Electronic device and communication method thereof

Abstract

An electronic device and a communication method thereof are disclosed. The electronic device includes a housing, a universal serial bus (USB) port, an embedded control unit, a central processing unit, a power supply unit, and a multiplexing control unit. The USB port, the embedded control unit, the central processing unit, the power supply unit, and the multiplexing control unit are disposed in the housing. The multiplexing control unit has a first mode of use and a second mode of use. The multiplexing control unit is normally in the first mode of use and switches to the second mode of use upon receiving a switching signal. In the first mode, the multiplexing control unit is powered by the power supply unit, and the multiplexing control unit establishes a first transmission path between the central processing unit and the USB port. In the second mode of use, the multiplexing control unit is powered by an external device connected to the USB port, and the multiplexing control unit establishes a second transmission path between the embedded control unit and the USB port.

Description

TECHNICAL FIELD

[0001] The present application relates to an electronic device, and more particularly to an electronic device capable of using a universal serial bus (USB) port as a multi-functional connection interface and a communication method thereof.

BACKGROUND

[0002] In the current product design with small size, the hardware circuit arranged in the electronic device has a dedicated debug / program interface, and a connection port for connecting a test / program device is arranged on the printed circuit board (PCB) to enable the developer to debug and design the hardware circuit through the connection port during the development stage of the electronic device.

[0003] In some product designs, the connection port arranged on the PCB is covered by the shell of the electronic device after the assembly of the electronic device. Therefore, after the completion of the electronic device, if the internal hardware circuit needs to be debugged / programmed again, the shell of the electronic device must be removed first, and then the hardware circuit can be debugged / programmed through the connection port arranged on the PCB. However, the removal of the shell of the electronic device is complicated, especially when the entire device is glued and cannot be removed. In addition, the removal of the shell of the electronic device also causes concerns about the waterproofness, appearance, and functionality of the electronic device.

[0004] In other product designs, a connection port is additionally arranged on the shell of the electronic device to enable the test / program device to be connected to the connection port through the connection port. However, the additional arrangement of the connection port on the shell of the electronic device not only destroys the overall appearance of the electronic device, but also increases the complexity of the waterproof design of the electronic device.

SUMMARY

[0005] In an embodiment, an electronic device includes a shell, a universal serial bus (USB) port, an embedded control unit, a central processing unit, a power supply unit, and a multiplexing control unit. The USB port is arranged on the shell. The embedded control unit, the central processing unit, the power supply unit, and the multiplexing control unit are arranged in the shell. The multiplexing control unit has a first use mode and a second use mode. The multiplexing control unit is normally in the first use mode and switches to the second use mode when a switching signal is received. In the first use mode, the multiplexing control unit is powered by the power supply unit, and the multiplexing control unit establishes a first transmission path between the central processing unit and the USB port. In the second use mode, the multiplexing control unit is powered by an external device connected to the USB port, and the multiplexing control unit establishes a second transmission path between the embedded control unit and the USB port.

[0006] In one embodiment, a communication method for an electronic device includes connecting an external device to the electronic device via a universal serial bus (USB) port of the electronic device, receiving power from the external device via the USB port when the electronic device is in a power-off state, and establishing a transmission path between the USB port and an embedded controller of the electronic device according to a switching signal.

[0007] In one embodiment, a communication method for an electronic device includes connecting a first data multiplexer of the electronic device to a second data multiplexer, establishing a transmission path between a universal serial bus (USB) port and a central processing unit (CPU) of the electronic device according to a first connection technology, and establishing a transmission path between the USB port and the CPU according to a second connection technology according to a switching signal.

[0008] In summary, the electronic device and the communication method thereof according to the embodiments of the present application can switch the transmission path of the USB port via the multiplexer control unit, so that the developers can directly connect the external device to the electronic device for debugging / development testing of the embedded controller and / or the CPU via the USB port for external data transmission. Therefore, the development, design, maintenance, service analysis, etc. of the electronic device can be more rapid, convenient and reliable.

[0009] The detailed features and advantages of the present application are described in detail in the following embodiments, which are sufficient for any person skilled in the art to understand the technical content of the present application and to implement it. According to the content disclosed in the present specification, the scope of the patent application and the drawings, any person skilled in the art can easily understand the related purposes and advantages of the present application.

DRAWINGS

[0010] Figure 1 The schematic block diagram of the first embodiment of the electronic device.

