Abstract:
An electronic apparatus in which a memory unit containing a memory and a controller to access the memory in response to an externally input command can be installed. The electronic apparatus comprises a first acquiring section which acquires identification information from the memory unit, a second acquiring section which, on the basis of the identification information acquired by the first acquiring section, acquires one from a plurality of control programs to control the controller of the memory unit, and a setting section which sets an operating environment so as to apply the control program acquired by the second acquiring section to the process of inputting and outputting data to and from the memory unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2004-089475, filed Mar. 25, 2004, the entire contents of which are incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to an electronic apparatus acting as a host to which a memory unit with a built-in controller IC, such as a memory card, can be connected and a method of controlling the memory unit. 
   2. Description of the Related Art 
   With the recent remarkable progress in semiconductor manufacturing technology, memory cards with a built-in controller IC are getting larger in capacity rapidly. This enables electronic devices acting as hosts to which memory cards are connected, such as digital still cameras or digital video cameras, to handle large-volume content, such as moving images or music. 
   A host which handles large-volume content is required to finish inputting and outputting data to and from a memory card quickly. That is, faster data transfer between the memory card and the host is considered important. For this reason, a method of setting the data transfer speed to a value suitable for each memory card has been proposed (refer to, for example, Jpn. Pat. Appln. KOKAI Publication No. 7-320018). 
   In the method disclosed in Jpn. Pat. Appln. KOKAI Publication No. 7-320018, the data transfer between the memory card and the host is carried out at the access speed specified in the access speed information acquired from the memory card. Therefore, even when any type of memory card is installed, the data transfer best suited to the memory card is performed. 
   As described above, data is always input to or output from the memory card via the controller IC. Therefore, use of only the optimization of the data transfer speed between the memory card and the host makes it difficult to maximize the performance of the memory card. 
   For example, the specifications of the memory card, including the block size of the memory built in the memory card and the procedure by which the controller IC accesses the memory, differ from maker to maker or depending on the time when the memory card was developed. When data is input and output by a standardized method without recognizing the difference in the specifications, it is possible that a specific command will be often used for the controller IC even though the controller IC is weak in the access procedure based on the specific command or that data writing unsuitable for the block boundary of the memory will be performed frequently. In such a case, even if the data transfer speed between the memory card and the host is optimized, it is difficult to shorten the time required to input and output the data to and from the memory card. Therefore, there has been a desire for an electronic apparatus capable of maximizing the performance of a memory card, taking the specifications of the card into account, and a method of controlling a memory unit connected to the apparatus. 
   BRIEF SUMMARY OF THE INVENTION 
   According to a first aspect of the invention, there is provided an electronic apparatus in which a memory unit containing a memory and a controller to access the memory in response to an externally input command can be installed, the electronic apparatus comprising: a first acquiring section which acquires identification information from the memory unit; a second acquiring section which, on the basis of the identification information acquired by the first acquiring section, acquires one from a plurality of control programs to control the controller of the memory unit; and a setting section which sets an operating environment so as to apply the control program acquired by the second acquiring section to the process of inputting and outputting data to and from the memory unit. 
   According to a second aspect of the invention, there is provided a memory unit with a controller comprising: a memory which stores identification information to determine a control program for the controller; and a transmitting section which, at the request of an external device, transmits the identification information read from the memory to the external device. 
