Abstract:
A dynamic power management system for USB hub and method thereof are described. The dynamic power management system includes a host device, a power unit and a hub device. A power management module disposed in the hub device dynamically adjusts the power-supplying statuses of ports in the hub device and further reduces the cost of power transformer externally connected to the hub device.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 100123565 filed in Taiwan, Republic of China on Jul. 4, 2011, the entire contents of which are hereby incorporated by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a power management system and method thereof, and more particularly to a dynamic power management system for universal serial bus (USB) hub and method thereof. 
     BACKGROUND OF THE INVENTION 
     Recently, the connection ports with universal serial bus (USB) protocol are widely applicable to portable electronic products, e.g. cell phone and digital camera. When these portable electronic products are connected to the hub for use, several execution modes are performed for communication and each of execution modes consumes the current with different magnitude level wherein the supplying current is distributed to each port of the hub. For example, when an electronic product is connected to one port, its execution mode is fixed and the available supplying current is decreased if the more and more electronic products are added. Meanwhile, a new electronic product is put into another port and the consumed current of the electronic product is greater than the available supplying current, the electronic product cannot correctly operate. Even if the previous connected product is removed from the hub, the new product cannot still operate. It is required to remove the new product from the port and reconnect the new product. Such the situation is quite inconvenient since the supplying current corresponding to each port cannot be adjusted correctly. 
     Although external transformer can be used in the hub to increase the supplying current of the hub, the current from the transformer is limited due to cost consideration. Specifically, when the ports in the hub are increased, the transformer must provide more current for the ports. Therefore, the port amount of conventional hub for the electronic products is considerably limited. That is, since the supplying current of the ports cannot be adjusted, the electronic products lack the flexibility for the user. Consequently, there is a need to develop a novel power management to solve the aforementioned problems. 
     SUMMARY OF THE INVENTION 
     One objective of the present invention provides a dynamic power management system for universal serial bus (USB) hub and method thereof to perform the port status conversion based on the enabling or disabling the port status by using the power management module for dynamically adjusting the status conversion associated with the supplying current of the ports and to save the cost of the external power source, e.g. transformer, of the hub device. 
     Another objective of the present invention provides a dynamic power management system for universal serial bus (USB) hub and method thereof. The dynamic power management system includes a host device, a power unit and a hub device. The power unit provides a supplying current. The USB hub device establishes a communication link to the host device and receives the supplying current from the power unit. In another embodiment, the host device may be another USB hub device so that USB hub device can receive the commands from or transmit the messages to the upstream host device via another USB hub device. 
     The USB hub device further includes a plurality of ports, a power management module and the hub function module. The ports have an upstream port and a plurality of downstream ports wherein the host device is coupled to the USB hub device via the upstream port. 
     The power management module receives the supplying current and calculates an available current based on the supplying current. The available current is generated by computing the supplying current, the request current of the peripheral and a consumed current of the hub function module. Specifically, the available current is equal to the difference between the supplying current and consumed current with respect to request current. That is, the available current is to subtract the consumed current of the peripheral devices and the USB hub device from the supplying current wherein the request current is generating when the USB hub device inquires the host device. 
     The hub function module detects and manages the usage status of the ports. In other words, the hub function module detects whether the ports are in either enable or disable status so that the host device communicates with the peripheral devices and manages the peripheral devices connected to the downstream ports. 
     The power management module compares the available current with a request current of the peripheral device to determine whether the available current is greater than the request current when a peripheral device is connected to one of the downstream ports. Further, the hub function module determines an execution mode of the port connected to the peripheral device based on the compared result between the available current and the request current. 
