WO2005116845A1

WO2005116845A1 - Usb device

Info

Publication number: WO2005116845A1
Application number: PCT/JP2005/009360
Authority: WO
Inventors: Shinichi Egashira; Ryo Sakai
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2004-05-26
Filing date: 2005-05-23
Publication date: 2005-12-08

Abstract

[MEANS FOR SOLVING PROBLEMS] A USB device (2) comprising an input/output unit (11) for communicating data with a computer (1), a main function unit (13) constituting a main function of the USB device (2), a driver storage memory (14) storing a device driver, a USB control unit (12) having descriptor information A1 including product information which are the same as one another and class information representing the USB mass storage class and descriptor information A2 including class information representing the class to which the main function belongs, and an incorporation judging register (15) representing whether or not the device driver is incorporated in the computer (1).

Description

Specification

USB device

Technical field

The present invention relates to a USB (Universal) connected to an electronic device such as a computer and a digital home appliance.

In particular, it relates to technology for installing a dedicated device driver when connecting a USB device to a computer.

Background art

[0002] In general, a device connected to a computer includes, in addition to the device, an external storage device such as a CD-ROM or a floppy disk (registered trademark) drive for installing a device driver in the computer. Required.

[0003] The same applies to USB devices, which are currently dominant in the peripheral field of the computer field. When you purchase the device, in most cases, the device driver is attached to the media 3 such as a floppy disk or CD-ROM as shown in Fig. 7, and you can use it to install the device driver. Become.

[0004] When installing the device driver of the USB device 2, the computer 1 determines the USB device by referring to the descriptor information A unique to the USB device.

[0005] As shown in FIG. 8, the descriptor information A of the USB device 2 includes a vendor ID, a product ID, and a revision ID (al), a class code, a subclass code, and a protocol (a2).

[0006] On the other hand, as shown in FIG. 9, an INF file B, which is a driver information file stored in the storage device of the computer 1, includes a vendor ID, a product ID, and a revision ID (bl), a class code, and a subclass code. And protocol (b2).

[0007] First, the computer 1 compares the vendor ID, product ID, and revision ID (al) obtained from the descriptor information A of the USB device 2 with the vendor ID, product ID, and revision ID (bl) of the INF file. Compare and if they match, incorporate the device driver (cl) specified in the INF file.

[0008] If there is no match, then the class code and subclass The protocol and protocol (a2) are compared with the class code, subclass code and protocol (b2) of the INF file B. If they match, the device driver (c2) specified in the INF file B is changed to ^ a.

If they still do not match, it is determined that the device driver corresponding to the USB device 2 is saved in the storage device of the computer 1, and the device driver is not installed. In this case, install a device driver for external recording media such as CD-ROM or floppy disk.

[0010] Furthermore, in recent years, digital home appliances having functions as USB devices have been rapidly increasing, and dedicated device drivers are rarely prepared to use those functions. In addition, some digital home appliances have a function as a USB host, and some products incorporate Windows (registered trademark).

Patent Document 1: Japanese Patent Application Laid-Open No. 2003-114859 (Pages 2-3, Figure 1-2)

Disclosure of the invention

Problems to be solved by the invention

[0011] When installing a device driver for a USB device from an external recording medium 3 such as a CD-ROM or a floppy disk, a floppy disk drive or a CD-ROM for reading information such as a device driver from the media card. A device such as a ROM drive is required. Recently, there is no floppy disk drive or CD-ROM drive! Computers are also generally used mainly for notebook computers.

[0012] In addition, when a device driver is installed in a digital home appliance having a function as a USB device, an external storage medium or an alternative means is required similarly to a computer. However, the ability to connect external storage media to such digital home appliances is not always the case.

[0013] As described above, in the field of digital home appliances that are not limited to computers, there are widespread issues related to USB.

[0014] Further, even if there is an external recording medium such as a floppy disk drive or a CD-ROM drive or an alternative means, if the recording medium storing the device driver is lost, the device is used. You can't do that. [0015] Many prior art documents have attempted to solve this problem also for USB devices. For example, Patent Document 1 mentioned above is a technology that attempts to solve this problem by storing a device driver for a computer in a USB device.

[0016] However, some problems described below are hidden in this prior art document, and a total solution including the stability of the system of the computer has been reached.

