WO2006038260A1

WO2006038260A1 - Usb storage system and usb storage device

Info

Publication number: WO2006038260A1
Application number: PCT/JP2004/014357
Authority: WO
Inventors: Shinichi Suzuki; Atsuyuki Ikeya
Original assignee: Renesas Technology Corp.
Priority date: 2004-09-30
Filing date: 2004-09-30
Publication date: 2006-04-13
Also published as: JPWO2006038260A1

Abstract

There are included, for example, a plurality of USB hosts comprising a USB host [1] (10a) and a USB host [2] (10b); and a USB reader/writer (11) that is connected to an external medium (13), such as a memory card or the like, and that can also be connected to the plurality of USB hosts via respective USB cables (12a,12b). The software or the like in the USB reader/writer (11) includes a function or the like for rejecting a write request from one of the USB hosts during writing into the external medium (13) from the other. In this way, a shared access of the external medium (13) by the plurality of USB hosts can be realized.

Description

Specification

USB storage system and USB storage device

Technical field

[0001] The present invention relates to a USB (Universal Serial Bus) storage system and a USB storage device, and more particularly to a technology effective when applied to a USB storage system and a USB storage device that are connected to a plurality of hosts. is there.

Background art

According to a study by the present inventor, the following technologies can be considered for the USB storage system.

[0003] In recent years, USB storage devices that handle external media such as memory cards and floppy disks (registered trademark) as removable disks due to their ease of use with plug-and-play functions and improved data transfer speed according to the USB 2.0 standard There are many (hereinafter referred to as USB reader / writers).

Disclosure of the invention

Problems to be solved by the invention

[0004] By the way, as a result of studies by the present inventor regarding the technology of the USB storage system as described above, the following has become clear.

[0005] With the recent price reduction of PCs (Personal Computers), the number of users who use multiple PCs is increasing. Under such circumstances, the configuration of the USB storage system usually has a configuration as shown in FIG. FIG. 10 is a schematic diagram showing an example of the configuration of the USB storage system of the technology studied as the premise of the present invention, and (a) to (c) show different configuration examples.

[0006] First, in FIG. 10 (&), 113 1 I cable 102 Nyo; 38 USB writer 101a which is connected to the host 1 ³ Ji 100, one such as an SD (Secure Digital) memory card or floppy disk External media can be inserted. In Fig. 10 (b), a plurality of different types such as USB reader / writer 101b force CF (CompactFlash (registered trademark)) card, SD memory card and Memory Stick (registered trademark) connected in the same way as in Fig. 10 (a). External media [1], [2], ..., [N] can be inserted. In Fig. 10 (c), the USB reader / writer 101c connected in the same way as in Fig. 10 (a) is connected to multiple external media [1], [2] of the same type that have MMC (MultiMediaCard (registered trademark)) card power. , ..., [N] can be inserted.

[0007] However, in any configuration, the correspondence between the USB host PC and the external media is one-to-one or one-to-many. Therefore, for example, when an external medium having a user power using a plurality of PCs is used on a plurality of PCs (USB host PCs), for example, an operation as shown in FIG.

FIG. 11 is a diagram for explaining the work contents when a specific external medium is used by a plurality of USB host PCs in the USB storage system of the technology studied as the premise of the present invention. In other words, after using external media on the USB host PC [l] 110a, connect to the USB host PC [1] 110a !, disconnect the USB cable 112 (S110), and connect the USB cable to the USB host PC [2] 112 Is connected (S111), the work is performed.

[0009] As described above, when a specific external medium is used on a plurality of PCs, the user needs to perform troublesome work such as reconnecting the USB cable. Each time the USB cable is reconnected, the USB network must be reconfigured by plug-and-play and external media such as memory cards must be initialized, which wastes time and power.

[0010] Therefore, an object of the present invention is to provide a USB storage system and a USB storage device capable of improving time efficiency when used by a plurality of hosts.

