A USB master-slave switching circuit of a multimedia screen, a multimedia screen and a multimedia system

Abstract

The application discloses a USB master-slave switching circuit of a multimedia screen and a vehicle-mounted multimedia system, which comprises a microprocessor MPU, a first analog switch, a second analog switch, a USB hub, a detection circuit and a USB interface connector; the microprocessor MPU is connected with a channel switching common terminal of the first analog switch through a USB end; a first channel end of the first analog switch is connected with a first channel end of the second analog switch, and a second channel end of the first analog switch is connected with an input end of the USB hub; a common terminal of the second analog switch is connected with a USB port in the USB interface connector, and a second channel end of the second analog switch is connected with an output of the USB hub; and other outputs of the USB hub are connected with other USB ports of the USB interface connector respectively. The application is aimed at the multimedia screen with only one USB port of the MPU, and solves the problems of USB port expansion and OTG function reservation through a low-cost USB master-slave switching circuit.

Description

Technical Field

[0001] This invention relates to the field of USB technology, and in particular to a USB master-slave switching circuit for a multimedia screen and an in-vehicle multimedia system. Background Technology

[0002] With technological advancements, the trend towards intelligent automotive cockpits is gradually becoming mainstream. Customer demand for multiple USB channels is also increasingly evident. Multimedia screen hosts, in addition to connecting to standard USB flash drives, may also need to connect external devices such as TBOX, instrument clusters, and DABs. Currently, to adapt to rapid application iterations, MPU manufacturers are increasingly using mobile phone chips to modify their automotive specifications. MPUs modified for automotive use typically only have one USB port, posing a challenge to product development and design. This necessitates adding a HUB chip (USB HUB) to meet the demand for multiple USB ports. However, adding a standard USB HUB results in the loss of the MPU's native OTG functionality. Applications requiring OTG functionality, such as debugging and program upgrades, become unavailable. These are non-mainstream functions for end users, but they still need to be retained (common HUB chips can only be used in USB mode as the primary mode; OTG functionality requires USB mode to be secondary). Currently, one solution to this problem is to use a costly USB hub that supports USB master-slave mode expansion. However, there are few available models of USB hubs that can provide OTG function transfer, and they are expensive, which poses a serious challenge to the cost control of the entire vehicle in the increasingly competitive automotive market. Summary of the Invention

[0003] The main objective of this invention is to overcome the aforementioned deficiencies in the prior art and propose a USB master-slave switching circuit for a multimedia screen and an in-vehicle multimedia system that is compatible with and supports the expansion of ordinary USB hub ports and USB OTG functions. It retains the USB OTG function with low cost without affecting the daily use scenarios of end users.

[0004] The present invention adopts the following technical solution:

[0005] On one hand, a USB master-slave switching circuit for a multimedia screen includes: a microprocessor (MPU), a first analog switch, a second analog switch, a USB hub, a detection circuit, and a USB interface connector; the MPU is connected to the common terminal of the channel switching of the first analog switch via a USB port; the first channel terminal of the first analog switch is connected to the first channel terminal of the second analog switch, and the second channel terminal of the first analog switch is connected to the input terminal of the USB hub; the common terminal of the second analog switch is connected to a USB port in the USB interface connector, and the second channel terminal of the second analog switch is connected to one output of the USB hub. The other outputs of the USB hub are connected to other USB ports of the USB interface connector. The microprocessor (MPU) is connected to one end of the detection circuit via the USB_ID terminal. The other end of the detection circuit sends a first level signal to the USB_ID terminal when an external USB_ID input is detected, and sends a second level signal to the USB_ID terminal when the external USB_ID input is detected to be disconnected. The MPU sets the master / slave mode according to the level signal of the USB_ID terminal. In slave mode, it controls the first channel of the first analog switch to be turned on and the first channel of the second analog switch to be turned on, without connecting to the USB hub, thus realizing the USB OTG function. In master mode, it controls the second channel of the first analog switch to be turned on and the second channel of the second analog switch to be turned on, thus connecting to the USB hub and realizing the multi-USB usage function.

[0006] Preferably, the MPU sends a high / low level signal through the first IO port to control the channel switching of the first analog switch.

