Patent Publication Number: US-2010125689-A1

Title: Electronic apparatus capable of receiving different types of memory cards

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to memory cards, and more particularly to memory stick cards and secure digital cards. 
     2. Description of the Related Art 
     Flash memory cards can store large amounts of data without the requirement of an external power supply to maintain the data. In addition, flash memory cards meet size requirements of portable devices due to its smaller size. Flash memory cards are therefore popular with manufactures of digital portable devices such as digital cameras, handheld computers, mobile telephones, music players, and portable memory drives. 
     Although there are several types of flash memory cards which are fabricated, the memory stick (MS) cards and secure digital (SD) cards are currently the most popular. Meanwhile, some electronic devices storing data with flash memory cards, are capable of accessing more than one type of memory card for user convenience. In addition, a card reader must access different types of memory cards for a host device. The electronic devices capable of accessing different types of memory cards must therefore, first identify the type of the memory card, before the memory cards are accessed. 
     Referring to  FIG. 2 , a block diagram of a portion of a conventional electronic apparatus  200  accessing different types of memory cards are shown. The electronic apparatus  200  comprises a memory card  202 , a socket  204 , an interface circuit  206 , and a controller IC  208 . The memory card  202  is inserted into the socket  204  to be accessed by the controller IC  208 . When the memory card is inserted into a slot of the socket  204 , a plurality of pins of the socket  204  are coupled to the memory card  202  to receive different signals exchanged between the memory card  202  and the controller IC  208 . The memory card  202  may be a secure digital card or a memory stick card. 
     Referring to  FIG. 1A , a table listing multiple signals exchanged between a secure digital card  202  and the controller IC  208  is shown. The multiple signals include a clock signal SD_CLK, a command signal SD_CMD, and four data signals SD_D 0 , SD_D 1 , SD_D 2 , and SD_D 3 . While the clock signal SD_CLK is only sent from the controller IC  208  to the secure digital card  202 , data of the other signals SD_CMD, SD_D 0 , SD_D 1 , SD_D 2 , and SD_D 3  are exchanged in both directions. 
     Referring to  FIG. 1B , a table listing multiple signals exchanged between a memory stick card  202  and the controller IC  208  is shown. The multiple signals include a clock signal MS_CLK, a bus state signal MS_BS, and four data signals MS_D 0 , MS_D 1 , MS_D 2 , and MS_D 3 . While the clock signal MS_CLK and MS_BS are only sent from the controller IC  208  to the memory stick card  202 , data of the other signals MS_D 0 , MS_D 1 , MS_D 2 , and MS_D 3  are exchanged in both directions. 
     After the socket  204  receives the signals with multiple pins, the signals must be transferred to a plurality of input/output (IO) pins of the controller IC  208 . The interface circuit  206  couples the pins of the socket  204  to the IO pins of the controller IC  208  with a plurality of signal lines, thus enabling the signals to be exchanged between the memory card  202  and the controller IC  208 . In addition, the voltages of the pins of the socket  204  must be kept at predetermined initial values before signals are exchanged between the memory card  202  and the controller IC  208  through the pins. If the memory card  202  is a memory stick card, the memory stick card lowers the voltages of the pins to an initial voltage of a ground level when the memory stick card  202  is inserted into the socket  204 . If the memory card  202  is a secure digital card, the interface circuit  206  raises the voltages of the pins to an initial voltage of a high level when the secure digital card  202  is inserted into the socket  204 . 
     Referring to  FIG. 3A , a block diagram of a portion of a conventional interface circuit  300  of the electronic apparatus  200  of  FIG. 2  is shown. The socket  204  receives signals listed in the table of  FIG. 1B  from a memory stick card  202  with corresponding pins MS_CLK, MS_BS, MS_D 0 , MS_D 1 , MS_D 2 , and MS_D 3 . The socket  204  also receives signals listed in the table of  FIG. 1A  from a secure digital card  202  with corresponding pins SD_CLK, SD_CMD, SD_D 0 , SD_D 1 , SD_D 2 , and SD_D 3 . The controller IC  208  receives signals from the memory card  202  with a plurality of IO pins IC_IO a , IC_IO b , IC_IO c , IC_IO d , IC_IO e , and IC_IO f . 
     The interface circuit  300  couples each of the IO pins of the controller IC  208  to one of the pins receiving a signal from the MS card and one of the pins receiving a signal from the SD card to reduce the required number of IO pins. For example, the MS_BS pin and the SD_CMD pin are coupled to the IC_IO a  pin, the MS_CLK pin and the SD_CLK pin are coupled to the IC_IO b  pin, and the MS_D 0  pin and the SD_D 0  pin are coupled to the IC_IO c  pin. 