[0011] Another object of the present invention is to provide a USB storage system and a USB storage device that can save power when used by a plurality of hosts.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

Means for solving the problem

[0013] Among the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows. [0014] A USB storage system according to the present invention includes a plurality of USB hosts and a USB function including a function as an external storage medium, and data transfer based on the USB protocol between the USB function and the plurality of USB hosts. Is to do. The USB function has a function that enables a plurality of USB hosts to perform shared access to the USB function external storage medium in a state where a plurality of USB hosts are connected to the USB function. It becomes something.

[0015] As a result, when the USB function as an external storage medium is used by multiple USB hosts, work and processing such as reconnection of the USB cable and initialization associated therewith are not required, and time efficiency is improved. It is possible to improve the power consumption.

[0016] Here, the function that enables the shared access is performed, for example, by one USB host among a plurality of USB hosts executing a process of writing to the external storage medium of the USB function. While there are multiple USB hosts, it includes a function to reject write requests from other USB hosts.

[0017] With this, it becomes possible to prevent the data power stored in the USB function as the external storage medium from being destroyed by writing from multiple USB hosts.

[0018] Further, the plurality of USB hosts include a first USB host and a second USB host, and the function of enabling the shared access is a USB function generated by the first USB host. If a second write request for the external storage medium is generated from the second USB host during the processing of the first write request for the external storage medium, the second USB host It includes a function that notifies the rejection of the write request and continues the processing of the first write request! / Speak.

[0019] The function of the USB function as an external storage medium is realized by, for example, a memory card. As a result, it is possible to reduce the memory card initialization process, which has been required every time the USB cable is reconnected, improving the time efficiency and saving power.

[0020] The USB storage system according to the present invention includes a plurality of USB hosts and a USB function including a function as an external storage medium. Multiple USB connector terminals to which multiple USB hosts are connected, a function for transferring data based on the USB protocol between multiple USB hosts, and a USB function external storage medium based on a predetermined protocol It has a function to transfer data, a function to convert the USB protocol and the predetermined protocol to each other, and one USB host among a plurality of USB hosts can write to the external storage medium of the USB function. While processing is in progress, it has a function to reject write requests generated from other USB hosts.

Here, the function of rejecting the write request is realized by a program process by a computer provided in the USB function, and the program process is a write request to the external storage medium from the one USB host. A step of setting an operation flag when accepting the operation, a step of releasing the operation flag when processing of the accepted write request is completed, and a write from the other USB host while the operation flag is set. And a step of notifying the other USB host of rejection of the generated write request when the request is generated. That is, by adding a function for rejecting the write request to the software, it becomes possible to easily realize sharing of an external storage medium by a plurality of USB hosts. Note that the step of notifying the rejection of the write request can be performed using data of a request sense command, for example.

[0022] The USB storage device of the present invention includes a plurality of USB connector terminals connected to a plurality of USB hosts, and a media connector terminal connected to an external storage medium, and the plurality of the plurality of USB connector terminals based on a USB protocol. Data transfer to and from a USB host is possible, and a plurality of USB hosts are connected to the plurality of USB connector terminals and an external storage medium is connected to the media connector terminal. The US B host has a function that enables shared access to external storage media.

[0023] Note that examples of the external storage medium include a memory card. The USB storage device includes a plurality of media connector terminals, and a plurality of the same type or different types of memory cards are connected to the plurality of media connector terminals. You may make it. In addition, the USB storage device can be provided with a bridge function that can arbitrarily set the connection between the plurality of USB connector terminals and the plurality of media connector terminals.

The invention's effect

[0024] The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows.

[0025] In a USB function having a function as an external storage medium, a function for enabling shared access of the external storage medium by a plurality of USB hosts is provided.

The time efficiency when using the external storage medium by the B host can be improved, and power saving can be achieved.

Brief Description of Drawings

FIG. 1 is a schematic view showing an example of the system configuration of a USB storage system according to an embodiment of the present invention.

2 is a diagram showing an example of a logical configuration of a USB host in the USB storage system of FIG.

FIG. 3 is a diagram showing an example of a logical configuration of a USB reader / writer in the USB storage system of FIG. 1.

4 is a perspective view showing an example of the external shape of a USB reader / writer in the USB storage system of FIG.