     In the present invention, a dynamic power management method for universal serial bus (USB) hub, which is applicable to a dynamic power management system, wherein the dynamic power management system comprises a host device, a power unit generating a supplying current, a hub device coupled to the host device and the power unit, and the hub device has a power management module, a hub function module and a plurality of ports, the method comprising the steps of: 
     (a) activating a USB hub device; 
     (b) establishing a communication link between the USB hub device and a host device; 
     (c) calculating an available current of the USB hub device based on a supplying current by the power management module; 
     (d) detecting whether an added peripheral device is connected to one of a plurality of ports of the USB hub device by the hub function module, if yes, proceed to step (e) and if no, proceed to (d); 
     (e) acquiring a request current of the added peripheral device by the power management module; 
     (f) comparing the available current with the request current by the power management module for determining whether the available current is less than the request current, if yes, proceed to step (g) and if no, proceed to step (h); 
     (g) reconnecting the added peripheral device to one of the ports by the hub function module, downgrading an execution mode of the port connected to the added peripheral device, and returning to the step (e); and 
     (h) completing the connection between the added peripheral device and the USB hub device. 
     The present invention provides a dynamic power management system for universal serial bus (USB) hub and method thereof to perform the port status conversion based on the enabling or disabling the port status by using the power management module for dynamically adjusting the status conversion associated with the supplying current of the ports and to save the cost of the external power source, e.g. transformer, of the hub device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1A  is a schematic block diagram of a dynamic power management system for universal serial bus (USB) hub according to a first embodiment of the present invention; 
         FIG. 1B  is a schematic block diagram of a dynamic power management system for universal serial bus (USB) hub according to a second embodiment of the present invention; 
         FIG. 2A  is a schematic block diagram of a dynamic power management system for universal serial bus (USB) hub and the downgraded execution mode thereof according to one embodiment of the present invention; 
         FIG. 2B  is a schematic block diagram of a dynamic power management system for universal serial bus (USB) hub and the upgraded execution mode thereof according to one embodiment of the present invention; 
         FIG. 2C  is a schematic block diagram of a dynamic power management system for universal serial bus (USB) hub and the status conversion of ports thereof according to one embodiment of the present invention; 
         FIG. 2D  is a schematic block diagram of a dynamic power management system for universal serial bus (USB) hub and the status conversion of ports thereof according to another embodiment of the present invention; 
         FIG. 3A  is a flow chart of a dynamic power management method for universal serial bus (USB) hub and the downgraded execution mode according to one embodiment of the present invention; 
         FIG. 3B  is a flow chart of a dynamic power management method for universal serial bus (USB) hub and the upgraded execution mode according to one embodiment of the present invention; 
         FIG. 3C  is a flow chart of performing the port status conversion according to one embodiment of the present invention; and 
         FIG. 3D  is a flow chart of performing the port status conversion according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1A  is a schematic block diagram of a dynamic power management system  100 A for universal serial bus (USB) hub according to a first embodiment of the present invention. The dynamic power management system  100 A includes a host device  102 , a power unit  104  and a hub device  106 , e.g. a universal serial bus (USB) hub device. The USB hub device  106  is coupled to the host device  102  and the power unit  104 , respectively. The power unit  104  may be an external power source and/or battery for providing a supplying current. The USB hub device  106  establishes a communication link to the host device  102  and receives the supplying current from the power unit  104 . In another embodiment, the host device  102  may be another USB hub device (not shown) so that USB hub device  106  can receive the commands from or transmit the messages to the upstream host device (not shown) via another USB hub device (not shown). 
     The USB hub device  106  further includes a plurality of ports  108 , a power management module  110  and the hub function module  112 . The hub function module  112  is coupled to the power management module  110  and the plurality of ports  108 , respectively. The ports  108  have an upstream port  108 E and a plurality of downstream ports  108 A˜ 108 D wherein the host device  102  is coupled to the USB hub device  106  via the upstream port  108 E. In this case, the ports  108  is composed of an upstream port  108 E and four downstream ports  108 A˜ 108 D, but not limited. A plurality of peripheral devices  118  are connected to the USB hub device  106  via the downstream ports  108 A˜ 108 D. 