[0007] Preferably, the MPU controls the channel switching of the second analog switch by sending a high / low level signal through the second IO port.

[0008] Preferably, both the first analog switch and the second analog switch are turned on by default via the second channel.

[0009] Preferably, the first level signal is a low level signal, and when the MPU detects that the level signal at the USB_ID terminal has become a low level signal, the MPU sets the USB terminal working mode of the MPU to slave mode.

[0010] Preferably, the second level signal is a high level signal, and the MPU sets the USB terminal working mode to master mode when it detects that the level signal of the USB_ID terminal has become a high level signal.

[0011] Preferably, the USB_ID terminal of the MPU is set to a high-level signal by default.

[0012] Preferably, the USB interface connector includes at least a USB flash drive USB port, a USB TBOX interface, and a USB instrument interface.

[0013] On the other hand, a multimedia screen includes: an LCD screen and the USB master-slave switching circuit; the LCD screen is connected to the microprocessor MPU.

[0014] In another aspect, an in-vehicle multimedia system includes: a multimedia screen and an external control module for the multimedia screen; the multimedia screen includes an LCD screen and the USB master-slave switching circuit; the LCD screen is connected to the microprocessor (MPU); the external control module for the multimedia screen is connected to the detection circuit to enable or disable the external USB_ID input.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] This invention, through a USB master-slave switching circuit including a microprocessor MPU, a first analog switch, a second analog switch, a USB hub, a detection circuit, and a USB interface connector, can achieve the expansion of multiple USB channels in a HUB at low cost, while also meeting the need for the microprocessor MPU to switch to slave mode during USB ADB debugging or program download. Attached Figure Description

[0017] Figure 1 This is a circuit diagram of the USB master-slave switching of a multimedia screen in slave mode according to an embodiment of the present invention.

[0018] Figure 2 This is a circuit diagram of the USB master-slave switching of a multimedia screen in master mode according to an embodiment of the present invention. Detailed Implementation

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

[0020] In the description of this invention, it should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or device comprising said element.

[0021] In the description of this invention, it should be noted that the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed", "equipped", "sleeved / connected", "connected", etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal conduction of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] See Figure 1 and Figure 2 As shown, this invention discloses a USB master-slave switching circuit for a multimedia screen, used in an in-vehicle multimedia system. The in-vehicle multimedia system includes: a multimedia screen 1 and an external control module 2; the multimedia screen 1 includes an LCD screen 10 and a USB master-slave switching circuit; the LCD screen 10 is connected to the microprocessor MPU 11 of the USB master-slave switching circuit to realize interaction between the LCD screen 10 and the USB master-slave switching circuit, i.e., inputting control signals from the LCD screen 10 to the USB master-slave switching circuit and obtaining and displaying USB usage status information from the USB master-slave switching circuit; the external control module 2 is connected to the detection circuit 15 to connect or disconnect the external USB_ID input, thereby controlling the USB terminal of the microprocessor MPU 11 to operate in slave mode or master mode.

[0024] Specifically, the USB master-slave switching circuit of the multimedia screen includes: a microprocessor MPU 11, a first analog switch 12, a second analog switch 13, a USB hub 14, a detection circuit 15, and a USB interface connector 16; the microprocessor MPU 11 is connected to the common channel switching terminal of the first analog switch 12 via a USB port; the first channel terminal of the first analog switch 12 is connected to the first channel terminal of the second analog switch 13, and the second channel terminal of the first analog switch 12 is connected to the input terminal of the USB hub 14; the common terminal of the second analog switch 13 is connected to one USB port of the USB interface connector 16, and the second channel terminal of the second analog switch 13 is connected to one output of the USB hub 14; the other outputs of the USB hub 14 are respectively connected to other USB ports of the USB interface connector 16; the microprocessor MPU... 11 is connected to one end of the detection circuit 15 via the USB_ID terminal. The other end of the detection circuit 15 sends a first level signal to the USB_ID terminal when an external USB_ID input is detected, and sends a second level signal to the USB_ID terminal when the external USB_ID input is detected to be disconnected. The MPU sets the master / slave mode according to the level signal of the USB_ID terminal. In slave mode, it controls the first channel of the first analog switch 12 to be turned on and the first channel of the second analog switch 13 to be turned on, and does not connect to the USB hub 14 to realize the USBOTG function. In master mode, it controls the second channel of the first analog switch 12 to be turned on and the second channel of the second analog switch 13 to be turned on, and connects to the USB hub 14 to realize the multi-USB usage function.

