Abstract:
A cover for mounting to a Universal Serial Bus (USB) electronic device, the USB electronic device includes a shell defining an opening and a USB connector exposed at the opening. The USB connector includes a GND pin and an ID pin. The cover includes a main body and an elastomeric push button; the main body engagably attaches to the shell and covers the opening; the elastomeric push button is formed on the main body and is configured for powering on or off the USB electronic device; the elastomeric push button includes two metal pins connected with each other and configured for short-circuiting the GND pin to the ID pin when the elastomeric push button is depressed.

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an electronic device, and particularly, to a USB electronic device including an interface cover. 
     2. Description of Related Art 
     Many electronic devices have an interface, like an USB interface, which uses an interface cover to protect the interface. However, the interface cover can only be used to keep the USB interface free from dust and water. Therefore, what is needed is an interface cover to overcome the problems mentioned above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of an electronic device with an interface cover. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a schematic, isometric view showing a cover on a partial view of a USB electronic device in accordance with one exemplary embodiment. 
         FIG. 2  is a schematic, perspective view showing an inside of the cover on the partial view of the USB electronic device of  FIG. 1 . 
         FIG. 3  is a schematic, isometric view showing a USB connector of a USB electronic device in accordance with one exemplary embodiment. 
         FIG. 4  is a schematic, isometric view showing a cover in accordance with one exemplary embodiment. 
         FIG. 5  is a block diagram of the USB electronic device of  FIG. 1 . 
         FIG. 6  is a circuit of the USB electronic device of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a Universal Serial Bus (USB) electronic device  100  includes a shell  10  and a cover  20  attached to the shell  10 . 
     Referring to  FIG. 2  and  FIG. 4 , an USB connector  11  is covered by the cover  20  attached to the shell  10 . A projection  24  is mounted on a main body  26  of the cover  20 , and a convex edge  241  is positioned on the end part of the projection  24  to fix the cover  20  to the shell  10 . A hook  25  is mounted on the main body  26 , when the cover  20  covers the USB connector  11 , the hook  25  can fix the other end of the cover  20  to the shell  10 . The hook  25  can be detached from the shell  10  to expose the USB connector  11  when a user wants to connect a peripheral device (not shown) to the USB electronic device  100  through the USB connector  11 . A space (not shown) is reserved between the shell  10  and the end with the hook  25  to allow the user to detach the hook  25  and dig out the cover  20  from the shell  10 . 
     Referring to  FIG. 3 , the USB connector  11  includes a number of pins  111 , the pins  111  include a GND pin and an ID pin. 
     Referring to  FIG. 4 , an elastomeric push button  21  is set on the cover  20 . A recess  22  is formed on the corresponding inner side surface of the elastomeric push button  21  to allow the user to push the elastomeric push button  21  toward the inner side of the elastomeric push button  21 . Two metal pins  23  are connected together and mounted on the recess  22 . When the elastomeric push button  21  is pressed, the two metal pins  23  contact to the GND pin and the ID pin of the pins  111  of the USB connector  11  respectively to short-circuit the ID pin to the GND pin; when the elastomeric push button  21  is released, the two metal pins  23  are detached from the pins  111 . In the present embodiment, the two metal pins  23  may be H-shaped or U-shaped. 
     Referring to  FIG. 5 , the USB electronic device  100  includes a power switch circuit  30 , a delay circuit  40 , a reset circuit  50 , and a processor  60 . The ID pin of the USB connector  11  is connected to a voltage input pin (VIN) of the processor  60  through the power switch circuit  30 ; when the user presses the elastomeric push button  21 , the ID pin is grounded through the GND pin and at a low voltage level, and the power switch circuit  30  generates a power-on signal or a power-off signal to the VIN of the processor  60  to enable the processor  60  to switch the power of the USB electronic device  100 . 
     The ID pin of the USB connector  11  is further connected to a RESET pin of the processor  60  through the delay circuit  40  and the reset circuit  50 . When the elastomeric push button  21  is pressed, the delay circuit  40  begins to charge and outputs a voltage to the reset circuit  50 ; when the elastomeric push button  21  is pressed for over a period of time, the reset circuit  50  generates a RESET control signal to the processor  60  through the RESET pin to allow the processor  60  to restart the USB electronic device  100 . 
     Referring to  FIG. 6 , the ID pin of the USB connector  11  is connected with a +5V standby voltage output terminal (VEXT) through a resistor R 1  and a switch Q 1 . In the present embodiment, the switch Q 1  is a pnp transistor; a base of the switch Q 1  is connected with the ID pin of the USB connector  11  through the resistor R 1 ; an emitter of the Q 1  is connected with the VEXT. 
