Patent Publication Number: US-2011072168-A1

Title: Data transfer system with different operating modes

Description:
BACKGROUND 
     A CompactFlash (CF) card is a mass storage device that conforms to the CompactFlash standard. The CompactFlash Association (CFA) developed the CompactFlash standard and subsequently published CompactFlash+ specification (CF+) and CompactFlash Specification Revision 4.0 (CF4). The earlier type of CF cards utilizes common memory data storages. Currently, CF+ and CF4 cards are expanded to include input/output (I/O) devices or magnetic disk data storages, depending on specific applications. The CF+ and CF4 cards support a higher data transfer rate than the earlier type of CF cards. 
     The earlier type of CF cards may only operate in the PC Card ATA (Advanced Technology Attachment) using memory mode. CF4 and CF+ cards can operate in the PCMCIA (Personal Computer Memory Card International Association) mode which includes the PC Card ATA using I/O mode and the PC Card ATA using memory mode. Moreover, the CF4 cards can operate in the True IDE (integrated development environment) mode and the CF+ cards may also function in the True IDE mode. In each mode, data is transferred according to a corresponding read/write timing cycle. Therefore, CF, CF+ and CF4 cards operating in different modes may have different data transfer rates. 
     Typically, a controller is used to control data transfer between a host (e.g., a computer) and a storage device. The controller is usually set in a predetermined mode to communicate with the storage device according to a predetermined data transfer rate. However, as CF, CF+ and CF4 cards may support different data transfer rates, the data transfer performance may be reduced. For example, if the controller is set in the PC Card ATA using memory mode, a CF+/CF4 card operating in the PC Card ATA using memory mode may have a lower data transfer rate compared to the CF+/CF4 card operating in the True IDE mode. 
     SUMMARY 
     In one embodiment, an electronic system includes an input/output (I/O) interface and a controller coupled to the I/O interface and a storage medium. The controller can select an operating mode from multiple operating modes based on a type of the storage medium. At least two of the operating modes have different data transfer rates. The controller can operate in the selected operating mode to transfer data between the I/O interface and the storage medium according to a data transfer rate of the selected operating mode. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features and advantages of embodiments of the claimed subject matter will become apparent as the following detailed description proceeds, and upon reference to the drawings, wherein like numerals depict like parts, and in which: 
         FIG. 1  shows a data transfer system with multiple operating modes according to one embodiment of the present invention. 
         FIG. 2  shows a data transfer system with multiple operating modes according to another embodiment of the present invention. 
         FIG. 3  shows a data transfer system with multiple operating modes according to another embodiment of the present invention. 
         FIG. 4  is a flowchart of a method for controlling data transfer according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the embodiments of the present invention. While the invention will be described in conjunction with these embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. 
     Embodiments described herein may be discussed in the general context of computer-executable instructions residing on some form of computer-usable medium, such as program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc., that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or distributed as desired in various embodiments. 
     Some portions of the detailed descriptions which follow are presented in terms of procedures, logic blocks, processing and other symbolic representations of operations on data bits within a computer memory. These descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. In the present application, a procedure, logic block, process, or the like, is conceived to be a self-consistent sequence of steps or instructions leading to a desired result. The steps are those requiring physical manipulations of physical quantities. Usually, although not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated in a computer system. 
     It should be borne in mind, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise as apparent from the following discussions, it is appreciated that throughout the present application, discussions utilizing the terms such as “detecting,” “selecting,” “enabling,” “transferring,” “setting” or the like, refer to the actions and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system&#39;s registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices. 
     By way of example, and not limitation, computer-usable media may comprise computer storage media and communication media. Computer storage media includes volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules or other data. Computer storage media includes, but is not limited to, random access memory (RAM), read only memory (ROM), electrically erasable programmable ROM (EEPROM), flash memory or other memory technology, compact disk ROM (CD-ROM), digital versatile disks (DVDs) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information. 
     Communication media can embody computer-readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism and includes any information delivery media. The term “modulated data signal” means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, radio frequency (RF), infrared and other wireless media. Combinations of any of the above should also be included within the scope of computer-readable media. 
     Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be recognized by one of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the present invention. 
