Patent Publication Number: US-2003233507-A1

Title: Electronic card with multiple interfaces

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to an electronic card and, more particularly, to an electronic card with multiple interfaces.  
       [0003] 2. Description of Related Art  
       [0004] With advances in electronic technology, various electronic devices, such as notebook computers, palm computers, PDAs (personal digital assistants), are getting smaller in size. These diminutive electronic devices provide convenience to the user due to their portability and data processing capability. However, because of their small size, such an electronic device generally has only basic processing circuitry. For other circuit modules, such as add-on memory, modem, network card, etc., have to be provided to the electronic device by inserting a corresponding electronic card therein. This electronic card can also be inserted into a personal computer for enabling data communications or increasing storage space.  
       [0005] Conventionally, such an electronic card has one interface only, for example, an USB or Compact Flash (CF) interface. Therefore, this electronic card can only be plugged into a corresponding slot. If the electronic device does not provide the corresponding slot or the corresponding slot has been occupied by another electronic card, this electronic card cannot be plugged into the electronic device and cannot be used.  
       [0006] Therefore, it is desirable for the above conventional electronic card to be improved so as to mitigate and/or obviate the aforementioned problems.  
       SUMMARY OF THE INVENTION  
       [0007] The objective of the present invention is to provide an electronic card with multiple interfaces that dramatically increases electronic card applications.  
       [0008] To achieve the objective, the electronic card with multiple interfaces of the present invention includes: at least two interface connection ports, which includes a first interface connection port and a second interface connection port; an interface signal converter for converting second interface port connection signals to predetermined interface signals, the predetermined interface corresponding and connecting to the first interface connection port; a first switch device arranged between the second interface connection port and the interface signal converter; a second switch device arranged between the interface signal converter and the predetermined interface; and at least one card loading detection device for detecting whether the first interface connection port is connected to an electronic device, wherein, if the first interface connection port is connected to an electronic device, the card loading detection device turns off the first and second switch devices, if the first interface connection port is not connected to an electronic device the card loading detection device turns on the first and second switches.  
       [0009] Other objectives, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0010]FIG. 1 is a block diagram of the electronic card with multiple interfaces in accordance with a first embodiment of the present invention;  
     [0011]FIG. 2 is a circuit diagram of the card loading detection device shown in FIG. 1;  
     [0012]FIG. 3 is a circuit diagram of the first switch device shown in FIG. 1;  
     [0013]FIG. 4 is a circuit diagram of the second switch device shown in FIG. 1;  
     [0014]FIG. 5 is a block diagram of the electronic card with multiple interfaces in accordance with a second embodiment of the present invention; and  
     [0015]FIG. 6 is a block diagram of the electronic card with multiple interfaces in accordance with a third embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0016] With reference to FIG. 1, there is shown a preferred embodiment of an electronic card with multiple interfaces in accordance with the present invention, wherein the electronic card in this embodiment is a memory card with a CF interface and an USB interface. When the CF interface is active, the USB interface is automatically off-line such that both interface signals will not interfere with each other.  
     [0017] As shown in FIG. 1, the memory card with multiple interfaces includes a CF interface connection port  11 , a CF interface  12 , a card loading detection device  13 , an USB interface connection port  14 , a first switch device  15 , a second switch device  16 , an interface signal converter  17  and a CF memory  18 . The CF interface connection port  11  and the USB interface connection port  14  are provided to plug the memory card into the CF or USB interface slot of an electronic device, such as a PC  19  (Personal Computer). When the CF interface connection port  11  is connected to the PC  19 , the card loading detection device  13  detects the connection status and outputs a control signal to turn off the first and second switch devices  15  and  16 , so as to isolate the USB interface connection port  14  from the interface signal converter  17  and the CF interface connection ports  11 , thereby preventing the USB signals from interfering with the CF interface  12 , allowing accurate data transfer to/from the CF memory  18 .  
     [0018] When the CF interface connection port  11  is disconnected from the PC  19 , the card loading detection device  13  detects the connectionless status and outputs a control signal to turn on the first and second switches  15  and  16 , such that the USB interface connection port  14  can be connected to the PC  19 . With the interface signal converter  17  conversion, the USB interface signals can be converted into CF interface signals, so as to transfer data to/from the CF memory  18 .  
