Abstract:
A portable storage apparatus capable of freely changing a data bus width and a method of setting the data bus width of the apparatus are provided, where the portable storage apparatus has at least one command line and a plurality of data lines, and includes a non-volatile memory, a command packet decoder, and a control unit, such that the non-volatile memory stores data, the command packet decoder receives command packets through a command line and outputs command information by decoding the received command packets, the command packet decoder receives a data transmit command packet or a data request command packet and outputs a write command or a read command, address information, and data bus width information, the control unit performs a control operation in response to the command information and selects all or some of the plurality of data lines in response to the data bus width information and receives or transmits the data through the selected data line, and controls data writing or reading of the non-volatile memory in response to the write command or the read command and the address information, thereby not requiring the data bus width to be set in advance and enabling free adjustment of the data bus width, if necessary.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims foreign priority under 35 U.S.C. § 119 to Korean Patent Application No. 2003-40482, filed on Jun. 21, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present disclosure relates to a portable storage apparatus and method, and more particularly, to a portable storage apparatus and method for changing a data bus width. 
   2. Description of the Related Art 
   Generally, a portable storage apparatus is used in a digital apparatus, such as in a camcorder, a digital camera, a personal digital assistant (PDA), an MPEG-1 Layer 3 (MP3) player, and the like. A portable storage apparatus typically includes a MultiMediaCard (MMC), secure digital (SD) memory card, CompactFlash (CF) Card, memory stick, or other storage media. An example of a conventional memory card is disclosed in U.S. Pat. No. 6,446,163. 
   A portable storage apparatus has multiple data bus widths. The data bus width in the portable storage apparatus is changed in accordance with a current host to which the apparatus is connected in order to accommodate data communications for hosts having different data bus widths. Thus, a conventional portable storage apparatus includes a predetermined register in which data bus width information is stored. The data bus width in the portable storage apparatus is preset by the host when the portable storage apparatus is connected to the host. Such a conventional portable storage apparatus will be explained with reference to  FIG. 1 . 
     FIG. 1  is a block diagram illustrating a conventional portable storage apparatus in signal communication with a host. As shown in  FIG. 1 , a portable storage apparatus  2  includes a command pin P 1  for receiving a command packet, electric power source pins P 2  and P 3 , a clock signaling pin P 4 , and a plurality of data pins D 1  through DN. The command pin P 1 , the electric power source pins P 2  and P 3 , the clock signaling path P 4 , and the plurality of data pins D 1  through DN are respectively connected to a host  1 . In addition, the portable storage apparatus  2  further includes a command packet decoder  30 , a control unit  40 , a first register  50 , a flash memory  60 , a data buffer  70 , and a second register  80 . The command packet decoder  30  includes a packet receiving unit  31 , a command field decoder  32 , and an argument field decoder  33 . The packet receiving unit  31  is connected to the command pin P 1  through a command line  10 , and the control unit  40  is connected to the data buffer  70  through a plurality of data lines  20 . 
   A process of setting a data bus width in the portable storage apparatus  2  having the above structure will be explained. If the portable storage apparatus  2  is connected to the host  1 , the host  1  transmits a command packet CMD_PK for setting the data bus width. The packet receiving unit  31  of the command packet decoder  30  receives a command packet CMD_PK through the command line  10  and divides the received command packet CMD_PK into a command field CMD_FD and an argument field ARG_FD. The command field decoder  32  outputs command information CMD_IF by decoding the command field CMD_FD. The argument field decoder  33  outputs data bus width information BUS_IF by decoding the argument field ARG_FD. The control unit  40  receives the command information CMD_IF and recognizes this information as a command for setting the data bus width. Furthermore, the control unit  40  receives the data bus width information BUS_IF and stores it at a first register  50 . Thereafter, the control unit  40  transmits and receives data by selecting all or some of the plurality of data lines  20 , based on the data bus width information BUS_IF. Moreover, the command field decoder  32  outputs a write or a read command by decoding the command field CMD_FD when transmitting and receiving general data. The argument field decoder  33  outputs an address signal by decoding the argument field ARG_FD when transmitting and receiving the general data. 
   Therefore, the data bus width is set before any data bus communication with the host in the conventional portable storage apparatus. This conventional method is only useful for a case where there is no need to change the data bus width for a long period of time, that is, when the portable storage apparatus is connected to only one host. However, if the data bus width is required to change frequently, such as when the portable storage apparatus is connected to several hosts, the data bus width is reset in advance whenever the host is changed. Accordingly, the host must separately transmit the command packet for setting the data bus width in advance, and furthermore, the data bus width is reset whenever the host is changed in the conventional portable storage apparatus. 