     The power management module  110  receives the supplying current and calculates an available current based on the supplying current. The available current is generated by computing the supplying current, the request current of the peripheral  118  and a consumed current of the hub function module  112 . Specifically, the available current is equal to the difference between the supplying current and consumed current with respect to request current. That is, the available current is to subtract the consumed current of the peripheral devices  118  and the USB hub device  106  from the supplying current wherein the request current is generating when the USB hub device  106  inquires the host device  102 . 
     The hub function module  112  detects and manages the usage status of the ports  108 . In other words, the hub function module  112  detects whether the ports are in either enable or disable status so that the host device  102  communicates with the peripheral devices  118  and manages the peripheral devices  118  connected to the downstream ports  108 A˜ 108 D. 
     The power management module  110  compares the available current with a request current of the peripheral device  118  to determine whether the available current is greater than the request current when a peripheral device  118  is connected to one of the downstream ports  108 A˜ 108 D. Further, the hub function module  112  determines an execution mode of the port  108  connected to the peripheral device  118  based on the compared result between the available current and the request current. The execution mode is selected from one group consisting of a SuperSpeed mode, a High-Speed mode, a FullSpeed mode and a LowSpeed mode, which are compatible to USB protocol. In one embodiment, the execution mode of the port  108  may be one of a plurality of predetermined current intervals. For example, a first predetermined current interval is lower than 0.1 ampere (A), a second predetermined current interval is between 0.1 and 0.3 ampere (A), a third predetermined current interval is between 0.3 and 0.5 ampere (A), and a fourth predetermined current interval is between 0.5 and 0.9 ampere (A), but not limited. 
       FIG. 1B  is a schematic block diagram of a dynamic power management system  100 B for universal serial bus (USB) hub according to a second embodiment of the present invention. The dynamic power management system  100 B in  FIG. 1B  is similar to the dynamic power management system  100 A in  FIG. 1A . The difference is that the host device  102  and the upstream port  108 E in the dynamic power management system  100 B are omitted and the power unit  104  only provides the supplying current to the USB hub device  106 . In one case, the USB hub device  106  may be a USB hub compound or USB OTG (on-the-go) device. The rest of the components of the dynamic power management system  100 B are the same as these of the dynamic power management system  100 A, which are omitted here. 
     Please refer to  FIG. 2A  and  FIG. 3A .  FIG. 2A  is a schematic block diagram of a dynamic power management system  100 A for universal serial bus (USB) hub and the downgraded execution mode thereof according to one embodiment of the present invention.  FIG. 3A  is a flow chart of a dynamic power management method for universal serial bus (USB) hub and the downgraded execution mode according to one embodiment of the present invention. 
     The dynamic power management method for universal serial bus (USB) hub is applicable to a dynamic power management system  100 A, wherein the dynamic power management system  100 A includes a host device  102 , a power unit  104  generating a supplying current, and a hub device  106  coupled to the host device  102  and the power unit  104 . The hub device  106  has a power management module  110 , a hub function module  112  and a plurality of ports  108 . The dynamic power management method includes the following steps. 
     In step S 300 , a USB hub device  106  is activated. 
     In step S 302 , a communication link between the USB hub device  106  and a host device  102  is established. 
     In step S 304 , the power management module  110  calculates an available current of the USB hub device  106  based on a supplying current. 
     In one embodiment, as shown in  FIG. 2A , the supplying current generated from the power unit  204  is 2.5 ampere (A), the consumed current of the power management module  110  is 0.1 ampere (A), and the consumed current of the first peripheral device  118 A and the second peripheral device  118 B are 0.9 ampere (A), respectively, which are operated in a SuperSpeed mode. Thus, the available current of the USB hub device  106  calculated by the power management module  110  based on the supplying current is 0.6 ampere (A). 
     In step S 306 , the hub function module  112  detects whether a newly added peripheral device  118  is connected to one of a plurality of ports  108  of the USB hub device  106 . If yes, proceed to step S 308  and if no, continuously perform the step S 306 . As shown in  FIG. 2A , the hub function module  112  detects that the added third peripheral device  118 C is connected to the third port  108 C wherein the first and second peripheral devices  118 A,  118 B are connected to the first and second ports  108 A,  108 B, respectively. 