     [0019]FIG. 2 is a circuit of the card loading detection device  13  shown in FIG. 1. As known to those skilled in the art, there is a card detection (CD) pin specified in the CF interface specification, this pin is in a “low” state when an electronic card is plugged in the CF interface. Thus, when the CF interface connection port  11  connects with the PC  19 , the CF interface connection port  11  CD pin is grounded and induces a short-circuit current. The card loading detection device  13  has an OP amplifier  21  to detect the short-circuit current, wherein the OP amplifier  21  positive input IN (+) connects to ground, and the negative input IN (−) is connected to the CD pin and the OP amplifier  21  output via a feedback resistor Rf. With this negative feedback, the differential voltage between the positive input IN (+) and the negative input IN (−) is close to zero; that is, the positive input IN (+) and the negative input IN (−) are virtually grounded. Thus, there is a feedback current Irf flowing into the negative input IN (−) and a voltage is induced onto the feedback resistor Rf. The inverter  22 , uses the inverted voltage to control the first and second switches  15  and  16 .  
     [0020]FIG. 3 is a circuit of the first switch  15  shown in FIG. 1, which includes a plurality of analog switches  31 , each connecting one USB interface connection port  14  pin to the interface signal converter  17 . The analog switches  31  on or off positions are controlled by the card loading detection device  13 .  
     [0021] The aforementioned interface signal converter  17  is a serial to parallel signal converter. It can convert the USB interface serial signals (VCC, D+, D−, GND) to CF interface parallel signals (Control, Address, Data).  
     [0022]FIG. 4 is a circuit of the second switch device  16  shown in FIG. 1, which includes a plurality of bi-directional tri-state buffers  41 , each connecting one interface signal converter  17  pin to the CF interface  12 . The bi-directional tri-state buffers  41  on or off positions are controlled by the card loading detection device  13 .  
     [0023] The aforementioned electronic card with CF and USB interfaces can be expanded to have three or more interfaces. As shown in FIG. 5, the second preferred embodiment of the present invention is a memory card with CF, USB and ISA interfaces, wherein the card loading detection device  502  for detecting the CF interface connection port  501  simultaneously controls the switch devices  504  and  505  at two ends of an USB-to-CF interface signal converter  503  and the switch devices  507  and  508  at two ends of an ISA-to-CF interface signal converter  506 . The card loading detection device  510  for detecting the USB interface connection port  509  controls the switch devices  507  and  508  at two ends of the ISA-to-CF interface signal converter  506 . Accordingly, when the CF interface connection port  501  connects to the PC  500 , the card loading detection device  502  simultaneously turns off the switch devices  504 ,  505 ,  507  and  508  to isolate the USB and ISA signals from the CF interface  512 , thereby ensuring correct CF memory  513  operation.  
     [0024] When the CF interface connection port  501  is not connected to the PC  500  and the USB interface connection port  509  is connected to the PC  500 , the card loading detection device  510  turns off the switch devices  507  and  508  to isolate the ISA interface signals from the CF interface  512 , so as to prevent the CF interface  512  from being interfered with. The switch devices  504  and  505  are turned on, such that USB interface connection port  509  signals can be converted to CF interface  512  signals by the USB-to-CF interface signal converter  503 , whereby the host can access the CF memory  513  through the USB interface. When the CF interface connection port  501  and the USB interface connection port  509  are not connected and the ISA interface connection port  511  is connected to the PC  500 , the switch devices  507  and  508  are on, such that the ISA interface connection port  511  signals can be converted into CF interface  512  signals by the ISA-to-CF interface signal converter  506 , whereby the host can access the CF memory  513  through the ISA interface.  
     [0025]FIG. 6 shows a third embodiment of the present invention, which is a memory card with CF, USB and IDE interfaces. This embodiment is similar to the previous one except that the IDE interface connection port  611  replaces the ISA interface connection port  511 . Because the CF memory  513  interface is an IDE interface, there is no need to have an interface signal converter for the IDE interface connection port  611 , and only a switch device  607  is provided to connect the IDE interface connection port  611  to the CF memory  613 . The card loading detection device  602  for detecting the CF interface connection port  601  and the card loading detection device  610  for detecting the USB interface connection port  609  both control the switch device&#39;s  607  on/off position.  
     [0026] In view of the foregoing, it is known that the present invention can appropriately turn on/off the switch devices by detecting the electronic card connection, so as to prevent active interface signals from being interfered with by inactive interface signals. Furthermore, with signal conversions , a single electronic card can be connected to an electronic device via the CF, USB, ISA and IDE interfaces, thereby achieving multiple interfacing and dramatically increasing electronic card applications.  
     [0027] Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.