     Embodiments in accordance with the present invention provide data transfer systems with multiple operating modes. A controller in the system can operate in multiple operating modes to control the data transfer between a host and a client, e.g., a storage medium. Advantageously, the controller can select an operating mode from multiple operating modes based on a type of the storage medium, and operate in the selected operating mode to communicate with the storage medium according to a corresponding data transfer rate in the selected operating mode. Furthermore, the selected operating mode can include multiple sub-modes. The controller can select an operating sub-mode from multiple sub-modes based on a predetermined operation standard. As a result, the data transfer performance between the host and the storage medium can be improved. 
       FIG. 1  shows a data transfer system  100  according to one embodiment of the present invention. In the example of  FIG. 1 , the data transfer system  100  includes a host  102 , an interface  120 , a controller  140 , and a client. In one embodiment, the client includes a storage medium  106 . The storage medium  106  can be, but is not limited to, a CF+ card or a CF4 card. The controller  140  and the interface  120  transfer data between the host  102  and the storage medium  106 . The interface  120  can be, but is not limited to, a peripheral component interconnect (PCI) interface, a PCI extended (PCI-X) interface, or a PCI express (PCIe) interface. The host  102  can be an electronic device or system, such as a computer, a personal digital assistance (PDA), a mobile phone, or the like. The host  102  can read data from the storage medium  106  or write data into the storage medium  106 . 
     The interface  120  can serve as an I/O (input/output) interconnect between the host  102  and the controller  140 . The information transferred between the host  102  and the controller  140  can include data information and control information. In one embodiment, the host  102  operates as a master to initiate a data transfer. In this instance, the host can send the control information to the controller  140 . The control information can enable the hand-shake between the host  102  and the controller  140  before the data information is transferred. The control information can define a characteristic of the data transfer, for example, whether the data is written into the storage medium  106  or read out from the storage medium  106 . For example, the data information can be transferred from the host  102  to the controller  140  in a write operation, and the data information can be transferred from the controller  140  to the host  102  in a read operation. The control information can also indicate a status of the data transfer, for example, start/initiation of the data transfer. In another embodiment, the storage medium  106  can operate as a master to initiate a data transfer. In this instance, the storage medium can send the control information to the controller  140 . 
     In one embodiment, the interface  120  can analyze the information transferred from the host  102  to determine if the host  102  transfers data information or control information. The interface  120  can selectively transfer the information through a data path  174  or a control path  176  depending on whether the host  102  transfers the data information or the control information. If the host transfers the data information, the data can be sent to the controller  140  through the data path  174 . If the host  102  transfers the control information, the control information can be sent to the controller  140  through the control path  176 . Moreover, the interface  120  can packet the data information from the controller  140  into data readable by the host  102  (computer-readable data) and transfer the data to the host  102 . 
     The controller  140  can transfer the data information between the interface  120  and the storage medium  106 . Advantageously, the controller  140  coupled between the interface  120  and the storage medium  106  can operate in multiple operating modes to control the data transfer between the host  102  and the storage medium  106 . In one embodiment, at least two of the operating modes have different data read/write timing cycles. A read cycle is the time needed between the start of a read operation and the start of the next read cycle. Similarly, a write cycle is the time needed between the start of a write operation and the start of the next write cycle. Therefore, at least two of the operating modes have different data transfer rates. In one embodiment, the multiple modes include, but are not limited to, a PCMCIA mode and a True IDE mode. In the PCMCIA mode, the data is transferred according to a corresponding write/read timing of the PCMCIA standard. In the True IDE mode, the data is transferred according to a corresponding write/read timing of the True IDE standard. 
     Advantageously, the controller  140  can select an operating mode from the multiple operating modes based on a type of the storage medium  106 . Since different types of the storage medium  106  may support different data transfer modes, the controller  140  can transfer data between the host  102  and the storage medium  106  in a mode that is compatible with the storage medium  106 . For example, if the storage medium  106  is a CF+ or CF4 card, the controller  140  can select the PCMCIA mode or True IDE mode as the operating mode. In other words, the controller  140  can be a universal controller and can select a proper operating mode according to the type of the storage medium  106 . The controller  140  can operate in the selected operating mode to enable the data transfer between the I/O interface  120  and the storage medium  106  according to a corresponding data read/write timing cycle and a corresponding data transfer rate of the selected operating mode. In one embodiment, if more than one mode in the multiple operating modes are compatible with the storage medium  106 , the controller  140  can select a mode that provides desired data transfer performance, e.g., relatively high data transfer rate, as the operating mode. 