FIG. 5 is an explanatory diagram showing an example of the operation outline of the USB reader / writer of FIG. 3.

FIG. 6 is a processing flowchart showing an example of interface software processing in the USB reader / writer of FIG. 3.

7 is a process flow diagram for explaining an example of the operation in the system configuration of FIG.

FIG. 8 is a schematic diagram showing an example of a system configuration obtained by extending FIG. 1 in the USB storage system according to the embodiment of the present invention.

FIG. 9 is a schematic diagram illustrating an example of a configuration in which a plurality of external media can be shared by a plurality of USB hosts in a USB storage system according to an embodiment of the present invention. FIG. 10 is a schematic diagram showing an example of the configuration of the USB storage system of the technology studied as a premise of the present invention, and (a) to (c) show different configuration examples.

FIG. 11 is a diagram for explaining work contents when a specific external medium is used by a plurality of USB host PCs in the USB storage system of the technology studied as a premise of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

FIG. 1 is a schematic diagram showing an example of the system configuration of a USB storage system according to an embodiment of the present invention. The USB storage system shown in Fig. 1 is connected to multiple USB hosts consisting of, for example, USB host [1] 10a and USB host [2] 10b, and multiple USB hosts via USB cables 12a and 12b respectively. It consists of USB reader / writer 11 Typical examples of USB hosts include personal computers.

[0029] The USB reader / writer 11 is a USB storage device having a function as an external storage medium. For example, an external medium (external storage media) 13 such as a memory card or a floppy disk can be connected. It has become. Note that in Fig. 1, it is possible to apply 3 or more USB hosts. For simplicity, the following explanation assumes that there are 2 USB hosts.

[0030] 113 hosts [1] 10 & and 1; 38 hosts [2] 101) are configured as shown in FIG. FIG. 2 is a diagram showing an example of the logical configuration of the USB host in the USB storage system of FIG. The USB host shown in Fig. 2 has an application layer, a system software layer, and a hardware layer from the upper layer to the lower layer.

[0031] The application layer includes application software 20. Typical examples of the application software 20 include an explorer having a function for operating folders and files, and an audio play having a music data playback function. Yer. When performing USB transfer, the application layer sends and receives data to and from the system software layer.

[0032] The system software layer manages the hardware layer, and performs conversion based on the USB protocol on the transmission / reception data between the application layer and the hardware layer. As software for performing such processing, the system software layer includes a USB mass storage class driver 21a and a USB bus driver 21b.

[0033] The USB mass storage class driver 21a performs management of a command transport, a data transport, a status transport, and the like defined by a standard called a USB mass storage class. The USB bus driver 21b performs processing common to each USB class, such as transaction management.

[0034] The hardware layer includes a USB host controller 22! /. The USB host controller 22 is electrically connected to the USB reader / writer via the USB cable 23, and is a hardware that processes the USB host's electrical signals such as detecting the connection of the USB reader / writer and sending / receiving packets to / from the USB reader / writer. Wear.

On the other hand, the USB reader / writer 11 has a configuration as shown in FIG. 3 and FIG. FIG. 3 is a diagram showing an example of the logical configuration of the USB reader / writer in the USB storage system of FIG. FIG. 4 is a perspective view showing an example of the outer shape of the USB reader / writer in the USB storage system of FIG.

[0036] The USB reader / writer shown in FIG. 3 includes, for example, a USB function module [1] (hereinafter, USB module [1]) 30 and a USB function module [2] (hereinafter, USB module [2]) 31. Includes 2 USB function modules, external media module 32, interface software (hereinafter referred to as interface software) 33, etc.

[0037] The USB module [1] 30 includes a USB mass storage class firmware [1] 30a that is software and a USB function controller [1] 30b that is hardware, and a USB host [1 ] Etc. Similarly, the USB module [2] 31 includes a USB mass storage class firmware [2] 31a and a USB function controller [2] 3 lb, and is connected to a USB host [2], etc. via a USB cable 12b. The external media module 32 includes an external media firmware 32 a that is software and an external media host controller 32 b that is hardware, and is connected to the external media 13.

