Type-C CC control signal acquisition and identification channel automatic switching circuit designed by using discrete device

Abstract

The invention discloses a Type-C CC control signal acquisition and identification channel automatic switching circuit designed by using discrete devices, the circuit comprises an interface module, a detection module, a logic module, an execution module and a terminal module, and the interface module adopts a Type-C connector as a physical port; the detection module monitors the levels of the CC1 and CC2 pins to determine the insertion direction of the plug; the logic module processes the direction signal to generate a control signal; the execution module switches a signal channel according to the control signal; and the terminal module communicates with the effective signal channel through the execution module. Equipment using the circuit can realize automatic switching of Type-C interface signal channels, and supports non-polar use of the interface.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit technology, and more specifically to an automatic channel switching circuit for acquiring and recognizing Type-CC control signals using discrete components. Background Technology

[0002] The Type-C interface has become the mainstream USB interface standard for electronic products, offering numerous advantages over earlier USB interfaces, such as eliminating the need for directional plugging / unplugging, providing more signal channels, supporting higher data transfer rates, and being compatible with more communication protocols and external devices. However, the Type-C interface has two sets of transceiver signal channels (TX1 / RX1 and TX2 / RX2), while most chips supporting USB 3.2 only have a single transceiver channel, requiring the CC signal line for direction identification and communication link establishment. Currently, the common practice is to use a dedicated Type-C CC protocol chip, but this is costly, and most devices require a main control chip, making it unsuitable for simple Type-C devices without an internal processor, thus limiting its application scope. Summary of the Invention

[0003] The purpose of this application is to provide an automatic channel switching circuit for the acquisition and identification of Type-C CC control signals using discrete components, which is used to realize the automatic switching of USB signal channels in the Type-C interface to support the non-polarity (reverse plugging and unplugging) use of the interface.

[0004] To achieve the above objectives, this application provides the following technical solution: an automatic channel switching circuit for acquiring and identifying Type-C CC control signals using discrete components, including an interface module: using a Type-C connector as the physical port of the system for establishing an electrical connection with an external Type-C cable or device, which has configuration channels CC1 and CC2, high-speed signal channels TX1 / RX1 and TX2 / RX2, and other signal pins; Detection module: Connected to the CC1 and CC2 pins of the interface module, used to continuously monitor the level status of the CC1 and CC2 pins and convert them into logic signals to determine the insertion direction of the plug; Logic module: Connected to the detection module, it receives the direction signal sent by the detection module, acts as a hardware state machine to perform debouncing and verification processing on the direction signal, and generates accurate, jitter-free control signals; Execution module: Connected to the logic module, it physically connects or disconnects the signal path according to the control signal of the logic module, thereby switching the signal channel; Terminal module: Connected to the execution module, serving as the core of the device's services, and communicating with the currently active signal channel through the execution module.

[0005] Preferably, the interface module includes: The Type-C PORT (connector J1), as the physical interface of the system, provides a connection to standard Type-C cables and has pins CC1, CC2, TX1 / RX1, TX2 / RX2, VBUS, GND, auxiliary channels SBU1 and SBU2. Resistors R1 and R2 are used for testing. Resistors R3 and R4 are used as auxiliary channel bias resistors; High-speed digital common-mode inductors L1-L5 are used to filter common-mode interference on signal lines; Low parasitic capacitance ESD transistors ED1-ED8 are used for electrostatic discharge protection.

[0006] Preferably, the detection module includes a dual-channel low-noise comparator LM393(U1) and a voltage divider network. The dual-channel low-noise comparator LM393(U1) is connected to the CC1 and CC2 pins of the interface module through the voltage divider network. According to the USB Type-C standard protocol, it identifies the voltage change caused by the configuration of the pull-up (Rp) and pull-down (Rd) resistors on the CC pin, compares the voltage values ​​of the two pins CC1 and CC2, determines the insertion direction of the plug, and outputs a digital logic signal representing the current connection status and direction.

[0007] Preferably, the logic module includes: The rectifier diode D1, capacitor C3, and resistor R15 are used to filter the CC1_LOW and CC2_LOW signals, converting the high-speed switching signals into analog signals. An amplifier circuit consisting of transistor Q1, resistors R19 and R17 amplifies the filtered signal. The driver stage, composed of transistor Q2, resistors R18, R20 and R21, improves the output switching speed and driving capability. The logic buffer U2 (such as SN74LVC2G07) performs level shaping on the logic signal output by transistor Q2 to achieve anti-jitter and output stable logic high and low level signals.