     Moreover, in one embodiment, the operating mode selected by the controller  140  can include multiple sub-modes. The controller  140  can select an operating sub-mode from the multiple sub-modes based on a predetermined operation standard. For example, the PCMCIA mode can include multiple sub-modes, such as a PC card ATA using I/O mode and a PC card ATA using memory mode. When the controller  140  operates in the PC card ATA using I/O mode or a PC card ATA using memory mode, the storage medium  106  uses different signals to communicate with the controller  140 . For example, when the storage medium  106  is a CF+ or CF4 card and when the controller  140  operates in the PC card ATA using I/O mode, the storage medium  106  uses signals at the pins  34  and  35  of the storage medium  106  to communicate with the controller  140 . In one embodiment, the controller  140  uses the signal IORD at the pin  34  to read data from the storage medium  106 , and uses the signal IOWR at the pin  35  to write data from the host  102  into the storage medium  106 . However, when the controller  140  operates in the PC card ATA using memory mode, the storage medium  106  does not use the signals at the pins  34  and  35 , in one embodiment. By way of example, when the storage medium  106  is a CF+ or CF4 card and when the controller  140  operates in the PC card ATA using memory mode, the storage medium  106  uses signals at the pins  9  and  36  of the storage medium  106  to communicate with the controller  140 . In one embodiment, the controller  140  uses the signal OE at the pin  9  to read data from the storage medium  106 , and uses the signal WE at the pin  36  to write data from the host  102  into the storage medium  106 . However, when the controller  140  operates in the PC card ATA using I/O mode, the controller  140  uses the signal OE at the pin  9  to read data from configuration registers of the storage medium  106 , and uses the signal WE at the pin  36  to write data into the configuration registers in the storage medium  106 . 
     The True IDE mode can include multiple sub-modes, such as a primary I/O (PIO) mode, a multiword direct memory access (MDMA) mode, and an ultra direct memory access (UDMA) mode. By way of example, when the storage medium  106  is a CF+ or CF4 card and when the controller  140  operates in the PIO mode, there is an interrupt after a predetermined length of data, e.g., 512 bit of data, is transferred from the host  102  to the storage medium  106 . When the controller  140  operates in the MDMA mode, all the data can be transferred from the host  102  to the storage medium  106  at one time without any interrupt. When the controller  140  operates in the UDMA mode, the storage medium  106  can operate as a master, e.g., the storage medium  106  can initiate a data transfer from the storage medium  106  to the host  102 . In this embodiment, the storage medium  106  can send control information, e.g, a DMA request, to the controller  140  to initiate the data transfer. The PIO mode can further include multiple PIO modes. The multiple PIO modes may have different read/write timing cycles. Similarly, the MDMA mode can further include multiple MDMA modes. The multiple MDMA modes may have different read/write timing cycles. The UDMA mode can further include multiple UDMA modes. The multiple UDMA modes may also have different read/write timing cycles. The controller  140  can select an operating sub-mode from the multiple sub-modes based on a predetermined operation standard. 
     In one embodiment, the predetermined operation standard is a data transfer rate standard. The controller  140  selects an operating sub-mode to obtain a desired data transfer rate, e.g., a relatively high data transfer rate, of the data transfer between the I/O interface  120  and the storage medium  106 . In another embodiment, the predetermined operation standard is a priority standard. The controller  140  can determine a priority of the data transfer request and selects an operating sub-mode according to the priority of a data transfer request of a data transfer between the I/O interface  120  and the storage medium  106 . For example, in the data transfer system  100 , the request for the data transfer between the host  102  and the storage medium  106  may coexist with other requests such as an interrupt request. If the priority of the request for the data transfer between the host  102  and the storage medium  106  is relatively high, the mode selection block  130  can select an operating sub-mode that supports a relatively high data transfer rate. If the priority of the request for the data transfer between the host  102  and the storage medium  106  is relatively low, the mode selection block  130  can select an operating sub-mode that supports a relatively low data transfer rate. In one embodiment, the mode-select block  130  executes a computer-executable program to select the operating mode and/or the sub-mode. 