[0017] 1. When switching between the USB mass storage function and the main function, no notification is sent to the computer side, so it is determined that the device is suddenly disconnected, and the operation on the computer side becomes unstable. For example, an error may occur in the processing of the USB host driver installed in the computer, and the USB device may not be recognized correctly by the computer.

[0018] 2. A resident program is used to determine whether the device driver is built into the computer or not. However, when the number of USB devices increases, the number of resident applications is required, which is not practical. If the USB host is a digital home appliance, it may not have much memory, so the number of resident applications that can be executed is further limited.

[0019] 3. When the device driver is already installed, the means for switching from the drive function to the main function on the USB device side is not specified.

Means for solving the problem

[0020] The present invention takes the following means in order to solve the above problems.

[0021] The USB device according to the present invention

An input / output unit for transmitting and receiving data to and from an electronic device;

A main function unit that constitutes a main function of the USB device;

A driver storage memory for storing a device driver,

A USB control unit in which the product information is the same as each other, and the class information includes descriptor information indicating the USB mass storage class and the class information indicating the class to which the main function belongs.

Is provided.

In the above, the USB mass storage class is a standard for operating a storage device such as a CD-ROM or a DVD-ROM by USB. This USB mass storage class Having the descriptor information allows the electronic device to recognize the USB device as a USB mass storage device and enables the installation of a device driver for the USB main function.

When the USB device is connected to the electronic device, the USB control unit transmits descriptor information for the USB mass storage class in response to a request from the electronic device. The electronic device first determines whether or not a device driver for the main function exists in the electronic device based on the descriptor information for the USB mass storage class. When present, the electronic device incorporates device drivers for its primary function. If not present, the electronic device incorporates a device driver for the standard USB mass storage class. USB devices behave as USB mass storage class devices. This allows the electronic device to treat the USB device in the same way as a floppy disk drive or CD-ROM drive. That is, the electronic device can freely access the driver storage memory of the USB device. Then, the device driver for the main function is read from the driver storage memory and installed in the electronic device.

In the above configuration, a preferable configuration further includes a built-in determination register that indicates whether or not the device driver is built in the electronic device.

[0025] The built-in determination register is set to a non-built-in state when the electronic device is connected to the electronic device, and the USB control unit controls the electronic device based on the USB mass storage class descriptor information. When it is determined that the state is the built-in state, the built-in determination register is updated to the built-in state.

[0026] The USB control unit reads the device driver from the driver storage memory when the electronic device determines that the electronic device is in a non-incorporated state based on the descriptor information for the USB mass storage class. And installing the device driver in the electronic device, and updating the installed status determination register to the installed status after the electronic device has installed the device driver.

[0027] The USB control unit updates the installed state determination register to the installed state based on the reception of a unique vendor request from the electronic device.

[0028] After installing the device driver, the USB control unit switches between the USB mass storage function and the main function based on the reception of a bus reset or a mass storage reset from the electronic device. By the way, in the case of a USB device (for example, a DVD drive) whose main function operates in the USB mass storage class, the present invention may be developed as follows.

That is, the USB device according to the present invention

A main function unit constituting a function belonging to the mass storage class as a main function of the USB device, a driver storage memory for storing a device driver,

If the class information has descriptor information indicating a USB mass storage class, and the electronic device determines that the device driver has been installed based on the descriptor information,! A USB control unit that reads the driver and installs it on the electronic device

Is provided.

[0031] In the above, the USB control unit switches from the USB mass storage function to the main function based on the reception of the vendor request of the electronic device.

[0032] Further, the USB control unit determines whether or not the device driver is built in the electronic device by a unique vendor request, and when the device driver is built in, controls by the main function described above. Then, when the device driver is controlled as a USB mass storage device, the device driver is read from the driver storage memory and installed in the electronic device, and then the control is switched to the main function.

In this case, when the device driver of the USB device is installed on the electronic device side, the USB device is operated by the main function, and when the device driver is not yet installed, the USB device is operated as a USB mass storage device. Device drivers can be installed automatically.

By the way, after a USB device is connected to an electronic device to make it usable, the connection may be disconnected and then reconnected. The connection may be switched to another electronic device. The following configuration responds to this.

That is, the USB device according to the present invention

An input / output unit for transmitting and receiving data to and from an electronic device; A main function unit that constitutes a main function of the USB device;

A driver storage memory for storing a device driver,

A USB control unit in which the product information is identical to each other, and the class information includes descriptor information indicating the USB mass storage class and the class information indicating the class to which the main function belongs;

A descriptor information holding flag for holding which of the two types of descriptor information is active,

Is provided.