[0038] Similar to the USB host logical configuration, these configurations can be divided into an application layer, a system software layer, and a hardware layer. When classified by such a logical configuration, the application layer includes interface software 33. The interface software 33 is software that controls data transfer between the USB modules [1] 30, [2] 31 and the external media module 32.

[0039] The interface software 33 further has a function of performing a response process when a write request is generated from the other USB module during a response process of a write request from one USB module to the external medium 13. I have. The interface software 33 is stored in, for example, a ROM or the like provided in the USB reader / writer, and the interface software 33 is executed by, for example, a microcomputer and a RAM provided in the USB reader / writer. The same applies to various software in the system software layer described later.

[0040] The system software layer includes USB mass storage class firmware [1] 30a, [2] 31a and external media firmware 32a. USB mass storage class firmware [1] 30a (or [2] 31a) controls the USB function controller [1] 30b (or [2] 31b) and performs processing specific to the USB mass storage class. The external media firmware 32a performs transaction management of the external media 13 and control of the external media host controller 32b.

[0041] The hardware layer includes a USB function controller [1] 30b, [2] 31b and an external media host controller 32b. USB function controller [1] 30b, [2] 3 lb processes USB function electrical signals such as packet transmission and reception. The external media host controller 32b performs electrical signal processing such as command transmission to the external medium 13, reception of a response from the external medium 13, and data transmission / reception with the external medium 13.

[0042] Such a USB reader / writer has an outer shape as shown in FIG. 4, for example. In the USB reader / writer shown in FIG. 4, for example, a housing 40 is provided with two USB connectors [l] 41a, [2] 41b and an external media connector (external media slot) 42. The USB connectors [l] 41a and [2] 41b are USB function connectors, and are connected to the USB hosts [1] and [2] by USB cables 12a and 12b, respectively. External media such as a memory card or floppy disk is inserted and connected to the external media connector 42.

[0043] In the system configuration as described above, the present invention is characterized in that the USB host [1] and the USB host

It is to realize shared access of external media by [2]. In order to realize this, as described in Fig. 3, a USB reader / writer is provided with a plurality of USB modules, and the interface software is used to arbitrate when processing requests are simultaneously generated from a plurality of USB modules. The function is realized. The details of the arbitration function of this interface software will be described below.

[0044] The request from the USB host to the USB reader / writer includes a request to write data to the external media memory (hereinafter referred to as a write request), a request to read data from the external media memory (hereinafter referred to as a read request), and a USB There is a request to acquire the status and information of the reader / writer (hereinafter referred to as status acquisition request).

[0045] Even when there are two USB hosts, the request from the USB host and the corresponding processing of the USB reader / writer in response to the request do not overlap in time, or the memory contents of the external media are not changed even if they overlap There is no particular problem. In other words, in the read request and status acquisition request, the data stored in the external media can be stored by using exclusive control such that the USB reader / writer's interface software does not overlap with each other's requests and external media. There is no serious problem such as destruction. The problem occurs when two USB hosts are used when a write request is issued from another USB host during processing of a write request from a USB host that has USB reader / writer capabilities. Therefore, for example, this problem is avoided by the following operation.

[0046] The USB reader / writer receives a write request from another USB host (USB host [1]) during the processing of a write request from a USB host (USB host [2]). If the request is received, the request from the USB host [1] is rejected and the write request from the USB host [2] is rejected. Continue handling. In other words, the operation outline is as shown in FIG.

FIG. 5 is an explanatory diagram showing an example of the operation outline of the USB reader / writer of FIG. In Figure 5, when the interface software 33 in the USB reader / writer receives a write request [2] from the USB module [2] 31, it returns an acceptance response to the USB module [2] 31 and writes to the external media module 32. Send data corresponding to request [2]. When the write request is received from the USB module [1] 30 during the processing for handling the write request from the USB module [2] 31, the interface software 33 virtually transmits to the USB module [1] 30. Notify that the external media 13 is in operation and reject the request from the USB host [1].

