JP2005275501A - Device system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve an initialization process when a device different from a device currently connected to a system is connected to the system. <P>SOLUTION: When a controller 101 with a first device connected in a data transfer mode is further connected with a second device, the controller 101 shifts the first device to a standby state before shifting the second device to an idle state. The first card, which is in a standby state, does not receive the latter command to save a state transition process. This can shorten an access start time for the device to realize an improved initialization process when a device different from a device currently connected to the system is connected to the system. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a device system and a technology for improving the efficiency of the initialization process in the device system, for example, a technology effective when applied to a multimedia card.

  Memory cards are rapidly spreading as external storage devices such as personal computers and multi-function terminals. As one of the memory cards, a multimedia card standardized by MMCA (MultiMedia Card Association) which is a standardization organization is widely known. This multimedia card is used for digital camera still image recording, cellular phone data recording, portable music player music recording, and the like (see, for example, Patent Document 1).

Japanese Patent Laying-Open No. 2003-50980 (from the second paragraph)

  According to the multimedia card standard, a plurality of multimedia cards can be controlled by a single host system. In the MMC mode of the MMC standard, data transfer is possible after the host system changes the state of the card to a data transfer mode such as a standby state or a transfer state. The process necessary for this state transition is defined as an initialization process.

  However, when a second memory card different from the first memory card is newly joined in a state where the first memory card that is currently joined is set to the data transfer mode, the first memory card and the second memory card are connected together. The inventor of the present application has found that the memory card is also initialized by the system, and the time and power required for the memory card are wasted.

  It is an object of the present invention to improve the initialization process when a device other than the device currently coupled to the system is coupled to the system.

  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.

  The following is a brief description of an outline of typical inventions disclosed in the present application.

  That is, when a device system is configured to include a host system and a plurality of devices that can be detachably coupled to the host system, the host system is in a state where the currently coupled first device is in the data transfer mode. When a second device different from the first device is coupled, the controller includes a controller capable of transitioning the second device to an idle state after transitioning the first device to a standby state.

  According to the above means, when the first device that is currently coupled is in the data transfer mode and the second device different from the first device is coupled, the controller can Then, the second device is changed to the idle state. Since the first card is in the standby state, the above command is not received and the state transition process is omitted. This can reduce the start time of access to the device and achieves an improved initialization process when a device other than the device currently coupled to the system is coupled to the system.

  Further, the controller can receive only the device in the data transfer mode when the second device different from the first device is coupled in a state where the first device currently coupled is in the data transfer mode. After the first device is changed to the standby state by issuing the first command, the second command for changing the second device to the idle state can be issued.

  The first command is a broadcast type command that can be received only by a device in the data transfer mode, and the device that receives the broadcast command is defined not to capture the second command. The device can be a multimedia card.

  The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.

  That is, the access start time to the device can be shortened, and the efficiency of the initialization process when a device other than the device coupled to the system is coupled can be improved.

  FIG. 1 shows a multimedia card system which is an example of a device system according to the present invention. The multimedia card system shown in FIG. 1 includes a host system 10 and a plurality of devices, for example, multimedia cards (hereinafter simply referred to as “cards”) 11 detachably connectable thereto. The host system 10 includes a hardware part, a system software part, and an application software part. Although not particularly limited, the hardware unit includes a card controller 101 that controls the operation of the card 11-11 by transmission / reception of commands, responses, and data. In particular, as will be described in detail later, the card controller 101 uses the data transfer mode when a memory card other than the memory card is coupled in a state where the currently coupled memory card is in the data transfer mode. After the memory card is transitioned to the standby state, another memory card is initialized by transitioning to the idle state. The system software unit includes a driver 102 that controls the card controller 101 and a file system 103 that manages data as files. The application software section includes an application system 104 such as an audio-related player or recorder.

  FIG. 2 shows a card initialization process in a system to be compared with the multimedia card system shown in FIG. Hereinafter, a case where the second card 11-2 is newly attached to the host system 10 in which the first card 11-1 is already connected and is in the data transfer mode will be described.