     In the example of  FIG. 1 , the controller  140  includes a data buffer  142 , a register  144 , a mode selection block  130 , a multiplexer (MUX)  152 , and a core block  160 . The data buffer  142  can buffer the data information from the interface  120  and provide the data information to the core block  160 . The data buffer  142  can also buffer the data information from the core block  160  and provide the data information to the interface  120 . The register  144  can store the control information received from the interface  120  when the host  102  operates as a master or from the storage medium  106  when the storage medium  106  operates as a master, and can store mode data indicative of the multiple operating modes and sub-modes in which the controller  140  can operate. The mode data can be accessed by the mode selection block  130  to select the operating mode and/or sub-mode for the controller  140 . In one embodiment, the register  144  also stores data which indicates if the data transfer is completed and which can be accessed by the host  102 . In this instance, the core block  160  can generate the data indicative of the completion of the data transfer. In another embodiment, the host  102  can determine if the data transfer is completed by itself. 
     The core block  160  is coupled to the data buffer  142  and can include multiple cores. Each core can operate in a corresponding mode to communicate with the storage medium  106 . In one embodiment, a core can be a micro-controller and can generate signals (e.g., read/write signal) according to the read/write timing of a corresponding mode to enable a data transfer process. The storage medium  106  receives the signals generated by the core and responses accordingly. For example, if the host  102  initiates a data transfer to write data into the storage medium  106 , the corresponding core can generate a write signal according to the control information from the host  102 . In response, the storage medium  106  receives the data information transferred from the host  102 . If the host  102  initiates a data transfer to read data from the storage medium  106 , the corresponding core can generate a read signal according to the control information from the host  102 . In response, the storage medium  106  transfers/provides the data information to the host  102 . In one embodiment, if an operating mode is selected, a corresponding core can be enabled according to the selected operating mode to communicate with the storage medium  106 . The data can be transferred between the host  102  and the storage medium  106  via the enabled core. 
     In one embodiment, before any operating mode is selected by the mode selection block  130 , the controller  140  operates in a default mode and a default core that can operate in the default mode is used to communicate with the storage medium  106 . 
     The mode selection block  130  can select an operating mode from the multiple operating modes based on the type of the storage medium  106  and select an operating sub-mode from the multiple sub-modes based on a predetermined operation standard. More specifically, the mode selection block  130  can access the mode data stored in the register  144  indicative of multiple modes and sub-modes in which the controller  140  can operate. The mode selection block  130  can detect the type of the storage medium  106  and the mode(s) supported by the storage medium  106 . In one embodiment, the mode selection block  130  can send an identification command to the register  144  to request identity information of the storage medium  106 . Data indicating the identification command can be written into the register  144 . The default core in the core block  160  can monitor the register  144  and can generate a signal requesting identity information of the storage medium  106  accordingly. In response, the storage medium  106  can send data indicative of the type of the storage medium  106  and the mode(s) supported by the storage medium  106  to the register  144  via the default core. Thus, the mode selection block  130  can access the identity information of the storage medium  106  in the register  144 . The mode selection block  130  selects an operating mode which is compatible with the storage medium  106  from the multiple modes. In one embodiment, if more than one mode in the multiple modes are compatible with the storage medium  106 , the mode selection block  130  can select a mode that provides desired data transfer performance, e.g., relatively high data transfer rate, as the operating mode. If the selected operating mode includes multiple sub-modes, the mode selection block  130  can further select an operating sub-mode according to the predetermined operation standard from the corresponding multiple sub-modes. 
     Once the operating mode is selected, the mode selection block  130  can configure the controller  140  to operate in the selected operating mode or sub-mode. In one embodiment, the mode selection block  130  configures the controller  140  by writing the corresponding mode data indicative of the selected operating mode and/or sub-mode into the register  144 . 
     The multiplexer  152  is coupled to the register  144  and the core block  160  for enabling one of the cores according to the mode data indicative of the selected operating mode and/or sub-mode in the register  144 . Consequently, the enabled core can communicate with the storage medium  106 , for example, to transfer the data information to the storage medium  106 , according to the data transfer rate in the selected operating mode and/or sub-mode. 