   SUMMARY OF THE INVENTION 
   These and other drawbacks and disadvantages of the prior art are addressed by a portable storage apparatus capable of freely changing a data bus width, and a method of setting the data bus width. 
   According to an aspect of the present disclosure, there is provided a portable storage apparatus having at least one command line and a plurality of data lines, the apparatus comprising at least one non-volatile memory storing data; a command packet decoder for receiving command packets through the command line and outputting command information by decoding the command packets; and a control unit for performing control operations in response to the command information, wherein the command packet decoder receives one of a data transmit command packet and a data request command packet and outputs one of a write command and a read command, address information, and data bus width information, and wherein the control unit selects all or some of the plurality of data lines in response to the data bus width information and receives or transmits the data through the selected data line, and controls data writing or reading of the non-volatile memory in response to the write command or the read command and the address information. 
   According to another aspect of the present disclosure, there is provided a method of setting a data bus width in a portable storage apparatus including a command line and a plurality of data lines for connecting to a host, the method comprising: (a) connecting the portable storage apparatus to the host; (b) receiving from the host a command packet comprising at least one of a data transmit command packet and a data request command packet, including the data bus width information; (c) dividing the received command packet into a command field and an argument field; (d) outputting the data bus width information by decoding the argument field; (e) selecting at least one the plurality of data lines in response to the data bus width information, and passing data through the selected at least one data line selected; and (f) returning to step (c) if an additional data transmit command packet or data request command packet is received. 
   According to yet another aspect of the present disclosure, there is provided a method of setting a data bus width in a portable storage apparatus including a command line and a plurality of data lines for connecting to a host, the method comprising: (a) connecting the portable storage apparatus to the host; (b) receiving from the host a command packet comprising at least one of a data transmit command packet and a data request command packet, including the data bus width information from the host; (c) dividing the received command packet into a command field and an argument field; (d) outputting the data bus width information by decoding the command field; (e) selecting at least one of the plurality of data lines in response to the data bus width information, and passing data through the selected at least one data line; and (f) returning to step (c) if an additional data transmit command packet or data request command packet is received. 
   These and other aspects, features and advantages of the present disclosure will become apparent from the following description of exemplary embodiments, which is to be read in connection with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other features and advantages of the present disclosure will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which: 
       FIG. 1  is a block diagram illustrating a portable storage apparatus and a host according to the prior art; 
       FIG. 2  is a block diagram illustrating a portable storage apparatus capable of freely changing a data bus width according to a first embodiment of the present disclosure; 
       FIG. 3A  is a schematic diagram illustrating an example of a data transmit command packet, which a host shown in  FIG. 2  sends to a portable storage apparatus; 
       FIG. 3B  is a schematic diagram illustrating an argument field shown in  FIG. 3A  in further detail; 
       FIG. 4  is a flow chart illustrating a process of setting a data bus width in a portable storage apparatus shown in  FIG. 2 ; 
       FIG. 5  is a block diagram illustrating a portable storage apparatus capable of freely changing a data bus width according to a second embodiment of the present disclosure; 
       FIGS. 6A through 6C  are schematic diagram examples of a command field included in a data transmit command packet and a data request command packet which a host shown in  FIG. 5  sends to a portable storage apparatus; and 
       FIG. 7  is a flow chart illustrating a process of setting a data bus width in a portable storage apparatus shown in  FIG. 5 . 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   The present disclosure will now be described more fully with reference to the attached drawings, in which exemplary embodiments thereof are shown. This disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concept of the disclosure to those skilled in the art. In the drawings, the forms of elements may be exaggerated for clarity. To facilitate understanding, like reference numerals have been used, where possible, to designate like elements throughout the figures. 
     FIG. 2  is a block diagram illustrating a portable storage apparatus capable of freely changing a data bus width according to a first exemplary embodiment of the present disclosure. Referring to  FIG. 2 , a portable storage apparatus  200  is in signal communication with a host  100 . The portable storage apparatus  200  includes a command line  210 , a data line  220 , a command packet decoder  230 , a control unit  240 , a flash memory  250 , a data buffer  260 , and a data register  270 . In addition, the portable storage apparatus  200  further includes a command pin P 1 , electric power source pins P 2  and P 3 , a clock pin P 4 , and a plurality of data pins D 1  through DN (where N is a natural number greater than 1). The command line  210  is connected to the command pin P 1 . 