[0011] Figure 2 The flowchart of one embodiment of the communication method.

[0012] Figure 3 The schematic block diagram of the first embodiment of the electronic device. Figure 1 The schematic block diagram of one embodiment in which the USB port is used as a general-purpose transmission port.

[0013] Figure 4 The schematic block diagram of one embodiment in which the USB port is used as a general-purpose transmission port. Figure 1 The schematic block diagram of one embodiment in which the USB port is used as a debugging / development testing port.

[0014] Figure 5This is a schematic block diagram of a second embodiment of the electronic device.

[0015] Figure 6 for Figure 5 A schematic diagram of an embodiment of an electronic device.

[0016] Figure 7 This is a flowchart illustrating another embodiment of the communication method.

Detailed Implementation Methods

[0017] Figure 1 This is a schematic block diagram of a first embodiment of the electronic device. Please refer to... Figure 1 The electronic device 100 includes a housing 110, a universal serial bus port 120, an embedded control unit 130, a central processing unit 140, a power supply unit 150, and a multiplexing control unit 160. The power supply unit 150 is coupled to the embedded control unit 130 and the central processing unit 140. The multiplexing control unit 160 is coupled to the central processing unit 140, the power supply unit 150, and the universal serial bus port 120.

[0018] A Universal Serial Bus (USB) port 120 is disposed in the housing 110. The USB port 120 can be used to connect to an external device 200 having a corresponding port, enabling communication between the external device 200 and the electronic device 100. In some embodiments, the USB port 120 may be a port using USB 2.0 or USB 3.0 connection technology, and the external device 200 can be connected to or disconnected from the USB port 120 of the electronic device 100 via plugging and unplugging; however, this invention is not limited thereto.

[0019] An embedded control unit 130 is disposed within the housing 110. The embedded control unit 130 can be used to perform specific tasks to achieve specific functions of the electronic device 100. For example, the embedded control unit 130 can perform specific tasks by controlling peripheral devices connected to the electronic device 100 or other circuits in the electronic device 100, thereby enabling the electronic device 100 to achieve or exhibit specific functions.

[0020] In some embodiments, the embedded control unit 130 may be an embedded controller (EC), a Super I / O chip, or other suitable embedded circuitry, and the present invention is not limited thereto.

[0021] The central processing unit 140 is disposed in the housing 110. The central processing unit 140 can have various important functions, such as being responsible for the operation of various departments in the electronic device 100 and various arithmetic and logical operations, and is actually the core circuit of the electronic device 100. In some embodiments, the central processing unit 140 can be a central processing unit (CPU), a microprocessor, or other core circuit with various operation functions.

[0022] The power supply unit 150 is disposed in the housing 110. The power supply unit 150 can be used to receive and store power, and the power stored therein is one of the sources for supplying the electronic device 100 to operate.

[0023] In an embodiment, the power supply unit 150 continuously provides power to the embedded control unit 130 to maintain the operation of the embedded control unit 130, regardless of whether the electronic device 100 is in a powered-on state or a powered-off state. Therefore, the embedded control unit 130 can wait for a start instruction in the powered-off state, and upon receiving the start instruction, cause the power supply unit 150 to provide power to the USB interface 120, the central processing unit 140, and the multiplexing control unit 160, so that the electronic device 100 enters the powered-on state. And, upon receiving a shutdown instruction, cause the power supply unit 150 to stop supplying power to the USB interface 120, the central processing unit 140, and the multiplexing control unit 160, so that the electronic device 100 can enter the powered-off state.

[0024] In some embodiments, the power supply unit 150 can be various types of batteries or other suitable energy storage elements.

[0025] The multiplexing control unit 160 is disposed in the housing 110. The multiplexing control unit 160 can be used to control the transmission path between the USB interface 120 and other circuits in the electronic device 100.

[0026] Figure 2 Flowchart of an embodiment of a communication method. Please refer to Figures 1 to 2 In an embodiment of the communication method, the electronic device 100 can connect to the external device 200 using the USB interface 120 (step S11). When the electronic device 100 is in a powered-off state, the electronic device 100 can receive power from the external device 200 via the USB interface 120 (step S12). Then, the electronic device 100 can use the multiplexing control unit 160 to establish a transmission path between the USB interface 120 and the embedded control unit 130 according to the switching signal S1 under the power supply of the external device 200 (step S13).

