JP2010049303A - Memory controller, non-volatile storage device, access device, and non-volatile storage system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem, wherein the control of user data and management information data, while an access device keeps matching of file properties, when power supply turn off is difficult, in a non-volatile storage system capable of issuing advance commands. <P>SOLUTION: A command scheduler 162 controls to give Seq(sequence) numbers to the user data and the management information data and write the management information data having the same Seq number, after writing of the user data having the same Seq number is completed. Consequently, even if power supply is turned off during writing, matching of file property can be maintained. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention includes a memory controller that controls a nonvolatile memory, a nonvolatile memory device including the nonvolatile memory and the memory controller, an access device that accesses the nonvolatile memory device, and the nonvolatile memory device and the access device. The present invention relates to a nonvolatile storage system provided.

  The demand for nonvolatile memory devices including a rewritable nonvolatile memory is increasing, especially for semiconductor memory cards. Non-volatile storage devices are more expensive than optical discs and tape media, but due to merits such as small size, light weight, earthquake resistance, and ease of handling, portable devices such as digital still cameras and mobile phones The demand for recording media is widening. This nonvolatile storage device includes a flash memory as a nonvolatile main storage memory, and has a memory controller that controls the flash memory. The memory controller performs read / write control on the flash memory in response to a read / write instruction from an access device such as a digital still camera or a personal computer (personal computer) main body.

  Flash memory built into products such as semiconductor memory cards and portable audio devices requires a relatively long time to write to and erase from the memory cell array, which is a storage unit. It has a structure that can be written. Specifically, it is composed of a plurality of physical blocks (erase units), each physical block includes a plurality of pages (write units), erase is performed in units of physical blocks, and writing is performed in units of pages.

  Such a nonvolatile storage device is attached to an access device such as a digital still camera, and is regarded as a removable disk from the access device side and managed by a file system such as a FAT file system. The FAT file system manages file data for each “cluster” using a file allocation table (hereinafter referred to as FAT), and writes file data to a nonvolatile storage device such as a semiconductor memory card. The file data is allocated to the free cluster, and the file data and the cluster number (logical address) to which the file data is allocated are designated in the nonvolatile storage device.

  File data is roughly divided into user data, which is the actual data, and FAT1, FAT2, and directory entries (hereinafter abbreviated as DIR), which are management information data for managing user data. FAT1 is file allocation information in units of clusters described above. FAT2 is a backup of FAT1, and holds the same contents as FAT1 in another area of the nonvolatile storage device. DIR is data in which file attributes such as file name and file write time are held. It is assumed that the FAT information is normal only when the contents of FAT1 and FAT2 completely match.

  By the way, a semiconductor memory card such as an SD card has a significant role as a bridge medium that can easily share data among a plurality of hosts, and is characterized by being easily mounted and removed from a host. Therefore, there is a possibility that the semiconductor memory card is removed by the user's intention or carelessness while writing data from the host to the semiconductor memory card. At this time, if a mismatch occurs between the user data and the FAT data, the already recorded file data cannot be read correctly.

  As means for solving the above, in Patent Document 1, address management information corresponding to a physical area in which old data has been rewritten is set to an invalid scheduled state, and writing is prohibited until a series of write processing ends. There is disclosed a method of returning to a state before writing, that is, a state in which old data remains even if a failure such as power interruption occurs due to extraction or the like during data writing.

  FIG. 7 is a block diagram illustrating a conventional nonvolatile storage system including an SD card which is one of nonvolatile storage devices and an access device such as a video camera. FIG. 8 is a diagram showing an example of the logical address space of the nonvolatile memory 770 of the SD card shown in FIG. FIG. 8 shows that FAT1 and FAT2 data are stored in predetermined positions in the system area 772, and user data and DIR are stored in the user data area 771.

  Access device 700 and SD card 710 are connected by an interface bus 720. The access device 700 includes an application 730, a file system 740, and an SD card I / F unit 750. On the other hand, the SD card 710 includes an access device I / F unit 760 and a nonvolatile memory 770. The access device I / F unit 760 includes a command analysis unit 761 and a write control unit 762, and the nonvolatile memory 770 includes a user data area 771 and a system area 772.

  The application 730 includes an API calling unit 731 and a user data input unit 732. The user data input unit 732 is a supply source of user data to be written into a file, and may be supplied from a storage device (not shown) inside the access device 700 or may be an I / F (not shown) from the outside of the access device 700. (Not shown).

  The file system 740 includes a command generation unit 741, a write address generation unit 742, and a management information data generation unit 743.

  For writing user data to the SD card 710, when the application 730 calls the API from the API calling unit 731, the command generation unit 741 issues a Write command on the interface bus 720, and the write address generation unit 742 writes the write destination logical address. Is supplied to the SD card I / F unit 750, and the write command and user data to be written supplied from the user data input unit 732 are transferred onto the interface bus 720.

