USB HUB chip, device and mobile device

Abstract

The utility model discloses a USB HUB chip, a device and a mobile device. The USB HUB chip includes a control unit, a routing module, a mode input pin, an edge detection circuit, a timer and a switching module. The mode input pin, the edge detection circuit, the timer and the switching module are all connected to the control unit, and the mode input pin is connected to the edge detection circuit; at least a first USB transceiver, a second USB transceiver, at least a first USB port and a second USB port, the device and the mobile device all include a USB HUB chip, and the first USB port and the second USB port can be externally connected to a host or a device. The utility model can switch the upstream port of the USB HUB, has a simple structure, low cost, and does not affect the transmission effect.

Description

Technical Field

[0001] The utility model relates to USB communication technology, in particular to a USB HUB (hub) chip, a device and a mobile device. Background Art

[0002] USB HUB is a USB hub, which is a commonly used computer peripheral device. It can be used to expand the USB host port for PC (computer), PAD (tablet), POS machine, handheld game console or other mobile devices. The main functions and technical characteristics of HUB are defined in a special chapter in the USB specification. As a device or system, HUB usually consists of a single HUB chip plus a small amount of auxiliary circuits. In applications, the upstream port (upstream facing port) of HUB is usually connected to the USB host port of a computer or tablet as a USB device. Multiple USB downstream ports (downstream facing ports) are extended from HUB, each of which is used as a USB host port to connect to several USB devices.

[0003] With the diversification of mobile devices and USB communication technology application scenarios, the traditional HUB with a single upstream port and multiple downstream ports no longer meets the requirements. For example, in some mobile devices, the main control chip expands multiple USB downstream ports through the HUB chip, which are respectively connected to the USB keyboard, USB collector, and USB printer. The first working scenario is that the mobile device acts as a USB root host, and its main control chip is connected to the upstream port of the HUB chip; the second working scenario is that the mobile device is connected to a PC (or server) through a USB port. At this time, the computer is the final USB root host, and the mobile device is only used as a USB device. Its main control chip should be connected to the downstream port of the HUB chip. For this type of switchable upstream port application, the current solution is to use two pairs of external analog switches. The upstream port PHY1 has a built-in pull-up resistor Rpu1, and the downstream port PHY1 has a built-in pull-down resistor Rpd2. The downstream ports PHY3, PHY4, and PHY5 are the same as PHY2, which are simplified in the figure. Figure 1 As shown in the figure, the main control chip switches the upstream port and downstream port of the HUB through two sets of analog switches according to the instructions. The figure is only for illustration. In fact, each set of analog switches includes two, which control the D+ and D- lines of the USB port respectively. However, since the analog switch chip inevitably has a few ohms of on-resistance and a few pF of pin capacitance, when it is connected in series in the 480Mbps, 5Gbps or even 40Gbps USB communication line, it will affect the transmission line characteristic impedance to generate signal reflection and significantly reduce the quality of USB signals, especially the high-frequency attenuation is more obvious, resulting in a shorter transmission distance, and even failing to pass the signal eye diagram (Eye Diagrams) compliance test defined in the USB specification. Summary of the invention

[0004] Purpose of the invention: In order to solve the problem in the prior art that the traditional USB HUB uses an external analog switch to switch the upstream port, which affects signal transmission, the utility model provides a USB HUB chip, device and mobile device.

[0005] Technical solution: A USB HUB chip, including:

[0006] Control unit;

[0007] Routing module;

[0008] Mode input pin, connected to the input end of the edge detection circuit and the control unit;

[0009] An edge detection circuit, the output end of which is connected to a control unit;

[0010] Timer, connected to the control unit;

[0011] at least a first USB transceiver and a second USB transceiver;

[0012] At least a first USB port and a second USB port, the first USB port is connected to a first USB transceiver, and the second USB port is connected to a second USB transceiver, the first USB transceiver and the second USB transceiver are both dual-mode transceivers supporting USB host and device, and both are built-in host pull-down resistors and device pull-up resistors that comply with USB specifications, and whether the host pull-down resistors and the device pull-up resistors are enabled is controlled by a control unit;

[0013] The switching module includes a first physical end, a second physical end, a first digital end, a second digital end and a control end, wherein the first physical end, the second physical end, the first digital end, the second digital end and the control end are respectively connected to a first USB transceiver, a second USB transceiver, an upstream port of a routing module, a downstream port of the routing module and a control unit.