[0025] In this embodiment, a first analog switch 12 and a second analog switch 13 (which are dedicated analog switches for USB signals and are general-purpose chips) that meet the USB communication frequency are introduced to switch signals, thus solving the problem of USB port expansion and the need to retain USB OTG function on a specified port.

[0026] from Figure 1 and Figure 2 As can be seen, the connection relationships between the parts are as follows:

[0027] The first analog switch 12 has its common terminal connected to the USB terminal of the microprocessor MPU 11, and its lower default second channel terminal HSD11 is connected to the input terminal of the USB hub 14.

[0028] The second analog switch 13 has its common terminal connected to the signal coming from a USB port (the USB port of the flash drive in the figure) of the USB interface connector 16, and its lower default second channel terminal HSD21 is connected to an output terminal (USB1 in the figure) of the USB hub 14.

[0029] The USB hub 14 has its input end connected to the default second channel end HSD11 at the bottom of the first analog switch 12, one output end USB1 connected to the second analog switch 13, and the other two external output segments USB2 and USB3 connected to the other two USB ports of the USB interface connector 16 (the USB TBOX interface and the USB instrument interface in the figure).

[0030] The detection circuit 15 is used to detect the level signal of the external USB_ID input, and after detection, it feeds back the detection status to the microprocessor MPU 11;

[0031] The USB interface connector 16 provides an interface for connecting external devices, including devices such as USB flash drives, TBOX communication devices, and instrument communication devices.

[0032] It should be noted that the first analog switch 12 and the second analog switch 13 also include a control terminal (not shown in the figure) connected to the microprocessor MPU 11 to perform channel switching according to the control signal sent by the MPU.

[0033] The following will explain the operating modes of the USB port of the microprocessor MPU 11, namely slave mode (implementing USB OTG function) and master mode (implementing multiple USB usage function).

[0034] (1) See Figure 1 As shown, when downloading programs or using ADB for debugging on the multimedia screen 1, the USB of the microprocessor MPU11 needs to be set to slave mode. The switching steps are as follows:

[0035] ① The microprocessor MPU 11 controls the first analog switch 12 through the IO port, so that the first analog switch 12 is in state 1, and the upper first channel of the first analog switch 12 is turned on.

[0036] ② The microprocessor MPU 11 controls the second analog switch 13 through the IO port, so that the second analog switch 13 is in state 1, at which time the upper first channel of the second analog switch 13 is turned on;

[0037] At this point, the USB conduction channel bypasses the USB hub 14, and the USB output of the MPU goes directly to the USB port of the USB interface connector 16.

[0038] ③ The external control module 2 of the multimedia screen (the interface input of the multimedia screen 1) switches the state of the USB_ID pin of the microprocessor MPU 11, so that the USB end of the microprocessor MPU 11 works in slave mode.

[0039] It should be noted that the USB_ID pin of the microprocessor MPU 11 is usually pulled high by default, in master mode; when an external trigger causes the state of the USB_ID pin of the microprocessor MPU 11 to become 0, the MPU enters slave mode.

[0040] (2) See Figure 2 As shown, when the device is working normally, all USB ports on the USB interface connector 16 are in normal use. The USB port of the microprocessor MPU 11 needs to be set to master mode. The switching steps are as follows:

[0041] ① The microprocessor MPU 11 controls the first analog switch 12 through the IO port, so that the first analog switch 12 is in the default 0 state. At this time, the lower second channel of the first analog switch 12 is opened.

[0042] ② The microprocessor MPU 11 controls the second analog switch 13 through the IO port, so that the second analog switch 13 is in the default 0 state. At this time, the lower second channel of the second analog switch 13 is opened.