  The host system 10 detects that a new card 11-2 has been inserted (201). The host system 10 issues a command CMD0 for setting all the cards in the idle state (202). When the card 11-2 receives the command CMD0, the card 11-2 transitions to an idle state (203B). Since the command CMD0 is received by the card in a state other than the inactive state, the card 11-1 in the data transfer mode (standby state, transfer state, etc.) also receives the command CMD0 and transitions to the idle state (203A). The host system 10 issues a command CMD1 (204) and inquires the card 111-2 about OCR (operating voltage range).

  When the card 11-1 and the card 11-2 receive the command CMD1, they return their own OCRs to the host system 10, respectively. Further, if the card power-up process is completed, transition to the ready state is made (205A, 205B).

  The host system 10 checks whether the power-up process of all the cards is completed based on the OCR received from the card 111-2 (206). If not completed, the host system 10 repeats issuing the command CMD1 and checking the response, and waits for completion of the power-up process of all cards.

  The host system 10 issues a command CMD2 and inquires of the card 111-2 about a CID (static ID) (207). The command CMD2 is received only by the ready card. When the card receives the command CMD2, it tries to return its own CID to the host system 10, but compares its own CID with the CID on the bus in binary, and stops output if they are different. That is, only the card having the maximum CID outputs the CID. Here, assuming that the CID of the card 11-1 is smaller than the CID of the card 11-2, the card 11-2 transmits the CID to the host system 10, and transits to the identified state (208B). The card 11-1 stops transmitting and remains in the ready state (208A). The host system 10 issues a command CMD3 to the card 11-2 that has received the CID (209), and assigns RCA (dynamic relative address on the bus). Here, the RCA assigned to the card 11-2 is “2”. The command CMD3 is received only by the card in the identified state. Upon receiving the command CMD3, the card 11-2 transitions to the standby state (210). Since the card 11-1 is in the ready state, the command CMD3 is not received. The host system 10 issues a command CMD2 and inquires of the card 111-2 about the CID (211). Upon receiving the command CMD2, the card 11-1 returns its CID to the host system 10 (212). Since the card 11-2 is in the standby state, it does not receive the command CMD2. The host system 10 issues a command CMD3 to the card 11-1 that has received the CID, and assigns an RCA (213). Here, it is assumed that the RCA assigned to the card 11-1 is “1”. When the card 11-1 receives the command CMD3, the card 11-1 shifts to a standby state (214). Since the card 11-2 is in the standby state, it does not receive the command CMD3. With the above operation, the two cards 11-1 and 11-2 are set in the data transfer mode. For example, data transfer between the host system 10 and the card 11-2 is performed according to the following procedure.

  The host system 10 sets “2” (= RCA of the card 11-2) in the RCA, and issues a command CMD7 (215). Upon receiving the command CMD7, the card 11-2 transitions to the transfer state (216B). Since the card 11-1 is different from its own RCA, it does not receive the command CMD7 and remains in the standby state (216A). The host system 10 issues a read or write command. Only the card in the transfer state receives the read or write command. Upon receiving a read or write command (218), the card 11-2 transmits data to the host system 10 if it is a read, and receives data from the host system 10 if it is a write. Since the card 11-1 is in a standby state, it does not receive a read or write command.

  FIG. 3 shows a card initialization process in the multimedia card system shown in FIG.

  Hereinafter, as in the case shown in FIG. 2, a case where the second card 11-2 is newly attached to the host system 10 in which the first card 11-1 is already connected and is in the data transfer mode will be described.

  The host system 10 detects that a card 11-2 is newly inserted into a certain port, and issues a command CMD14 (302). The CMD 14 is a broadcast type command received only by a card in the data transfer mode, and has no response. Further, it is defined that the card that has received CMD14 transitions to a standby state while retaining the same RCA as that received before, and ignores CMD0 transmitted immediately after CMD14. Since the card already in the data transfer mode receives CMD14, it transitions to the standby state. When the first card 11-1 receives the command CMD14, the first card 11-1 transitions to a standby state while retaining the same RCA as that before the reception (305). Since the second card 11-2 is not in the data transfer mode, the command CMD14 is not received.

  Following the issuance of the command CMD14, the host system 10 issues the command CMD0 (304). When receiving the command CMD0, the second card 11-2 transitions to the idle state (305). Since the first card 11-1 has received the command CMD14, the command CMD0 issued immediately thereafter is not received.