  The access device I / F unit 760 uses the command analysis unit 761 to interpret the command. When the command is accompanied by data like a Write command, the application 730 transfers the user data supplied from the user data input unit 732 via the interface bus 720 via the SD card I / F unit 750.

  When the access device I / F unit 760 receives user data, the write control unit 762 writes the user data to a specified logical address in the user data area 771.

  On the other hand, FAT data is written as follows. When the application 730 calls the synchronous API from the API calling unit 731, the command generation unit 741 issues a Write command of FAT1 data, and subsequently transfers the FAT1 data of the management information data generation unit 743 via the SD card I / F unit 750. Transfer via the interface bus 720.

  When the access device I / F unit 760 receives the FAT1 data, the write control unit 762 writes the FAT1 data to a designated logical address in the system area 772.

  Thereafter, a write command for FAT2 data and DIR data is issued in the same manner, and the former is written in the system area 772 and the latter is written in the user data area 771, thereby completing the file synchronization API.

  FIG. 9 is a diagram illustrating, in time series, commands and file data on the interface bus 720 when user data such as moving images is continuously recorded in the nonvolatile storage system of FIG. In the current SD card, another command cannot be issued while processing is being executed inside the card (busy state). Further, when the API calling unit 731 calls the API, it is blocked until a predetermined process is completed.

  In addition, in the logical address space, file data cannot be read / written with a single command in a discontinuous area. Further, normally, in writing file data, user data must first be written as described above, and after the above has been completed normally, corresponding management information data such as FAT must be written. If the management information data and the user data are written in this order, the FAT is correctly updated when the power is shut off due to removal or the like during the writing of the user data, but the corresponding user data may not be updated. For this reason, when reading the file data, a cluster of user data that has failed to be written is read, and the data cannot be read correctly. In the order of user data and management information data, for example, the method described in Patent Document 1 can prevent inconsistencies when reading file data.

  When the API calling unit 731 of the application 730 issues a write API for user data a, the command generation unit 741 of the file system 740 issues “Write (user data a)” and subsequently supplied from the user data input unit 732. User data a is transferred from the access device 700 to the SD card 710. Since the writing speed to the non-volatile memory 770 is lower than the transfer speed on the normal interface bus 720 and there is an overhead such as address conversion and programming in the write control unit 762, even if a predetermined user data transfer is completed Since the processing inside the SD card 710 is not completed, the busy state continues for a while. In the busy state, commands on the interface bus 720 cannot be issued.

  After the writing of the user data a is completed and the busy state is released, the API calling unit 731 of the application 730 can call the synchronous API. At this time, the file system 740 can issue a Write command of FAT1a data corresponding to the user data a via the SD card I / F unit 750.

  When the FAT1a Write command is issued at time T1, the FAT1a data is subsequently transferred. Thereafter, the FAT2a and DIRa Write commands are issued in the same manner. Note that the management information data of FAT1, FAT2, and DIR are usually small in size, and therefore, here, it is considered that data transfer completion and busy state cancellation are almost simultaneous.

After the writing of DIRa is completed, the API calling unit 731 of the application 730 can issue a writing API of user data b.
JP 2005-243000 A

  As described above, in the conventional nonvolatile storage system, even if the command or file data is not transferred on the interface bus 720, the command cannot be issued if the SD card is in the busy state. There was a problem that the bus could not be used efficiently.

  Therefore, an object of the present invention is to efficiently use the interface bus by issuing another command even during command processing such as writing file data.

  In order to achieve the above object, the present invention provides a memory controller for controlling data recording to a nonvolatile memory, a read / write control unit for writing data to the nonvolatile memory or reading data from the nonvolatile memory, and externally. A command packet indicating a processing request and a data packet having data to be written to the non-volatile memory are received, a packet analysis unit for analyzing the received packet, a processing request included in the command packet is accumulated, and an execution timing of the required processing is determined. A packet scheduler that receives a command packet when the read / write controller is writing data to or reading data from the nonvolatile memory, and sends a processing request for the command packet to the command scheduler. It is characterized by accumulating .

  As a result, even when the memory controller is writing data to or reading data from the nonvolatile memory, the packet analyzer can receive a command packet from the outside.

  Further, according to the present invention, in the memory controller described above, the received packet has a common identifier for the associated command packet and data packet, and includes a management unit that manages an execution status of a processing request included in the command packet by the identifier. The command scheduler is characterized by managing the next process to be executed and the execution time based on the execution status.

  As a result, the command scheduler can identify (recognize) the relationship between individual command packets and data packets.

  The above-described invention can also be realized as a nonvolatile storage device including the memory controller and the nonvolatile memory described above. In this case, the present invention can be realized as an information storage medium for recording various information (data).

  Further, the present invention relates to a command generation unit that generates a processing request to a nonvolatile storage device and an associated data to be transferred to the nonvolatile storage device in an access device that instructs data writing to the nonvolatile storage device having a nonvolatile memory An identifier generation unit that assigns a common identifier to a processing request to be generated, and generates a data packet and a command packet having a common identifier from data to be transferred and the processing request, and detects a processing state of the nonvolatile storage device A data buffer unit that outputs only a command packet to the nonvolatile storage device when the nonvolatile storage device is processing may be provided.