[0043] At this point, the USB port of the microprocessor MPU 11 connects to the USB hub 14, and then to the USB flash drive USB port, USB TBOX interface and USB instrument interface of the USB interface connector 16, expanding to 3 USB ports.

[0044] ③ Disconnect the setting pin of the external USB_ID input. The USB end of the microprocessor MPU 11 will work in master mode by default. At this time, all three USB ports can be connected to peripherals and used normally.

[0045] It should be noted that the external control module 2 for the multimedia screen is used to control the connection or disconnection of the external USB_ID input. The external USB_ID input can typically be the vehicle's 12V or 24V, or grounded; the appropriate method is selected based on the actual application. In one example embodiment, if the USB_ID is on the main connector, it will be connected to the vehicle's 12V or 24V input; if the USB_ID is on a dedicated debugging socket, it will be grounded.

[0046] The above are merely specific embodiments of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention using this concept shall be considered as infringing upon the protection scope of the present invention.

Claims

1. A USB master-slave switching circuit for a multimedia screen, characterized in that, include: Microprocessor (MPU), first analog switch, second analog switch, USB hub, detection circuit and USB interface connector; The microprocessor (MPU) is connected to the common terminal of the channel switching of the first analog switch via a USB port. The first channel terminal of the first analog switch is connected to the first channel terminal of the second analog switch, and the second channel terminal of the first analog switch is connected to the input terminal of the USB hub. The common terminal of the second analog switch is connected to a USB port in the USB interface connector, and the second channel terminal of the second analog switch is connected to one output of the USB hub. The other outputs of the USB hub are connected to other USB ports of the USB interface connector. The MPU is connected to one end of a detection circuit via a USB_ID port. The other end of the detection circuit sends a first-level signal to the USB_ID port when an external USB_ID input is detected, and sends a second-level signal to the USB_ID port when the external USB_ID input is detected to be disconnected. The MPU sets the master / slave mode according to the level signal of the USB_ID port. In slave mode, it controls the first channel of the first analog switch to be on and the first channel of the second analog switch to be on, without connecting to the USB hub, thus realizing USB... The OTG function, in main mode, controls the second channel of the first analog switch to be turned on, and controls the second channel of the second analog switch to be turned on, connecting to the USB hub to realize the function of multiple USB ports.

2. The USB master-slave switching circuit for a multimedia screen according to claim 1, characterized in that, The MPU controls the channel switching of the first analog switch by sending high / low level signals through the first IO port.

3. The USB master-slave switching circuit for a multimedia screen according to claim 1, characterized in that, The MPU controls the channel switching of the second analog switch by sending high / low level signals through the second IO port.

4. The USB master-slave switching circuit for a multimedia screen according to claim 1, characterized in that, Both the first and second analog switches are configured to have the second channel turned on by default.

5. The USB master-slave switching circuit for a multimedia screen according to claim 1, characterized in that, The first level signal is a low level signal. When the MPU detects that the level signal at the USB_ID terminal has become a low level signal, the MPU sets the USB terminal working mode of the MPU to slave mode.

6. The USB master-slave switching circuit for a multimedia screen according to claim 1, characterized in that, The second level signal is a high level signal. When the MPU detects that the level signal at the USB_ID terminal has changed to a high level signal, the MPU sets the USB terminal working mode to the master mode.

7. The USB master-slave switching circuit for a multimedia screen according to claim 1, characterized in that, The USB_ID terminal of the MPU is set to a high-level signal by default.

8. The USB master-slave switching circuit for a multimedia screen according to claim 1, characterized in that, The USB interface connector includes at least a USB flash drive USB port, a USB TBOX interface, and a USB instrument interface.

9. A multimedia screen, characterized in that, include: The LCD screen and the multimedia screen as described in any one of claims 1 to 8 have a USB master-slave switching circuit; the LCD screen is connected to the microprocessor MPU.

10. A vehicle-mounted multimedia system, characterized in that, include: Multimedia screen and external control module for multimedia screen; The multimedia screen includes an LCD screen and a USB master-slave switching circuit for the multimedia screen as described in any one of claims 1 to 8; the LCD screen is connected to the microprocessor MPU; the external control module of the multimedia screen is connected to the detection circuit to enable or disable the external USB_ID input.

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