KR101374801B1 - Usb keyboard apparatus and method capable of supporting n-key rollover with bios compatibility - Google Patents

Abstract

An N-key rollover USB keyboard apparatus according to embodiments of the present invention can include a descriptor storage unit including a descriptor, in which a report size, which is a field size of an item to be reported to a host device in compliance with the standard of a universal serial bus (USB) human interface device (HID), and a report count representing the number of fields of the item are declared, a USB device controller for analyzing a request received therein from the host device to set one of a boot protocol mode and a report protocol mode, and for outputting a report containing key codes, which are created through the key pressing of a user, as items to the host device, and a report creating unit for creating a report containing six typical key codes according to a boot protocol if the set protocol mode is the boot protocol mode, for creating a report containing key codes for typical keys by number corresponding to the report count declared in the descriptor storage unit if the set protocol mode is the report protocol mode, and for outputting the creating report to the USB device controller. [Reference numerals] (10) N-key rollover USB keyboard apparatus; (12) Report generating unit; (13) descriptor storage unit; (131) Usage table; (132) Report descriptor; (14) USB device controller; (141) Protocol setting unit; (15) USB interface

Description

USB KEYBOARD APPARATUS AND METHOD CAPABLE OF SUPPORTING N-KEY ROLLOVER WITH BIOS COMPATIBILITY}

The present invention relates to a keyboard device, and more particularly, to a USB keyboard device.

Universal Serial Bus (USB) technology is a communications architecture that allows a host device, such as a personal computer (PC), to connect to a variety of peripherals using only four cables.USB is really just a serial communication link. It is the USB protocol to set up and run a USB device at startup of the device or when the host device is plugged in during operation.

USB devices can be classified into several classes of devices. Each device class defines a common operating method and protocol. USB device classes include, for example, display classes, communication classes, audio classes, mass storage classes, and human interface classes.

The human interface class or human interface device (HID) class may include not only keyboards, mice, keypads, joysticks, trackballs, gaming controllers, but also USB devices such as bar code readers, thermometers, and measuring instruments.

The USB HID keyboard delivers the data loaded with key codes in one payload, ie, "reports", to the USB host device, or PC, using the USB protocol with respect to key presses and releases on the keyboard.

In the past, a keyboard dedicated PS / 2 keyboard port delivered a key code of a key pressed or released, and the host device was able to receive a key pressed code simultaneously because it was treated as a keyboard interrupt. Thus, as long as the keyboard device is designed to correctly recognize multiple key presses or releases, and if the host device can handle keyboard interrupts quickly enough, no matter how many keys are pressed simultaneously, the host device will not be able to recognize them. There was no particular limitation on the number of pressed keys present.

The number of keys that can be processed is called N-key rollover. In the days when PS / 2 interface keyboards were used, N-key rollover was a hardware problem that scans for key presses and breaks within the keyboard device. For example, in the matrix method, key blocking or ghosting, which is not recognized when the adjacent key is pressed in a specific key combination, may easily occur, and the N-key rollover problem may be considered to eliminate such key blocking or ghosting.

However, the USB HID keyboard developed by the USB method must share the USB port with other USB devices, and the key press / release event is handled as a message rather than an interrupt, so it can be used to deliver unlimited key codes of keys pressed simultaneously. New constraints were created by the protocol itself.

The USB HID keyboard delivers four special key codes, ALT, CTRL, SHIFT, and GUI keys, and key codes for the press events of six common keys in a single report, so that key press events exceed six consecutive times. If so, key codes corresponding to six or more pressed events are missing or ignored. For example, the G key press event after keyboard A press, S press, D press, F press, G press, and F press is not included in the report until there is a release event among the already pressed keys.

While USB keyboards typically support the delivery of up to six common key press / release key codes, some say that Braille keyboards must press up to six dot keys at the same time. This is because the Basic Input / Output System (BIOS) that runs before loading is designed to statically accept only 8-byte reports with four special keys and six common key codes for HID keyboards.

This simultaneous key restriction is not a major problem in a typical usage environment, but has caused considerable inconvenience in some applications using complex key combinations, such as graphic editing tools, CAD, games, and compositions.