   According to a third aspect of the invention, there is provided a method of controlling a memory unit in an electronic apparatus in which the memory unit containing a memory and a controller to access the memory in response to an externally input command can be installed, the method comprising: acquiring identification information from the memory unit; selecting one from a plurality of control programs to control the controller of the memory unit, on the basis of the acquired identification information; and setting an operating environment so as to apply the selected control program to the process of inputting and outputting data to and from the memory unit. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       FIG. 1  schematically shows the configuration of a host and a memory card according to an embodiment of the present invention; 
       FIG. 2  shows an example of a memory card control program held in the profile information storage section of the host; 
       FIGS. 3A and 3B  are diagrams to explain memory card control, taking into account the actual block size of the memory card executed on the host; 
       FIGS. 4A to 4C  are diagrams to explain first memory card control, taking into account the characteristic for a write command of the memory card executed on the host; 
       FIGS. 5A to 5C  are diagrams to explain second memory card control, taking into account the characteristic for a write command of the memory card executed on the host; 
       FIGS. 6A to 6C  are diagrams to explain third memory card control, taking into account the characteristic for a write command of the memory card executed on the host; 
       FIG. 7  is a flowchart for the operation procedure for memory card control performed by the host; and 
       FIG. 8  shows an application of memory card control performed by the host. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Hereinafter, referring to the accompanying drawings, an embodiment of the present invention will be explained. 
     FIG. 1  schematically shows the configuration of a host  1  and a memory card  2 . The host  1  is a portable terminal, such as a digital still camera, a digital video camera, or PDA (personal Digital Assistant). The host  1  includes a CPU  11 , a memory card control section  12 , a host memory card interface  13 , and a profile information storage section  14 . 
   The CPU  11  controls the overall operation of the host  1 . Under the control of the CPU  11 , the memory card control section  12  issues various data input and output commands for the installed memory card  2  on the basis of the control procedure prescribed in a memory card control program  121  explained later. The host memory card interface  13  controls the transmission and reception of data and commands between the memory card  2  and the host on the basis of the instruction given by the memory card control section  12 . 
   The memory card control section  12  has a general-purpose memory card control program  121  which prescribes the control procedure, one of the standard specifications of the memory card  2 . The general-purpose memory card control program  121  is applied to the memory card control section  12  in the initial state. The profile information storage section  14 , which is composed of, for example, a nonvolatile memory, holds a plurality of memory card control programs meeting separate specifications each of which prescribes the control procedure suitable for the characteristic of a specific memory card  2 . That is, the specification of, for example, a card interface controller  22  in the memory card  2  differs from manufacturer to manufacturer, with the result that the access procedure for a flash memory  23  differs from manufacturer to manufacturer. Since there are various actual block sizes of the flash memory  23 , it is necessary to hold a plurality of memory card control programs  121  complying with the specifications determined by individual manufacturers. 
     FIG. 2  shows an example of the memory card control program  121  held in the profile information storage section  14 . In this example, two types of memory card control programs compatible with Company A&#39;s products and three types of memory card control programs compatible with Company B&#39;s products, that is, a total of five types of memory card programs  121 , are held in the profile information storage section  14 . In addition, data corresponding to the actual block size of the flash memory are held so as to correspond to the respective memory card control programs. That is, the host  1  is set so as to be capable of maximizing the performance of each of the five types of memory cards manufactured by Company A and Company B, according to the memory card control programs held in the profile information storage section  14 . This will be explained later. 
   The memory card  2  includes a memory card interface  21 , a card interface controller  22 , and a flash memory  23 . 
   The memory card interface  21  controls the transmission and reception of commands and data between the memory card  2  and the host memory card interface  13  of the host  1 . In response to the command received from the host  1  via the memory card interface  21 , the card interface controller  22  accesses the flash memory  23  and returns the result to the host  1  via the memory card interface  21 . 
   The flash memory  23 , which is composed of, for example, NAND EEPROM cells, is a storage medium which stores various contents, including still images, moving images, and music. In the flash memory  23 , a profile ID  231  is stored. The profile ID  231  is composed of, for example, a type number which enables the type of the memory card  2  to be identified. The profile ID  231  is stored in, for example, a Vendor Unique information description area all of the memory cards have. The profile ID  231  has been caused to correspond to the program number of the memory card control program  121  held in the profile information storage section  14  of  FIG. 2 . 
   In the host  1  and memory card  2  configured as described above, the memory card  2  is installed in the host  1  whose power supply is on or the power supply of the host  1  is turned on, with the memory card  2  installed in the host. Then, in the host  1 , the CPU  11  detects the installation of the memory card  2  and initializes the memory card  2  to make the card  2  readable and writable. 