     Two card insertion pins SD_INS and MS_INS of the socket  204  are used to respectively detect insertion of the secure digital card and the memory stick card. When the secure digital card or the memory stick card is inserted into the slot of the socket  204 , one of the voltages of the corresponding card insertion pins SD_INS and MS_INS is lowered to the ground. The interface circuit  300  comprises two modules  302  and  304  setting the voltages of the pins of the socket  204  to predetermined initial voltages. When a secure digital card is inserted, the voltage of the pin SD_INS is lowered to ground to turn on the transistor  312 , thereby raising the voltage of the node  306  to a high level V DD , wherein the node  306  is coupled to the pins of the socket  204 . When a memory stick card is inserted, the voltage of the pin MS_INS is lowered to ground to turn on the transistors  314  and  316 , thereby lowering the voltage of the node  308  to ground V GND , wherein the node  308  is coupled to the pins of the socket  204 . 
     Referring to  FIG. 3B , another portion  350  of the conventional interface circuit  300  of the electronic apparatus  200  of  FIG. 2  is shown. The circuit portion  350  comprises two diodes  352  and  354 . When the voltages of any one of the card insertion pins MS_INS and SD_INS are lowered, one of the diodes  352  and  354  is turned on, thereby lowering the voltage of a card detection pin IC_CD of the controller IC  208 . Referring to  FIG. 4 , a flowchart of a method  400  for card detection for the controller IC  208  is shown. The controller IC  208  first detects the voltage of the card detection pin IC_CD (step  402 ). If the voltage of the card detection pin IC_CD is at a low level (step  404 ), the controller IC  208  first sends SD card detecting commands to the memory card  202  to detect whether the memory card  202  is a secure digital card (step  406 ). If the memory card  202  is not a secure digital card (step  408 ), the controller IC  208  then sends MS card detecting commands to the memory card  202  to detect whether the memory card  202  is a memory stick card (step  410 ). 
     The interface circuit  300 , however, cannot directly determine whether the memory card  202  inserted into the socket  204  is a memory stick card or a secure digital card according to the voltage of the card detection pin IO_CD. The controller IC  208  therefore must send MS card detecting commands and SD card detecting commands in turns to determine the type of the memory card  202 . When a secure digital card  202  receives MS card detecting commands, the secure digital card may be confused by the MS card detecting commands, resulting in an error state for the secure digital card. When a MS card receives SD card detection commands, the MS card may be confused by the SD card detecting commands. In addition, the controller IC  208  requires an extra pin IO_CD for card detection, increasing the required number of IO pins of the controller IC  208 , thus increasing hardware costs. A novel interface circuit for coupling the socket  204  and the controller IC  208  is therefore required. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention provides an electronic apparatus capable of receiving a first-type memory card or a second-type memory card. In one embodiment, the electronic apparatus comprises a socket, a controller circuit, and an interface circuit. The socket is coupled to the first-type memory card through a set of first pins and is coupled to the second-type memory card with a set of second pins. The controller circuit accesses the first-type memory card or the second-type memory card via a plurality of input/output (IO) pins, and determines which of the first-type memory card and the second-type memory card is inserted into the socket according to the voltage of a target IO pin selected from the IO pins. The interface circuit coupled between the socket and the controller circuit has a plurality of signal lines connecting one of the IO pins to one of the first pins and one of the second pins and sets the voltage of the target pin to different values according to whether the first-type memory card or the second-type memory card is inserted into the socket. 
     The invention also provides an interface circuit, coupled between a socket and a controller circuit. In one embodiment, the socket is coupled to the memory stick card with a set of first pins when the memory stick card is inserted therein and is coupled to the secure digital card with a set of second pins when the secure digital card is inserted therein. The interface circuit comprises a plurality of signal lines and a card identification circuit. The signal lines connects one of a plurality of input/output (IO) pins of the controller circuit to one of the first pins and one of the second pins. The card identification circuit sets the voltage of a target signal line selected from the signal lines to different values according to whether the memory stick card or the secure digital card is inserted into the socket to enable the controller circuit to determine which of the memory stick card and the secure digital card is inserted into the socket according to the voltage of the IO pin coupled to the target signal line. 