  Thus, the access device can select a packet to be output to the nonvolatile storage device by detecting the processing state of the nonvolatile storage device. Therefore, the access device can output a command packet to the nonvolatile memory device even when data is written or read in the nonvolatile memory device.

  Furthermore, the present invention is characterized in that, in the above access device, the identifier generation unit assigns a common identifier only for a processing request related to management information of the data associated with the data to be transferred to the nonvolatile storage device. There may be.

  As a result, the nonvolatile storage device can identify (recognize) the relationship between individual command packets and data packets.

  The present invention can also be realized as a nonvolatile storage system including the above-described nonvolatile storage device and access device. In this case, data and commands can be efficiently transferred from the access device to the nonvolatile storage system efficiently as a whole system including an information storage medium for recording information (data) and an access device (host device) connected thereto. Can be transferred.

  According to the present invention, by issuing another command before or during execution of a certain command from the access device, the throughput of command processing is improved, and the interface bus can be used efficiently.

(First embodiment)
FIG. 1 is a block diagram showing a method for implementing a nonvolatile memory system according to an embodiment of the present invention. In FIG. 1, the nonvolatile storage system includes an access device 100 and a nonvolatile storage device 110, and both are connected via an interface bus 120.

  The access device 100 includes an application 130, a file system 140, and a nonvolatile storage device I / F unit 150.

  The application 130 includes an API calling unit 131 and a user data input unit 132. The file system 140 includes a command generation unit 141, a write address generation unit 142, a Seq # generation unit 143, and a management information data generation unit 144. The nonvolatile storage device I / F unit 150 includes a header generation unit 151, a SubSeq # generation unit 152, and a data buffer 153.

  On the other hand, the nonvolatile storage device 110 includes an access device I / F unit 160 and a nonvolatile memory 170. The access device I / F unit 160 includes a packet analysis unit 161, a command scheduler 162, a command execution unit 163, a write control unit 164, and a Seq # management unit 165. The nonvolatile memory 170 includes at least a user data area 171 and a system area 172. The logical address space in the user data area 171 and the system area 172 in the nonvolatile memory 170 is the same as that in FIG.

  FIG. 2 is a diagram illustrating a packet configuration on the interface bus 120 in the present embodiment.

  FIG. 2A shows a basic form of a packet on the interface bus 120. The packet includes a packet number indicating the packet transmission order (hereinafter abbreviated as packet #), a packet ID indicating whether the packet is a command, data indicating a packet, a header including the packet length indicating the packet length, and a payload indicating the contents of the packet. Consists of The header has a common format regardless of whether the packet is a command or data. On the other hand, the format of the payload changes depending on the packet ID.

  FIG. 2B shows a packet structure of the Write command as an example of the command. The Write command packet has a header consisting of packet #, packet ID (here “command” is set), packet length, command type (here “Write” is set), and what data is written. Data type (“user data”, “FAT1”, etc. are set), Seq number, and SubSeq number (hereinafter abbreviated as Seq # and SubSeq #, respectively). Seq # and SubSeq # will be described later.

  FIG. 2C shows a packet structure of user data transferred from the access device 100 to the nonvolatile storage device 110 by the user data write command. The user data packet follows a header consisting of packet #, packet ID (here “data” is set), packet length, data type (here “user data” is set), Seq #, SubSeq #. , A write destination address (logical address), and a user data entity (including an error correction code).

  FIG. 2D shows a packet configuration of FAT1 data transferred from the access device 100 to the non-volatile storage device 110 by the FAT1 data Write command as an example of management information data. The FAT1 data packet has a header including a packet #, a packet ID (here, “data” is set), a packet length, a data type (here, “FAT1” is set), Seq #, SubSeq #, It consists of a write destination address (logical address) and a FAT1 data entity (including an error correction code and the like).

  Hereinafter, an operation when data is written from the access device 100 to the nonvolatile memory device 110 will be described with reference to FIGS. 1 and 2. At this time, one or more data packets are transmitted on the interface bus 120 subsequent to one Write command packet.

  First, the Write command packet will be described. An API for data writing is called by the API calling unit 131 in the application 130. At this time, at least the data length and the data reference destination are instructed to the file system 140 in accordance with the above instruction. The data reference destination is a predetermined area of the user data input unit 132 for user data, and the management information data generation unit 144 for management information data.

  In the file system 140, the command generation unit 141 generates a write command on the interface bus 120. Further, the Seq # generation unit 143 generates Seq # of the Write command. Seq # is a numerical value for associating management information data corresponding to user data and a command for recording these data, and is generated by the Seq # generation unit 143 according to a certain rule. In the present embodiment, for simplification of description, it is generated so as to increase monotonously. The file system 140 supplies the above-described Write command and Seq # to the data buffer 153 in the nonvolatile storage device I / F unit 150.