[0048] More specifically, this operation outline is realized by a processing flow as shown in FIG. 6, for example. FIG. 6 is a process flow diagram showing an example of interface software processing in the USB reader / writer of FIG. First, the interface software 33 is activated after the external medium 13 is connected or after the USB cable 12a (or 12b) is connected (S601), and enters an event waiting state. The events received by interface software 33 include USB module (US B module [1] 30 or USB module [2] 31) powerful read requests and write requests, and read completion notifications from external media module 32 (interface software Read completion notification corresponding to 33 read requests) and write completion notification (write completion notification corresponding to interface software 33 write request).

[0049] When the USB module [1] 30 (or [2] 31) has a read request while waiting for an event (S602), the content of the read request is analyzed and lead identification information is created (S603). The lead identification information is used to identify read requests when multiple read requests overlap. The lead identification information includes a read request ID, a USB module number for identifying the requested USB module, a read address, and a read size force. After creating the read identification information, a read request is made to the external media module 32 (S604). Next, it shifts to the event waiting state.

[0050] When the USB module [1] 30 (or [2] 31) power is requested to be written in the event waiting state (S605), it is determined whether or not the operation state flag is ON (S606). The operation status flag is a flag indicating that writing to the external media 13 is in progress. This is used for exclusive control so that the writing process to the external medium 13 does not overlap, and the initial value is OFF.

[0051] If the operation status flag is ON, an operation status notification is created and sent to the corresponding USB module [1] 30 (or [2] 31) to reject the write request (S607). On the other hand, if the operation status flag is OFF, the operation status flag is turned ON (S608). Thereafter, a write request is made to the external media module 32 (S609). Next, it shifts to an event waiting state.

[0052] When a read completion notification is received from the external media module 32 while waiting for an event (S610), the ID and read identification information are analyzed (S611), and the corresponding USB module [1] 30 (or [2] 31), the corresponding read data is transmitted (S612). Next, it shifts to the event waiting state.

If there is a write completion notification from the external media module 32 while waiting for an event (S613

), Set the operation status flag to OFF, and cancel that writing is in progress (S6

14). Next, it shifts to an event waiting state.

In the event waiting state, the state of the external medium 13 is checked (S615), and if the external medium 13 is removed, the process is terminated. If it has not been removed, the event waiting state is continued.

[0055] As described above, depending on the system configuration and its operation, etc.

It is possible to share and use external media on the B host. Thus, for example, the following effects (1) and (2) can be obtained.

[0056] (1) When a specific external medium is used by a plurality of USB hosts, it is not necessary to perform troublesome work when the user sequentially connects the USB cables. Also multiple US

Even if a B host is connected, a USB reader / writer that supports plug-and-play and other features such as USB and memory cards can be realized.

[0057] (2) No need to connect USB cables sequentially,

Re-initializing external media such as SD memory cards can be omitted. As a result, the time efficiency can be improved and the power can be saved.

Next, an example of the operation of the entire system in FIG. 1 will be described with reference to FIG. Figure 7 FIG. 2 is a process flow diagram for explaining an example of the operation in the system configuration of 1. In Figure 7! The following describes an example of processing when the USB host [1] 10a transmits a data write request to the USB reader / writer 11 while the USB host [2] 10b in FIG. 1 is writing data. Here, data transfer conforming to the generally known USB mass storage standard shall be performed. In the following, description will be made in association with the processing numbers in FIG.

[0059] (1) 113 Host [2] 101) issues a write [2] request C BW (Command Block Wrapper) defined in the USB mass storage class to the USB reader / writer 11. CBW is a packet that is defined in the USB mass storage class and stores commands that the USB host requests the USB function and related contents.

[0060] (2) When the USB reader / writer 11 receives the write [2] request CBW, it analyzes the number of data in the write address. Also, write [2] request CBW is converted to the command format specific to external media 13. That is, protocol conversion is performed.

(3) After the conversion is completed, the USB reader / writer 11 issues a write [2] command converted into the specific command format to the external medium 13.

[0062] (4) When the external medium 13 receives the write [2] command, it analyzes the write address and the number of data.

[0063] (5) USB host [2] 10b transmits the write [2] data to the USB reader / writer 11 in the format defined by the USB mass storage class.