     The invention also provides a method of accessing a first-type memory card and a second-type memory card. First, a socket capable of accepting the first-type memory card with a set of first pins or accepting the second-type memory card with a set of second pins is provided, wherein the socket lowers the voltage of a first-type card insertion pin when the first-type memory card exists in the socket. A controller circuit accessing the first-type memory card or the second-type memory card via a plurality of input/output (IO) pins provided. An interface circuit is then deployed between the controller circuit and the socket, wherein the interface circuit couples one of the IO pins to one of the first pins and one of the second pins, and raises the voltage of a signal line coupling to one of the IO pins when the voltage of the first-type card insertion pin is lowered to enable the controller circuit to determine which of the first-type memory card and the second-type memory card is inserted into the socket according to the voltage of the IO pin coupled to the signal line. 
     A detailed description is given in the following embodiments with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIG. 1A  shows a table listing multiple signals exchanged between a secure digital card and a controller IC; 
         FIG. 1B  shows a table listing multiple signals exchanged between a memory sick card and a controller IC; 
         FIG. 2  is a block diagram of a portion of a conventional electronic apparatus accessing different types of memory cards; 
         FIG. 3A  is a block diagram of a portion of a conventional interface circuit of the electronic apparatus of  FIG. 2 ; 
         FIG. 3B  shows another portion of the conventional interface circuit of the electronic apparatus of  FIG. 2 ; 
         FIG. 4  is a flowchart of a conventional method for card detection for the controller IC; 
         FIG. 5  is a block diagram of an electronic apparatus capable of receiving more than one type of memory card according to the invention; 
         FIG. 6A  shows an embodiment of an SD card interface circuit according to the invention; 
         FIG. 6B  shows an embodiment of an MS card interface circuit according to the invention; 
         FIG. 7A  shows an embodiment of the controller IC coupling circuit according to the invention; 
         FIG. 7B  shows an embodiment of a card identification circuit corresponding to the controller IC coupling circuit of  FIG. 7A  according to the invention; 
         FIG. 8A  shows another embodiment of a controller IC coupling circuit according to the invention; 
         FIG. 8B  shows an embodiment of a card identification circuit corresponding to the controller IC coupling circuit of  FIG. 8A  according to the invention; 
         FIG. 9  shows an embodiment of a card identification circuit according to the invention; and 
         FIG. 10  is a flowchart of a method for identifying the type of a memory card for the controller IC according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims. 
     Referring to  FIG. 5 , a block diagram of an electronic apparatus  500  capable of receiving more than one type of memory card according to the invention is shown. The electronic apparatus  500  comprises a socket  504 , an interface circuit  506 , and a controller IC  508 . A memory card  502  is inserted into the socket  504  to be accessed by the controller IC  508 . In one embodiment, the memory card  502  may be a memory stick (MS) card or a secure digital (SD) card. When the memory card  502  inserted into the socket  504  is a memory stick card, the socket  504  is coupled to the memory card  502  with a set of first pins including a clock pin MS_CLK, a bus state pin MS_BS, and four data pins MS_D 0 ˜MS_D 3 . When the memory card  502  inserted into the socket  504  is a secure digital card, the socket  504  is coupled to the memory card  502  with a set of second pins including a clock pin SD_CLK, a command pin SD_CMD, and four data pins SD_D 0 ˜SD_D 3 . In addition, the socket  504  lowers the voltage of an MS card insertion pin MS_INS when a memory stick card  502  is inserted therein, and the socket  504  lowers the voltage of an SD card insertion pin SD-INS when a secure digital card  502  is inserted therein. 
     The interface circuit  506  comprises an SD card interface circuit  512 , an MS card interface circuit  514 , a card identification circuit  516 , and a controller IC coupling circuit  518 . The SD card interface circuit  512  comprises a plurality of signal lines respectively coupled to the second pins. Referring to  FIG. 6A , an embodiment of an SD card interface circuit  612  according to the invention is shown. A secure digital card  602   a  is inserted into the socket  604 , and a plurality of signal lines of the SD card interface circuit  612  is coupled to the second pins of the socket  604  for transmitting signals SD_CLK, SD_CMD, SD_INS, and SD_DO SD_D 3 . In addition, the SD card interface circuit  612  raises the voltages of the second pins to an initial voltage of a high level V DD  when the secure digital card  602   a  is inserted into the socket  604 . 
     The MS card interface circuit  514  also comprises a plurality of signal lines respectively coupled to the first pins. Referring to  FIG. 6B , an embodiment of an MS card interface circuit  614  according to the invention is shown. A memory stick card  602   b  is inserted into the socket  604 , and a plurality of signal lines of the MS card interface circuit  614  is coupled to the first pins of the socket  604  for transmitting signals MS_CLK, MS_BS, MS_INS, and MS_D 0 ˜MS_D 3 . When the memory stick card  602   b  is inserted into the socket  504 , the memory stick card  602   b  automatically lowers the voltages of the first pins to an initial voltage of a ground level. 