  In addition to the above, the nonvolatile storage device I / F unit 150 adds the header generated by the header generation unit 151 and the SubSeq # generated by the SubSeq # generation unit 152 to generate a Write command packet. At this time, the packet ID of the header is “command”. In the case of command packets, termination information is always set for SubSeq #. Hereinafter, it is assumed that SubSeq # is 8 bits long, and the termination information is defined as 0xFF.

  The Write command packet is supplied to the packet analysis unit 161 of the nonvolatile storage device 110 via the interface bus 120.

  The packet analysis unit 161 analyzes the packet ID included in the packet header. As a result of the analysis, when the command is determined, the command scheduler 162 is supplied with the content of the command (in this case, “Write”) and Seq #. Thereafter, the command scheduler 162 supplies the accumulated commands to the command execution unit 163 at an appropriate timing, so that the commands are executed.

  Next, the case of a data packet will be described. The data packet is transferred when there is a transfer request from the nonvolatile storage device 110 to the access device 100. When there is a request for a data packet from the nonvolatile storage device 110, the write destination address generation unit 142 detects a writable area on the nonvolatile memory 170 with the above-described issuance of the Write command, and the logical address thereof. Is generated as a write address and supplied to the data buffer 153. Further, the Seq # generation unit 143 generates Seq # of the file data and supplies it to the data buffer 153. Further, the substance of the data to be written is accumulated in the data buffer 153 from the data reference destination on the user data input unit 132 or the management information data generation unit 144 described above.

  In addition to the above, the nonvolatile storage device I / F unit 150 adds the header generated by the header generation unit 151 and the SubSeq # generated by the SubSeq # generation unit 152 to generate a data packet. At this time, the packet ID of the header is “data”.

  SubSeq # is a numerical value when file data having the same Seq # is packet-divided and transmitted on the interface bus 120, and is set to increase monotonically within the same Seq #. SubSeq # of the last packet of the same Seq # is set to 0xFF (termination information). The unit for packet division is determined by the nonvolatile storage device I / F unit 150 based on the buffer size in the access device 100 and the nonvolatile storage device 110, the transfer speed of the interface bus 120, and the like. It is desirable that the size per page or a multiple thereof. Since the management information data is small in size, it is desirable to transmit management information data having the same Seq # in one packet. In this case, SubSeq # = 0xFF.

  The data packet is supplied to the packet analysis unit 161 of the nonvolatile storage device 110 via the interface bus 120.

  The packet analysis unit 161 analyzes the packet ID included in the packet header. As a result of analysis, when it is determined that the data is data, the content of the packet is accumulated in the write control unit 164. The write control unit 164 converts the data type analysis and the write address multiplexed in each data packet into a physical address on the nonvolatile memory 170, and then the user data area 171 of the nonvolatile memory 170, or It is written at a predetermined address in the system area 172. Note that the management information data is written to another area without overwriting the same data that has already been written in order to take measures against power interruption during the writing. When all the management information data is correctly written, the previous management information data is erased or invalidated. As a result, even if management information data fails to be written due to power interruption, it is possible to maintain consistency between user data and management information data using previous management information data.

  When data is normally written in a predetermined area of the nonvolatile memory 170, the write control unit 164 notifies the Seq # management unit 155 of the data type, Seq #, and SubSeq # of the packet that has been normally written.

  The Seq # management unit manages Seq # and SubSeq # of normally written data for each data type.

  The command scheduler 162 supplies the command to be executed next to the command execution unit 163 while referring to the accumulated commands and the information of the Seq # management unit 165.

  The command execution unit 163 analyzes and executes the command supplied from the command scheduler 162. Specifically, when a write command of data with Seq # = 2 is executed, the access device 100 is requested to transfer the file data via the interface bus 120 as in the case of Seq # 1. Upon receiving the transfer request, the access device 100 transmits a data packet of the file data stored in the data buffer 153 to the nonvolatile storage device 110 via the interface bus 120, and a predetermined area of the nonvolatile memory 170. To write to.

  FIG. 3 shows a write command issuance timing of user data and management information data, a timing at which a command is actually executed by the command execution unit 163, and a timing at which a packet of user data and management information data is transmitted in this embodiment. FIG. FIG. 4 is a diagram illustrating transition of management information of the Seq # management unit 165 accompanying the sequence execution illustrated in FIG. In the following description, user data, FAT1 data, FAT2 data, and DIR data are referred to as symbols U, A, B, and C, respectively, for convenience of explanation. It is assumed that commands having the same Seq # and management information data are transmitted in one packet. That is, SubSeq # of these packets is always termination information (0xFF).