[0036] Further, a reset switch for resetting the descriptor information holding flag is provided.

[0037] Once the USB device is connected to the electronic device, the device driver is installed in the electronic device.

When the USB device can be used, the descriptor information holding flag is set. Therefore, in the second connection, the procedure of using the descriptor information for the USB mass storage class can be omitted, and the time can be reduced.

When switching connection to an electronic device with a different OS (operating system), the reset switch is operated to reset the descriptor information holding flag. Make use possible.

The invention's effect

By using the present invention, it is not necessary to use an external storage device such as a floppy disk drive or a CD-ROM drive when installing a device driver of a USB device. In other words, even an electronic device that does not have a floppy disk drive or a CD-ROM drive can use a USB device without going through complicated procedures such as adding devices.

[0040] In addition, since the USB device and the device driver can be collectively managed, the installation program can be collectively managed.

Further, if a bus reset or the like is used to switch the function of the USB device, it is possible to prevent the adverse effects caused by the forced switching.

Brief Description of Drawings

[FIG. 1] A block diagram showing a configuration of a USB device according to Embodiment 1 of the present invention.

FIG. 2 is an operation sequence diagram of a USB device and a computer according to Embodiment 1 of the present invention. FIG. 3 is an operation sequence diagram of a USB device and a computer according to Embodiment 1 of the present invention.

FIG. 4 is a block diagram showing a configuration of a USB device according to a second embodiment of the present invention.

FIG. 5 is an operation sequence diagram of a USB device and a computer according to Embodiment 2 of the present invention.

FIG. 6 is a block diagram showing a configuration of a USB device according to Embodiment 3 of the present invention.

FIG. 7 is an explanatory diagram of a mode of installing a device driver of a USB device in a computer according to the related art

[Figure 8] Illustration of descriptor information of USB device

[Figure 9] Illustration of device driver information of INF file

Explanation of symbols

[0043] 1 computer

2 USB devices

3 Device driver installation disk

11 Input / output section

12 USB controller

13 Main function section

14 Driver storage memory

15 Built-in judgment register

16 Descriptor information holding flag

17 Reset switch

A Descriptor information of USB device

Descriptor information for Al USB mass storage class

A2 Descriptor information for main function

B INF file

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of a USB device according to the present invention will be described in detail with reference to the drawings. Note that a description will be given using a computer as an example of an electronic device.

(Embodiment 1)

FIG. 1 is a block diagram showing a configuration of a USB device according to Embodiment 1 of the present invention. The USB device 2 includes an input / output unit 11 for transmitting and receiving data to and from the computer 1, a USB control unit 12 for controlling the USB device 2, and a main function unit for storing the original functions of the USB device 2. 13, a driver storage memory 14 for storing a device driver, and a built-in determination register 15. The built-in determination register 15 is for determining whether or not the device driver of the USB device 2 is installed in the computer 1. The USB control unit 12 has two types of descriptor information Al and A2. The descriptor information Al, A2 is used by the computer 1 to obtain product information (device type and manufacturer information).

[0047] Descriptor information A2 for the main function is dedicated to device driver installation, and describes the contents of the main function (class) that the USB device 2 originally has. In addition, the descriptor information A1 for the mass storage class describes the contents regarding the USB mass storage class for the purpose of installing the device driver. The USB mass storage class is a standard for operating storage devices such as CD-ROM and DVD-ROM by USB. The USB control unit 12 further has control software for operating the USB mass storage class.

[0048] The USB device 2 operates as a main function when the device driver of the USB device 2 is installed in the computer 1, and operates as a USB mass storage class device when the device driver is not installed. In the latter case, the device driver of the driver storage memory 14 is read out and installed in the computer 1 by the operation of the USB mass storage class.

Next, the operation of the system configured as above according to the present embodiment will be described with reference to the operation sequence of FIG.

Before the USB device 2 is connected to the computer 1, its built-in determination register 15 is set to a non-built-in state (HR = 0).

When the connection of the USB device 2 to the computer 1 is confirmed, the computer 1 starts an erasure process and acquires information necessary for using the USB device 2. That is, the computer 1 requests the descriptor information A of the USB device 2.