  The host system 10 issues a command CMD1 (306) and inquires the card for OCR. When the second card 11-2 receives the command CMD 1, it returns its own OCR to the host system 10. Also, if the card power-up process is completed, a transition is made to the ready state (307). Since the card 11-1 is in the standby state, it does not receive the command CMD1. The host system 10 checks whether or not the power-up process of all cards is completed based on the OCR received from the card (308). If not completed, the host system 10 repeatedly issues the command CMD1 and examines its response, and waits for the end of the power-up process for all cards.

  The host system 10 issues a command CMD2 and inquires the card about the CID. Upon receiving the command CMD2, the card 11-2 returns its CID to the host system 10. Since the first card 11-1 is in the standby state, it does not receive the command CMD2. The host system 10 issues a command CMD3 to the second card 11-2 that has received the CID, and assigns an RCA. However, the RCA to be assigned is different from those of other cards including the card 11-1 already in the standby state. Here, the RCA of the card 11-1 is “1”, and “2” is assigned to the card 11-2. Since the RCA of the card 11-1 is assigned by the host system 10 when the card 11-1 is connected, the host system 10 can assign different RCAs to the card 11-2.

  When receiving the command CMD3, the second card 11-2 transitions to the standby state (312). Further, since the card 11-1 is in the standby state, the command CMD3 is not received. By the above operation, the card 11-2 can be shifted to the standby state that is the data transfer mode while maintaining the standby state of the first card 11-1. For example, when the host system 10 and the second card 11-2 transfer data, the following steps 313 to 317 are possible.

  The host system 10 sets “2” (= RCA of the card 11-2) in the RCA, and issues a command CMD7 (313). When receiving the command CMD7, the second card 11-2 transitions to the transfer state (315). Since the first card 11-1 is different from its own RCA, it does not receive the command CMD7 and remains in the standby state. The host system 10 issues a read or write command (316). This read or write command is received only by the transferred card. The second card 11-2 receives a read or write command, transmits data to the host system 10 if it is a read, and receives data from the host system 10 if it is a write (317). At this time, since the first card 11-1 is in a standby state, it does not receive a read or write command.

  According to the above example, the following operational effects can be obtained.

  (1) When the host system 10 having a card already in the data transfer mode recognizes that a new card has been connected, it issues a command CMD14. The first card 11-1 that has received the command CMD14 does not receive the command CMD0. Only the newly connected second card 11-2 receives CMD0 and transitions to the “idle state”. Thereafter, only the newly connected second card changes the state of CMD1 reception → “ready state” → CMD2 reception → “identify state” → CMD3 reception → “standby state”. On the other hand, since the first card 11-1 is in the “standby state”, the above command is not received and the state transition process is omitted.

  (2) Since the access start time to the card can be shortened by the effect of the above (1), the performance of the system can be improved.

  (3) Due to the effect of (1) above, useless commands and responses between the host system 10 and the card 11 can be omitted, so that power saving can be achieved.

  Although the invention made by the present inventor has been specifically described above, the present invention is not limited thereto, and it goes without saying that various changes can be made without departing from the scope of the invention.

  For example, it can be realized by an existing command. In this method, after a new card is detected, a value other than 0 (hereinafter referred to as CMD0 ′) is set in the argument of CMD0 instead of CMD14. In the MMC standard, the argument of CMD0 is defined as 0. In addition to the normal CMD0 function, CMD0 ′ can be defined as having a function of transitioning to a “standby state” when a card already in the data transfer mode receives. FIG. 4 shows the flow in that case.

  The host system 10 detects that the card 2 is newly inserted into a certain port, and issues CMD0 ′ (402). Since the first card 11-1 is in the data transfer mode, when it receives CMD0 ', it transitions to the standby state (403). Since the second card 2 is not in the data transfer mode, when it receives CMD0 ′, it transitions to the idle state (404). The host system 10 issues CMD1 and inquires the card for OCR (405). Thereafter, the initialization process is the same as in the case of FIG.

  According to the process shown in FIG. 4, since the issue of CMD14 is omitted, further time reduction and power saving of the initialization process can be obtained. In addition, since it is not necessary to add a new command (CMD14), it becomes easy to update the standard and develop the host system 10 and the card corresponding thereto.

  Further, only a specific card can be initialized by a command.