  When the access device 100 detects that the nonvolatile storage device 110 is attached, the nonvolatile storage device I / F unit 150 transmits an “Initialize” command packet to the nonvolatile storage device 110 via the interface bus 120. The access device I / F unit 160 that has received the above is supplied to the command scheduler 162 after being analyzed by the packet analysis unit 161. Since the Initialize command is irrelevant to data writing to the non-volatile memory 170, it is immediately supplied to the command execution unit 163 and becomes executable. By the Initialize command, the nonvolatile storage device 110 including the management information initialization of the Seq # management unit 165 is initialized. FIG. 4A shows management information of the Seq # management unit 165 at time T0 after the completion of this command processing.

  When the access device 100 tries to execute writing of predetermined user data, the API calling unit 131 of the application 130 calls the writing API. At this time, the file system 140 is also notified of the write data length (size 1).

  The file system 140 generates a Write command in the command generation unit 141, generates Seq # = 1 in the Seq # generation unit 143, and supplies the Seq # = 1 to the nonvolatile storage device I / F unit 150. The nonvolatile storage device I / F unit 150 generates a “Write (U [1])” command packet that is a Write command of user data with Seq # = 1, and transmits the command packet to the nonvolatile storage device 110 via the interface bus 120. To do. The access device I / F unit 160 that has received the above is supplied to the command scheduler 162 after being analyzed by the packet analysis unit 161.

  Since the command scheduler 162 is writing user data, the command scheduler 162 is immediately supplied to the command execution unit 163 and becomes executable.

  With the execution of the Write (U [1]) command, the access device I / F unit 160 requests the user data packet “U [1]” from the nonvolatile storage device I / F unit 150 via the interface bus 120. .

  The nonvolatile storage device I / F unit 150 generates a user data packet U [1] -1 having SubSeq # = 1 generated by the SubSeq # generation unit 152 and transmits the user data packet U [1] -1 to the access device I / F unit 160. Here, U [1] -1 means a data packet of SubSeq # = 1 among user data U [1] of Seq # = 1. The size of each user data packet is determined by the nonvolatile storage device I / F unit 150 according to the specifications of the interface bus 120, the size of the data buffer 153, and the like.

  The access device I / F unit 160 that has received the above is analyzed by the packet analysis unit 161, and is written to a predetermined address in the user data area 171 of the nonvolatile memory 170 through processing such as address conversion by the write control unit 164.

  In this embodiment, the command scheduler 162 in the access device I / F unit 160 can store commands and execute instructions at a predetermined timing. Therefore, the application 130 is in the busy state in the nonvolatile storage device 110. Even so, it is possible to transmit a command packet. Therefore, when the API calling unit 131 calls the synchronous API during the transfer of the user data packet of U [1] -1, the file system 140 (nonvolatile storage device I / F unit 150) is stored in the nonvolatile storage device 110. If the transfer of the packet of U [1] -1 is completed even in the busy state, the nonvolatile storage device I / F unit 150 reads “Write (A [1] which is a Write command of FAT1 data of Seq # = 1. ]) ”Command packets can be sent to the non-volatile storage device 110 via the interface bus 120.

  The access device I / F unit 160 that has received the above is supplied to the command scheduler 162 after being analyzed by the packet analysis unit 161.

  Since the command scheduler 162 is writing user data, the command scheduler 162 is immediately supplied to the command execution unit 163 and becomes executable.

  The command scheduler 162 refers to the management information (FIG. 4A) of the Seq # management unit 165 and detects that the writing of user data with Seq # = 1 is not completed. Therefore, the Write (A [1]) command remains accumulated in the command scheduler 162. The command scheduler 162 periodically refers to the management information of the Seq # management unit 165 while the commands are accumulated.

  At time T1 when the writing of the user data U [1] -1 has been completed normally, the writing control unit 164 notifies the Seq # management unit 165 of normal writing of Seq # = 1 and SubSeq # = 1. As a result, the management information of the Seq # management unit 165 is updated as shown in FIG. At the same time, the busy state is released.

  When busy is released, U [1] -2, which is the next user data packet, is transferred. In this case, the busy state is again entered, but it is possible to issue a command related to the synchronous API issue as described above. That is, the non-volatile storage device I / F unit 150 sends a FAT2 with Seq # = 1, a “WRITE (B [1])” or “Write (C [1])” command packet that is a DIR Write command to U [1 ] -2 It becomes possible to transmit after completion of packet transfer. Then, the command scheduler 162 receives the write command, transmits the command packet, and refers to the management information (FIG. 4B) of the Seq # management unit 165 to complete the writing of the user data with Seq # = 1. Detect that it is not. Therefore, the Write (B [1]) and Write (C [1]) commands remain accumulated in the command scheduler 162 in the same manner.

  When all the data having the data length size1 designated at the time of writing U [1] can be packetized on the data buffer 153, U [1] -E meaning the last packet is generated, and the access device I / F unit 160. At time T2 when the writing of U [1] -E is normally completed, the writing control unit 164 notifies the Seq # management unit 165 of normal writing of Seq # = 1 and SubSeq # = 0xFF. As a result, the management information of the Seq # management unit 165 is updated as shown in FIG. 4C, and the busy state is released at the same time.