[0027] In one embodiment of step S13, the multiplexing control unit 160 has two modes of use (hereinafter referred to as a first mode of use and a second mode of use, respectively). The multiplexing control unit 160 is normally in the first mode of use, and can switch from the first mode of use to the second mode of use upon receiving a switching signal S1.

[0028] In the first mode of use, the multiplexing control unit 160 establishes a first transmission path between the central processing unit 140 and the universal serial bus transmission port 120, so that the external device 200 can communicate with the central processing unit 140 via the first transmission path in a unidirectional or bidirectional manner through a mode connected to the universal serial bus transmission port 120. At this time, the universal serial bus transmission port 120 is used as a general-purpose transmission port.

[0029] In the second mode of use, the multiplexing control unit 160 establishes a second transmission path between the embedded control unit 130 and the universal serial bus transmission port 120, so that the external device 200 can communicate with the embedded control unit 130 via the second transmission path in a unidirectional or bidirectional manner through a mode connected to the universal serial bus transmission port 120. At this time, the universal serial bus transmission port 120 is used as a transmission port for debugging / development testing.

[0030] In one embodiment, the second mode of use of the multiplexing control unit 160 can only be used when the electronic device 100 is in a powered-off state, so as to avoid the universal serial bus transmission port 120 from being unable to be used as a general-purpose transmission port due to an erroneous switch when the electronic device 100 is in a powered-on state, and so that a developer can perform debugging / development testing on the embedded control unit 130 in the electronic device 100 via the universal serial bus transmission port 120 without having to start up the entire electronic device 100 into an operating system.

[0031] Since in the powered-off state, the power supply unit 150 of the electronic device 100 does not provide power to the universal serial bus transmission port 120, the central processing unit 140, and the multiplexing control unit 160 to operate. At this time, if debugging / development testing is to be performed, the external device 200 can supply power to the multiplexing control unit 160 through the universal serial bus transmission port 120, so that the multiplexing control unit 160 can switch to the second mode of use according to the switching signal S1 and turn on the second transmission path, so that the external device 200 can communicate with the embedded control unit 130 via the second transmission path.

[0032] In one embodiment, the electronic device 100 further comprises a user interface unit 180. The user interface unit 180 is disposed on the housing 110, and the user interface unit 180 is coupled to the multiplexing control unit 160. The user interface unit 180 can generate a switching signal S1 according to the input of a user.

[0033] In some embodiments, the user interface unit 180 can be a mechanical switch assembly, a button assembly, or the like, which can generate a corresponding switching signal S1 according to the switching, pressing, or the like action of a user, but the present application is not limited thereto. In other embodiments, the user interface unit 180 can be a keyboard, and a user can generate a switching signal S1 by pressing a specific key or a specific combination of keys on the keyboard.

[0034] In one embodiment, the multiplexing control unit 160 can switch back to the first use mode according to another switching signal S2 generated by the user interface unit 180. However, the present application is not limited thereto, and in another embodiment, when the electronic device 100 re-enters the power-on state, the multiplexing control unit 160 can be reset to switch back to the first use mode.

[0035] Figure 3 For Figure 1 an embodiment in which the universal serial bus transmission port is used as a general-purpose transmission port. Please refer to Figure 3 , the external device 200 can be a USB device 210. In one embodiment, the USB device 210 can be a USB flash disk, an external hard disk, a mobile phone, or a host, or the like. When the USB device 210 is connected to the universal serial bus transmission port 120 of the electronic device 100 and the multiplexing control unit 160 is in the first use mode, the multiplexing control unit 160 establishes a first transmission path between the universal serial bus transmission port 120 and the central processing unit 140, so that the central processing unit 140 can perform data transmission with the USB device 210 via the first transmission path. For example, the central processing unit 140 of the electronic device 100 can read, write, and / or delete the data stored in the USB device 210 via the first transmission path, and the central processing unit 140 can also copy the data stored in the USB device 210 to the electronic device 100, or copy the data stored in the electronic device 100 to the USB device 210.

[0036] In another embodiment, the USB device 210 can be a peripheral input device such as a mouse or a keyboard. When the USB device 210 is connected to the USB port 120 of the electronic device 100 and the multiplexing control unit 160 is in the first usage mode, the multiplexing control unit 160 establishes a first transmission path between the USB port 120 and the CPU 140, so that the USB device 210 can transmit input signals generated in response to user actions to the CPU 140 of the electronic device 100 through the first transmission path, and the CPU 140 can perform corresponding control according to the input signals.

