JP2015028714A - Communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an impact on an external device, enable completion of continuable file transfer (backup) without interruption, and make it possible to prevent damage to a recording medium at a backup destination even if the recording medium has shifted to a read-only mode during communication with the external device.SOLUTION: A device prevents communication interruption due to an error occurring at a time of connection with an external apparatus, at the device using a recording medium that shifts to a read-only mode when an alternative block runs out.

Description

  The present invention relates to a communication device connected to an external device.

  In recent years, a flash memory has been used as a recording medium of an imaging apparatus.

  The data format of the flash memory is divided into units called blocks, and data is erased / written in units of blocks. When the number of times of erasing / writing data in a block exceeds a predetermined number, the reliability of writing data in the block may decrease, or the block may become unusable in some cases.

  In the flash memory, a spare area called a substitute block is provided. If a bad block occurs in a block used for data recording, the flash memory itself can be used even if a bad block occurs to some extent by disabling the bad block and using an alternative block. We are taking measures to avoid being lost.

  However, if the user has used the same flash memory for a long time, the reliability of stored data will decrease as the number of data rewrites in the flash memory increases, and the number of defective blocks will increase, resulting in the entire flash memory It may become unusable.

  The conventional flash memory has a function of making all data in the flash memory read-only when the alternative block is used up as disclosed in Patent Document 1.

JP-A-9-163293

  When transferring a file recorded on a recording medium to an external device (backup), write the data indicating that the transferred file has been transferred (rewrite the archive attribute), and duplicate the same file the next time it is transferred And it is generally done not to backup.

  However, in the above-described prior art, even if the recording medium changes to read-only during file transfer to the external device, the external device does not issue a command for acquiring whether or not the read-only is used in the situation where the recording medium is not inserted or removed Therefore, it cannot be notified to the external device that it has become read-only.

  Therefore, an external device that has not notified that it has become read-only issues a write command to rewrite the archive attribute during backup, but is forced to respond with an error because it has changed to read-only.

  In this case, the external device receives an error during backup, and stops halfway even if all backups are not completed. Furthermore, as a more serious influence, there is a possibility that the external device hangs up or malfunctions due to an unexpected error from the recording medium (and the external device recognizes) that should be writable. In addition, if the external device writes the received file on a recording medium such as an optical disk, the loss of the disk also occurs.

  In order to solve the above problems, the present invention provides a recording medium having a first state and a second state, a communication unit for communicating with an external device, and a request acquired by the communication unit. In a communication apparatus comprising: an execution unit that executes the process; and a determination unit that determines whether the request acquired by the communication unit is a first request or a second request. When the recording medium is in the first state Sends a first or second response according to the result of the execution means, and if the recording medium is in the second state, the first means A response is transmitted, and when the determination means is a second request, a second response is transmitted.

  According to a second aspect of the present invention, a recording medium having a replacement block area that replaces a defective block, and a remaining amount of the replacement block area are detected, and a first state or state of the recording medium is detected according to a detection result. State determination means for determining the second state, communication means for communicating with the external device, execution means for executing the request acquired by the communication means, and the request acquired by the communication means are the first request and the first request And a request judging means for judging one of the two requests. When the recording medium is in the first state, a first response or a second response is sent according to the result of the execution means. And when the recording medium is in the second state, the request determination means transmits a first response when the request is the first request, and when the request determination means is the second request, Sending a second response

  According to the present invention, even if the recording medium changes to read-only during communication with the external device, the influence on the external device is prevented and the continuous file transfer (backup) can be completed without interruption. In addition, loss of the backup destination recording medium can be prevented.

It is a block diagram which shows schematic structure of the communication apparatus to which this invention is applied. It is a control flowchart of the communication apparatus to which this invention is applied. It is a control flowchart of the communication apparatus to which this invention is applied. It is a figure of an archive attribute change command specification at the time of defining as an original command of PTP.

  The present invention will be described below with reference to the drawings. In addition, embodiment shown here is an example to the last, Comprising: It is not necessarily limited to this embodiment.

  FIG. 1 is a block diagram showing a schematic configuration of a communication apparatus common to the first and second embodiments in which the present invention is implemented. As shown in FIG. 1, the connection method according to the present embodiment is implemented with a configuration of a communication device 100, an external device 120, and a connection cable 130. The communication device 100 and the external device 120 are connected via a connection cable 130. Reference numeral 100 denotes a communication apparatus to which the present invention is applied. In the following embodiments, a video camera will be described as an example, but a device such as a still camera may be used. The video camera 100 operates as a device device defined by the USB standard.

  Reference numeral 101 denotes a CPU that controls the operation of each unit, and is a part that performs information acquisition of a recording medium, which will be described later, and communication processing with an external device. A RAM 102 is used by the CPU 101 as a work area. It is also used to temporarily hold sector numbers in which attribute information of all files recorded on the recording medium is recorded.