[0064] (6) Upon receiving the write [2] data, the USB reader / writer 11 converts the write [2] data into a data format specific to the external media 13. That is, protocol conversion is performed.

(7) After the conversion is completed, the USB reader / writer 11 writes the converted write to the external medium 13.

[2] Send data.

[0066] (8) When the external medium 13 receives the converted write [2] data, it writes it in its own memory.

[0067] (1,) Here, the USB host [l] 10a issues a write defined by the USB mass storage class [1] CBW to the USB reader / writer 11 to write data to the memory of the external media 13 To do. [0068] (2,) The USB reader / writer 11 is able to receive the write [1] request CBW. 113 Host [2] 10 b write [2] The request is being processed, so the USB host [1] 10a On the other hand, write [1] rejects the request. That is, an operation state notification for notifying that the external media 13 is virtually in an operation state is created by the processing of the interface software 33 described above.

[0069] Here, as an example of how to create an operation status notification, the ASC (Additional Sense Code) in the data of the request sense (Request Sense) command defined by the SCSI command of the USB mass storage class is set to 04. , H and ASCQ (Additional Sequence Code Qualifier) are set to 07, h. The request sense command data is data returned to the host when the USB host generates a request sense command to the USB reader / writer.

[0070] (3 ') After the completion of the operation status notification, the USB reader / writer 11 transmits the operation status notification (request sense command data in this case) to the USB host [l] 10a.

[0071] (4 ') When the USB host [l] 10a receives the operation state notification, the USB host [1] 10a recognizes that data cannot be written to the memory of the external medium 13 and notifies the host application or the like.

(9) The external medium 13 notifies the USB reader / writer 11 of the completion of the writing of the converted write [2] when the data writing is completed.

[0073] (10) When the USB reader / writer 11 receives the completion notification, it writes it. [2] Completion CSW (

Command Status Wrapper) CSW is a bucket that is defined in the USB mass storage class and used when the USB host acquires the execution results for the CBW with the USB function.

[0074] (11) After conversion is complete, USB reader / writer 11 writes to USB host [2] 10b [2] Complete CS

Send W.

[0075] (12) USB host [2] 10b receives the write [2] completion CSW, recognizes that the write operation has ended, and completes the write operation.

[0076] By the system configuration and operation as described above, conforming to the USB mass storage standard Data transfer allows external media to be shared by multiple hosts.

By the way, in the description so far, a case where one external medium is shared by a plurality of USB hosts is taken as an example. However, the present invention is not limited to this, and as shown in FIG. It is also possible to share with the host.

FIG. 8 is a schematic diagram showing an example of a system configuration in which FIG. 1 is expanded in the USB storage system according to the embodiment of the present invention. In Figure 8, USB reader / writer

82 USB hosts [l] 80a, [2] 80b, ···, [Ν] 80η force ^ connected, and USB reader / writer 82 has N external media [1] 83a, [ 2] 83b, ···, [N] 83n is purchased.

[0079] In a normal UBS storage system, as described in Fig. 10, it is possible for a single USB host to access N different types or types of external media. Therefore, when N USB hosts are connected to the USB reader / writer 82, N different external media such as CF cards, SD memory cards, and memory sticks can be shared by the N USB hosts. . Of course, the same applies to N external media of the same type. This makes it possible to increase the efficiency of connection work and initial setting operation by N times compared to a normal UBS storage system.

[0080] As shown in FIG. 9, a plurality of external media can be shared by a plurality of USB hosts by providing a bridge function in the USB reader / writer. FIG. 9 is a schematic diagram illustrating an example of a configuration in which a plurality of external media can be shared by a plurality of USB hosts in the USB storage system according to the embodiment of the present invention. The US B reader / writer shown in Fig. 9 has multiple USB connectors [1] 90a, [2] 90b, ..., [N] 90n and multiple external media connectors [1] 91a, [2 ] 91b, ···, [Ν] 91η, and these USB connectors [1] 90a— [N] 90η and multiple external media connectors [1] 9 la— [N] 9 In It has a bridge function 92 that can arbitrarily set the connection between them.