Therefore, in order to overcome this simultaneous key limitation, Korean Patent Application No. 2010-0019961 discloses that two logical USB keyboard devices are configured internally in the keyboard device, and the first logical USB keyboard event is performed after six or less general key press events. If you configure a report and send it to a USB host, but there are more than six general key press events, the report is sent with key codes that correspond to seven to twelve general key press events on the second logical USB keyboard. It is proposed to configure and transfer to USB host. The user still felt like using a single physical keyboard, so it seemed as if the six-key limitation was solved.

However, since the host device receives key input from different keyboard devices, the key press event after 7 times may not be properly processed depending on the key combination.

In addition, some of the many expensive USB keyboards that provide N-key rollover on the market, some of them may cause recognition problems at the BIOS level and fail to enter BIOS setup keyboard commands on the host device, thus preventing them from entering the BIOS setup screen. There have been reports of malfunctions, such as failing or even stopping the host device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a USB keyboard device capable of N-key rollover and a method of providing an N-key rollover function without problems in BIOS compatibility at boot time.

A method for providing an N-key rollover function according to an aspect of the present invention is a method for providing an N-key rollover function in a USB keyboard device including a descriptor storage unit, a USB device controller, and a report generation unit.

Determining, by the USB device controller, whether a request received from a host device is a Set_Protocol request;

If the request is a Set_Protocol request, setting, by the USB device controller, the report generator to a boot protocol mode;

Generating, by the report generator, an 8-byte long report including a special key field, a spare field, and key code fields of six general keys according to a user's key press;

If the request is not a Set_Protocol request, determining, by the USB device controller, whether the request received from the host device is a Get_Descriptor request;

If the request is a Get_Descriptor request and the class descriptor type of the wValue part included in the Get_Descriptor request is Report, setting, by the USB device controller, the report generator in report protocol mode;

9 or more bytes including a special key field, a spare field, and key code fields of the number of general keys corresponding to the report count, with reference to a predetermined report count declared in a report descriptor stored in the descriptor storage unit. Generating a report of size; And

The USB device controller may include transmitting the generated report to a host device.

According to an embodiment, if the request is a Set_Protocol request, the step of setting, by the USB device controller, the report generator to a boot protocol mode,

If the request is a Set_Protocol request and the protocol type wValue part included in the Set_Protocol request means Boot Protocol, the USB device controller may set the report generator to boot protocol mode.

According to one embodiment, the predetermined report count declared in the report descriptor may be seven or more.

According to another aspect of the present invention, there is provided a method for providing an N-key rollover function in a USB keyboard device including a descriptor storage unit, a USB device controller, and a report generation unit.

Analyzing, by the USB device controller, a request received at a host device side;

Setting, by the USB device controller, the report generator to one of a boot protocol mode and a report protocol mode according to a request analysis result;

If the report generator is set to a boot protocol mode, generating a 8-byte long report including a special key field, a spare field, and key code fields of six general keys according to a user's key press;

When the report generating unit is set to the report protocol mode, a special key field and a spare field and key code fields of the number of general keys corresponding to the report count are referred to by referring to a predetermined report count declared in the report descriptor stored in the descriptor storage unit. Generating a report having a size of at least 9 bytes including the data; And

The USB device controller may include transmitting the generated report to a host device.

According to one embodiment, the USB device controller, the step of analyzing the request received from the host device side,

Determining, by the USB device controller, whether the request is a Set_Protocol request and a protocol type wValue part included in the Set_Protocol request means Boot Protocol; And

The USB device controller may include determining whether the request is a Get_Descriptor request and whether the class descriptor type of the wValue part included in the Get_Descriptor request is a report.

According to an embodiment of the present disclosure, the step of setting the report generator to one of a boot protocol mode and a report protocol mode according to a request analysis result may include:

Setting, by the USB device controller, the report generator as a boot protocol mode if the request is a Set_Protocol request and the protocol type wValue part included in the Set_Protocol request means Boot Protocol as a result of analyzing the request; And

If the request is a Get_Descriptor request and the class descriptor type of the wValue part included in the Get_Descriptor request is Report, the USB device controller sets the report generator to report protocol mode. Can be.

N-key rollover USB keyboard device according to another aspect of the present invention,

According to the Universal Serial Bus (USB) Human Interface Device (HID) specification, the report descriptor declares the report size, which is the field size of the item to report to the host device, and the report count, which is the number of fields of the item. Descriptor storage including;

A USB device controller for analyzing a request received from the host device to set a protocol mode of one of a boot protocol mode and a report protocol mode, and to transmit a report to the host device, the report including key codes by a user's key press as an item. ; And

If the set protocol mode is the boot protocol mode, a report including 6 general key codes is generated according to the boot protocol. If the set protocol mode is the report protocol mode, the number of general keys corresponding to the report count declared in the descriptor storage is generated. A report generation unit may generate a report including key codes, and output the generated report to the USB device controller.