  Reference numeral 103 denotes a recording medium capable of recording still images and moving image streams. This may be built-in or removable. The recording medium 103 has a plurality of recording blocks including replacement blocks for defective blocks. The recording medium 103 has an internal controller, and when the recording block designated as the recording destination is a defective block, data is recorded in the alternative block. Further, the recording medium 103 is changed to a read-only recording medium when all the alternative blocks are used up. At this time, the controller of the recording medium 103 outputs information indicating that the recording medium is a read-only recording medium to the CPU 101.

  Reference numeral 104 denotes a portion for determining whether the recording medium 103 is readable / writable or read-only, and acquiring the recording information of the recording medium 103. Reference numeral 105 denotes a communication unit that communicates with the external device 120, and transmits data to the connected external device 120 and receives commands and data from the external device 120. Reference numeral 106 denotes a part for determining whether or not the command received from the external device 120 is a request for rewriting file attribute information. As an example of the external device 120, a PC (Personal Computer) is used, but a device such as a recorder or a DVD writer may be used. The PC 120 operates as a host device defined by the USB standard. The PC 120 includes a communication unit that communicates with a video camera (not shown), a display unit, a CPU, a RAM, and the like. As an example of the connection cable 130, a connection cable conforming to the USB standard is used. Hereinafter, a connection cable compliant with the USB standard is referred to as a “USB cable”. The USB cable is configured to include four lines of VBUS, D +, D-, and GND.

<First Embodiment>
Based on FIG. 2, a description will be given of the control for switching the response content of a command in accordance with the state of a recording medium in the connection of the video camera embodying the present invention and a PC with a USB cable. In the following embodiments, a USB mass storage class protocol and command will be described as an example. However, a unique protocol or a unique command for the same processing may be used. In the present embodiment, the file system of the recording medium will be described by taking FAT 16 as an example, but the present invention does not limit the file system.

  In step S201, connection of the USB cable is detected. The cable connection is detected by detecting the voltage of the USB signal line VBUS at a high level. This voltage is applied by a PC connected to the opposite side of the USB cable based on the USB standard. To start communication, the pull-up resistor of the USB D + signal line is controlled to ON, and the D + signal is controlled to the High level. The connection partner PC detects this voltage change in the signal line, recognizes the connection of the video camera, and starts USB communication.

  In step S202, the voltage level of the USB VBUS signal is detected. If the voltage level is low, the process proceeds to step S203 and communication is terminated. If the VBUS signal voltage is high level, the process proceeds to step S204 without terminating the communication.

  In step S204, it is determined whether or not the recording medium 103 has already been read-only at the start of communication (whether or not writing is possible) or has changed to read-only after the start of communication.

  In step S205, the recording information acquisition unit 104 analyzes the file system type described in the MBR, which is the management data of the file system of the recording medium 103, identifies the file format, and is described in the management data such as BPB. The sector numbers in which the file attributes (attributes) of the directory entries of all the files are recorded are extracted using the sector size, cluster size, FAT size, etc., and are expanded in the RAM 102.

  In step S206, it is determined whether or not a command has been received. If it has not been received, the process proceeds to step S202 to determine again the end of communication.

  If a command has been received, the process proceeds to step S207 to check whether the command is a WRITE command.

  If the received command is not the WRITE command, the process proceeds to step S212 to execute the command, and the command execution result is transmitted in step S213.

  On the other hand, if the command received in step S207 is a WRITE command, the process proceeds to step S208 to determine whether the recording medium 103 is read-only. If it is not read-only, the process proceeds to step S212, and a WRITE command is executed.

  When the WRITE command is issued to the read-only recording medium, the process proceeds to step S209, and the sector number developed in the RAM 102 in step S205 is included within the range of the write data size from the write address of the WRITE command. For example, it is determined that the file attribute has been changed, and the process proceeds to step S210 without executing the command, and a response indicating that the command was successful is transmitted to the PC.

  If it is determined in step S209 that the WRITE command is another data write (rewrite), the process proceeds to step S211 and a response indicating that the command cannot be executed (failed) is transmitted to the PC.

  In addition, another example which determines whether it is a change of a file attribute in step S209 is given below.

  When communication using a unique protocol corresponding to mass storage is used, external devices that are communication partners are limited, and the communication specifications of the external devices are clear and limited. In this case, if it is clear that the command corresponding to the WRITE command issued from the external device is issued only for changing the file attribute, the determination using the sector number is omitted, and the WRITE command is It may be determined that this is a change in file attributes.

<Second Embodiment>
Based on FIG. 3, a description will be given of the control for switching the response content of a command in accordance with the state of the recording medium in the connection between the video camera and the PC implementing the present invention with a USB cable. In the following embodiments, a PTP (Picture-Transfer-Protocol) vendor unique (unique) command in the USB still image capture device class will be described as an example. It does not matter.