   The command packet decoder  230  includes a packet receiving unit  231 , a command field decoder  232 , and an argument and bus information decoder  233 . The packet receiving unit  231  receives a data transmit command packet CMD_PK 1  or a data request command packet CMD_PK 2  from a host  100  through the command line  210 , and divides it into a command field CMD_FD and an argument field ARG_FD. The command field decoder  232  outputs a read command READ or a write command WRITE by decoding the command field CMD_FD. The argument and bus information decoder  233  outputs address information ADD and data bus width information BUS_IF by decoding the argument field ARG_FD. Although it is not illustrated in  FIG. 2 , the command packet decoder  230  further receives various command packets other than the data transmit command packet CMD_PK 1  and the data request command packet CMD_PK 2  from the host  100 . The command packet decoder  230  outputs command information by decoding the various received command packets. 
   An example of the data transmit command packet is shown in  FIG. 3A .  FIG. 3A  is a schematic diagram illustrating an example of a data transmit command packet, which a host  100  sends to a portable storage apparatus  200 . 
   The data transmit command packet includes a command field CMD, argument fields ARG 1  through ARG 4 , and a cyclic redundancy checking (CRC) field as shown in  FIG. 3A . The command field CMD and the argument fields ARG 1  through ARG 4  include predetermined bits. 
   The respective argument fields ARG 1  through ARG 4  can be formed of eight bits from B 7  to B 0 . In this case, the argument fields ARG 1  through ARG 4  become 32 bits in total. Some bits among the 32 bit argument fields ARG 1  through ARG 4  indicate the data bus width information BUS_IF. For instance, among the argument fields ARG 1  through ARG 4 , the argument field ARG 1  may include the data bus width information BUS_IF. A more detailed explanation will follow. 
   The two most significant bits B 7  and B 6  among the bits B 7  through B 0  of the argument field ARG 1  are assumed to indicate the data bus width information BUS_IF and the portable storage apparatus  200  is assumed to have the maximum eight bit data bus width. In a case where values of the two most significant bits B 7  and B 6  are “00,” “01,” “10,” they can respectively indicate one bit, four bits, and eight bits data bus width. The number of predetermined bits representing the data bus width information BUS_IF, if necessary, can be increased or decreased. Although, the most significant bits B 7  and B 6  are shown to represent the data bus width information BUS_IF in  FIG. 3B , some of the bits B 5  through B 0  may represent the data bus width information BUS_IF. In addition, the argument field ARG 1  is shown to include the data bus width information BUS_IF in  FIG. 3B , however, one of the argument fields ARG 2  through ARG 4  may include the data bus width information BUS_IF. 
   Furthermore, the maximum data bus width in the portable storage apparatus  200  can be increased or decreased if necessary, the data bus width information BUS_IF can indicate the data bus width in the various bits. 
   Referring back to  FIG. 2 , the control unit  240  is connected to the data buffer  260  via the data line  220 . The data line  220  includes a plurality of data lines DL 1  through DLN (N is a natural number more than 1). 
   The control unit  240  selects parts or all of the plurality of data lines DL 1  through DLN and transmits or receives data via the selected data lines, in response to the data bus width information BUS_IF. 
   The control unit  240  stores data received from the host  100  in a flash memory  250  or reads the data requested by the host  100  from the flash memory  250 . 
   The data buffer  260  is connected to the control unit  240  through the plurality of data pins DL 1  through DLN. Also, the data buffer  260  is connected to the data register  270  connected to the plurality of data pins D 1  through DN. The data buffer  260  receives read data from the control unit  240  through the selected data line and outputs the read data to the data register  270 . The data register  270  transmits the read data to the host  100  through all or some of the plurality of data pins D 1  through DN. 
   Moreover, the data register  270  receives write data from the host  100  through all or some of the plurality of data pins D 1  through DN and outputs the write data to the data buffer  260 . The data buffer  260  outputs the write data through the selected data line to the control unit  240 . 
   Operations of setting the data bus width in the portable storage apparatus  200  having the above structure will be explained with reference to  FIGS. 2 through 4 .  FIG. 4  is a flow chart illustrating an exemplary process of setting a data bus width in a portable storage apparatus shown in  FIG. 2 . 