     In step S 308 , the power management module  110  acquires a request current of the added peripheral device  118 . As shown in  FIG. 2A , the power management module  110  acquires a request current, e.g. 0.9 ampere (A) of the added peripheral device  118 C. 
     In step S 310 , the power management module  110  compares the available current with the request current for determining whether the available current is less than the request current. If yes, proceed to step S 312  and if no, proceed to step S 314 . 
     In step S 312 , the hub function module  110  reconnects the added peripheral device  118  to one of the ports and downgrades an execution mode of the port  108  connected to the added peripheral device  118 . The step S 308  is returned. As shown in  FIG. 2A , since the available current 0.6 ampere (A) is less than the request current 0.9 ampere (A), the execution mode of the third port  108 C connected to the third peripheral device  118 C is downgraded. For example, the higher execution mode with the SuperSpeed mode is downgraded to the lower execution mode with the High-Speed mode and the hub function module  110  reconnects the third peripheral device  118 C via the third port  108 C. Meanwhile, because the third port  108 C does not support the higher execution mode with the SuperSpeed mode, the third peripheral device  118 C is connected to the USB hub device  106  with the High-Speed mode based on USB protocol wherein the request current of the peripheral device  118 C is 0.5 ampere (A) which is less than the available current 0.6 ampere (A). 
     In one embodiment, as shown in  FIGS. 2A and 3A  and according to the compared result in step S 310  and the descriptions in step S 312 , the hub function module  110  compares the available current 0.6 (A) with the request current 0.9 (A) and the compared result is that the available current 0.6 (A) is less than the request current 0.9 (A). Meanwhile, the first port  108 A and the second port  108 B are capable of providing the first peripheral device  118 A and the second peripheral device  118 B with their request current. That is, the standard execution modes of the first port  108 A and the second port  108 B correspond to the request current of the first peripheral device  118 A and the second peripheral device  118 B so that the first peripheral device  118 A and the second peripheral device  118 B operate in standard execution modes. For example, the standard execution mode, SuperSpeed mode, maps to the request current 0.9 (A). Further, when the third peripheral device  118 C is connected to the third port  108 C, the third port  108 C cannot provide the third peripheral device  118 C with the request current but can provide a low current which is lower than the request current of third peripheral device  118 C. Thus, the low current corresponds to the downgraded execution mode of the third port  108 C so that the third peripheral device  118 C operates in downgraded execution mode, e.g. High-Speed mode. 
     In another embodiment, as shown in  FIGS. 2A and 3A , when the compared result is that the available current greater than the request current, the third port  108 C is capable of providing the third peripheral device  118 C with the request current. That is, standard execution mode supported by the third port  108 C corresponds to the request current of the third peripheral device  118 C so that the third peripheral device  118 C operates in standard execution mode, e.g. SpuerSpeed mode with the request current 0.9 (A). 
     Therefore, the dynamic power management system  100 A of the present invention performs the steps of the downgraded execution mode based on the compared result between the available current and the request current for dynamically adjusting the status conversion associated with the supplying current of the ports  108 . 
     In step S 314 , the connection between the added peripheral device  118  and the USB hub device  106  is complete. As shown in  FIG. 2A , the connection between the first peripheral device  118 C and the USB hub device  106  is complete. 