[0008] Preferably, the execution module includes multiple high-speed multiplexers, which contain multiple electronic switches, have two sets of inputs (corresponding to TX1 / RX1 and TX2 / RX2 of Type-C respectively) and one set of outputs (connected to the terminal module), and connect or disconnect the signal path according to the instructions of the control logic, while being responsible for the synchronous switching of the USB 2.0 D+ / D- signals and SBU signals.

[0009] Preferably, the execution module consists of two-stage multiplexers (U3, U4), wherein: The U3 (CH482x series) is a bidirectional analog multiplexer for high-speed USB differential signals, used to switch the connection direction of the TX / RX positive and negative pairs according to the direction control signal (CC1_MUX); The U4 (CH42E series) is a low-speed control signal multiplexing switch used to dynamically switch between the UART debug signal and the Type-C SBU channel based on the CC1_CC2_XOR control signal. Capacitors C5, C6, C7, C8, and C9 form a power supply filter circuit used to stabilize a multi-channel switching power supply.

[0010] Preferably, the terminal module is a storage controller or a USB hub, which communicates with the currently valid and unique set of signal channels through the execution module, without needing to have the ability to process Type-C logic.

[0011] Preferably, the device uses this automatic switching circuit to automatically switch the Type-C interface signal channel, supporting the use of the interface without polarity.

[0012] In summary, the technical effects and advantages of this invention are as follows: Significantly reduced costs: Traditional solutions using dedicated Type-C control chips are costly and have limited component supply cycles. This invention uses general-purpose discrete components to build the identification and switching circuit, with component costs far lower than dedicated chip solutions. This effectively reduces the overall BOM cost, and discrete components are widely available, making it suitable for cost control and supply chain optimization in mass production environments.

[0013] Flexible structure and high adjustability: The CC1 / CC2 signal detection network and control logic, implemented with discrete components, allow for flexible adjustment of resistor and capacitor parameters or logic polarity to meet different application requirements, and are compatible with various master control interfaces and signal standards. The multi-channel analog switch module can be independently configured with switching logic, facilitating the expansion of various interface modes (such as high-speed data / debugging dual mode), offering greater design freedom and scalability, and is suitable for various Type-C master and peripheral combination designs.

[0014] High reliability and easy debugging and maintenance: The circuit is based on hardware level analysis and discrete component logic control, eliminating the need for MCU software assistance and reducing identification failures caused by timing delays and firmware errors. The signal paths between functional modules are clear, allowing for individual debugging, testing, and optimization; in case of anomalies, testing and fault location are more intuitive, facilitating on-site maintenance.

[0015] Low power consumption and fast response: The identification circuit adopts a pure hardware signal level comparison and direct drive method, and the response is determined only by the RC time constant, resulting in fast speed and low power consumption. Low on-resistance analog switching devices are used for switching high-speed differential channels to ensure signal integrity and low interference characteristics.

[0016] The design boasts strong portability, reducing development workload: The universal hardware control interface signals (CC1_MIX, CC1_CC2_XOR) can directly connect to different main control platforms, reducing software adaptation and protocol design work. The same circuit architecture can adapt to different product models and application scenarios (such as USB communication ports, debug ports, expansion docks, etc.), shortening the overall R&D cycle. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart of an automatic channel switching circuit for acquiring and recognizing Type-C CC control signals using discrete components, as described in an embodiment of this application. Figure 2 This is a schematic diagram of the Type-C connector circuit in an embodiment of this application; Figure 3 This is a circuit diagram of the CC state detection and direction determination circuit in an embodiment of this application; Figure 4 This is a circuit diagram of the hardware state machine of the control logic generator in the embodiments of this application; Figure 5 This is a circuit diagram of a high-speed signal switching switch in an embodiment of this application. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] In the description of this disclosure, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this disclosure. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] In this document, the term "comprising" is intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0022] Example: An automatic channel switching circuit for Type-C CC control signal acquisition and identification designed using discrete components, comprising: (a) Interface module The interface module uses a Type-C connector (Type-C PORT, i.e., connector J1) as the physical port of the system. It is the bridge for establishing an electrical connection between the entire circuit and external Type-C cables or devices, and has configuration channels CC1 and CC2, high-speed signal channels TX1 / RX1 and TX2 / RX2, as well as other signal pins such as VBUS, GND, auxiliary channel SBU1 and SBU2 pins, etc.

[0023] Resistors R1 and R2 serve as test resistors, playing a role in circuit debugging or testing, facilitating the measurement and verification of specific parameters.

[0024] Resistors R3 and R4 serve as auxiliary channel bias resistors, providing appropriate bias voltages for auxiliary channels SBU1 and SBU2 to ensure stable signal transmission in these channels.