[0037] Figure 4 For Figure 1 Figure 1 is a schematic diagram of an embodiment of the present application in which the USB port is used as a debugging / development test port. Referring to Figure 1, an electronic device 100 is provided. The electronic device 100 can be a mobile phone, a personal digital assistant (PDA), a digital camera, a digital music player, a digital video player, a digital video recorder, a digital TV, a computer, or any other electronic device. The electronic device 100 comprises a USB port 120, a CPU 140, an embedded control unit 130, and a multiplexing control unit 160. Figure 4 For example, in one embodiment, the external device 200 can be a test / programmer fixture 220. When the test / programmer fixture 220 is connected to the USB port 120 of the electronic device 100 and the multiplexing control unit 160 is in the second usage mode, the multiplexing control unit 160 establishes a second transmission path between the USB port 120 and the embedded control unit 130, so that the test / programmer fixture 220 can transmit test signals to the embedded control unit 130 through the second transmission path, and read result signals returned by the embedded control unit 130 to perform debugging tests. In addition, the test / programmer fixture 220 can also reprogram the embedded control unit 130 through the second transmission path, or directly program new programs into the embedded control unit 130.

[0038] In some embodiments, the electronic device 100 can be internally provided with test lines. Therefore, when the test / programmer fixture 220 is connected to the USB port 120 of the electronic device 100 and the multiplexing control unit 160 establishes the second transmission path between the USB port 120 and the embedded control unit 130 due to being in the second usage mode, the test / programmer fixture 220 can receive the result signals transmitted by the embedded control unit 130 through the second transmission path. However, the present application is not limited thereto.

[0039] In some embodiments, when the type of the connection port of the test / program fixture 220 is compatible with the type of the USB port 120 of the electronic device 100, the connection port of the test / program fixture 220 can be directly connected to the USB port 120 of the electronic device 100. However, the present application is not limited thereto, and in other embodiments, when the type of the connection port of the test / program fixture 220 is not compatible with the type of the USB port 120 of the electronic device 100, for example, when the connection port of the test / program fixture 220 is a pin header or a flexible flat cable, the test / program fixture 220 can be connected to the USB port 120 of the electronic device 100 through the interface conversion of the relay connection module 300.

[0040] In an embodiment, when the test / program fixture 220 is connected to the USB port 120 of the electronic device 100 in the power-off state, the test / program fixture 220 can supply power to the user interface unit 180 through the USB port 120. Therefore, in the power-off state, the user interface unit 180 can still generate the switching signal S1 according to the input of the user to cause the electronic device 100 to switch to the second usage state.

[0041] Figure 5 a schematic block diagram of a second embodiment of an electronic device, Figure 6 a schematic block diagram of an embodiment of an electronic device, Figure 5 a schematic block diagram of an embodiment of an electronic device, Figure 7 a flowchart of another embodiment of a communication method. Please refer to Figures 5 to 7 In an embodiment, the multiplexing control unit 160 can include at least two data multiplexers, or multiplexers (hereinafter referred to as a first data multiplexer 161 and a second data multiplexer 162). In addition, the electronic device 100 further includes a storage unit 170. The first data multiplexer 161 is coupled to the USB port 120, the central processing unit 140, the power supply unit 150, the second data multiplexer 162, the storage unit 170, and the user interface unit 180. The second data multiplexer 162 is coupled to the central processing unit 140, the power supply unit 150, and the user interface unit 180.

[0042] In one embodiment, the first data multiplexer 161 can have two transmission lines 1611, 1612, and each of the transmission lines 1611, 1612 can be composed of 6 wires. In some embodiments, 4 wires of the first transmission line 1611 of the first data multiplexer 161 are connected to the central processing unit 140, and the remaining 2 wires are connected to the second data multiplexer 162. 2 wires of the second transmission line 1612 of the first data multiplexer 161 are connected to the embedded control unit 130, and the remaining 4 wires are connected to the storage unit 170.

[0043] In some embodiments, the 4 wires of the first transmission line 1611 of the first data multiplexer 161 can be connected to the central processing unit 140 by USB3.0 connection technology. The 2 wires of the second transmission line 1612 of the first data multiplexer 161 can be connected to the embedded control unit 130 by 2-wire JTAG (also known as Spy-Bi-wire, SBW) connection technology, and the remaining 4 wires of the second transmission line 1612 can be connected to the storage unit 170 by Series Peripheral Interface (SPI) technology.