  Steps S301 to S303 are the same as steps S201 to S203 in FIG. 2 described in the first embodiment, and are therefore omitted.

  In step S304, it is determined whether a command has been received. If it has not been received, the process proceeds to step S302 to determine again the end of communication.

  If a command has been received, the process proceeds to step S305 to check whether the command is a WRITE command. The WRITE command includes an object write represented by SendObject and an object attribute change command.

  If the received command is not a WRITE command, the process proceeds to step S310 to execute the command, and the command execution result is transmitted in step S311.

  On the other hand, if the command received in step S305 is a WRITE command, the process proceeds to step S306 to determine whether the recording medium 103 is read-only. If it is not read-only, the process proceeds to step S310, and a WRITE command is executed.

  When a WRITE command is issued for a read-only recording medium, the process proceeds to step S307, and it is determined whether the command is a command for changing an archive attribute. Although the command for changing the archive attribute is not defined in the PTP standard, a command code of MSN (Most Significant Nibble) 9 can be used as a vendor unique (unique) command. For example, the command in FIG. 4 is defined as an archive attribute change command, and if this command is received, it is determined that the file attribute has been changed, and the process proceeds to step S308 without executing the command. Send to PC.

  If it is determined in step S307 that the WRITE command is object writing or other data writing (rewriting), the process proceeds to step S309, and a response indicating that the command cannot be executed (failed) is transmitted to the PC.

  Although the present invention has been described in detail based on preferred embodiments thereof, the present invention is not limited to these specific embodiments, and various forms within the scope of the present invention are also included in the present invention. included. A part of the above-described embodiments may be appropriately combined.

  Also, when a software program that realizes the functions of the above-described embodiments is supplied from a recording medium directly to a system or apparatus having a computer that can execute the program using wired / wireless communication, and the program is executed Are also included in the present invention.

  Accordingly, the program code itself supplied and installed in the computer in order to implement the functional processing of the present invention by the computer also realizes the present invention. That is, the computer program itself for realizing the functional processing of the present invention is also included in the present invention.

  In this case, the program may be in any form as long as it has a program function, such as an object code, a program executed by an interpreter, or script data supplied to the OS.

  As a recording medium for supplying the program, for example, a magnetic recording medium such as a hard disk or a magnetic tape, an optical / magneto-optical storage medium, or a nonvolatile semiconductor memory may be used.

  As a program supply method, a computer program that forms the present invention is stored in a server on a computer network, and a connected client computer downloads and programs the computer program.

100 ... Communication device 101 ... CPU
102 ... RAM
103 Recording medium 104 Recording information acquisition unit 105 Communication unit 106 Request determination unit 120 External device 130 USB cable

Claims (10)

A recording medium having a first state and a second state;
A communication means for communicating with an external device;
Execution means for executing the request acquired by the communication means;
Determination means for determining whether the request acquired by the communication means is a first request or a second request;
In a communication device comprising:
When the recording medium is in the first state,
Depending on the result of the execution means, a first or second response is transmitted,
When the recording medium is in the second state,
If the determination means is a first request, send a first response;
A communication apparatus characterized by transmitting a second response when the determination means is a second request. A recording medium having a replacement block area for replacing a bad block;
State determination means for detecting the remaining amount of the area of the alternative block and determining a first state or a second state of the recording medium according to a detection result;
A communication means for communicating with an external device;
Execution means for executing the request acquired by the communication means;
Request determination means for determining whether the request acquired by the communication means is a first request or a second request;
In a communication device comprising:
When the recording medium is in the first state,
Depending on the result of the execution means, a first or second response is transmitted,
When the recording medium is in the second state,
If the request determination means is a first request, send a first response,
If the request determination means is a second request, a communication apparatus is characterized in that a second response is transmitted. The communication apparatus according to claim 1, wherein the first state is a state where writing is possible, and the second state is a state where writing is impossible. The first request is a request to write file data to the recording medium, and the second request is a request to rewrite a file attribute to the recording medium. The communication apparatus according to claim 2. The first response is a response indicating that the request was not successful, and the second response is a response indicating that the request was successful. The communication apparatus according to claim 2. The state determination means determines a first state when the replacement block area is usable, and determines a second state when the replacement block area is unusable. The communication device according to claim 1. The communication according to claim 6, wherein the state in which the area of the substitute block is unusable is a state in which the remaining amount of the area of the substitute block is no longer remaining in the area of the substitute block. apparatus. The state in which the area of the replacement block is unusable is a state in which the remaining amount of the replacement block area is insufficient to replace a defective block. The communication device described. 3. The communication apparatus according to claim 1, wherein the communication unit is a protocol that does not involve a file system in command execution, typified by USB mass storage. The communication apparatus according to claim 1 or 2, wherein the communication means is a protocol in which a file system is interposed in command execution, typified by a Picture Transfer Protocol.