[0025] High-speed digital common-mode inductors L1-L5 are installed on the corresponding signal lines, and their main function is to filter common-mode interference on the signal lines. During high-speed signal transmission, common-mode interference can affect signal quality. Common-mode inductors can effectively suppress this interference and ensure signal purity.

[0026] Low parasitic capacitance ESD transistors ED1-ED8 are connected to each critical signal pin for electrostatic discharge (ESD) protection. When an ESD event occurs, the ESD transistors quickly conduct, diverting the static charge to ground, preventing damage to other components in the circuit and protecting the stability and reliability of the entire circuit.

[0027] (II) Detection Module The detection module mainly consists of a dual-channel low-noise comparator LM393 (U1) and a voltage divider network. It is connected to the CC1 and CC2 pins of the interface module to continuously monitor the voltage levels of these two pins.

[0028] According to the USB Type-C standard protocol, when the plug is inserted, the CC pin has pull-up (Rp) and pull-down (Rd) resistors. Different orientations will result in different voltages on the CC1 and CC2 pins. A voltage divider network divides the voltages on the CC1 and CC2 pins and then inputs them to a dual low-noise comparator U1. The comparator compares these two voltage values, determines the insertion orientation of the plug based on the comparison result, and outputs a digital logic signal representing the current connection state and orientation. For example, if the voltage on the CC1 pin is higher than the voltage on the CC2 pin, the comparator may output a high-level signal to indicate one insertion orientation; conversely, it will output a low-level signal to indicate the other insertion orientation.

[0029] (III) Logic Module The logic module receives the direction signal from the detection module, performs debouncing and verification processing on it, and generates a precise, jitter-free control signal.

[0030] The circuit consisting of rectifier diode D1, capacitor C3, and resistor R15 filters the CC1_LOW and CC2_LOW signals. Since the signal output by the detection module may contain high-speed jumps and noise, this filtering circuit can convert it into a smoother analog signal, removing high-frequency noise and interference.

[0031] The amplifier circuit consisting of transistor Q1, resistors R19 and R17 amplifies the filtered signal. Because the filtered signal may have a small amplitude, insufficient to drive subsequent circuits, the amplifier circuit strengthens the signal, making it capable of driving the subsequent circuits.

[0032] The driver stage, composed of transistor Q2, resistors R18, R20, and R21, further improves the output switching speed and driving capability. In practical applications, rapid and stable switching of signal channels is required, and the role of the driver stage is to ensure that the control signal can control the action of the execution module in a timely and effective manner.

[0033] The logic buffer U2 (such as SN74LVC2G07) performs level shaping on the logic signal output by transistor Q2 to achieve anti-jitter functionality. After the series of processing steps, the logic signal may still have some minor jitter. The logic buffer can remove this jitter and output a stable logic high and low level signal as the final control signal.

[0034] (iv) Execution Module The execution module physically connects or disconnects the signal path according to the control signals from the logic module, thereby switching the signal channel. It includes multiple high-speed multiplexers, contains multiple electronic switches, and has two sets of inputs (corresponding to TX1 / RX1 and TX2 / RX2 of Type-C respectively) and one set of outputs (connected to the terminal module).

[0035] In this embodiment, the execution module consists of two-stage multiplexers (U3, U4): The U3 (CH482x series) is a bidirectional analog multiplexer for high-speed USB differential signals, used to switch the connection direction of the TX / RX positive and negative pairs according to the direction control signal (CC1_MUX). When the control signal output by the logic module indicates that the plug is inserted in a certain direction, the U3 will connect the corresponding TX1 / RX1 or TX2 / RX2 signal to the output terminal accordingly, ensuring that the high-speed differential signal can be transmitted correctly.

[0036] The U4 (CH42E series) is a low-speed control signal multiplexing switch used to dynamically switch between the UART debug signal and the Type-C SBU channel based on the CC1_CC2_XOR control signal. In different operating modes, switching between the UART debug signal and the SBU channel signal may be required, and the U4 can flexibly accomplish this task based on the control signal.

[0037] Capacitors C5, C6, C7, C8, and C9 form a power supply filter circuit, connected to the power supply pins of the multiplexer, to stabilize the power supply to the multiplexer. A stable power supply is crucial for the normal operation of the multiplexer; the filter circuit removes ripple and noise from the power supply, ensuring the multiplexer operates in a stable power environment.

[0038] (v) Terminal Module The terminal module, which can be a storage controller or USB hub, communicates with the currently active, unique set of signal channels via the execution module. The terminal module does not need to handle Type-C logic, as the switching of signal channels and the processing of Type-C interface logic are already handled by the preceding modules. For example, when the execution module activates the TX1 / RX1 signal channel according to a control signal, the terminal module can then transmit data with external devices through that channel.