  Immediately after time T2, the command scheduler 162 refers to the management information (FIG. 4C) of the Seq # management unit 165 and detects that the writing of user data with Seq # = 1 is completed. As a result, the command scheduler 162 supplies a Write (A [1]) command among the accumulated commands to the command execution unit 163. As a result, the Write (A [1]) command is executed, and the access device I / F unit 160 requests the access device 100 to transfer the data packet, and sends the data packet of A [1] via the interface bus 120. Receive. The access device I / F unit 160 that has received the above is analyzed by the packet analysis unit 161, and is written to a predetermined address in the system area 172 of the nonvolatile memory 170 through processing such as address conversion by the write control unit 164. As described in the conventional nonvolatile storage system, in the case of management information data, it is considered that data transfer completion and busy state cancellation are almost simultaneous.

At time T3 when the writing of A [1] data is completed normally, the management information of the Seq # management unit 165 becomes as shown in FIG. 4D. When instructed to write # 2, the nonvolatile storage device I / F unit 150 sends a “Write (U [2])” command packet, which is a write command of user data of Seq # = 2, to the interface bus 120. To the non-volatile storage device 110. At this time, since other commands (Write (B [1]) and Write (C [1])) are accumulated in the command scheduler 162, the Write (U [2]) command is stored in the command scheduler 162. Accumulated in.

  Thereafter, when the Write (B [1]) command and the Write (C [1]) command are sequentially executed, the command stored in the command scheduler 162 is only the Write (U [2]) command. At this time, a Write (U [2]) command is supplied to the command execution unit 163. As a result, the Write (U [2]) command is executed, and the access device I / F unit 160 requests the access device 100 to transfer the data packet, and the user data packet U [2] − via the interface bus 120. 1 is transmitted to the access device I / F unit 160.

  At time T4 when the writing of C [1] data is normally completed, the management information of the Seq # management unit 165 is as shown in FIG. At this time, since the user data and management information data of Seq # = 1 are all written correctly, it means that the data of Seq # = 1 can be consistent as file data. That is, even if the power is cut off immediately after time T4, the user data of Seq # = 1 can be correctly read using the management information data of Seq # = 1.

  As described above, in this embodiment, when compared with a conventional nonvolatile storage system, the nonvolatile storage device 110 is in a busy state by allowing commands to be accumulated in the nonvolatile storage device. However, subsequent command packets can be transmitted during that time, and the bus can be used efficiently. As a result, the throughput of the system at the time of writing can be improved.

  In addition, by instructing execution of commands stored in the non-volatile storage device at an appropriate timing, the management information data is always written after completion of writing of the corresponding user data, which causes a power shutdown during writing. However, the file can be read correctly. Specifically, after the time T3, when a power interruption occurs while B [1] data is being written, the contents of the FAT1 data and the FAT2 data of Seq # = 1 are different, and the file name included in the DIR, etc. Information will not be updated correctly. Therefore, in this case, at the time of restart, management information data before A [1] data writing is restored, and U [1] is invalidated. Thereby, the reproduction of the file data before writing the user data U [1] is successful.

The access device 100 can detect whether or not the nonvolatile storage device 110 is in a busy state by detecting the state of a dedicated pin of the interface bus 120 or executing an inquiry command from the access device 100. It is.
(Second Embodiment)
FIG. 5 is a diagram for explaining a second embodiment of the present invention. In FIG. 5, 500 is an access device, 540 is a file system, 550 is a nonvolatile storage device I / F unit, 554 is a Seq size setting unit, and 555 is a Seq # generation unit.

  The access device 500 includes an application 130, a file system 540, and a nonvolatile storage device I / F unit 550.

  The file system 540 includes a command generation unit 141, a write address generation unit 142, and a management information data generation unit 144.

  The nonvolatile storage device I / F unit 550 includes a header generation unit 151, a SubSeq # generation unit 152, a data buffer 153, a Seq size setting unit 554, and a Seq # generation unit 555.

  Hereinafter, an operation when data is written from the access device 100 to the nonvolatile memory device 110 in the second embodiment will be described focusing on differences from the first embodiment.

  In the first embodiment, the Seq # is set every time the API calling unit 131 calls the write API and the file system 140 issues the Write command.

  On the other hand, in the present embodiment, the size of user data having the same Seq # by the application 130 (hereinafter referred to as Seq size) is set in advance in the Seq size setting unit 554 of the nonvolatile storage device I / F unit 550. The Seq # generation unit 555 inside the nonvolatile storage device I / F unit 550 sets the same Seq # for each Seq size. At this time, every time Seq size data is written, the access device 500 automatically updates (synchronizes) the management information data without issuing a synchronization API. At this time, Seq # is not set when the file system 540 issues a Write command. Therefore, when the file system 540 issues a command to the nonvolatile storage device I / F unit 540, the Seq # of the Write command packet in FIG. 2B is Don't Care.