[0044] In addition, the second data multiplexer 162 can have two transmission lines 1621, 1622, and each of the transmission lines 1621, 1622 can be composed of 2 wires. Here, the wires of the first transmission line 1621 and the wires of the second transmission line 1622 of the second data multiplexer 162 are both connected to the central processing unit 140.

[0045] In some embodiments, the first transmission line 1621 of the second data multiplexer 162 can be connected to the central processing unit 140 by a first connection technology, such as a USB2.0 connection interface, and the second transmission line 1622 of the second data multiplexer 162 can be connected to the central processing unit 140 by a second connection technology, such as Universal Asynchronous Receiver Transmitter (UART) connection technology.

[0046] In one embodiment, when the multiplexing control unit 160 adopts the first usage mode in the power-on state, the first data multiplexer 161 can enable the first transmission line 1611 and the second data multiplexer 162 can enable the first transmission line 1621, so that the external device 200 connected to the USB transmission port 120 can be connected to the USB 3.0 connection interface of the CPU 140 via the first data multiplexer 161 and can be connected to the USB 2.0 connection interface of the CPU 140 via the second data multiplexer 162. In other words, the first transmission path established by the multiplexing control unit 160 in the first usage mode can be composed of the first transmission line 1611 of the first data multiplexer 161 and the first transmission line 1621 of the second data multiplexer 162, and at this time the USB transmission port 120 is used for transmission by applying the USB interface (step S21).

[0047] In addition, when the multiplexing control unit 160 adopts the second usage mode in the power-off state, the first data multiplexer 161 can enable the second transmission line 1612 and the second data multiplexer 162 does not enable any transmission line, so that the external device 200 connected to the USB transmission port 120 can be connected to the SBW connection interface of the embedded control unit 130 and the SPI connection interface of the storage unit 170 via the first data multiplexer 161. In other words, the second transmission path established by the multiplexing control unit 160 in the second usage mode can be composed of the second transmission line 1612 of the first data multiplexer 161. At this time, the external device 200 can communicate with the embedded control unit 130 through the SBW connection interface established between the USB transmission port 120 and the embedded control unit 130 in the power-off state, and can communicate with the storage unit 170 through the SPI connection interface established between the USB transmission port 120 and the storage unit 170.

[0048] In one embodiment, the multiplexing control unit 160 further includes a third usage mode, and the multiplexing control unit 160 can be switched to the third usage mode according to the switching signal S3 generated by the user interface unit 180 (step S22).

[0049] In the third usage mode, the multiplexing control unit 160 establishes a third transmission path between the CPU 140 and the USB transmission port 120, so that the external device 200 can be connected to the USB transmission port 120 to enable one-way or two-way communication with the CPU 140 via the third transmission path. At this time, the USB transmission port 120 is used as a transmission port for debugging / development testing.

[0050] When the multiplexing control unit 160 adopts the third usage mode in the power-on state, the first data multiplexer 161 can enable the first transmission line 1611 and the second data multiplexer 162 can enable the second transmission line 1622, so that the external device 200 connected to the USB transmission port 120 can be connected to the USB3.0 connection interface of the central processing unit 140 via the first data multiplexer 161 and can be connected to the UART connection interface of the central processing unit 140 via the second data multiplexer 162. In other words, the third transmission path established by the multiplexing control unit 160 in the third usage mode can be composed of the first transmission line 1611 of the first data multiplexer 161 and the second transmission line 1622 of the second data multiplexer 162, and the external device 200 can communicate with the central processing unit 140 through the USB3.0 connection interface and the UART connection interface established by the central processing unit 140 through the USB transmission port 120 (step S23).

[0051] In an embodiment, the first data multiplexer 161 of the multiplexing control unit 160 can be powered by the power supply unit 150 or by the external device 200 through the USB transmission port 120, and the second data multiplexer 162 is powered by the power supply unit 150. Therefore, the first usage mode and the third usage mode of the multiplexing control unit 160 can only be used when the electronic device 100 is in the power-on state, and the second usage mode of the multiplexing control unit 160 can be used when the electronic device 100 is in the power-on state or the power-off state. However, in order to avoid the user from switching the USB transmission port 120 to be unable to be used as a general transmission port due to an error when the electronic device 100 is in the power-on state, the second usage mode of the multiplexing control unit 160 can also be limited to be used only when the electronic device 100 is in the power-off state.