   After the memory card  2  has been initialized, the CPU  11  instructs the memory card control section  12  to acquire the profile ID  231  from the memory card  2 . Receiving the instruction, the memory card control section  12  issues a command group for reading the profile ID  231  to the memory card  2 . Command group issuing control at that time is performed by the general-purpose memory card control program  121  applied in the initial state. 
   The command group issued from the memory card control section  12  is transferred via the host memory card interface  13  and memory card interface  21  to the card interface controller  22  of the memory card  2 . According to the command, the card interface controller  22  reads the profile ID  231  from the flash memory  23 . The read-out profile ID  231  is transferred via the memory card interface  21  to the host  1 . In the host  1 , the profile ID  231  is transferred from the memory card control section  12  to the CPU  11 . 
   The CPU  11  acquires the memory card control program  121  with the program number caused to correspond to the received profile ID  231  from the profile information storage section  14  and transfers the control program  121  to the memory card control section  12 . The memory card control section  12  resets the operating environment so as to use the memory card control program  121  transferred from the CPU  11  in place of the general-purpose control program  121  applied in the initial state. From this time on, the memory card control section  12  issues a command group on the basis of the reset memory card control program  121 . 
   When a memory card  2  other than the five types of memory cards manufactured by Company A and Company B has been installed, that is, when a specified profile ID  231  has not been acquired or when the memory card control program  121  with the program number caused to correspond to the acquired program file ID  231  does not exist in the profile information section  14 , the CPU  11  continues holding the general-purpose memory card control program  121  applied in the initial state and the memory card control section  12  does not reset the operating environment. 
   As described above, the memory card control program  121  corresponding to the memory card  2  installed in the host  1  enables the memory card section  12  to be controlled. Next, a concrete example of the specifications of the memory card  2  considered in each of the memory card control programs  121  will be explained. 
   (1) Actual Block Size (Block Boundary) of the Flash Memory  23   
   The actual block size (boundary) of the memory card might differ from the value in the specifications, depending on the capacity of the flash memory  23 , the performance of the card interface controller  22 , or the like. Therefore, if the control procedure making no account of the actual block size is applied in all cases, the performance of the memory card  2  might be impaired seriously. 
   Suppose a memory card  2  whose actual block size is 128 kilobytes has been installed, although the value of the block size in the specifications is 16 kilobytes. Consider a case where two sets of about 70 kilobytes of data (data  1  and data  2 ) are written into the memory card  2 .  FIG. 3A  shows a case where two data items are written when the block size is 16 kilobytes, the value in the specifications.  FIG. 3B  shows an example of writing two data items, taking the actual block size (128 kilobytes) into account. 
   When the block size has been recognized as 16 kilobytes, the value in the specifications, it is the most common for the memory card control section  12  of the host  1  to write first data  1  using five blocks from the begin block and thereafter write second data  2  using five blocks from the sixth block. In this case, however, the second data is actually written to extend over the end of the begin block and the beginning of the second block. When viewed from the card interface controller  22  of the memory card  2 , it is difficult to say that suitable control is performed. 
   In contrast, when the block size has been recognized as 128 kilobytes, the actual size, the memory card control section  12  of the host  1  tries to write the first data  1  into the begin block and then write the second data  2  into the second block as shown in  FIG. 3B . In this case, since data writing is done as required, the card interface controller  22  of the memory card  2  is not forced to do overhead work. 
   Overhead work will be explained more specifically. In the procedure shown in  FIG. 3A , when a request to write data  2  is made, the first block composed of eight blocks including five blocks in which data  1  has been stored is read temporarily. The first half of data  2  is stored in the three blocks of them. Thereafter, the first block is written back. This work is originally unnecessary work and therefore overhead work. After the overhead work is finished, the second half of data  2  is written into the relevant part of the second block. In this way, the performance of the memory card  2  deteriorates seriously. 