[0014] Furthermore, it also includes a detection and identification circuit, one end of which is connected to the second USB port, and the other end is connected to the control unit, and the detection and identification circuit is used to detect and identify the USB host or device connected to the second USB port.

[0015] Furthermore, the detection and identification circuit includes a voltage detection circuit, one end of the voltage detection circuit is connected to the second USB port, and the other end of the voltage detection circuit is connected to the control unit.

[0016] Furthermore, the control unit directly controls the host pull-down resistor and the device pull-up resistor in the first USB transceiver and the second USB transceiver, or the control unit indirectly controls the host pull-down resistor and the device pull-up resistor in the first USB transceiver and the second USB transceiver through a switching module.

[0017] Furthermore, the edge detection circuit is used to provide at least one of a reset input signal and a wake-up input signal to the control unit.

[0018] Furthermore, the control unit is a HUB controller or a microcontroller.

[0019] Furthermore, the switching module is implemented by a digital logic circuit, and the switching module includes a first state and a second state. When in the first state, the first USB port is connected to the upstream port of the routing module, and the second USB port is connected to the downstream port of the routing module; when in the second state, the first USB port is connected to the downstream port of the routing module, and the second USB port is connected to the upstream port of the routing module.

[0020] A USB HUB device includes the above-mentioned USB HUB chip.

[0021] A mobile device comprises the above-mentioned USB HUB chip and a main control chip, wherein the first USB port of the USB HUB chip is connected to the USB pin of the main control chip, the mode input pin of the USB HUB chip is connected to the I / O control pin of the main control chip; and the second USB port of the USB HUB chip is connected to the external USB port of the mobile device.

[0022] Furthermore, it also includes a bias voltage circuit, which includes a weak pull-up resistor and a weak pull-down resistor, both of which are connected to the D+ pin of the second USB port of the USB HUB chip. The weak pull-up resistor and the weak pull-down resistor divide the voltage so that the D+ pin of the second USB port is in the range of 0.4V to 0.75V when the second USB port is idle, and the resistance range of the weak pull-down resistor is 30KΩ to 300KΩ.

[0023] Compared with the prior art, the USB HUB chip, device and mobile device provided by the utility model have the following beneficial effects:

[0024] (1) The upstream port of the USB HUB can be switched as needed, so that the same USB port can be used as an upstream port to connect to a USB host or as a downstream port to connect to a USB device; in particular, for mobile devices containing the USB HUB chip, it can detect and identify the type of device connected to the external USB port, so as to automatically switch to the upstream port, making its application more convenient;

[0025] (2) The circuit structure is simple, the high-frequency radiation is small, and it can all be built into a single chip;

[0026] (3) It can be realized without external analog switches, saving two pairs of external analog switches and low cost;

[0027] (4) There is no on-resistance and pin capacitance of the external analog switch, which makes the transmission high-frequency characteristics good and the transmission distance long, in line with USB technical specifications and can ensure the compatibility of the USB interface. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of a USB HUB upstream port switching circuit in the prior art;

[0029] Figure 2 This is a schematic diagram of the main internal structure of the USB HUB chip in Example 1;

[0030] Figure 3 This is a schematic diagram of an application of a mobile device containing a USB HUB chip in Example 1;

[0031] Figure 4 This is a connection diagram of the detection and identification circuit in the second embodiment. DETAILED DESCRIPTION

[0032] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments.

