplying power or the expansion dock is charging the device.

[0047] The CPU also determines whether the voltage of the ADC pin is the fifth preset value (e.g., 0.6V). If so, it determines that the type of the connected device is an expansion dock with a charger connected. The CPU also determines whether the voltage of the ADC pin is the sixth preset value (e.g., 0.9V). If so, it determines that the type of the connected device is an expansion dock without a charger connected.

[0048] In summary, the customized expansion dock of this invention does not require a PD protocol chip, thus saving costs. The mobile terminal with a Type-C interface of this invention identifies the type of access device through an access device determination module, and the first analog switch and the second analog switch selectively connect to the access device determination module or the central processing module, so that the mobile terminal can identify other general-purpose devices and can also be used with the customized expansion dock.

[0049] The basic concepts have been described above. Obviously, for those skilled in the art, the above disclosure is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0050] Furthermore, this application uses specific terms to describe embodiments of the application. For example, "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic related to at least one embodiment of the application. Therefore, it should be emphasized and noted that "an embodiment," "one embodiment," or "an alternative embodiment" mentioned twice or more in different locations in this specification do not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0051] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not specifically singular and may include plural forms. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0052] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0053] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. In addition, although the terminology used in this application is selected from commonly known and used terms, some terms mentioned in this application's specification may have been chosen by the applicant according to his or her judgment, and their detailed meanings are explained in the relevant sections of this description. Moreover, this application should be understood not only through the actual terms used, but also through the meaning implied by each term.

[0054] Some aspects of this application can be executed entirely by hardware, entirely by software (including firmware, resident software, microcode, etc.), or by a combination of hardware and software. The aforementioned hardware or software may be referred to as a "data block," "module," "engine," "unit," "component," or "system." The processor may be one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DAPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, or combinations thereof. Furthermore, aspects of this application may manifest as computer products residing in one or more computer-readable media, including computer-readable program code. For example, computer-readable media may include, but are not limited to, magnetic storage devices (e.g., hard disks, floppy disks, magnetic tapes, etc.), optical discs (e.g., compressed CDs, digital multifunction DVDs, etc.), smart cards, and flash memory devices (e.g., cards, sticks, key drives, etc.).

[0055] Similarly, it should be noted that, in order to simplify the description of the present application and thus aid in the understanding of one or more embodiments of the invention, the foregoing description of the embodiments of the present application sometimes combines multiple features into a single embodiment, drawing, or description thereof. However, this disclosure method does not imply that the subject matter of the application requires more features than those mentioned in the claims. In fact, the embodiments contain fewer features than all the features of the single embodiments disclosed above.

[0056] Although this application has been described with reference to specific embodiments, those skilled in the art should recognize that the above embodiments are only used to illustrate this application, and various equivalent changes or substitutions can be made without departing from the spirit of this application. Therefore, any changes or modifications to the above embodiments within the essential spirit of this application will fall within the scope of the claims of this application.

Claims

1. A mobile terminal with a Type-C interface, comprising a first Type-C interface, characterized in that, Also includes: The access device determination module is used to identify the type of access device based on the voltage of the CC1 and CC2 pins of the first Type-C interface, and send the type of access device to the central processing module. A central processing module, connected to the access device determination module, is used to issue a first control signal and a second control signal according to the type of the access device. When the type of the access device is received as an OTG cable or docking station, the central processing module obtains the voltage of the CC1 pin and the voltage of the CC2 pin from the access device determination module. When the voltage of the CC1 pin is a third preset value, the first control signal issued is a no-switching instruction and the second control signal is a switching instruction. When the voltage of the CC2 pin is the third preset value, the first control signal issued is a switching instruction and the second control signal is a no-switching instruction. A first analog switch is connected to the CC1 pin of a first Type-C interface and is used to selectively connect to the access device determination module or the central processing module according to the first control signal. The second analog switch is connected to the CC2 pin of the first Type-C interface and is used to selectively connect to the access device determination module or the central processing module according to the second control signal. The default state of the first analog switch and the second analog switch is connected to the access device determination module. The first analog switch and the second analog switch are used to select to connect to the access device determination module according to the no-switching instruction and to select to connect to the central processing module according to the switching instruction. The charging module is connected to the VBUS pin of the first Type-C interface.

2. The mobile terminal as described in claim 1, characterized in that, The central processing module includes a central processing unit and a pull-up unit. The central processing unit includes an ADC pin, which is connected to the first analog switch and the second analog switch through the ADC pin. The ADC pin is pulled up to a preset voltage by the pull-up unit.

3. The mobile terminal as described in claim 2, characterized in that, The access device determination module is used to determine the type of the access device according to the following strategy: When the voltages of both the CC1 and CC2 pins are at the first preset value, the type of the access device is determined to be an earphone; When either the voltage of the CC1 pin or the CC2 pin is a second preset value, the type of the access device is determined to be a charging cable; When the voltage of either the CC1 pin or the CC2 pin is a third preset value, the type of the access device is determined to be an OTG cable or a docking station.

4. The mobile terminal as described in claim 3, characterized in that, When the type of the access device is received as headphones or charging cable, the first control signal and the second control signal issued by the central processing module are non-switching instructions; the first analog switch and the second analog switch are used to select to continue connecting with the access device determination module according to the non-switching instructions.

5. The mobile terminal as described in claim 1, characterized in that, The central processing module is also used to detect the voltage of the ADC pin, determine whether the voltage of the ADC pin is a fourth preset value, and if so, determine that the type of the access device is an OTG line.

6. The mobile terminal as described in claim 1, characterized in that, The central processing module is also used to determine whether the voltage of the ADC pin is the fifth preset value. If it is, the type of the access device is determined to be an expansion dock with a connected charger.

7. The mobile terminal as described in claim 1, characterized in that, The central processing module is also used to determine whether the voltage of the ADC pin is the sixth preset value. If it is, the type of the access device is determined to be an expansion dock without a charger connected.

8. The mobile terminal as described in any one of claims 1 to 7, characterized in that, The central processing module is connected to the access device determination module via an I2C interface.

9. A docking station, comprising a second Type-C interface, wherein the second Type-C interface is connected to a first Type-C interface of a mobile terminal as described in any one of claims 1 to 7, characterized in that, Also includes: The first pull-down circuit includes a first resistor, which is connected to the CC2 pin of the second Type-C interface, and the CC2 pin is pulled down to ground through the first resistor; The second pull-down circuit includes a second resistor, a third resistor, and a transistor. The second resistor is connected to the CC1 pin of the second Type-C interface. The CC1 pin is pulled down to ground through the second resistor. The second resistor is also connected in parallel with the third resistor. The third resistor and the transistor are connected in series. The charging interface is connected to the VBUS pin of the second Type-C interface and to the transistor.

10. The expansion dock as described in claim 9, characterized in that, The transistor is an NMOS transistor, and the charging interface is connected to the gate of the NMOS transistor.

11. The expansion dock as described in claim 9, characterized in that, The first resistor is 5.1K ohms and the second resistor is 100K ohms.

12. The expansion dock as described in claim 9, characterized in that, It also includes a diode, the anode of which is connected to the charging interface, and the cathode of which is connected to the VBUS pin of the Type-C interface.

13. The expansion dock as described in claim 9, characterized in that, It also includes a USB interface, which is connected to the DP and DM pins of the second Type-C interface.

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