     Please refer to  FIGS. 2B and 3B .  FIG. 2B  is a schematic block diagram of a dynamic power management system  100 A for universal serial bus (USB) hub and the upgraded execution mode thereof according to one embodiment of the present invention.  FIG. 3B  is a flow chart of a dynamic power management method for universal serial bus (USB) hub and the upgraded execution mode according to one embodiment of the present invention. For an example of  FIG. 2A , the first port  108 A, the second port  108 B and the third port  108 C are connected to the first peripheral device  118 A, the second peripheral device  118 B and the third peripheral device  118 C wherein the first port  108 A and the second port  108 B are capable of providing the first peripheral device  118 A and the second peripheral device  118 B with the request current respectively. That is, the standard execution modes of the first port  108 A and the second port  108 B correspond to the request current of the first peripheral device  118 A and the second peripheral device  118 B so that the first peripheral device  118 A and the second peripheral device  118 B operate in standard execution modes. For example, the standard execution mode, SuperSpeed mode, maps to the request current 0.9 (A). Further, the third port  108 C cannot provide the third peripheral device  118 C with the request current but can provide a low current which is lower than the request current of third peripheral device  118 C. Thus, the low current corresponds to the downgraded execution mode of the third port  108 C so that the third peripheral device  118 C operates in downgraded execution mode, e.g. High-Speed mode. 
     In one case of  FIG. 3B , the dynamic power management method further includes the following steps after the step S 304  (shown in  FIG. 3A ). 
     In step S 320 , the power management module  110  determines whether the available current is increased. If yes, proceed to step S 322  and if no, proceed to step S 306 . As shown in  FIG. 2B , the available current has the increment of 0.9 (A) when the second peripheral device  118 B is removed from the second port  108 B. 
     In step S 322 , the hub function module  112  checks whether another port of the USB hub device connected to another peripheral device  118  is executed in a downgraded execution mode. If yes, proceed to the step S 324  and if no, proceed to the step S 306 . As shown in  FIG. 2B , the third peripheral device  118 C is connected to the third port  108 C of the USB hub device  106  and operated in downgraded execution mode, e.g. High-Speed mode and the step S 324  proceeds. 
     In step S 324 , the hub device  106  inquires a user whether another peripheral device  118  is reconnected. If yes, proceed to the step S 326  and if no, proceed to the step S 306 . As shown in  FIG. 2B , the hub device  106  inquires a user whether the third peripheral device  118 C is reconnected and it is required to reconnect the third peripheral device  118 C. 
     In step S 326 , the hub function module  112  upgrades the downgraded execution mode of another port  108  of the USB hub device  106  connected to another peripheral device  118 , reconnects another peripheral device  118  to one of the ports  108  and return to the step S 308 . As shown in  FIG. 2B , the hub function module  112  upgrades the downgraded execution mode, e.g. High-Speed mode, of the third port  108 C of the third peripheral device  118 C to the upgraded execution mode, e.g. SuperSpeed mode. Therefore, the dynamic power management system  100 A of the present invention performs the steps of the downgraded execution mode based on the compared result between the available current and the request current for dynamically adjusting the status conversion associated with the supplying current of the ports  108  of the hub device  106 . It should be noted that the procedure of the upgraded execution mode in  FIG. 3B  can be performed after the step S 314  in  FIG. 3A . 
     Please refer to  FIGS. 2C and 3C .  FIG. 2C  is a schematic block diagram of a dynamic power management system  100 A for universal serial bus (USB) hub and the port status conversion thereof according to one embodiment of the present invention.  FIG. 3C  is a flow chart of performing the port status conversion according to one embodiment of the present invention. In one embodiment of  FIG. 2C , the supplying current from the power unit  104  is 2.5 (A), the consumed current of the hub function module  110  is 0.05 (A), and the consumed current of the first, second and third peripheral devices  118 A,  118 B and  118 C, respectively in the execution mode of SuperSpeed is 0.8 (A). Thus, the available current of the USB hub device  106  calculated by the power management module  110  based on the supplying current is 0.05 (A). 
     In one embodiment of  FIG. 3C , the dynamic power management method further includes the following steps after the step S 310  (shown in  FIG. 3A ), i.e. after the power management module  110  compares the available current with the request current and the compared result is that the available current is less than the request current. 