[0033] Embodiment 1:

[0034] A USB HUB chip, such as Figure 2 ,include:

[0035] Control unit;

[0036] Routing module;

[0037] Mode input pin, connected to the input end of the edge detection circuit and the control unit;

[0038] An edge detection circuit, the output end of which is connected to the control unit, and is used to provide at least one of a reset input signal and a wake-up input signal to the control unit;

[0039] Timer, connected to the control unit;

[0040] At least the first USB transceiver PHY1 and the second USB transceiver PHY2 are usually HUB-specific PHYs, which are connected to the D+ and D- pins, as well as the RX+ / RX- and TX+ / TX- pins of the Super Speed ​​USB to achieve USB signal reception and transmission. For example, in this embodiment, there are five USB transceivers (PHYs), and a common USB HUB has five USB transceivers (including one upstream port and four downstream ports). Other numbers of USB transceivers can also be set as needed;

[0041] At least a first USB port and a second USB port, for example, there are five USB ports in this embodiment, and one USB port corresponds to one USB transceiver. The first USB port is connected to the first USB transceiver, and the second USB port is connected to the second USB transceiver. The first USB transceiver and the second USB transceiver are both dual-mode transceivers that support USB hosts and devices, and both have built-in host (Host) pull-down resistors Rpd1 (D+ and D- in pairs), Rpd2 (D+ and D- in pairs) and device (Device) pull-up resistors Rpu1, Rpu2 that comply with the USB specification. The host pull-down resistor and the device pull-up resistor are controlled by the control unit to be enabled or not. In practice, each host pull-down resistor and device pull-up resistor can be connected in series with the switch respectively, and the control unit controls the opening / closing of the switch, thereby enabling the host pull-down resistor or the device pull-up resistor. Usually Rpd takes 15 KΩ and Rpu takes 1.5 KΩ. In addition, the present embodiment further comprises a third USB transceiver, a fourth USB transceiver, a fifth USB transceiver and a third USB port, a fourth USB port and a fifth USB port, wherein the third USB transceiver, the fourth USB transceiver and the fifth USB transceiver support USB host mode, have a built-in host pull-down resistor and are connected to an external device. In addition, one or all of the third to fifth USB ports may also be designed as a USB port identical to the second USB port, and may be connected to both a USB host and a USB device.

[0042] The switching module includes a first physical terminal A1, a second physical terminal A2, a first digital terminal B1, a second digital terminal B2 and a control terminal C. The first physical terminal A1, the second physical terminal A2, the first digital terminal B1, the second digital terminal B2 and the control terminal C are respectively connected to a first USB transceiver, a second USB transceiver, an upstream port of a routing module, a downstream port of a routing module and a control unit. The switching module is implemented by digital logic circuits such as an AND gate, an OR gate, and a MUX selector. The switching module includes a first state and a second state. When in the first state, the first USB port is connected to the upstream port of the routing module, and the second USB port is connected to the downstream port of the routing module; when in the second state, the first USB port is connected to the downstream port of the routing module, and the second USB port is connected to the upstream port of the routing module. Under the control of the control unit, the switching module selects which of PHY1 and PHY2 is connected to the upstream port of the routing module and which is connected to the downstream port, thereby selecting which of the first USB port and the second USB port is used as the upstream port and which is used as the downstream port.

[0043] The host pull-down resistor and device pull-up resistor can be as follows Figure 2 As shown, the control unit is directly connected and controlled. Obviously, the control unit can also indirectly control or select the levels of these control signals through the switching module to achieve the same effect.

[0044] The control unit is a HUB controller or a microcontroller.

[0045] The mode input pin is used to input a mode signal to indicate which port the upstream port is switched to. On the one hand, as a serial bus that supports real-time plug-in and unplugging, direct hard switching of the upstream port usually causes misjudgment of USB connection and disconnection detection and affects signal integrity. On the other hand, the USB HUB must support sleep, and the mode input pin cannot affect the USB HUB entering or exiting the sleep state regardless of whether it is at a high level or a low level. The system clock of the USB HUB in sleep is usually turned off. In this embodiment, an edge detection circuit (or change detection circuit) is connected to the output end of the mode input pin to asynchronously wake up the USB HUB in sleep, and the change of the mode input pin is used as the starting point to suspend the function of the USB HUB or reset the USB HUB. After the timer is set for a period of time, the control unit controls the switching module according to the new level of the mode input pin, and turns on the built-in device pull-up resistor or host pull-down resistor of the corresponding PHY. Based on the cooperation of the edge detection circuit, the timer and the control unit, it is ensured that the level state of the module input pin does not affect entering sleep, and can exit sleep when changing, ensuring the integrity of USB disconnection and connection and complying with USB specifications.