[0052] The USB control unit 12 of the USB device 2 requested for the descriptor information A Check register 15 for Here, since the state is the non-embedded state (HR = 0), the descriptor information A1 for the USB mass storage class is transmitted as the descriptor information A.

Here, the descriptor information A1 for the USB mass storage class includes a vendor ID, a product ID, and a revision ID, a class code, a subclass code, and a protocol. The vendor ID, product ID, and revision ID are the same as the descriptor information A2 for the main function. The class code, subclass code and protocol are exclusive to the USB mass storage class. However, this applies only when the revision ID is set.

Next, the computer 1 compares the vendor ID, product ID, and revision ID obtained from the descriptor information A1 with the vendor ID, product ID, and revision ID of the INF file B stored in the computer 1. .

[0055] (l) Descriptor information for USB mass storage class A1 comparison result = field of match If the comparison results in a match, computer 1 is a device for USB device 2 specified in INF file B Install the driver and make the USB device 2 usable. The device driver incorporated in the computer 1 issues a device request at initialization. This device request is designed to be vendor specific.

The USB control unit 12 of the USB device 2 that has received the device request unique to the vendor sets the built-in determination register 15 to the built-in state (HR = 1).

Next, the device driver incorporated in the computer 1 issues a bus reset to the USB device 2.

Next, the computer 1 starts the emanation processing of the USB device 2 again.

Next, the USB control unit 12 of the USB device 2 checks the built-in determination register 15, and since the state is the built-in state (HR = 1), the main function of the computer 1 is Send the descriptor information A2 for use.

[0060] As described above, the computer 1 is used for the USB device 2 incorporated by specifying the INF file B. The USB device 2 can be used by using the device driver. The USB control unit 12 of the USB device 2 activates the main function unit 13 to enable the main function of the USB device 2 to operate.

[0061] (2) Comparison result of descriptor information A1 for USB mass storage class = mismatch

On the other hand, when the above-described comparison between the vendor ID and product ID of the descriptor information A1 and the vendor ID and product ID of the INF file B results in a mismatch, the operation is as follows. This will be described with reference to the operation sequence of FIG.

[0062] As another means for searching for a device driver, the computer 1 stores the class code, subclass code, and protocol obtained from the descriptor information A1 for the USB mass storage class with the class code, subclass code, and protocol of the INF file B. Compare.

[0063] The descriptor information A1 describes that the USB device 2 is a device of the USB mass storage class. On the other hand, device drivers for USB mass storage class are included as standard equipment in Windows OS after WindowsME / 2000.

Therefore, if the computer 1 is a Windows corresponding to the above, the result of the above comparison is determined to be a match. In this case, the computer 1 incorporates a device driver for the USB mass storage class specified by the INF file B. The device driver for USB mass storage class in computer 1 does not issue the above-mentioned vendor-unique device request.

When the USB control unit 12 of the USB device 2 confirms that there is no issuance of a device request unique to the vendor, the USB control unit 12 determines that the device driver for the USB mass storage class is installed in the computer 1. The USB control unit 12 activates control software for operating the USB mass storage class on the driver storage memory 14, and accesses the driver storage memory 14 by using the control software. In this case, the USB device 2 behaves as a USB mass storage class device.

In other words, the USB device 2 can be treated by the computer 1 as equivalent to a storage device such as a floppy disk drive or a CD-ROM drive. The computer 1 uses the driver storage memory 14 of the USB device 2 as a storage medium such as a CD-ROM medium. Can be recognized. As a result, the computer 1 can freely access the driver storage memory 14. The main function unit 13 becomes irrelevant.

The device storage memory 14 of the USB device 2 stores a device driver for the main function of the USB device 2. The computer 1 can install a device driver for the main function of the USB device 2 by accessing the device driver. That is, the device driver for the main function of the USB device 2 can be installed in the computer 1 without using a medium such as a floppy disk or a CD-ROM.

[0068] A bus reset is used to switch between operation in the USB mass storage class and operation in the main function. As a result, the user does not need to be aware of the switching of the operation state. In addition, adverse effects on the computer 1 (Windows OS) can be prevented.

In the above configuration, the following USB device is also effective. The configuration is such that a driver installation program is stored in the driver storage memory 14.