   Referring to  FIG. 4 , the portable storage apparatus  200  is connected to the host  100  in step  1001 . The host  100  transmits the data transmit command packet CMD_PK 1  or the data request command packet CMD_PK 2  including the data bus width information BUS_IF to the portable storage apparatus  200 . The packet receiving unit  231  of the command packet decoder  230  in the portable storage apparatus  200  receives the data transmit command packet CMD_PK 1  or the data request command packet CMD_PK 2  through the command line  210  in step  1002 . Thereafter, the packet receiving unit  231  divides the received data transmit command packet CMD_PK 1  or the data request command packet CMD_PK 2  into a command field CMD_FD and an argument field ARG_FD in step  1003 . 
   The command field decoder  232  of the command packet decoder  230  outputs the write command WRITE or the read command READ by decoding the command field CMD_FD. The argument and bus information decoder  233  of the command packet decoder  230  outputs the data bus width information BUS_IF and the address information ADD by decoding the argument field ARG_FD in step  1004 . 
   In response to the data bus width information BUS_IF, the control unit  240  of the portable storage apparatus  200  selects all or some of the plurality of data lines DL 1  through DLN in step  1005 . Then, the control unit  240  receives or transmits data through the selected data lines in step  1006 . Finally, it is decided whether an additional data transmit or request command packet CMD_PK 1  or CMD_PK 2  is to be received in step  1007 , and returns to step  1003  if there is one of these command packets in step  1008 . 
     FIG. 5  is a block diagram illustrating a portable storage apparatus capable of freely changing a data bus width according to a second embodiment of the present disclosure. 
   Referring to  FIG. 5 , a portable storage apparatus  400  is in signal communication with a host  300 . The portable storage apparatus  400  includes a command line  410 , a data line  420 , a command packet decoder  430 , a control unit  440 , a flash memory  450 , a data buffer  460 , and a data register  470 . Furthermore, the portable storage apparatus  400  further includes a command pin P 1 , electric power source pins P 2  and P 3 , a clock pin P 4 , and a plurality of data pins D 1  through DN (where N is a natural number greater than 1). The command line  410  is connected to the command pin P 1 . 
   The command packet decoder  430  includes a packet receiving unit  431 , a command and bus information decoder  432 , and an argument field decoder  433 . The packet receiving unit  431  receives a data transmit command packet CMD_PK 1  or a data request command packet CMD_PK 2  from a host  300  through the command line  410 , and divides the received packet into a command field CMD_FD and an argument field ARG_FD. The command and bus information decoder  432  outputs a read command READ or a write command WRITE and information on a data bus width BUS_IF by decoding the command field CMD_FD. The argument field decoder  433  outputs address information ADD by decoding the argument field ARG_FD. 
   Although it is not illustrated in  FIG. 5 , the command packet decoder  430  further receives various command packets other than the data transmit command packet CMD_PK 1  and the data request command packet CMD_PK 2  from the host  300 . The command packet decoder  430  outputs command information by decoding the various received command packets. 
   In the meantime, an example of the command field of the data transmit command packet CMD_PK 1  and of the data request command packet CMD_PK 2  which the host  300  transmits to the portable storage apparatus  400  is illustrated in  FIGS. 6A through 6C . 
     FIG. 6A  represents an example of the command field of the data transmit command packet CMD_PK 1 . The command field of the data transmit command packet CMD_PK 1  includes predetermined bits as shown in  FIG. 6A . The command field is illustrated to have 8 bits from B 7  to B 0 . However, the number of bits of the command field can be increased or decreased, if necessary. Some of the bits of command field B 7  through B 0  indicate the data bus width information BUS_IF. That is, for example, the least significant bits B 1  and B 0  out of the bits B 7  through B 0  can indicate the data bus width information BUS_IF. Also, the bits B 7  and B 6  indicate start information START and the bits B 5  through B 2  indicate a write command WRITE. 
   The exemplary portable storage apparatus  400  is assumed to have a maximum eight bit data bus width. In this case, if the two least significant bits B 1  and B 0  are “00,” “01,” and “10,” said values respectively indicate a one bit, four bit, and eight bit data bus width. The number of bits representing the data bus width information BUS_IF can be increased or decreased, if necessary. 
   Moreover, the maximum data bus width of the portable storage apparatus  400  can be increased or decreased, if necessary, and the data bus width information BUS_IF can indicate the data bus width in various bits. 
     FIG. 6B  illustrates an example of the command field of the data request command packet CMD_PK 2 . Referring to  FIG. 6B , the command field of the data request command packet CMD_PK 2  includes predetermined bits. Composition of the command field shown in  FIG. 6B  is identical with that of the command field shown in  FIG. 6A , and thus, a detailed explanation will be omitted. The only difference is that bits B 5  through B 2  of the command field shown in  FIG. 6B  represent a read command READ. 