[0046] In the default state, the first USB port of the USB HUB is the upstream port, and the second USB port is the downstream port. The mode signal is input through the mode input pin. When the upstream port needs to be switched, the mode signal will change. The edge detection circuit can detect the signal change and transmit it to the control unit to reset or pause the USB HUB. The timer starts timing and ends the reset or pause after the timing. At the same time, the mode input pin will also transmit the mode signal to the control unit. After the timing ends, the control unit switches according to the mode signal, controls the switching module to connect the second USB port to the upstream port of the routing module, and the first USB port to the downstream port of the routing module. At the same time, PHY1 is controlled to turn on the host pull-down resistor, and PHY2 is controlled to turn on the device pull-up resistor.

[0047] A USB HUB device includes the above-mentioned USB HUB chip.

[0048] A mobile device, comprising the above-mentioned USB HUB chip, and also comprising a main control chip, such as Figure 3 As shown, the first USB port of the USB HUB chip is connected to the USB pin of the main control chip, and the mode input pin is connected to the I / O control pin of the main control chip and is driven by the main control chip. The second USB port of the USB HUB chip is connected to the external USB port of the mobile device. When a USB device is connected, the second USB port serves as the HUB downstream port. When a USB host (or server) is connected, the second USB port can be switched to an upstream port. The remaining USB ports (the third USB port, the fourth USB port, and the fifth USB port) are used to connect USB devices, respectively connected to various USB chips onboard the mobile device and / or connected to the external USB downstream port of the mobile device to support the insertion of external USB devices.

[0049] The built-in upstream port switching of the USB HUB chip is implemented by a switching module, which is implemented by a digital logic circuit. Compared with the external analog switch in the prior art, the chip area and cost of the former digital logic switching module are less than 1% of the latter; and the former works before the physical layer transceiver PHY module, and does not affect the high-frequency characteristics and eye diagram compliance test of the PHY output signal, while the latter analog switch is connected in series after the PHY output signal, and its on-resistance will affect the impedance matching and cause signal reflection, and its switch capacitance and pin capacitance will produce high-frequency attenuation affecting the eye diagram compliance test.

[0050] Embodiment 2:

[0051] Embodiment 2 is based on Embodiment 1, and a detection and identification circuit is added to facilitate automatic detection of whether the second USB port is connected to a host or a device. The detection and identification circuit includes a voltage detection circuit and a bias voltage circuit. The voltage detection circuit is located in the HUB chip, and the bias voltage circuit is located outside the chip. The bias voltage circuit and the voltage detection circuit are both connected to the second USB port, and the voltage detection circuit is connected to the control unit. The detection and identification circuit is used to detect and identify the USB host or device connected to the second USB port. When the second USB port is connected to a USB host or a USB device, the detection and identification circuit provides different signals to the control unit, and the control unit controls the switching of the upstream port or downstream port state in combination with the state of PHY2.

[0052] like Figure 4 As shown, it is an embodiment of the bias voltage circuit in the detection and identification circuit. The bias voltage circuit includes a weak pull-up resistor and a weak pull-down resistor, and the weak pull-up resistor and the weak pull-down resistor are both connected to the D+ pin of the second USB port of the USB HUB chip. The weak pull-up resistor and the weak pull-down resistor divide the voltage so that the D+ pin of the second USB port is in the range of 0.4V to 0.75V when the second USB port is idle, and the resistance range of the weak pull-down resistor is 30KΩ to 300KΩ. For example, in this embodiment, the weak pull-up resistor is selected as 330 KΩ, connected between the 3.3V power supply and the D+ pin; the weak pull-down resistor is selected as 75 KΩ, connected between the D+ pin and the ground. When connected to the USB host, the D+ pin drops below 0.2V, and when connected to the USB device, the D+ pin rises above 2V, which is detected and identified by the voltage detection circuit.

