Abstract:
A USB HUB is provided. The USB HUB comprises a wireless communication module, a storage module, a USB interface connected to a host outside of the USB HUB and a HUB controller. The storage module stores a driver program of the wireless communication module. The USB interface transfers data with the host. The HUB controller is coupled to the USB interface, the wireless communication module and the storage module. The HUB controller disables the storage module and enables the wireless communication module when the driver program has been installed in the host.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This Application claims priority of Taiwan Patent Application No. 099142307, filed on Dec. 6, 2010, the entirety of which is incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is related to a universal serial bus (USB) HUB and a power management method thereof, and more particularly to a USB HUB with wireless communications and a power management method thereof. 
     2. Description of the Related Art 
     A Universal Serial Bus (USB) is a serial bus standard to establish communications between a host and external devices, which supports hot plug and plug-and-play functions. A USB HUB is a device that expands a single USB port into several ports so that there are more ports available to connect various devices to a host system (e.g. PC). 
     According to USB specification, a maximum current that the host can provide to each USB port is up to 500 mA. However, if the device or module coupled to a USB HUB needs a larger current to keep normal operations, it is possible that current overload will occur. Large power consumption may cause unstable operation in the host system, causing the host system to crash. 
     BRIEF SUMMARY OF THE INVENTION 
     A USB HUB and a power management method thereof are provided. An embodiment of a USB HUB is provided. The USB HUB comprises a wireless communication module, a storage module, a USB interface connected to a host outside of the USB HUB and a HUB controller. The storage module stores a driver program of the wireless communication module. The USB interface transfers data with the host. The HUB controller is coupled to the USB interface, the wireless communication module and the storage module. The HUB controller disables the storage module and enables the wireless communication module when the driver program has been installed in the host. 
     Furthermore, an embodiment of a power management method for a universal serial bus (USB) HUB connected to a host is provided. The USB HUB comprises a function module and a storage module and the storage module is enabled. It is determined whether a driver program of the function module has been installed in the host. The storage module is disabled and the function module is enabled when the driver program of the function module has been installed in the host. 
     A detailed description is given in the following embodiments with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF 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. 1  shows a USB HUB according to an embodiment of the invention; and 
         FIG. 2  shows a power management method for a USB HUB having at least one function module according to an embodiment of 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. 
       FIG. 1  shows a USB HUB  100  according to an embodiment of the invention. The USB HUB  100  comprises a USB interface  110 , a HUB controller  120 , a power module  130 , a storage module  140  and a wireless communication module  150 . The USB interface  110  connects to a host system (e.g. a PC) through a USB port  112 . The HUB controller  120  is coupled to the USB interface  110 , and the HUB controller  120  controls data communications between the USB interface  110  and the host system. The storage module  140  comprises a memory controller  160  and a memory  170 . In the embodiment, the memory  170  is a flash memory, and the HUB control  120  controls the memory controller  160  to access the memory  170 . The wireless communication module  150  may be a mobile communications module (such as 3G, 3.5G, 3GPP long term evolution (LTE)) or a wireless local area network (WLAN) module that needs a large operating current in normal operations. It is to be noted that a driver program of the wireless communication module  150  is stored in the memory  170  of the storage module  140 . 
     In  FIG. 1 , the host system provides a power signal Spower (about 5V) to the power module  130  through the USB interface  110  when the USB HUB  100  is connected to the host system. The power module  130  comprises a voltage converter  180  and a power switch  190 . In the embodiment, the voltage converter  180  may be a DC to DC (DC/DC) converter, which generates the operating voltages V 11  and V 12  according to the power signal Spower from the USB interface  110  and an enable signal PWEN 1  from the HUB controller  120 , so as to supply power to the wireless communication module  150 . The operating voltages V 11  and V 12  have different voltage levels, such as 3.3V and 1.2V, for radio frequency (RF) circuits and baseband circuits within the wireless communication module  150 . The power switch  190  generates an operating voltage V 2  according to the power signal Spower and an enable signal PWEN 2  from the HUB controller  120 , so as to supply power to the storage module  140 . In the embodiment, the power switch  190  is a transistor that functions as a switch, thus simplifying design and decreasing cost of the power module  130 . 
     In the embodiments of the invention, the host system identifies the USB HUB  100  when the USB HUB  100  is connected to the host system for the first time. At this time, the host system supplies power to the USB HUB  100 , and the HUB controller  120  controls the power module  130  to supply power to the storage module  140 . Thus, the memory  170  of the storage module  140  is identified by the host system. Next, the HUB controller  120  transmits the driver program of the wireless communication module  150  stored in the memory  170  to the host system, so as to install the driver program in the host system. At this time, the host system only supplies power to the HUB controller  120  and the storage module  140  within the USB HUB  110  through the USB port  112 , thereby no large current is consumed (e.g. 210 mA). Next, after the driver program of the wireless communication module  150  is installed completely, the HUB controller  120  controls the power module  130  to supply power to the wireless communication module  150  and to stop supplying power to the storage module  140 , thus the host system may start to use the wireless communication module  150  for wireless communications. At this time, the host system only provides power to the HUB controller  120  and the wireless communication module  150  within the USB HUB  100  through the USB port  112 , thus avoiding current overload caused by simultaneously providing the power supply to all modules of the USB HUB. Specifically, the host system does not supply power to the wireless communication module  150  and the storage module  140  at the same time. 
     Furthermore, when the USB HUB  100  connects to the host system again, the host system only supplies power to the HUB controller  112  and the storage module  140  within the USB HUB  100  through the USB port  112 . However, once the host system identifies that the driver program of the wireless communication module  150  has been installed, the HUB controller  120  controls the power module  130  to supply power to the wireless communication module  150  and to stop supplying power to the storage module  140 , such that the host system only supplies power to the HUB controller  120  and the wireless communication module  150  within the USB HUB  100 , thereby avoiding the case wherein current flowing through the USB port  112  exceeds 500 mA. 
       FIG. 2  shows a power management method for a USB HUB (e.g. HUB  100  of  FIG. 1 ) having at least one function module according to an embodiment of the invention. First, the USB HUB is connected to a host system (step S 202 ). At this time, power supply of a storage module within the USB HUB is provided. Next, the host system identifies the connected USB HUB, to determine whether a driver program of the function module has been installed in the host system (step S 204 ). If the driver program of the function module has not been installed in the host system, the host system executes an installation procedure according to the driver program of the function module stored in the storage module of the USB HUB (step S 206 ). Next, the USB HUB stops supplying power to the storage module after the installation of driver program is completed, so as to disable the storage module (step S 208 ). Next, the USB HUB supplies power to the function module after the storage module is disabled, so as to enable the function module (step S 210 ). On the contrary, when it is determined that the driver program of the function module has been installed in the host system (step S 204 ), the USB HUB stops supplying power to the storage module, so as to disable the storage module (step S 208 ). Next, the USB HUB supplies power to the function module after the storage module is disabled, so as to enable the function module (step S 210 ). In other words, the function module and the storage module are not enabled at the same time. 
     In the embodiments of the invention, current exceeding 500 mA is prevented from flowing through a USB port, as supply power to the modules of the USB HUB that are not being used is stopped, thus increasing current efficiency. Furthermore, PCB temperature of the USB HUB is decreased by disabling the modules that are not being used, thereby lifetime and stability of the components within the USB HUB are increased. 
     While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. 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.