  When the user data write command is executed by the command execution unit 163, the nonvolatile memory device I / F unit 550 is requested to transfer the user data packet.

  The nonvolatile storage device I / F unit 550 holds user data stored in a predetermined area of the access device 500. The Seq size setting unit 554 monitors the data size packetized by the data buffer 153, and instructs the Seq # generation unit 555 to add the same Seq # to data having a preset Seq size.

  Therefore, for the data packet, Seq # given by the Seq # generation unit 555 is set together with SubSeq # in the nonvolatile storage device I / F unit 550.

  FIG. 6 shows a write command issuance timing of user data and management information data, a timing at which a command is actually executed by the command execution unit 163, and a timing at which a packet of user data and management information data is transmitted in this embodiment. FIG. The transition of management information of the Seq # management unit 165 accompanying the sequence execution shown in FIG. 6 is the same as that in FIG.

  Similar to the first embodiment, when the access device 500 detects the mounting of the nonvolatile memory device 110, an Initialize command is issued, and initialization of the nonvolatile memory device 110 is executed.

  Subsequently, the API calling unit 131 of the application 130 calls the Seq size setting API. Accordingly, the Seq size set by the Seq size setting API is set in the Seq size setting unit 554 of the nonvolatile storage device I / F unit 550.

  When the access device 500 tries to execute writing of predetermined user data, the API calling unit 131 of the application 130 calls the writing API. At this time, the write data length is not specified. Accordingly, the nonvolatile storage device I / F unit 550 transmits a “Write (U)” command packet, which is a write command of user data, to the nonvolatile storage device 110, and the command is stored in the command scheduler 162. Because there is nothing, it is executed immediately.

  Along with execution of the Write (U) command, the non-volatile storage device I / F unit 550 displays the user data supplied by the user data input unit 132 and the write destination address generated by the write address generation unit 142 in the data buffer 153. To supply.

  In the nonvolatile storage device I / F unit 550, the Seq # generation unit 555 sets 1 as the Seq #, the SubSeq # generation unit 152 sets 1 as the SubSeq #, and the data generated together with the header generated by the header generation unit 151 It is added to the user data on the buffer 153. In this way, the user data packet “U [1] −1” is transmitted on the interface bus 120.

  Similar to the first embodiment, even when the user data packet transfer of U [1] -1 is completed, the nonvolatile storage device 110 remains in the busy state until the user data is completely written to the nonvolatile memory 170. Thus, since the command scheduler 162 can store commands and instruct execution at a predetermined timing, the access device 500 can instruct writing of FAT1 data corresponding to Seq # = 1 at any timing. is there.

  When all the data of the Seq size set by the Seq size setting unit 554 can be packetized on the data buffer 153, U [1] -E meaning the final packet is generated, and is sent to the access device I / F unit 160. Send.

  The next time user data is transmitted, the Seq # generated by the Seq # generator 555 is 2.

  In the present embodiment, even if the data packet transmission of U [1] -E is completed, U [2] -1, which is a packet, can be transmitted with the next user data without issuing a Write command. . When the data writing is finished, the application 130 issues an interruption API from the API calling unit 131. As a result, data transfer and writing are immediately stopped, and “Write (A [2])” and “Write (B [2])”, which are Write commands for recording management information data at the current time in a file. , “Write (C [2]) is issued, data A [2], B [2], and C [2] are written, respectively, and the process ends.

  As described above, even in the present embodiment, when compared with a conventional nonvolatile storage system, by allowing commands to be accumulated in the nonvolatile storage device, even if the nonvolatile storage device 110 is in a busy state, In the meantime, subsequent command packets can be transmitted, and the bus can be used efficiently. As a result, the throughput of the system at the time of writing can be improved.

  Also, in the present embodiment, when user data is written continuously, a Seq size is set in advance, so that it is not necessary to issue a user data write command every time after the management information data writing is completed. The number of write command packets to be reduced can be reduced. Therefore, the data transfer efficiency can be improved more than before, and the bus efficiency can be increased. This is a particularly effective means for recording continuous moving image data.

  As in the first embodiment, the management information data is always written after the writing of the corresponding user data is completed by instructing execution of commands stored in the nonvolatile storage device at an appropriate timing. Therefore, the file can be read correctly even if the power is cut off during writing.

  In the first embodiment and the second embodiment, after the Write command becomes executable, data transfer is requested from the nonvolatile storage device to the access device. However, the capacity of the write control unit 164 is small. If it has a sufficient size, file data corresponding to the Write command is stored in advance in the write control unit 164 of the nonvolatile storage device, and if the write command is in an execution state, it is stored in the write control unit 164. It is also possible to write the file data in the nonvolatile memory 170. In this case, according to the amount of data that can be stored in the write control unit 164, a method of previously storing data and a method of requesting data transfer to the access device at the time of writing may be used.

  In the embodiment of the present invention, SubSeq # has been described as a monotonically increasing numerical value, but it may be possible only to identify whether it is termination information.