     The controller IC  508  accesses the memory card  502  via a plurality of input/output (IO) pins. The controller IC coupling circuit  518  then connects the IO pins of the controller IC  508  to the signal lines of the SD card interface circuit  512  and the MS card interface circuit  514  to exchange signals therebetween. Referring to  FIG. 7A , an embodiment of the controller IC coupling circuit  718  according to the invention is shown. The controller IC coupling circuit  718  comprises four signal lines  742 ,  744 ,  746 , and  748 . The signal line  742  couples an input/output (IO) pin IC_IO a  of the controller IC  508  to the MS_CLK pin of the socket  504 . The signal line  744  couples an IO pin IC_IO b  of the controller IC  508  to the SD_CLK pin and the MS_BS pin of the socket  504 . The signal line  746  couples an IO pin IC_IO c  of the controller IC  508  to the SD_CMD pin and the MS_D 0  pin of the socket  504 . The signal line  748  couples an IO pin IC_IO d  of the controller IC  508  to the SD_D 0  pin of the socket  504 . 
     Before the controller IC  508  starts to access the memory card  502 , the controller IC  508  must identify the type of the memory card  502 . Assume that the controller IC  508  determines whether a memory stick card  502  or a secure digital card  502  is inserted into the socket  504  according to the voltage of the pin IC_IO c . The card identification circuit  516  then sets the voltage of signal line  746  coupled to the pin IC_IO c  to different values according to whether a memory stick card or a secure digital card is inserted into the socket, thus enabling the controller IC  508  to determine whether the memory stick card or the secure digital card is inserted into the socket  504  according to the voltage of the pin IC_IO c . 
     Referring to  FIG. 7B , an embodiment of a card identification circuit  716  corresponding to the controller IC coupling circuit  718  of  FIG. 7A  according to the invention is shown. The card identification circuit  716  comprises a BJT transistor  722  having a base coupled to the MS card insertion pin MS_INS, a collector coupled to the high voltage source V DD , and an emitter coupled to the signal line  746  which is coupled to the pins MS_D 0  and SD_CMD of the socket  502 . When a memory stick card  502  is inserted into the socket  504 , the socket  504  lowers the voltage of the MS card insertion pin MS_INS to a ground level to turn off the BJT transistor  722 . Because the memory stick card  502  automatically lowers voltages of all first pins including the pin MS_D 0  to ground, and the pin SD_CMD is floating due to nonexistence of a secure digital card, the voltage of the signal line  746  is lowered to ground with that of the pin MS_D 0 . The voltage of the pin IC_IO c  is therefore lowered to ground, informing the controller IC  508  that a memory stick card is inserted into the socket  504 . 
     When a secure digital card  502  is inserted into the socket  504 , the voltage of the MS card insertion pin MS_INS is at a high level, turning on the BJT transistor  722 . When the BJT transistor  722  is turned on, the voltage of the signal line  746  at the emitter of the BJT  722  is raised to the high voltage V DD  at the collector of the BJT  722 . Because the memory stick card  502  does not exist, the pin MS_D 0  is floating, and the voltage of the signal line  746  is raised to the high level V DD . The voltage of the pin IC_IO c  is therefore raised to the high level V DD , informing the controller IC  508  that a secure digital card is inserted into the socket  504 . Thus, the controller IC  508  can determine the type of the memory card  502  inserted into the socket  504  according to the voltage of the pin IC_IO c . 
     Referring to  FIG. 8A , another embodiment of a controller IC coupling circuit  818  according to the invention is shown. The controller IC coupling circuit  818  comprises three signal lines  842 ,  844 , and  846 . The signal line  842  couples an input/output (IO) pin IC_IO a  of the controller IC  508  to the SD_CLK pin and the MS_CLK pin of the socket  504 . The signal line  844  couples an IO pin IC_IO b  of the controller IC  508  to the SD_CMD pin and the MS_BS pin of the socket  504 . The signal line  846  couples an IO pin IC_IO c  of the controller IC  508  to the SD_D 0  pin and the MS_D 0  pin of the socket  504 . 
