Abstract:
The present invention discloses a Universal Serial Bus (“USB”) device capable of remote wake-up through a special mask circuit. The USB device includes an Ethernet port to transmit a first signal in response to a predetermined network packet, a wake-up pin to transmit a second signal in response to a remote wake-up trigger signal, a remote wake-up circuit to generate a wake-up signal in response to either the first signal or the second signal, and a mask circuit to receive the wake-up signal and delay transmission of the wake-up signal to a remote USB host for a predetermined delay time.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Technical Field 
         [0002]    The present invention relates to a Universal Serial Bus device capable of remote wakeup, and more particularly, to a Universal Serial Bus device capable of remote wakeup through a special mask circuit. 
         [0003]    2. Background 
         [0004]    With current Universal Serial Bus (“USB”) technology, there are two types of wakeup methods. The first type of wakeup method is known as host resume, which is usually performed by a computer to wake up all system devices, including a USB device, so there is no problem with compatibility among devices. The second type of wakeup method is the device remote-wakeup method, which is usually executed by a USB to wake up a USB host. The device remote-wakeup method may suffer from compatibility issues and un-wakeup host problems. 
         [0005]      FIG. 1  shows a block diagram of a USB device  12  in prior art. The USB device  12  includes a USB port  111  that connects via a USB transmission line  14  to a USB port  112  of a USB host  10 ; a wakeup pin  18  to transmit a trigger signal to wake up the USB device  12 ; an Ethernet port  15  to receive specific network packets, such as Magic Packets and Wakeup Frames, from an external twist line  13  to wake up the USB device  12 ; and a remote wakeup circuit  16  to generate a wakeup signal to wake up the USB host  10  via the USB ports  111  and  112 . 
         [0006]    Referring to  FIG. 1 , when a USB device  12  is plugged into a USB host  10 , a signal is sent to the USB host  10  to indicate whether the USB device  12  supports the remote wakeup function, and a Set_Feature command is used to enable and activate the remote wakeup function of the USB device  12 . The USB host  10  sets the USB device  12  into a suspend mode through the USB ports  111 ,  112 . Next, the remote wakeup circuit  16  receives a specific packet from the Ethernet port  15  or an external switch trigger signal to wake up the USB device  12 , and then a signal is sent through the USB port  111  to wake up the USB host  10 . The USB host  10  then sends a Clear_Feature command to disable the remote wakeup function. The USB host  10  requires several seconds or several tens of seconds to enter the suspend mode. Because the USB device  12  is unable to know when the USB host  10  enters the suspend mode, and the USB host  10  does not specify the minimal remote wakeup time, the USB host  10  and the USB device  12  may operate in different modes, so the USB host  10  may have a compatibility issue and may not wake up. 
       SUMMARY 
       [0007]    The present invention discloses a USB device with remote wakeup function. A USB device with remote wakeup function according to one embodiment of the present invention comprises an Ethernet port, which transmits a first signal in response to a specific network packet, a wakeup pin, which transmits a second signal in response to a trigger signal, a remote wakeup circuit, which generates a wakeup signal in response to the first signal or the second signal, and a wakeup mask circuit, which is configured to receive the wakeup signal and, within a specific time interval, disable the wakeup signal transmission to a USB host. 
         [0008]    The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter, and form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures or processes for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The objectives and advantages of the present invention are illustrated with the following description and upon reference to the accompanying drawings in which: 
           [0010]      FIG. 1  shows a block diagram of a USB device in prior art; 
           [0011]      FIG. 2  shows a block diagram of a USB device including a wakeup mask circuit according to one embodiment of the present invention; and 
           [0012]      FIG. 3  shows the block diagram of the wakeup mask circuit in  FIG. 2  according to one embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    The embodiments of the present invention are shown in the following description with the drawings, wherein similar or same components are indicated by similar reference numbers. 
         [0014]    The present invention relates to a USB device with remote wakeup function. A specific network packet, which may include but is not limited to a remote wakeup packet of Wake-on-LAN, Magic Packet and Wake-up Frame, or an external hardware trigger, may be sent to wake up the device and through a USB port to wake up a USB host. 