[0070] The USB control unit 12 starts the installation program, reads out the device driver for the main meeting from the driver storage memory 14, and installs it in the computer 1. When the installation is completed, the built-in state is set in the built-in determination register 15 (HR = Do, then a bus reset is issued, and the computer 1 performs the enumeration process again. In this case, , Vendor ID, product ID, etc., match, and the main function of USB device 2 becomes available.

When the above processing is automated, it appears to the user that the device driver for the main function of the USB device 2 automatically incorporates the power to the computer 1 as well. No burden is imposed on the user.

(Embodiment 2)

Embodiment 2 of the present invention is directed to a USB device whose main function operates in the USB mass storage class. A typical example of such a USB device is a DVD drive.

As shown in FIG. 4, the USB device 2 includes an input / output unit 11, a USB control unit 12, a main function unit 13, and a driver storage memory 14 similar to those in the first embodiment. There is no built-in determination register 15 in the first embodiment. The USB control unit 12 that controls the USB device 2 has one type of descriptor information, and is a descriptor for the USB mass storage class. Information Al only. Descriptor information dedicated to the installation of the device driver for the main function of USB device 2.

Next, the operation of the system of the present embodiment having the above configuration will be described according to the operation sequence of FIG.

In the case where the device driver for the main function is installed in the computer 1, the results of the comparison of the vendor ID, the product ID, and the like do not match. Furthermore, the comparison of the class code, subclass code, etc. is consistent. As a result, as described above, the computer 1 incorporates the device driver for the standard USB mass storage class specified by the INF file B. In this case, the main function of the USB device 2 operates in the USB mass storage class.

To switch the operation mode of the USB device 2 to the main function after the device driver is installed, a device request unique to the vendor is transmitted. A bus reset is not necessary for re-emulation as in the first embodiment.

The present embodiment is useful when additionally installing a device driver for enhancing functions on a USB mass storage class device that is provided as standard equipment in the computer 1.

(Embodiment 3)

In the first and second embodiments, after the second use when the USB device is connected to the same computer many times, from when the USB device is connected to the computer until the USB device becomes usable on the computer It takes longer than usual USB devices. In addition, a USB device is equipped with a USB mass storage class device driver as standard equipment, and a computer and a device driver corresponding to the driver storage memory are stored. If you connect to a computer with a different installation mechanism, you will not be able to use USB devices.

A configuration corresponding to this is the configuration of the third embodiment of the present invention.

As shown in FIG. 6, the USB device 2 includes an input / output unit 11, a USB control unit 12, a main function unit 13, a driver storage memory 14, and a built-in determination unit similar to those in the first embodiment. Register 15 has descriptor information holding flag (hereinafter referred to as flag) 16 that holds which descriptor information Al or A2 is active, and reset switch 17 for flag 16 I have.

The flag 16 is set to, for example, “0” in the initial state so as to use the descriptor information A1 for the mass storage class. When “0” is set in the flag 16, when the USB device 2 is connected to the computer 1, the USB control unit 12 refers to the built-in determination register 15. Since the built-in determination register 15 is “0”, the device driver for the main function of the USB device 2 is built into the computer 1 through the same processing as in the first embodiment.

Then, the descriptor information A1 for the mass storage class is transmitted to the computer 1 in the above process. After once transmitting the descriptor information A1 for the mass storage class, the flag 16 is set to "1" and the descriptor information A2 for the main function is used. The flag 16 can be set in a nonvolatile memory in the USB device 2. The reset switch 17 is for returning the flag 16 to the initial state.

Next, the operation of the system of the present embodiment configured as described above will be described.

As in the first embodiment, it is assumed that the device driver of the USB device 2 has already been incorporated in the computer 1. In this case, the flag 16 is already set to "." Therefore, after that, when the USB device 2 is connected to the computer 1, the USB control unit 12 sees the flag 16. "1" is set Therefore, the device driver of USB device 2 can be recognized as already installed in computer 1 without using the built-in determination register 15, and only the descriptor information A2 for the main function should be used. become.

When the computer 1 issues the firmware processing, the USB control unit 12 does not perform the processing using the descriptor information A1 for the mass storage class. It performs the same operation as a normal USB device 2 that uses only the descriptor information A2 for the main function.

That is, the procedure using the disk storage unit information A1 for the mass storage class at the beginning of the connection in the case of the first embodiment is omitted. Therefore, the time from when the USB device 2 is connected to when it can be used can be reduced.