   To overcome this problem, each of the memory card control programs  121  executes the control procedure taking into account the actual block size (block boundary) of the corresponding memory card  2 , thereby maximizing the performance of the memory card  2 . 
   (2) the Characteristic of the Card Interface Controller  22  for Write Commands 
   The memory card  2  generally has a card interface controller  22  capable of accepting two data write commands, “single write” and “multi-write”, supplied from the host  1 . However, if a write command is applied, taking no account of the characteristic of the card interface controller  22 , the performance of the memory card  2  can be impaired seriously. 
   A single write is a command to write one sector of data in one command. A multi-write is a command to write n sectors of data consecutively in one command. Referring to  FIGS. 4A to 4C  and  FIGS. 5A to 5C , two approaches of processing a single write used in the card interface controller  22  will be explained. 
   First, referring to  FIGS. 4A to 4C , a first single write processing approach will be explained. One sector is assumed to contain 0.5 kilobytes. Consider a case where a block (block A) is overwritten with 1.5 kilobytes, that is, three sectors of data, in a single write. In  FIGS. 4A to 4C , the shaded region represents the part to be written into and all of the remaining part represent the part not to be written into. 
   As shown in  FIG. 4A , when a first single write command is received, a first one sector of data is written into a sector of block B corresponding to a sector to be written into of block A. At the same time, all of the data in the sectors not to be written into in block A are copied into block B. That is, a state where one sector of data is overwritten with block A is produced in block B. Thereafter, block A is deleted. Then, as shown in  FIG. 4B , when a second single write command is received, a state where the next one sector of data is overwritten with block B is produced in block C. Thereafter, block B is deleted. Then, as shown in  FIG. 4C , when a third single write command is received, a state where the next one sector of data is overwritten with block C is produced in block D. Thereafter, block C is deleted. As described above, in the first processing approach, when three sectors of data are written over a block, the block is moved and the data is copied and deleted each time a command is received. 
   Next, referring to  FIGS. 5A to 5C , a second single write processing approach will be explained. In this case, too, one sector is assumed to contain 0.5 kilobytes. Explanation will be given about a case where 1.5 kilobytes, or three sectors of data, are written into a block (block A) in a single write. 
   As shown in  FIG. 5A , when a first single write command is received, the first one sector of data is written into block B. As long as data is being written into consecutive locations, the block is not moved. As shown in  FIGS. 5B and 5C , a second single write command and a third single write command are executed consecutively. The sector to be written into this time in block B and the sector not to be written into in block A are correlated to each other so that these two blocks may function as a single block. One virtual block composed of these two blocks is moved at a time when the block is written into a location discontinuous with the block. As described above, in the second single write processing approach, when three sectors of data are written over a block, the moving (copying and erasing) of the block is not performed. 
   From what has been described above, it is seen that it is undesirable for the memory control program  121  corresponding to the memory card  2  to write data using “single write” when the card interface controller  22  of the memory card  2  uses the first processing approach in “single write.” 
     FIGS. 6A to 6C  show a general approach of processing “multi-write” in the card interface controller  22  of the memory card  2  using the first processing approach in “single write.” In this case, too, one sector is assumed to contain 0.5 kilobytes. Explanation will be given about a case where 1.5 kilobytes, or three sectors of data, are written over a block (block A) in a multi-write. 
   As shown in  FIGS. 6A to 6C , in the case of a multi-write command, all of three sectors of data are written into block B consecutively and then the data in the sectors not to be written into in block A are copied into block B. As a result, a state where three sectors of data have been written over with block A is produced in block B. This makes the block move only once. That is, it is seen that it is desirable that the memory card control program  121  corresponding to the memory card  2  should write data using “multi-write.” 