         [0015]      FIG. 2  shows a block diagram of a USB device  22  according to one embodiment of the present invention. Referring to  FIG. 2 , the USB device  22  includes a USB port  211 , a wakeup pin  28 , an Ethernet port  25 , a remote wakeup circuit  26  and a wakeup mask circuit  30 . 
         [0016]    As shown in  FIG. 2 , the USB device  22  connects through the USB port  211  and a USB transmission line  24  to a USB port  212  of a USB host  20  in order to wake up the USB host  20 . 
         [0017]    The wakeup pin  28  connects to an external pin of the USB device  22  to receive an external driving signal, such as a remote wakeup driving signal, and transmits the external driving signal to the remote wakeup circuit  26 . 
         [0018]    The Ethernet port  25  receives the specific network packet, such as WoL, from an external twist line  23  in order to wake up the USB device  22 . 
         [0019]    The remote wakeup circuit  26  generates a wakeup signal to wake up the USB host  20  through the wakeup mask circuit  30  and the USB ports  211  and  212 . 
         [0020]    In operation, the Ethernet port  25  receives the data packet transmitted by the twist line  23 . In response to a specific network packet, such as WoL, the Ethernet port  25  transmits a first signal to the remote wakeup circuit  26 . In response to the first signal from the Ethernet port  25 , or in response to a second signal (i.e., the external driving signal) from the wakeup pin  28 , the remote wakeup circuit  26  generates and sends a wakeup signal to the wakeup mask circuit  30 . When the wakeup mask circuit  30  receives the wakeup signal transmitted by the remote wakeup circuit  26 , the wakeup mask circuit  30  delays the transmission of the wakeup signal for a predetermined time interval before sends the same through the USB port  211 , USB transmission line  24 , USB port  212  to wake up the USB host  20 . 
         [0021]    The USB device  22  transmits information through the Ethernet port  25 , and supports a power saving mode defined by a USB protocol. Furthermore, the USB device  22  is woken up by a specific network packet from the Ethernet port  25  or by the driving signal from the wakeup pin  28 , and wakes up the USB host  20  via the USB ports  211  and  212 . The wakeup mask circuit  30  is allowed to mask wakeup events during a predetermined time delay set by a user, by delaying the sending of the wakeup signal for the predetermined time interval, and is allowed to send wakeup signals without any delay as the predetermined time delay is over. 
         [0022]      FIG. 3  shows a block diagram of the wakeup mask circuit  30  of  FIG. 2 . Referring to  FIG. 3 , the wakeup mask circuit  30  includes a time counter  301  and a mask circuit  302 . The USB device  22  allows the user to set the value of the time counter  301  through the USB port  211 , wherein the value of the time counter  301  is associated with a predetermined delay time, ranging from several seconds to several tens of seconds. In one embodiment of the present invention, the time counter  301  includes a countdown clock, and the mask circuit  302  includes a logic AND gate. 
         [0023]    In operation, when the USB device  22  enters a suspend mode, the time counter  301  activates a time count to count to the predetermined delay time and generates a control signal for the mask circuit  302 . The control signal exhibits a first state when the predetermined delay time is not reached, and exhibits a second state when the predetermined delay time is reached. The mask circuit  302 , in response to the first state of the control signal, masks or blocks a wakeup signal from the remote wakeup circuit  26 , and, in response to the second state of the control signal, i.e., as the time counter  301  counts to the predetermined delay time, allows the wakeup signal the remote wakeup circuit  26  to reach the USB host  20 . 
         [0024]    When the USB device  22  resumes from the suspend mode to a normal mode, the time counter  301  is reset to zero. The remote mask circuit  26  transmits the wakeup signal to wake up the USB host  20  through the USB ports  211  and  212 . 
         [0025]    Based on the embodiments of the present invention, the compatibility problem of the remote wakeup function can be resolved. If the USB device  22  enters a suspend mode earlier than the USB host  20 , and if the USB device  22  is triggered to wake up by an external device while the USB host  20  is entering the suspend mode, then the USB host  20  and the USB device  22  operate in different modes, which may result in the compatibility issue. However, in USB specifications, no minimal remote wakeup time is defined. The present invention can resolve the problem that the USB device  22  fails to wake up the USB host  20 , which may incur serious system error. 
         [0026]    Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. For example, many of the processes discussed above can be implemented in different methodologies and replaced by other processes, or a combination thereof. 
         [0027]    Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.