As a result of connecting USB device 2 to computer 1 as described above, it is assumed that flag 16 is set to “1.” In this case, disconnect the connection and reconnect to another computer 1. Here, the new connection target computer 1 has the device driver installed. No. In such a case, the USB device 2 cannot be used unless the flag 16 is set to 1 ". Therefore, the reset switch 17 is operated to reset the flag 16 to" 0 ". Then, the same processing as in the first embodiment is performed, and the device driver for the main function of the USB device 2 can be installed in the computer 1.

[0088] Further, it is conceivable to connect the USB device to a Windows PC and a computer having a different device driver installation mechanism.

[0089] Also in this case, the driver can be installed according to the procedure of the above-described method, and the USB device can be used. When the device connection is not installed on the computer, the device connection is recognized as mass storage class. After the driver is installed, the main function 13 of the USB device 2 can be used. At this time, the flag 16 in the nonvolatile memory is also set to "1". Thereafter, the flag 16 allows the main function 13 of the USB device 2 to be used at any time.

However, in this state, even if a computer to which the USB device 2 has not been connected before is connected, the main function 13 of the USB device 2 will operate. Clear flag 16 so that it is recognized as a mass storage class. As a result, the driver can be installed.

Industrial applicability

[0091] The present invention is useful as a technology for efficiently installing a device driver of a USB device in a computer. In addition, a computer is the only USB host that can be used. Digital home appliances that have the function of a USB host are also widely applicable.

Claims

The scope of the claims

[1] an input / output unit for transmitting and receiving data to and from an electronic device;

A main function unit that constitutes a main function of the USB device;

A driver storage memory for storing a device driver,

USB device equipped with.

[2] The USB control unit transmits the USB mass storage class descriptor information to the electronic device at the time of the first request for the descriptor information from the electronic device after connection with the electronic device. The USB device according to claim 1.

3. The USB device according to claim 2, further comprising a built-in determination register indicating whether the device driver is built into the electronic device.

[4] The built-in determination register is set to a non-built-in state when the electronic device is connected to the electronic device, and the USB control unit controls the electronic device based on the USB mass storage class descriptor information. 4. The USB device according to claim 3, wherein the built-in determination register is updated to the built-in state when the status is determined to be a built-in state.

[5] The USB control unit is configured to allow the electronic device to execute the USB mass storage class disk drive.

When it is determined that the device driver has not been installed, the device driver is read out from the driver storage memory and installed in the electronic device. After the device driver has been installed in the electronic device, the installed status determination register is set. 5. The USB device according to claim 4, wherein the USB device is updated to a loaded state.

6. The USB control unit according to claim 5, wherein the USB control unit updates the built-in determination register to the built-in state based on reception of a unique vendor request from the electronic device. USB device as described.

[7] The USB control unit, after the device driver is installed, switches between a USB mass storage function and the main function based on a bus reset or a mass storage reset received from the electronic device. USB device according to (5) or (6) vessel.

[8] The USB control unit determines whether or not the device driver is incorporated in the electronic device based on a unique vendor request, and when the device driver is incorporated, controls with the main function, and incorporates the device driver. 2. The method according to claim 1, wherein the device driver is read from the driver storage memory and installed in the electronic device by controlling the device as a USB mass storage device, and then control is switched to the main function. On-board USB device.

[9] an input / output unit for transmitting / receiving data to / from an electronic device;

The main function part that constitutes the function belonging to the mass storage class as the main function of the USB device

A driver storage memory for storing a device driver,

USB device equipped with.

10. The USB device according to claim 9, wherein the USB control unit switches to the main function based on the reception of a vendor request from the electronic device.

[11] The USB control unit determines whether or not the device driver is incorporated in the electronic device based on a unique vendor request, and when the device driver is incorporated, controls the main function and incorporates the device driver. The device according to claim 9, wherein the device driver is read from the driver storage memory and installed in the electronic device by controlling the device as a USB mass storage device, and then control is switched to the main function. On-board USB device.

[12] an input / output unit for transmitting / receiving data to / from an electronic device,

A main function unit that constitutes a main function of the USB device;

A driver storage memory for storing a device driver, A USB control unit in which the product information is identical to each other, and the class information includes descriptor information indicating the USB mass storage class and the class information indicating the class to which the main function belongs

USB device equipped with.

13. The USB device according to claim 12, further comprising a reset switch for resetting the descriptor information holding flag.