According to one embodiment, the USB device controller,

If the request received from the host device is a Set_Protocol request, the report generator may be set to a boot protocol mode.

According to one embodiment, the USB device controller,

If the request is a Get_Descriptor request and the class descriptor type of the wValue part included in the Get_Descriptor request is Report, the report generator may be set to report protocol mode.

According to one embodiment, the predetermined report count declared in the report descriptor may be seven or more.

According to the USB keyboard device capable of N-key rollover and the method for providing the N-key rollover function of the present invention, a report of 9 bytes or larger including seven or more general key events in succession can be transmitted to the host device.

According to the USB keyboard device capable of N-key rollover and the method of providing N-key rollover function of the present invention, 8 special key events and 6 general key events are transmitted to the host device according to the boot protocol when the BIOS is driven. After the OS has loaded, it can send a report to the host device with 9 bytes or larger reports of 8 special key events and 7 or more general key events, depending on the report protocol.

According to the USB keyboard device and the N-key rollover function providing method according to the present invention, since the report is generated by different boot protocol mode and report protocol mode, the boot procedure does not cause an error.

1 is a block diagram illustrating an N-key rollover USB keyboard device according to an embodiment of the present invention.
2 is a flowchart illustrating a method for providing an N-key rollover function in an N-key rollover USB keyboard device according to an embodiment of the present invention.

For the embodiments of the invention disclosed herein, specific structural and functional descriptions are set forth for the purpose of describing an embodiment of the invention only, and it is to be understood that the embodiments of the invention may be practiced in various forms, The present invention should not be construed as limited to the embodiments described in Figs.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

The keyboard device in the present invention includes a numeric keys and a keypad marked with operation keys, which are disposed on the right side of the keyboard device, unless otherwise explicitly interpreted. Also, for example, when a keyboard scan signal is mentioned, It should be understood that the signal also encompasses the keypad scan signal.

In the specification of the present invention, "simultaneous input" includes not only simultaneous key presses in time, but also a case where a key is pressed while another key is not yet released.

1 is a block diagram illustrating an N-key rollover USB keyboard device according to an embodiment of the present invention.

Referring to FIG. 1, the N-key rollover USB keyboard device 10 includes a keyboard scan unit 11, a report generator 12, a descriptor storage unit 13, a USB device controller 14, and a USB interface 15. It may include.

The keyboard scanning unit 11 detects an electrical signal that is activated when the user touches the key cap, for example, when the contact is contacted, thereby identifying which key cap has been pressed, or conversely, when the user touches the key cap An electrical signal that is deactivated while the contact is dropped can be detected to identify which key cap has been depressed.

The keyboard scan unit 11 may be designed to use individual contacts and conductor lines for all keys in the case of expensive keyboards, but in the case of inexpensive manufacture, the contacts are designed to share conductor lines per row or column It is possible.

The keyboard scan unit 11 scans the key scan codes of the keys and outputs them to the report generation unit 12 whenever a press or release of the key is identified.

The report generation unit 12 generates a report having a size specified by the standard when the USB device controller 14 is in the boot protocol mode according to the operation mode set according to whether the boot protocol or the boot protocol is set. In report protocol mode, you can create a report of the declared size.

Specifically, when the report generation unit 12 is set to the boot protocol mode, the report generation unit 12 generates key codes based on the key scan codes scanned from the keyboard scanning unit 11, and includes eight special keys, a spare field, and up to six general fields. Generates an 8 byte report consisting of the key codes of the key.

In addition, when the report generation unit 12 is set to the report protocol mode, the report generation unit 12 generates key codes based on the key scan codes scanned from the keyboard scanning unit 11, and then, in the report descriptor 132 stored in the descriptor storage unit 13. Generate a report of nine bytes or larger consisting of the key codes of eight special keys, spare fields, and seven or more general keys, depending on the specification you are declaring.

At this time, the report generation unit 12 may refer to the usage page 0x07 of the USB usage table 131 stored in the descriptor storage unit 13 to generate a key code from the key scan code. Can be.