     An operation example of transferring data from the host  102  to the storage medium  106  is described here. In one embodiment, the host  102  first transfers control information to the controller  140  through the interface  120  and the control path  176  to initiate a data transfer from the host  102  to the storage medium  106 . When the register  144  receives the control information, the mode selection block  130  can be enabled to select an operating mode. The mode selection block  130  can select the operating mode and can further select an operating sub-mode. Thus, the mode selection block  130  can set the controller  140  in the selected operating mode and the selected operating sub-mode. According to the operating mode and the operating sub-mode selected by the mode selection block  130 , the multiplexer  152  can enable one of the cores in the core block  160  to communicate with the storage medium  106 . The host  102  transfers the data information to the data buffer  142  through the interface  120  and the data path  174 . The data buffer  142  can provide the data information to enabled core in the core block  160 . As such, the data information can be sent to the storage medium  106 . The host  102  can access the register  144  to determine if the data transfer is completed, in one embodiment. 
     An operation example of transferring data from the storage medium  106  to the host  102  is described here. In one embodiment, the host  102  first sends control information to the controller  140  through the interface  120  and the control path  176  to request a data transfer from the storage medium  106  to the host  102 . After the controller  140  is set in the selected operating mode and the selected operating sub-mode by the mode selection block  130 , the multiplexer  152  can enable one of the cores in the core block  160  to communicate with the storage medium  106 . As such, the data can be transferred from the storage medium  106  to the core block  160 . Through the data buffer  142 , the data path  174 , and the interface  120 , the data can be sent to the host  102 . The host  102  can access the register  144  to determine if the data transfer is completed, in one embodiment. 
     As described above, the host  102  operates as a master to initiate a data transfer. In another embodiment, the storage medium  106  can operate as a master to initiate a data transfer. In this embodiment, the mode selection block  130  can be first enabled by the host  102  to select an operating mode. By way of example, when the storage medium  106  is a CF+ or CF4 card, the mode selection block  130  selects the True IDE mode as the operating mode and further selects the UDMA mode as the operating sub-mode. Thus, the mode selection block  130  sets the controller  140  in the UDMA mode. The multiplexer  152  enables a core in the core block  160  that can operate in the UDMA mode to communicate with the storage medium  106 . In the UDMA mode, the storage medium  106  operates as a master to initiate a data transfer between the storage medium  106  and the host  102 . 
     More specifically, the storage medium  106  sends control information to the controller  140  to initiate a data transfer, in one embodiment. The enabled core in the core block  160  can analyze the information transferred from the storage medium  106  to determine if the storage medium  106  transfers data information or control information. If the storage medium  106  transfers the control information, the core block  160  can analyze the control information to determine whether the storage medium  106  initiates a read operation (read data from the host  102 ) or a write operation (write data into the host  102 ). If the storage medium  106  transfers the data information, the controller  140  can transfer the data information through the data path  142 . If the storage medium  106  initiates a data transfer to write data into the host  102 , the enabled core can generate a read signal according to the control information from the storage medium  106 . In response, the host  102  receives the data information transferred from the storage medium  106  via the data path  174 . If the storage medium  106  initiates a data transfer to read data from the host  102 , the enabled core can generate a write signal according to the control information from the storage medium  106 . In response, the host  102  transfers/provides the data information to the storage medium  106  via the data path  174 . 
     Therefore, the controller  140  can select an operating mode based on the type of the storage medium  106 . Furthermore, the controller  140  can select an operating sub-mode according to a predetermined operation standard. Advantageously, the controller  140  can provide data transfer control adapted to various storage medium  106  and in accordance with various operation standards. 
     In one embodiment, before the storage medium  106  is coupled to the controller  140 , the controller  140  can be set in a default operating mode. In one embodiment, the default mode can be a mode that supports a relatively high data transfer rate. After the storage medium  106  is coupled to the controller  140 , the mode selection block  130  can determine if the default mode is compatible with the storage medium  106 . If the default mode is compatible with the storage medium  106 , the controller  140  can operate in the default mode to communicate with the storage medium  106 . Thus, higher data transfer performance can be achieved. If the default mode is not compatible with the storage medium  106 , the mode selection block  130  can select another mode. 