  That is, it is possible to initialize only a specific card by defining the command CMD14 in more detail. This is particularly effective when an error occurs in a certain card and it is necessary to initialize the card, or when it is necessary to reset the RCA of a specific card in relation to a higher-level application.

  FIG. 5 shows an example when an error occurs in a certain card 11-α and it is necessary to initialize it. When an error occurs in the card 11-α, the command CMD14 is issued, whereby only the card 11-α is initialized.

  FIG. 6 shows an example in the case where it is necessary to reset the RCA of a specific card due to the relationship with the upper application. In an example applied to a card reader application connected via USB, the application manages the RCA and the drive number in association with each other. In FIG. 6, it is assumed that the card 11-γ is a card that must be assigned to the drive E. Since the card 11-β has already been assigned to the drive E, when the card 11-γ is newly connected, it is necessary to initialize the card 11-β and the card 11-γ and reassign the RCA.

  To initialize only a specific card, information that associates the RCA and the card is set in the bitmap format in the argument of the command CMD14. Since the maximum number of cards that can be connected according to the MMC standard is 30, it can be managed with 30 bits.

  FIG. 7 shows a format example of the command CMD14.

  The card having received the command CMD14 and having the bit corresponding to the RCA of the argument and its own RCA match, changes to the standby state while holding the same RCA as that received, and receives the command CMD0 transmitted immediately after the command CMD14. Define to ignore. Further, it is defined that a card whose RCA does not match is that the command CMD14 is not valid, and the next command CMD0 is received and transitions to the idle state. A specific card can be initialized by the definition of the command CMD14.

  Further, an existing command may be extended to initialize a specific card.

  For example, it is possible to initialize only a specific card by extending the command CMD0 in the MMC standard. Define the extended command as CMD0 ″. FIG. 8 shows the format of the command CMD0 ″. This command CMD0 ″ differs from the command CMD0 only in arguments, and has the information for associating the RCA and the card in the bit map format as in the case of the command CMD14. A card that receives the command CMD0 ″ and whose bit corresponding to the RCA of the argument matches its own RCA is defined as transitioning to a standby state while retaining the same RCA as that received. A card whose RCA does not match is defined to transition to an idle state. When the argument is “0”, all the cards transition to the idle state, so that the command is compatible with the conventional command CMD0. A specific card can be initialized by the definition of the command CMD0 ″.

  In the above description, the multimedia card system, which is a field of use based on the invention made by the inventor, has been described. However, the present invention is not limited to this, and for example, one host system includes a plurality of host systems. The present invention can be widely applied to a device system having a form for controlling a device.

  The present invention can be applied on condition that a plurality of devices are combined.

1 is a block diagram illustrating an example of the overall configuration of a multimedia card system which is an example of a device card system according to the present invention. It is explanatory drawing of the initialization process of the card | curd in the system used as the comparison object of the multimedia card system shown by FIG. It is explanatory drawing of the initialization process of the card | curd in the multimedia card system shown by FIG. It is explanatory drawing of another initialization process of the card | curd in the said multimedia card system. It is explanatory drawing in case an error occurs in a card | curd and initialization is required. It is explanatory drawing in case the resetting of RCA of a specific card | curd is required by the relationship with a high-order application. It is format explanatory drawing of the command handled by the said multimedia card system. It is another format explanatory drawing of another command handled with the said multimedia card system.

Explanation of symbols

10 Host System 11 Card 11-1 First Card 11-2 Second Card 101 Card Controller 102 Driver 103 File System 104 Application

Claims (4)

A device system including a host system and a plurality of devices removably connectable thereto,
The host system transitions the first device to a standby state when a second device different from the first device is coupled while the first device coupled to the current device is in a data transfer mode. And a device system including a controller capable of transitioning the second device to an idle state. When the first device that is currently coupled is in the data transfer mode and a second device that is different from the first device is coupled, the controller can receive only the device that is in the data transfer mode. 2. The device system according to claim 1, wherein after issuing the 1 command to transition the first device to the standby state, the device system issues a second command for causing the second device to transition to the idle state. 3. The first command is defined as a broadcast type command that can be received only by a device in a data transfer mode, and the device that has received the broadcast command is defined not to capture the second command. Device system. The device system according to claim 1, wherein the device is a multimedia card.

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