For example, in scan code set 2, the make scan code for q is 0xE015, the break scan code is 0xE0F015, and the key code for q in the landing page is 14 (Hex). The report generation unit 12 recognizes that "q" is pressed if scan code 0xE015 is identified and includes the key code 14H in the report. Remove code 14H. The BIOS understands that "q" was pressed when the report included the key code 14H, and that "q" was no longer pressed when the key code 14H from the previous report disappeared from the current report.

The descriptor storage unit 13 includes descriptors for which the N-key rollover USB keyboard device 10 defines itself as a USB HID device, for example, a device descriptor, a configuration descriptor, and an interface descriptor. A descriptor, an endpoint descriptor, an HID descriptor, a report descriptor, a physical descriptor, and a string descriptor may be stored.

These descriptors are a kind of document in which various configuration information is declared. In particular, among these descriptors, the report descriptor 132 is passed to the HID class driver when the USB HID device is connected to the USB port. It tells the host device's HID class driver how to forward them.

The report descriptor 132 declares setting information such as a page number for referencing the item to be reported, a report size, which is the field size of the item, and a report count, which is the number of fields of the item. The USB device controller 14 reads the report descriptor 132 from the descriptor storage unit 13 and transfers it to the HID class driver.

If the report size declared in the report descriptor 132 is 8, the report count is 62, and the landing page is a key code, a total of 64 byte reports with 8 general key codes as items (1 byte per item) (8 special Key and spare fields).

The size of the report count takes into account the bandwidth that the keyboard device 10 may occupy among the entire bandwidth of the USB, the controller performance of the keyboard device 10, the message processing performance of the host device, the power consumption of the keyboard device 10, or the application compatibility. Can be determined.

Meanwhile, the USB device controller 14 may establish an electrical connection between the USB interface 15 and the host device, respond to various requests received from the host device, and further, the protocol setting unit 141 may host the host device. The report generating unit 12 is set to an operation mode of either the boot protocol mode or the report protocol mode according to the type and state of the protocol request received from the protocol request.

When the BIOS or OS is run on the host device, the BIOS or HID class driver of the OS typically sends a Get_Descriptor request to the USB keyboard device 10. When the Get_Descriptor request is received, the USB device controller 14 transmits descriptors stored in the descriptor storage unit 13 to the host device.

In addition, the HID class driver of the OS may send a Set_Descriptor request to the USB keyboard device 10 to change some descriptors. When the Set_Descriptor request is received, the USB device controller 14 may store the changed descriptor in the descriptor storage unit 13.

In addition, the HID class driver in the OS provides a Get_Report request that instructs the USB keyboard device 10 to send a specific report through the control pipe, a Set_Report request that forwards a specific report from the host device to the USB keyboard device 10, USB The Get_Idle request for detecting the current idle rate from the keyboard device 10 and the Set_Idle request for suppressing a specific report through the interrupt IN pipe until a specific event or time passes may be sent.

However, the request does not include direct information as to whether the sender is an OS or a BIOS, and since the USB keyboard device is not informed that the OS is transferring host control from the BIOS, the USB keyboard device 10 ) Does not directly know whether the host device is currently being controlled by the BIOS or the OS.

Nevertheless, the inventor of the present invention has found that the USB keyboard device 10 can strongly estimate whether the host device is under BIOS control or OS control by analyzing the parts constituting the requests.

Typically, when the BIOS has control of the system, it sends a Set_Protocol request to the USB keyboard device 10, and also sends a Get_descriptor request but does not ask for the report format, while the OS starts to control the system, while Get_Descriptor It has been observed that the report format is queried while sending the request to the USB keyboard device 10, but the Set_Protocol request is not actually sent.

First, when the BIOS has control, the BIOS enumerates a list of USB devices that are set to be able to act as boot devices among the USB devices connected to the host device first when the host device, such as a PC, starts up. do.

The BIOS may send a Get_Protocol request to answer the type of protocol currently set, a Set_Protocol request to set the protocol as the boot protocol, and a Get_Descriptor request to the USB devices listed as the boot device.

If the USB keyboard device 10 receives a Set_Protocol request to set the protocol as the boot protocol, then it can be determined that this request is obviously sent by the BIOS.