     Referring to  FIG. 8B , an embodiment of a card identification circuit  816  corresponding to the controller IC coupling circuit  818  of  FIG. 8A  according to the invention is shown. The card identification circuit  816  comprises two BJT transistors  822  and  832 , respectively having a base coupled to the MS card insertion pin MS_INS, and a collector coupled to the high voltage source V DD . The emitter of the transistor  822  is coupled to the signal line  844  which is coupled to the pins MS_BS and SD_CMD of the socket  502 , and the emitter of the transistor  832  is coupled to the signal line  846  which is coupled to the pins MS_D 0  and SD_D 0  of the socket  502 . Both the BJT transistors  822  and  832  functions similarly as the BJT transistor  722  of  FIG. 7B . The voltages of the pins IC_IO b  and IC_IO c  are therefore raised to the high level V DD  when a secure digital card is inserted into the socket  504  and lowered to ground V GND  when a memory stick card is inserted into the socket  504 . Thus, the controller IC  508  can determine the type of the memory card  502  inserted into the socket  504  according to the voltage of the pin IC_IO c  or the pin IC_IO b . 
     The card identification circuits  716  and  816  is triggered by the voltage of the MS card insertion pin MS_INS. A card identification circuit can also be triggered by the voltage of the SD card insertion pin SD_INS. Referring to  FIG. 9 , an embodiment of a card identification circuit  900  according to the invention is shown. The card identification circuit  900  comprises a PMOS transistor  924 , a NMOS transistors  926 , and a capacitor  938 . When a secure digital card is inserted into the socket  504 , the socket  504  lowers the voltage of the SD card insertion pin SD_INS to ground, turning on the PMOS transistor  924 . The voltage at the drain of the PMOS transistor  924  is therefore raised to a high level V DD  to inform the controller IC  508  that a secure digital card is inserted into the socket  504 . 
     When a memory stick card is inserted into the socket  504 , the voltage of the SD card insertion pin SD_INS is at a high level, turning on the NMOS transistor  926 , and the voltage at the drain of the NMOS transistor  926  is therefore lowered to ground V GND  to inform the controller IC  508  that a memory stick card is inserted into the socket  504 . The signal line coupled to the drain of the NMOS transistor  926  may be the signal line  844  of  FIG. 8A  or the signal line  746  of  FIG. 7A . 
     Referring to  FIG. 10 , a flowchart of a method  1000  for identifying the type of a memory card  502  for the controller IC  508  according to the invention is shown. The controller IC  508  first determines whether the type of the memory card  502  has been identified (step  1002 ). If not, the memory card  502  may be just inserted into the socket  504 . The controller IC  508  then detects voltage of a signal line which may be the pin IC_IO c  of  FIG. 7A  or the pins IC_IO b  and IC_IO c  of  FIG. 8A  (step  1004 ). If the voltage of the signal line is at a low level (step  1006 ), the memory card  502  is a memory stick card, and the controller IC  508  sends MS card detecting commands to the memory card  502  to verify that the memory card  502  is a MS card (step  1008 ). If the voltage of the signal line is at a high level (step  1006 ), the memory card  502  is a secure digital card, and the controller IC  508  sends SD card detecting commands to the memory card  502  to verify that the memory card  502  is a SD card (step  1010 ). Thus, a secure digital card  502  won&#39;t receive MS card detecting commands, and no errors are induced in the secure digital card. A MS card  502  won&#39;t receive SD card detecting commands, and no errors are induced in the MS card. 
     If the type of the memory card  502  has been identified (step  1002 ), the memory card  502  may be disconnected. If the memory card  502  has been identified as a SD card ( 1012 ), the controller IC  508  sends SD card detecting commands to the memory card  502  to determine whether the memory card  502  is disconnected (step  1014 ). If the memory card  502  has been identified as a MS card ( 1012 ), the controller IC  508  sends MS card detecting commands to the memory card  502  to determine whether the memory card  502  is disconnected (step  1016 ). 
     The invention provides an interface circuit identifying the type of a memory card. After a type of a memory card is identified, the interface circuit raises or lowers the voltage of an IO pin of a controller IC according to the type of the memory card. Thus, the controller IC can identify the type of the memory card in advance before card detecting commands are sent to the memory card, and no errors are induced. In addition, the IO pin for identifying the type of the memory card is an IO pin for transmitting signals between the memory card and the controller IC, thus reducing the number of pins required of the controller IC and reducing hardware costs. 
     In the above examples, MS card and SD card are recited for MS interface and SD interface respectively. It is known that MS interface may also support MS Pro card and SD interface may also support MMC card. Therefore, the inventive concept as disclosed above may also be applied on MS Pro card and MMC card. 
     While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.