  As the data type ID, a system in which secure data, which is data that cannot be accessed without a predetermined authentication process, such as key information for content protection, can be considered.

  In the first embodiment and the second embodiment, Seq # (Seq number), SubSeq # (SubSeq number), and the like are assigned in order to associate a command with data. Is not necessarily limited to these numbers. As long as the association between the command and the data can be distinguished from other associations, these may be other identification symbols (identifiers) such as alphabets or the like.

  In the first embodiment and the second embodiment, the embodiments have been described as the access device, the nonvolatile storage device, and the nonvolatile storage system including these, but the present invention is limited to this. It is not a thing. The access device I / F unit and the like of the nonvolatile storage system 110 can also be realized by an integrated circuit such as a memory controller provided with a calculation unit and the like. In that case, the nonvolatile storage device 110 includes a memory controller and a nonvolatile memory as main components, and each function realized by the access device I / F unit 160 and the like is executed by the arithmetic unit of the memory controller. Or an integrated circuit that realizes an equivalent function with a circuit configuration.

  In addition, the nonvolatile memory device described in the first embodiment and the second embodiment can be realized as a device (functional component or the like) having an equivalent function. For example, the nonvolatile memory device 110 can be implemented as a part of modules mounted on an electric circuit board or an integrated circuit in which these modules are integrated. In this case, the nonvolatile memory device described in the present invention can also be realized as a nonvolatile memory device (module).

  The present invention efficiently uses an interface bus by issuing a command prior to execution of a command from an access device in a removable non-volatile storage device that is likely to cause a power interruption during data writing. It proposes a method to improve the throughput of command processing, such as high-quality moving image shooting, devices that have applications that require high-capacity data to be written to nonvolatile memory at high speed, such as digital video cameras This is useful in a moving image recording / reproducing apparatus, a still image recording / reproducing apparatus such as a digital still camera, or a mobile phone.

The block diagram explaining the structure of the 1st Embodiment of this invention The figure explaining the format of each packet in this invention The figure explaining the relationship between the packet on the interface bus and command processing in the first embodiment The figure explaining the state transition of the Seq # management part in 1st Embodiment The block diagram explaining the structure of the 2nd Embodiment of this invention The figure explaining the relationship between the packet on the interface bus | bath in 2nd Embodiment, and command processing A block diagram illustrating the configuration of a conventional nonvolatile storage system The figure explaining the structural example of the logical address space of the conventional non-volatile storage system The figure explaining the relationship between the command and write data in the conventional nonvolatile memory system

Explanation of symbols

100, 500, 700 Access device 110 Non-volatile storage device 120 Interface bus 130, 730 Application 131, 731 API calling unit 132, 732 User data input unit 140, 540, 740 File system 141, 741 Command generation unit 142, 742 Write address Generation unit 143, 555 Seq # generation unit 144, 743 Management information data generation unit 150, 550 Non-volatile storage device I / F unit 151 Header generation unit 152 SubSeq # generation unit 153 Data buffer 160, 760 Access device I / F unit 161 761 Packet analysis unit 162 Command scheduler 163 Command execution unit 164, 762 Write control unit 165 Seq # management unit 170, 770 Non-volatile memory 171, 771 Zadeta regions 172,772 system area 554 Seq size setting unit 710 SD card 750 SD card I / F unit

Claims (6)

In a memory controller that controls data recording to a nonvolatile memory,
A read / write control unit for writing data to the nonvolatile memory or reading data from the nonvolatile memory;
A packet analysis unit for receiving a command packet indicating a processing request and a data packet having data to be written to the nonvolatile memory from outside, and analyzing the received packet;
A command scheduler for accumulating processing requests included in the command packet and managing execution timing of the requested processing;
The packet analysis unit receives a command packet when the read / write control unit is writing data to or reading data from the non-volatile memory, and stores a processing request for the command packet in a command scheduler. And memory controller. The memory controller of claim 1, wherein
The received packet has a common identifier in the associated command packet and data packet,
A management unit that manages the execution status of the processing request included in the command packet with the identifier;
The command scheduler manages processing to be executed next and execution time based on the implementation status. A nonvolatile storage device comprising the memory controller according to claim 1 and a nonvolatile memory. In an access device for instructing data writing to a nonvolatile storage device having a nonvolatile memory,
A command generation unit for generating a processing request to the nonvolatile storage device;
An identifier generating unit that assigns a common identifier to the processing request associated with data to be transferred to the nonvolatile storage device;
A data packet and a command packet having a common identifier are generated from the data to be transferred and the processing request, and the processing state of the nonvolatile storage device is detected. When the nonvolatile storage device is processing And a data buffer unit that outputs only command packets to the non-volatile storage device. 5. The access device according to claim 4, wherein the identifier generation unit assigns a common identifier only to a processing request related to management information of the data associated with data to be transferred to the nonvolatile storage device. apparatus. A non-volatile storage system comprising the non-volatile storage device according to claim 3 and the access device according to any one of claims 4 to 5.

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