Also, like the OS, the BIOS sends a Get_Descriptor request to the USB keyboard device 10, but since the BIOS assumes that it will report according to the boot protocol for the keyboard device as a boot device connected at boot time, the USB keyboard device 10 Do not ask for a report format. Thus, while the BIOS has control, it is unlikely that a Get_Descriptor request with a wValue part of 0x22 meaning Report is received.

On the other hand, when the OS is running on the host device, the HID class driver of the OS may send a Get_Descriptor request to the USB keyboard device 10. At this time, the OS attempts to know the report format of the USB keyboard device 10 through the Get_Descriptor request. For this purpose, the wValue part of the Get_Descriptor request must have a value of 0x22 indicating a report.

Thus, if the wValue part of the Get_Descriptor request is 0x22, meaning Report, the Get_Descriptor request can be determined to have been sent by the OS.

Therefore, if the host device receives the Set_Protocol request, the protocol setting unit 141 of the USB device controller 14 may regard the host device as a boot state in which the BIOS currently has control authority. In particular, if the wValue part set in the Set_Protocol request is "0", that is, a boot protocol, the protocol setting unit 141 of the USB device controller 14 may set the report generation unit 12 to the boot protocol mode. If the USB keyboard device 10 is set as a boot protocol, an 8-byte long report will be generated that includes special key fields and spare fields and key code fields of six general keys upon key input by the user.

According to an exemplary embodiment, a condition for determining whether the protocol setting unit 141 is in a boot state may further include a condition in which a request of another type is not received while the power is newly supplied or the USB host controller is initialized by rebooting.

If the host device receives the Get_Descriptor request and the class descriptor type of the wVaule part in the Get_Descriptor request is Report, that is, 0x22, the protocol setting unit 141 of the USB device controller 14 indicates that the host device has the current OS control right. Eggplant can be considered a normal state.

Accordingly, the protocol setting unit 141 of the USB device controller 14 sets the report generation unit 12 to the report protocol mode, and provides the report generation unit 12 with the report count declared in the report descriptor 132. It generates a report of 9 bytes or larger containing special key fields and spare fields and key code fields of 7 or more general keys.

The USB device controller 14 then sends the generated report to the host device via the USB interface 15.

2 is a flowchart illustrating a method for providing an N-key rollover function in an N-key rollover USB keyboard device according to an embodiment of the present invention.

Referring to FIG. 2, in step S21, the USB device controller 14 determines whether a request received from the host device is a Set_Protocol request.

Specifically, if the request received from the host device side is a Set_Protocol request, and the protocol type wValue part included in the Set_Protocol request indicates a Boot Protocol as "0", the USB device controller 14 may generate a report in step S22. (12) is set to the boot protocol mode, and in step S23, the report generator 12 reports an 8-byte long report including a special key field and a spare field and key code fields of six general keys according to a key input. Create

If the request received at the host device side is not a Set_Protocol request, at step S24, the USB device controller 14 determines whether the request received at the host device side is a Get_Descriptor request.

If the request received from the host device side in step S24 is a Get_Descriptor request and the class descriptor type of the wValue part included in the Get_Descriptor request is Report, in step S25, the USB device controller 14 reports the generation unit. Set (12) to Report Protocol Mode.

In step S26, the USB device controller 14 responds to the host device with the report descriptor 132 in which a predetermined report count is declared for the Get_Descriptor request of the host device.

In step S27, the report generation unit 12 refers to the predetermined report count previously declared in the report descriptor 132, and key codes of the number of general keys corresponding to the special key field, the spare field, and the report count. Create a report that is at least 9 bytes in size and contains fields.

In step S28, the USB device controller 14 transmits the generated report to the host device via the USB interface 15.

As a result, the N-key rollover USB keyboard device 10 determines whether the host having the control right of the host device is the BIOS or the OS, and transmits an 8-byte report to the host device while the OS has the control right. While you have control, you can send a report of more than 9 bytes to the host device.

This change in report size can be made automatically without user intervention or awareness, such as, for example, by running a report size selection switch, so that the N-key rollover function can be used on a USB keyboard without concern for compatibility or inconvenience.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Modification is possible. Accordingly, the spirit of the present invention should be understood only in accordance with the following claims, and all of the equivalent or equivalent variations will fall within the scope of the present invention.