       FIG. 2  shows a data transfer system  200  according to one embodiment of the present invention. Elements labeled the same as in  FIG. 1  have similar functions. In the example of  FIG. 2 , the data transfer system  200  includes the host  102 , the PCIe interface  120 , the controller  140 , and the storage medium  106 . The storage medium  106  can be, but is not limited to, a CF+ card or a CF4 card. The controller  140  and the PCIe interface  120  can transfer data between the host  102  and the storage medium  106 . 
     The PCIe interface  120  serves as an I/O interconnect to transfer data between the host  102  and the controller  140 . The Peripheral Component Interconnect Express (PCIe) is a computer interconnect standard having a relatively high speed data transfer rate. For example, a PCIe link is able to support up to 32 lanes and provide an effective 2.5 Gigabits/second/Lane/direction of raw bandwidth. Thus, the PCIe provides higher performance than the PCI and PCI-X. In addition, the PCIe supports the Hot-Plug/Hot-Swap. In the embodiment of  FIG. 2 , the PCIe interface  120  includes a PCIe physical layer (PHY)  222  and a PCIe core  224 . If the host  102  sends serial data to the PCIe interface  120 , the PCIe PHY  222  can transform the serial data into parallel data and provide the parallel data to the PCIe core  224 . The PCIe core  224  can analyze the parallel data to determine whether the information sent from the host  102  is data information or control information. The PCIe core  224  transfers the data information to the controller  140  through the data path  174  and transfers the control information to the controller  140  through the control path  176 . As such, the information from the host  102  can be sent to the controller  140  via the PCIe interface  120 . 
     Similarly, if the controller  140  transfers the data information to the PCIe interface  120 , the PCIe core  224  can packet the data information to provide the parallel data to the PCIe PHY  222 . The PCIe PHY  222  can transform the parallel data into the serial data and send the serial data to the host  102 . As such, the PCIe interface  120  can transfer the data information to the host  102 . 
     The controller  140  can communicate with the storage medium  106  to transfer data between the PCIe interface  120  and the storage medium  106 . In the example of  FIG. 2 , the controller  140  includes the data buffer  142 , the register  144 , the mode selection block  130 , the multiplexer  152 , and the core block  160 . In one embodiment, the core block  160  includes a PCMCIA core  246  and a True IDE core  248 . The PCMCIA core  246  can operate in the PCMCIA mode. The True IDE core  248  can operate in the True IDE mode. 
     The mode selection block  130  can select an operating mode according to the type of the storage medium  106  from the PCMCIA mode and the True IDE mode. Furthermore, if the selected operating mode includes multiple sub-modes, the mode selection block  130  can select an operating sub-mode according to a predetermined operation standard from the corresponding multiple sub-modes. 
     In the embodiment of  FIG. 2 , the mode selection block  130  includes a micro controller unit (MCU)  234  and a firmware  236 . The firmware  236  can store a computer-executable program. The MCU  234  can execute the computer-executable program in the firmware  236  to select the operating mode and/or sub-mode. The MCU  234  can read the mode data in the register  144  indicative of the operating modes and/or sub-modes in which the controller  140  can operate. The MCU  234  can issue an identification command (e.g., an Identify Device command if the storage medium  106  is a CF4 card) to detect the type of the storage medium  106  and the modes that the storage medium  106  can support. After selecting the operating mode and/or the operating sub-mode, the MCU  234  can issue a configuration command (e.g., a Set Feature command if the storage medium  106  is a CF4 card) to configure a register in the storage medium  106  to set the storage medium  106  in the selected operating mode and/or sub-mode, and can configure the register  144  to set the controller  240  in the selected operating mode and/or sub-mode by writing the mode data indicative of the selected operating mode and/or sub-mode in the register  144 . 
     According to the operating mode selected by the mode selection block  130 , the multiplexer  152  enables one of the PCMCIA core  246  and the True IDE core  248  according to the mode data indicative of the selected operating mode in the register  144 . Thus, the enabled core can communicate with the storage medium  106  according to the corresponding data transfer rate in the selected operating mode and/or sub-modes. In another embodiment, a single core can selectively operate in the PCMCIA mode or the True IDE mode to communicate with the storage medium  106 . Consequently, the data transfer between the host  102  and the storage medium  106  can be enabled. 