[0081] For example, the bridge function 92 includes a dip switch for each of the plurality of USB connectors [1] 90a— [N] 90η and the plurality of external media connectors [1] 91a— [N] 9 In. Alternatively, it can be realized by adding a selection function to the interface software 33 on the USB reader / writer. [0082] By using such a configuration, it is possible to arbitrarily select the connection between the USB host and the external medium, such as 1 to 1, 1 to N, N to 1, or N to N. Become. As another viewpoint, for example, when one external medium is shared by multiple USB hosts, the USB cable reconnection work required in the past can be replaced with the ONZOFF work of the dip switch. It becomes possible.

[0083] While the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention. There's nothing wrong!

Industrial applicability

[0084] The USB storage system of the present invention is particularly useful when applied to a system in which the USB function is a USB reader / writer compatible with various memory cards such as an SD memory card and a memory stick. This is not limited to this, but can be widely applied to systems equipped with a USB reader / writer that supports floppy disks and hard disks.

Claims

The scope of the claims

[1] A USB storage system having a plurality of USB hosts and a USB function including a function as an external storage medium, and transferring data based on the USB protocol between the plurality of USB hosts and the USB function Because

The USB function has a function that allows the plurality of USB hosts to perform shared access to the external storage medium of the USB function in a state where the plurality of USB hosts are connected to the USB function. US B storage system characterized by having.

[2] In the USB storage system according to claim 1,

The function that enables the shared access is performed while one USB host of the plurality of USB hosts is executing a write process on the external storage medium. A USB storage system that includes a function to reject write requests from other USB hosts.

[3] In the USB storage system according to claim 1,

The plurality of USB hosts include a first USB host and a second USB host, and the function enabling the shared access is a first for the external storage medium generated by the first USB host. When a second write request from the second USB host to the external storage medium occurs during the processing of the write request, the second USB host is denied the second write request. A USB storage system comprising a function of notifying and continuing processing of the first write request.

[4] In the USB storage system according to any one of claims 1 to 3,

The USB storage system characterized in that the function as the external storage medium is realized by a memory card.

[5] A USB storage system having a plurality of USB hosts and a USB function including a function as an external storage medium,

The USB function is

A plurality of USB connector terminals to which the plurality of USB hosts are connected; A function of performing data transfer based on a USB protocol with the plurality of USB hosts; a function of performing data transfer based on a predetermined protocol with the external storage medium; and the USB protocol and the predetermined protocol. Furthermore, while one USB host of the plurality of USB hosts is executing a write process on the external storage medium, the plurality of USB hosts A USB storage system that has a function to reject write requests from other USB hosts.

[6] The USB storage system according to claim 5,

The function of rejecting the write request is realized by program processing by a computer provided in the USB function,

The program processing is

Setting an operation flag when receiving a write request to the external storage medium from the one USB host;

Releasing the operation flag when processing of the accepted write request is completed;

A step of notifying the other USB host of rejection of the generated write request when a write request from the other USB host is generated while the operation flag is set. USB storage system characterized by

[7] In the USB storage system according to claim 6,

The USB storage system, wherein the step of notifying the rejection of the write request is performed using data of a request sense command.

[8] Provided with a plurality of USB connector terminals connected to a plurality of USB hosts and a media connector terminal connected to an external storage medium, and data between the plurality of USB hosts based on the USB protocol. A USB storage device that can be transferred,

In the state where the plurality of USB hosts are connected to the plurality of USB connector terminals and the external storage medium is connected to the media connector terminal, the plurality of US

A USB storage device comprising a function that enables a B host to perform shared access to the external storage medium.

[9] The USB storage device according to claim 8!

The USB storage device is characterized in that the external storage medium is a memory card.

[10] The USB storage device according to claim 8,

A plurality of media connector terminals;

A USB storage device, wherein a plurality of memory cards of the same type or different types are connected to the plurality of media connector terminals.

[11] The USB storage device according to claim 10,

A USB storage device having a bridge function that allows arbitrary setting of connections between the plurality of USB connector terminals and the plurality of media connector terminals