10 N-key rollover USB keyboard device
11 Keyboard Scanning Section 12 Report Generation Section
13 Descriptor storage 131 Usage table
132 Report Descriptor
14 USB Device Controller 141 Protocol Settings
15 USB interface

Claims (10)

A method for providing an N-key rollover function in a USB keyboard device including a descriptor storage unit, a USB device controller, and a report generator,
Determining, by the USB device controller, whether a request received from a host device is a Set_Protocol request;
If the request is a Set_Protocol request, setting, by the USB device controller, the report generator to a boot protocol mode;
Generating, by the report generator, an 8-byte long report including a special key field, a spare field, and key code fields of six general keys according to a user's key press;
If the request is not a Set_Protocol request, determining, by the USB device controller, whether the request received from the host device is a Get_Descriptor request;
If the request is a Get_Descriptor request and the class descriptor type of the wValue part included in the Get_Descriptor request is Report, setting, by the USB device controller, the report generator in report protocol mode;
9 or more bytes including a special key field, a spare field, and key code fields of the number of general keys corresponding to the report count, with reference to a predetermined report count declared in a report descriptor stored in the descriptor storage unit. Generating a report of size; And
And transmitting, by the USB device controller, the generated report to a host device. The method of claim 1, wherein if the request is a Set_Protocol request, the step of setting, by the USB device controller, the report generator to a boot protocol mode,
If the request is a Set_Protocol request and the protocol type wValue part included in the Set_Protocol request means Boot Protocol, the USB device controller is to set the report generator to boot protocol mode. How to provide N-key rollover function. The method according to claim 1, wherein the predetermined report count declared in the report descriptor is 7 or more. A method for providing an N-key rollover function in a USB keyboard device including a descriptor storage unit, a USB device controller, and a report generator,
Analyzing, by the USB device controller, a request received at a host device side;
Setting, by the USB device controller, the report generator to one of a boot protocol mode and a report protocol mode according to a request analysis result;
If the report generator is set to a boot protocol mode, generating a 8-byte long report including a special key field, a spare field, and key code fields of six general keys according to a user's key press;
When the report generating unit is set to the report protocol mode, a special key field and a spare field and key code fields of the number of general keys corresponding to the report count are referred to by referring to a predetermined report count declared in the report descriptor stored in the descriptor storage unit. Generating a report having a size of at least 9 bytes including the data; And
And transmitting, by the USB device controller, the generated report to a host device. The method of claim 4, wherein the analyzing of the request received from the host device side by the USB device controller comprises:
Determining, by the USB device controller, whether the request is a Set_Protocol request and a protocol type wValue part included in the Set_Protocol request means Boot Protocol; And
And determining, by the USB device controller, that the request is a Get_Descriptor request and that the class descriptor type of the wValue part included in the Get_Descriptor request is a Report. The method of claim 5, wherein the setting of the report generator to one of a boot protocol mode and a report protocol mode according to a request analysis result comprises:
Setting, by the USB device controller, the report generator as a boot protocol mode if the request is a Set_Protocol request and the protocol type wValue part included in the Set_Protocol request means Boot Protocol as a result of analyzing the request; And
Setting, by the USB device controller, the report generation unit to report protocol mode if the request is a Get_Descriptor request and the class descriptor type of the wValue part included in the Get_Descriptor request is Report as a result of analyzing the request; And providing an N-key rollover function in a USB keyboard device. According to the Universal Serial Bus (USB) Human Interface Device (HID) specification, the report descriptor declares the report size, which is the field size of the item to report to the host device, and the report count, which is the number of fields of the item. Descriptor storage including;
A USB device controller for analyzing a request received from the host device to set a protocol mode of one of a boot protocol mode and a report protocol mode, and to transmit a report to the host device, the report including key codes by a user's key press as an item. ; And
If the set protocol mode is the boot protocol mode, a report including 6 general key codes is generated according to the boot protocol. If the set protocol mode is the report protocol mode, the number of general keys corresponding to the report count declared in the descriptor storage is generated. And a report generator for generating a report including key codes and outputting the generated report to the USB device controller. The method of claim 7, wherein the USB device controller,
And if the request received from the host device is a Set_Protocol request, setting the report generator to a boot protocol mode. The method of claim 7, wherein the USB device controller,
And if the request is a Get_Descriptor request and the class descriptor type of the wValue part included in the Get_Descriptor request is Report, setting the report generator to report protocol mode. 8. The N-key rollover USB keyboard device according to claim 7, wherein a predetermined report count declared in said report descriptor is seven or more.

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