     Therefore, the controller  140  can control data transfer adapted to various storage medium  106  and in accordance with various operation standards. Furthermore, the storage medium  106  can communicate with host systems via the PCIe interface  120  having relatively high performance. As such, the performance of the data transfer can be further improved. Moreover, the controller  140  supports the hot plug since the PCIe interface  120  supports the hot plug. 
     In one embodiment, before the storage medium  106  is coupled to the controller  140 , the controller  140  is set in a default mode. In one embodiment, the default mode can be the True IDE mode. After the storage medium  106  is coupled to the controller  140 , the mode selection block  130  can issue an identification command (e.g., an Identify Device command if the storage medium  106  is a CF4 card) to the storage medium  106  to determine if the default mode is compatible with the storage medium  106 . If the default mode is compatible with the storage medium  106 , the MCU  234  can issue a configuration command (e.g., a Set Feature command if the storage medium  106  is a CF4 card) to set the storage medium  106  in the PCMCIA mode. 
       FIG. 3  shows a data transfer system  300  according to another embodiment of the present invention. Elements labeled the same as in  FIG. 2  have similar functions. 
     In the embodiment of  FIG. 3 , the mode selection block  130  can be located outside the controller  140 . The mode selection block  130  includes a driver  336 , e.g., a computer-executed program for selecting the operating mode and the operating sub-mode. In one embodiment, a signal processor (not shown) of the host  102 , for example, a central processing unit (CPU), can execute the driver  336  to perform the mode selection function. 
       FIG. 4  shows a flowchart  400  of a method for controlling data transfer according to one embodiment of the present invention.  FIG. 4  is described in combination with  FIG. 1 . Although specific steps are disclosed in  FIG. 4 , such steps are examples. That is, the present invention is well suited to performing various other steps or variations of the steps recited in  FIG. 4 . In one embodiment, the flowchart  400  is implemented as computer-executable instructions stored in a computer-readable medium. 
     In block  402 , a type of the storage medium  106  and the mode(s) supported by the storage medium  106  can be detected. In block  404 , an operating mode is selected from multiple operating modes based on the type of the storage medium  106 . For example, the mode selection block  130  in the controller  140  can access the mode data stored in the register  144  indicative of multiple modes and sub-modes in which the controller  140  can operate. The mode selection block  130  selects an operating mode which is compatible with the storage medium  106  from the operating modes. 
     In block  406 , an operating sub-mode is selected from multiple sub-modes according to a predetermined operation standard. In one embodiment, the selected operating mode may include multiple sub-modes. In this instance, the mode selection block  130  can further select the operating sub-mode from the corresponding sub-modes according to the predetermined operation standard, e.g., a data transfer rate standard or a priority standard. 
     In block  408 , the controller  140  can be enabled in the operating mode and/or sub-mode. The mode selection block  130  can configure the register  144  to set the controller  140  in the operating mode and/or sub-mode. In one embodiment, the mode selection block  130  can write the mode data indicative of the selected operating mode and/or sub-mode in the register  144  to set the controller  140  in the selected operating mode and/or sub-mode. 
     In block  410 , the controller  140  can transfer data between the storage medium  106  and the host  102  according a data transfer rate and a read/write timing cycle of the selected operating mode. According to the mode data that indicates the selected operating mode and/or sub-mode in the register  144 , the multiplexer  152  can enable a core in the core block  160 . As such, the enabled core can communicate with the storage medium  106  to exchange data with the storage medium  106  according to the data transfer rate and the read/write timing cycle of the selected operating mode. 
     While the foregoing description and drawings represent embodiments of the present invention, it will be understood that various additions, modifications and substitutions may be made therein without departing from the spirit and scope of the principles of the present invention as defined in the accompanying claims. One skilled in the art will appreciate that the invention may be used with many modifications of form, structure, arrangement, proportions, materials, elements, and components and otherwise, used in the practice of the invention, which are particularly adapted to specific environments and operative requirements without departing from the principles of the present invention. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims and their legal equivalents, and not limited to the foregoing description.