   In addition,  FIG. 6C  illustrates another example of the command field. The command field includes predetermined bits and eight bits from B 7  to B 0  in  FIG. 6C . The number of bits of the command field can be increased or decreased, if necessary. The bits B 7  and B 6  of the command field indicate the start information START, and the bits B 5  through B 0  indicate the write command WRITE or the read command READ including the data bus width information BUS_IF. A more detailed explanation will follow. 
   First, the portable storage apparatus  400  is assumed to have a maximum eight bit data bus width, and the bits B 5  through B 4  are assumed to indicate the write command WRITE if the bits have a value of ‘01’. 
   In this case, if the value of the bits B 5  through B 0  is ‘010001,’ said value can indicate the write command WRITE and a one bit data bus width. In addition, if the value of the bits B 5  through B 0  is ‘010010,’ said value can indicate the write command WRITE and a two bit data bus width. Also, if the value of the bits B 5  through B 0  is ‘011000,’ said value can indicate the write command WRITE and an eight bit data bus width. Thus, the write command WRITE or the read command READ and the data bus width can be expressed by using specific command codes. 
   In addition, the maximum data bus width in the portable storage apparatus  400  can be increased or decreased, if necessary, and the data bus width information can indicate the data bus width in various bits. 
   Referring back to  FIG. 5 , the control unit  440  is connected to the data buffer  460  through the data line  420 . The data line  420  includes a plurality of data lines DL 1  through DLN. 
   The control unit  440  selects all or some of the plurality of data lines DL 1  through DLN, and transmits or receives the data through the selected data line, in response to the data bus width information BUS_IF. 
   The control unit  440  stores data received from the host  300  in a flash memory  450  or reads the data requested by the host  300  from the flash memory  450 . 
   The data buffer  460  is connected to the control unit  440  through a plurality of data lines DL 1  through DLN. In addition, the data buffer  460  is connected to the data register  470  and the data register  470  is connected to the plurality of data pins D 1  through DN. The data buffer  460  receives read data from the control unit  440  through a selected data line and outputs the read data to the data register  470 . The data register  470  transmits the read data to the host  300  through all or some of the plurality of data pins D 1  through DN. 
   Moreover, the data register  470  receives write data from the host  300  through all or some of the plurality of data pins D 1  through DN and outputs the write data to the data buffer  460 . The data buffer  460  outputs the write data through the selected data line to the control unit  440 . 
   Operations of setting the data bus width in the portable storage apparatus  400  having the above structure will be explained with reference to  FIGS. 5 through 7 .  FIG. 7  is a flow chart illustrating a process of setting a data bus width in a portable storage apparatus shown in  FIG. 5 . 
   Referring to  FIG. 7 , the portable storage apparatus  400  is connected to the host  300  in a step  2001 . The host  300  transmits the data transmit command packet CMD_PK 1  or the data request command packet CMD_PK 2  including the data bus width information BUS_IF to the portable storage apparatus  400 . The packet receiving unit  431  of the command packet decoder  430  in the portable storage apparatus  400  receives the data transmit command packet CMD_PK 1  or the data request command packet CMD_PK 2  through the command line  410  in step  2002 . Thereafter, the packet receiving unit  431  divides the data transmit command packet CMD_PK 1  or the data request command packet CMD_PK 2  received into a command field CMD_FD and an argument field ARG_FD in step  2003 . 
   The command and bus information decoder  432  of the command packet decoder  430  outputs the write command WRITE or the read command READ and the data bus width information BUS_IF by decoding the command field CMD_FD in step  2004 . The argument field decoder  433  of the command packet decoder  430  outputs the address information ADD by decoding the argument field ARG_FD. 
   The control unit  440  of the portable storage apparatus  400  selects all or some of the plurality of data lines DL 1  through DLN in response to the data bus width information BUS_IF in step  2005 . Then, the control unit  440  receives or transmits data through the selected data lines in step  2006 . Finally, it is decided whether an additional data transmit or request command packet CMD_PK 1  or CMD_PK 2  is to be received in step  2007  and receives the additional data transmit command packet CMD_PK 1  or the data request command packet CMD_PK 2 , and two process returns to the step  2003  if one of the command packets exists in step  2008 . 
   Accordingly, the portable storage apparatus according to the present disclosure does not require a process of setting the data bus width in advance, since the data bus width information is received from the host when data is received or transmitted. In addition, the data bus width can be adjusted freely in the portable storage apparatus according to the present disclosure, because the data bus width is not required to be set in advance. 
   While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the pertinent art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.