[0053] The second embodiment can automatically detect and identify the type of device connected to the external USB port, so as to automatically switch to the upstream port, making its application more convenient.

Claims

1. A USB HUB chip, characterized in that: include: Control unit; Routing module; Mode input pin, connected to the input end of the edge detection circuit and the control unit; An edge detection circuit, the output end of which is connected to a control unit; Timer, connected to the control unit; at least a first USB transceiver and a second USB transceiver; At least a first USB port and a second USB port, the first USB port is connected to a first USB transceiver, and the second USB port is connected to a second USB transceiver, the first USB transceiver and the second USB transceiver are both dual-mode transceivers supporting USB host and device, and both are built-in host pull-down resistors and device pull-up resistors that comply with USB specifications, and whether the host pull-down resistors and the device pull-up resistors are enabled is controlled by a control unit; The switching module includes a first physical end, a second physical end, a first digital end, a second digital end and a control end, wherein the first physical end, the second physical end, the first digital end, the second digital end and the control end are respectively connected to a first USB transceiver, a second USB transceiver, an upstream port of a routing module, a downstream port of the routing module and a control unit.

2. The USB HUB chip according to claim 1, characterized in that: It also includes a detection and identification circuit, one end of which is connected to the second USB port and the other end is connected to the control unit. The detection and identification circuit is used to detect and identify a USB host or device connected to the second USB port.

3. The USB HUB chip according to claim 2, characterized in that: The detection and identification circuit comprises a voltage detection circuit, one end of the voltage detection circuit is connected to the second USB port, and the other end of the voltage detection circuit is connected to the control unit.

4. The USB HUB chip according to any one of claims 1 to 3, characterized in that: The control unit directly controls the host pull-down resistor and the device pull-up resistor in the first USB transceiver and the second USB transceiver, or indirectly controls the host pull-down resistor and the device pull-up resistor in the first USB transceiver and the second USB transceiver through a switching module.

5. The USB HUB chip according to any one of claims 1 to 3, characterized in that: The edge detection circuit is used to provide at least one of a reset input signal and a wake-up input signal to the control unit.

6. The USB HUB chip according to any one of claims 1 to 3, characterized in that: The control unit is a HUB controller or a microcontroller.

7. The USB HUB chip according to any one of claims 1 to 3, characterized in that: The switching module is implemented by a digital logic circuit, and the switching module includes a first state and a second state. When in the first state, the first USB port is connected to the upstream port of the routing module, and the second USB port is connected to the downstream port of the routing module; when in the second state, the first USB port is connected to the downstream port of the routing module, and the second USB port is connected to the upstream port of the routing module.

8. A USB HUB device, characterized in that: The invention comprises a USB HUB chip as described in any one of claims 1 to 7.

9. A mobile device, characterized in that: The USB HUB chip comprises any one of claims 1 to 7, and also comprises a main control chip, wherein the first USB port of the USB HUB chip is connected to the USB pin of the main control chip, the mode input pin of the USB HUB chip is connected to the I / O control pin of the main control chip; and the second USB port of the USB HUB chip is connected to the external USB port of the mobile device.

10. The mobile device according to claim 9, characterized in that The device also includes a bias voltage circuit, which includes a weak pull-up resistor and a weak pull-down resistor. Both the weak pull-up resistor and the weak pull-down resistor are connected to the D+ pin of the second USB port of the USB HUB chip. The weak pull-up resistor and the weak pull-down resistor divide the voltage so that the D+ pin of the second USB port is in the range of 0.4V to 0.75V when the second USB port is idle, and the resistance range of the weak pull-down resistor is 30KΩ to 300KΩ.

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