[0039] Overall workflow: When an external Type-C connector is inserted into the interface module, the detection module starts working. By monitoring the level changes of the CC1 and CC2 pins, it determines the insertion direction of the connector and outputs a digital logic signal. The logic module receives this signal, and after filtering, amplification, and shaping, generates a stable control signal. The execution module, based on the control signal, switches the corresponding signal channel through an internal multiplexer, enabling the terminal module to establish an effective communication connection with the external device. Throughout the process, regardless of whether the connector is inserted correctly or incorrectly, the circuit automatically switches the signal channel, ensuring normal data transmission and achieving polarity-free use of the Type-C interface.

[0040] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An automatic channel switching circuit for acquiring and recognizing Type-C CC control signals using discrete components, characterized in that, include: Interface module: It adopts a Type-C connector as the physical port of the system to establish an electrical connection with external Type-C cables or devices. It has configuration channels CC1 and CC2, high-speed signal channels TX1 / RX1 and TX2 / RX2 and other signal pins. Detection module: Connected to the CC1 and CC2 pins of the interface module, used to continuously monitor the level status of the CC1 and CC2 pins and convert them into logic signals to determine the insertion direction of the plug; Logic module: Connected to the detection module, it receives the direction signal sent by the detection module, acts as a hardware state machine to perform debouncing and verification processing on the direction signal, and generates accurate, jitter-free control signals; Execution module: Connected to the logic module, it physically connects or disconnects the signal path according to the control signal of the logic module, thereby switching the signal channel; Terminal module: Connected to the execution module, serving as the core of the device's services, and communicating with the currently active signal channel through the execution module.

2. The automatic switching circuit for Type-C interface signal channels according to claim 1, characterized in that, The interface module includes: The Type-C PORT, as the physical interface of the system, provides a connection to a standard Type-C cable and has CC1, CC2, TX1 / RX1, TX2 / RX2, VBUS, GND, auxiliary channel SBU1 and SBU2 pins. Resistors R1 and R2 are used for testing. Resistors R3 and R4 are used as auxiliary channel bias resistors; High-speed digital common-mode inductors L1-L5 are used to filter common-mode interference on signal lines; Low parasitic capacitance ESD transistors ED1-ED8 are used for electrostatic discharge protection.

3. The automatic switching circuit for Type-C interface signal channels according to claim 1, characterized in that, The detection module includes a dual-channel low-noise comparator LM393 and a voltage divider network. The dual-channel low-noise comparator LM393 is connected to the CC1 and CC2 pins of the interface module through the voltage divider network. According to the USB Type-C standard protocol, it identifies the voltage change caused by the pull-up and pull-down resistor configuration on the CC pin, compares the voltage values ​​of the two pins CC1 and CC2, determines the insertion direction of the plug, and outputs a digital logic signal representing the current connection status and direction.

4. The automatic switching circuit for Type-C interface signal channels according to claim 1, characterized in that, The logic module includes: The rectifier diode D1, capacitor C3, and resistor R15 are used to filter the CC1_LOW and CC2_LOW signals, converting the high-speed switching signals into analog signals. An amplifier circuit consisting of transistor Q1, resistors R19 and R17 amplifies the filtered signal. The driver stage, composed of transistor Q2, resistors R18, R20 and R21, improves the output switching speed and driving capability. The logic buffer U2 performs level shaping on the logic signal output by transistor Q2 to achieve anti-jitter and output stable logic high and low level signals.

5. The automatic switching circuit for Type-C interface signal channels according to claim 1, characterized in that, The execution module includes multiple high-speed multiplexers, each containing multiple electronic switches. It has two sets of inputs and one set of outputs. According to the instructions of the control logic, it connects or disconnects the signal path, and is also responsible for the synchronous switching of the USB 2.0 D+ / D- signals and SBU signals.

6. The automatic switching circuit for Type-C interface signal channels according to claim 5, characterized in that, The execution module consists of two levels of multiplexers, wherein: U3 is a bidirectional analog multiplexer for USB high-speed differential signals, used to switch the connection direction of the TX / RX positive and negative pairs according to the direction control signal; U4 is a low-speed control signal multiplexing switch, used to dynamically switch between UART debug signals and Type-C SBU channels based on the CC1_CC2_XOR control signals; Capacitors C5, C6, C7, C8, and C9 form a power supply filter circuit used to stabilize a multi-channel switching power supply.

7. The automatic switching circuit for Type-C interface signal channels according to claim 1, characterized in that, The terminal module is a storage controller or a USB hub.

8. A device using the Type-C interface signal channel automatic switching circuit as described in any one of claims 1-7, characterized in that, The device uses this automatic switching circuit to automatically switch the Type-C interface signal channel, supporting the use of the interface without polarity.

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