     The power switch circuit  30  includes a switch Q 2 , a switch Q 3 , and a switch Q 4 . In the present embodiment, the switch Q 2  and the switch Q 3  are npn transistors, and the switch Q 4  is a pMOSFET. A base of the switch Q 2  is connected with a collector of the switch Q 1  through a resistor R 3  and a resistor R 2 , and a voltage detection node P 1  between the resistor R 2  and the resistor R 3  is connected with a general purpose I/O  0  (GPIO  0 ); an emitter of the switch Q 2  is grounded and connected to the base of the switch Q 2  through a resistor R 4  and a resistor R 3 . A base of the switch Q 3  is connected to an emitter of the switch Q 3  through a resistor R 5  and a resistor R 6 , and a voltage input node P 2  between the resistor R 5  and the resistor R 6  is connected with a general purpose I/O  1  (GPIO  1 ). The emitter of the switch Q 3  is grounded, and collectors of the switch Q 2  and the switch Q 3  are connected to a source of the switch Q 4  through a resistor R 7 , a resistor R 8 , and a parallel branch of a capacitor C 1 ; the collectors of the switch Q 2  and the switch Q 3  are further connected with a gate of the switch Q 4  through the resistor R 7 . A drain of the switch Q 4  is connected with the VIN of the processor  60 , and the source of the switch Q 4  is further connected to the VEXT. 
     When the elastomeric push button  21  is pressed, the ID pin and the GND pin of the USB connector  11  is connected through the two metal pins  23  of the cover  20 ; the ID pin of the USB connector  11  is grounded through the GND pin and at a low voltage level, and thus the base of the switch Q 1  obtains a low voltage level. When the base of the switch Q 1  is at a low voltage level, the switch Q 1  is closed, and the base of the switch Q 2  and the voltage input node P 2  are connected to the VEXT to be at a high voltage level; when base of the switch Q 2  is at a high voltage level, the switch Q 2  is closed. The GPIO  1  outputs a 3.3V power-on voltage to the voltage input node P 2  when the high voltage level of the voltage detection node P 1  is detected by the GPIO  0 , and the base of the switch Q 3  obtains a high voltage level to close the switch Q 3 . When the switch Q 3  is closed, the switch Q 4  is closed to allow the VEXT to connect to the VIN of the processor  60 . The VIN obtains a +5V voltage from the VEXT and the USB electronic device  100  is booted when the switch Q 4  is closed. When the elastomeric push button  21  is released, the ID pin is disconnected from the GND pin and opens the switch Q 1 ; the voltage detection node P 1  is at a low voltage level to open the switch Q 2 ; the GPIO  1  outputs a 3.3V sustained voltage to maintain the power of the USB electronic device  100 . 
     When the elastomeric push button  21  is pressed while the USB electronic device  100  is on, the GPIO  0  detects the high voltage level of the voltage detection node P 1 , and the GPIO  1  outputs a 0V power-off voltage to the voltage input node P 2  to open the switch Q 3 . When the elastomeric push button  21  is released, the switch Q 2  is open to open the switch Q 4 . The +5V voltage from the VEXT to the VIN is cut off and the USB electronic device  100  is shutdown. 
     The delay circuit  40  includes a capacitor C 2 ; a negative electrode of the capacitor C 2  is grounded and a positive electrode of the capacitor C 2  is connected with the collector of the switch Q 1  through a resistor R 9 ; the positive electrode further connects to the negative electrode through the resistor R 9  and the resistor R 10 . A voltage output terminal P 3  is formed between the positive electrode and the resistor R 9 . 
     The reset circuit  50  includes a switch Q 5 ; in the present embodiment, the switch Q 5  is an nMOSFET. A gate of the switch Q 5  is connected with the voltage output terminal P 3  of the delay circuit  40 ; a source of the switch Q 5  is grounded; a drain of the Q 5  is connected with a power terminal VCC through a pull-up resistor R 11 . A voltage output terminal P 4  formed between the drain and the resistor R 11  is connected with the RESET pin of the processor  60 , and grounded through a capacitor C 3  or a zener diode D 1 . The processor  60  restarts the system when the RESET pin is at a low voltage level. 
     When the elastomeric push button  21  is pressed, the switch Q 1  is closed and the capacitor C 2  is connected to the VEXT to be charged through the resistor R 9  and the switch Q 1 ; the voltage output terminal P 3  reaches a pre-determined threshold of voltage when the elastomeric push button  21  is pressed for over a period of time, and the switch Q 5  is closed when the voltage output terminal P 3  reaches a pre-determined threshold of voltage; when the switch Q 5  is closed, the voltage output terminal P 4  is grounded to allow the RESET pin of the processor  60  to obtain a low voltage level, and the processor  60  restarts the USB electronic device  100 . When the elastomeric push button  21  is released, the ID pin is disconnected from the GND pin and the capacitor C 2  discharges through the resistor R 9  and the resistor R 10  to lower the voltage of the voltage output terminal P 3 , and the switch Q 5  is open; the voltage output terminal P 4  obtains a high voltage level from the power terminal VCC through the resistor R 11 , and the RESET pin of the processor  60  obtains a high voltage level from the voltage output terminal P 4 . 
     Therefore, the elastomeric push button  21  is capable of switching the power of the USB electronic device  100  as well as protecting the USB connector  11 . The user can switch the power of the USB electronic device  100  when pressing the elastomeric push button  21 , and restart the USB electronic device  100  when long pressing the elastomeric push button  21 . 
     Although the present disclosure has been specifically described on the basis of the exemplary embodiment thereof, the disclosure is not to be construed as being limited thereto. Various changes or modifications may be made to the embodiment without departing from the scope and spirit of the disclosure.