[0052] In some embodiments, the multiplexing control unit 160 can be a multiplexing controller (MUX). In addition, the storage unit 170 can be implemented by one or more storage elements. Each storage element can be a non-volatile memory such as a read-only memory (ROM) or a flash memory, or can be a volatile memory such as a random access memory (RAM), but the present application is not limited thereto.

[0053] In some embodiments, the storage unit 170 can be an internal storage element of the central processing unit 140, but the present application is not limited thereto. In other embodiments, the storage unit 170 can also be an external storage element independent of the central processing unit 140.

[0054] In summary, according to the electronic device and the communication method thereof, the transmission path of the USB transmission port is switched by the multiplexing control unit, so that the R&D personnel can directly connect the external device to the electronic device for debugging / development testing of the embedded control unit and / or the CPU via the USB transmission port for external data transmission, thereby making the development design, maintenance, service analysis, etc. of the electronic device faster, more convenient and reliable.

[0055] The technical content of the present application has been disclosed in the above-mentioned preferred embodiments, but it is not intended to limit the present application. Any person skilled in the art can make some changes and modifications without departing from the spirit of the present application, which should be covered by the scope of the present application. Therefore, the protection scope of the present application should be defined by the appended patent claims.

Claims

1. An electronic device, characterized by comprising: The electronic device comprises: a housing; a USB transmission port arranged in the housing; an embedded control unit arranged in the housing; a central processing unit arranged in the housing; a power supply unit arranged in the housing; and a multiplexing control unit arranged in the housing, wherein the power supply unit supplies power to the USB transmission port, the embedded control unit and the central processing unit in a power-on state of the electronic device, and does not supply power to the USB transmission port, the central processing unit and the multiplexing control unit in a power-off state of the electronic device; wherein in the power-on state, the multiplexing control unit is normally in a first use mode, in which the multiplexing control unit establishes a first transmission path between the central processing unit and the USB transmission port, so that the USB transmission port is used as a general-purpose transmission port; wherein in the power-off state, the multiplexing control unit receives power provided by an external device connected to the USB transmission port via the USB transmission port, and switches from the first use mode to a second use mode when a switching signal is received; and wherein in the second use mode, the multiplexing control unit establishes a second transmission path between the embedded control unit and the USB transmission port, so that the external device performs debugging / development testing on the embedded control unit via the second transmission path; and wherein the external device rewrites the program of the embedded control unit through the second transmission path, or directly burns a new program. Further comprising a user interface unit arranged in the housing, which is used to generate the switching signal. 2.The electronic device of claim 1, wherein, Further comprising a connection port arranged in the housing, which is used to connect an input device, and the switching signal is generated by the input device. 3.The electronic device of claim 1, wherein, The USB transmission port is a transmission port using a USB3.0 connection interface. 4.The electronic device of claim 1, wherein, The embedded control unit is connected to the multiplexing control unit through JTAG connection technology. 5.The electronic device of claim 1, wherein, In the first use mode, the external device connected to the USB transmission port communicates with the central processing unit via the first transmission path, and in the second use mode, the external device communicates with the embedded control unit via the second transmission path. 6.The electronic device of claim 1, wherein, The communication method comprises:

7. A communication method suitable for use in an electronic device, the method comprising: in a power-on state of the electronic device, using a power supply unit of the electronic device to supply power to a USB transmission port, a multiplexing control unit, an embedded control unit and a central processing unit of the electronic device; in the power-on state, using the multiplexing control unit to establish a first transmission path between the central processing unit and the USB transmission port, so that the USB transmission port is used as a general-purpose transmission port; in a power-off state of the electronic device, using the power supply unit to not supply power to the USB transmission port, the central processing unit and the multiplexing control unit; ​ In the off state, the multiplexing control unit receives power from an external device connected to the USB port via the USB port; and Under the power supplied by the external device, the multiplexing control unit establishes a second transmission path between the USB port and the embedded control unit upon receiving a switching signal, so that the external device can debug / development test the embedded control unit via the second transmission path; and wherein the external device rewrites the program of the embedded control unit through the second transmission path, or directly burns a new program.

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