   Even when receiving a multi-write command under the same conditions, the card interface controller  22  of the memory card  2  using the second processing approach in “single write” generally carries out the same operation as when receiving a single-write command. Specifically, the memory card control program  121  corresponding to the memory card  2  issues a multi-light command, when receiving a multi-write command. In this case, the memory card control program  121  performs complex control, for example, buffering data and writing the buffered data into consecutive locations. However, such control is useless. Therefore, from the viewpoint of load reduction, it is desirable that memory card control  121  corresponding to the memory card  2  use “single write” when receiving a multi-write command. 
   As described above, the control procedure taking into account the characteristic for write commands of the corresponding memory card  2  is determined in each of the memory card control programs  121 , which makes it possible to maximize the performance of the memory card  2 . 
   That is, since the host  1  of the embodiment takes into account the characteristics for the actual block size and write commands in the memory card control program  121  corresponding to each of the five types of memory cards  2  manufactured by Company A and Company B, the performance of each of the memory cards  2  can be maximized. 
     FIG. 7  is a flowchart to explain the operating procedure for memory card control in the host of the embodiment. 
   When the memory card  2  is installed, with its power supply on, or when the power supply is turned on, with the memory card  2  installed, the CPU  11  detects that the memory card  2  has been installed in the host  1 . When detecting the installation of the memory card  2 , the CPU  11  executes an initializing process to make the memory card  2  readable and writable (step A 1 ). Thereafter, the CPU  11  instructs the memory card control section  12  to acquire the profile ID  231  (step A 2 ). 
   When having acquired the profile ID  231  from the memory card  2  (YES in step A 3 ), the CPU  11  searches the profile information storage section  14  for the memory card control program  121  corresponding to the profile ID  231  (step A 4 ). As a result, if the profile information storage section  14  holds the memory card control program  121  corresponding to the profile ID  231  (YES in step A 5 ), the CPU  11  transfers the card control program  121  to the memory card control section  12 , which, from this time on, uses the memory card control program  121  in accessing the memory card  2  (step A 6 ). 
   On the other hand, if the profile ID  231  has not been acquired in step A 3 , or if the profile information storage section  14  does not hold the memory card control program  121  corresponding to the profile ID  231  in step A 5 , the CPU  11  instructs the memory card control section  12  to apply the general-purpose memory card control program  121  (step A 7 ). If the general-purpose memory card control program  121  has been applied in, for example, the initial state at the time of turning on the power supply, the memory card control section  12  keeps the present state in step A 7 . On the other hand, if the memory card control program  121  complying with any one of the individual specifications has been applied, the operating circumstance of the memory card control section  12  is returned to the initial state to apply the general-purpose memory card control program  121  instead of the present one. 
   In the host  1  of the embodiment, the profile information storage section  14  holds the memory card control program  121  corresponding to each of the memory cards  2 . The profile ID  231  is acquired from the installed memory card  2 , thereby selecting the corresponding one of the memory card control programs  121 . The memory card control program  121  is then set in the memory card control section  12 . This makes it possible to perform data input/output control suitable for each of the memory card specifications, which enables the performance of the memory card to be maximized. 
   In the embodiment, the host  1  has the profile information storage section  14  and causes the profile information storage section  14  to hold the memory card control program  121  corresponding to each of the memory cards  2 . However, as shown in  FIG. 8 , the host  1  does not necessarily have the profile information storage section  14 . For instance, the host  1  may have only the function of acquiring the corresponding memory card control program  121  and resetting the program and take in a desired one of the various memory card control programs  121  stored on an optical disk, such as CD-ROM, or another storage medium  41 . With this configuration, the memory card control program  121  stored in the storage medium  41  can be updated easily. For example, it is possible to cope easily with a change in the specifications of the memory card  2 . 
   Furthermore, for example, as shown in  FIG. 8 , a network interface  15  to communicate with a server  3  via a network may be provided in the host  1 , a profile information storage section  31  may be provided in the server  3  at a remote location, and the memory card control program  121  may be downloaded from the server  3  via the network interface  15  as needed. With this configuration, the profile information storage section  31  of the server  3  can be shared by a plurality of hosts  1 . 
   Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiment shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.