     In step S 340 , the hub function module  112  determines whether the added peripheral device  118  downgrades to a lowest execution mode. If yes, proceed to the step S 342  and if no, proceed to the step S 312 . As shown in  FIG. 3C , the hub function module  112  determines that the fourth peripheral device  118 D downgrades to a lowest execution mode, wherein the fourth peripheral device  118 D supports three kinds of execution modes including SuperSpeed mode, High-Speed mode and FullSpeed mode, and its request current is the lowest execution mode with FullSpeed mode. 
     In step S 342 , the hub function module  112  disables the port  108  connected to the added peripheral device  118 . As shown in  FIG. 3C , since the available current 0.05 (A) is far lower than the request current corresponding to the FullSpeed mode, the fourth port  108 D connected to the fourth peripheral device  118 D is disabled. 
     In step S 344 , the added peripheral device  118  is removed. As shown in  FIG. 3C , the fourth peripheral device  118 D is removed from the fourth port  108 D. 
     In step S 346 , the hub function module  112  enables the port  108  connected to the removed added peripheral device  118 . As shown in  FIG. 3C , after the fourth peripheral device  118 D is removed, the fourth port  108 D connected to the fourth peripheral device  118 D is enabled so that the fourth port  108 D can be provided for other peripheral device. Therefore, the dynamic power management system  100 A of the present invention performs the port status conversion based on the enabling or disabling status of the ports  108  for dynamically adjusting the status conversion associated with the supplying current of the ports  108 . It should be noted that the procedure of the port status conversion in  FIG. 3C  can be performed after the step S 314  in  FIG. 3A . 
     Please refer to  FIGS. 2D and 3D .  FIG. 2D  is a schematic block diagram of a dynamic power management system  100 A for universal serial bus (USB) hub and the status conversion of ports thereof according to another embodiment of the present invention.  FIG. 3D  is a flow chart of performing the port status conversion according to another embodiment of the present invention. In one embodiment of  FIG. 2D , the supplying current from the power unit  104  is 2.5 (A), the consumed current of the hub function module  110  is 0.05 (A), and the consumed current of the first, second and third peripheral devices  118 A,  118 B and  118 C, respectively in the execution mode of SuperSpeed is 0.8 (A). Thus, the available current of the USB hub device  106  calculated by the power management module  110  based on the supplying current is 0.05 (A). 
     In one embodiment of  FIG. 3D , the dynamic power management method further includes the following steps after the step S 314  (shown in  FIG. 3A ), i.e. after the connections between the added peripheral devices  118 A,  118 B,  118   c  and the USB hub device  106  are complete. 
     In step S 360 , the hub function module  112  checks whether the added peripheral device  118  is removed. If yes, proceed to the step S 364  and if no, continuously perform the step S 360 . As shown in  FIG. 3D , the hub function module  112  checks whether at lest one of the first, second and third peripheral devices  118 A,  118 B,  118 C is removed. For example, the second peripheral device  118 B is removed. 
     In step S 364 , the hub function module  112  enables the disabled port  108  connected to the removed added peripheral device  118  and returns to the step S 304  (shown in  FIG. 3A ). As shown in  FIG. 3D , the hub function module  112  enables the disabled fourth port  108 D connected to the removed fourth peripheral device  118 D wherein the fourth port  108 D is disabled originally. 
     In another embodiment of  FIG. 3D , the dynamic power management method further includes the following steps after the step S 314  (shown in  FIG. 3A ), i.e. after the connections between the added peripheral devices  118 A,  118 B,  118   c  and the USB hub device  106  are complete. 
     In step S 362 , the hub function module  112  checks whether a power supplying mode of the added peripheral devices  118  are switched. If yes, proceed to the step S 364  and if no, continuously perform the step S 362 . As shown in  FIG. 3D , the hub function module  112  checks whether a power supplying mode of the added peripheral devices  118 A,  118 B,  118 C are switched. If the hub device  106  provides the power for the peripheral devices  118 , it is termed as bus power mode and if external power source, e.g. battery, provides the power for the peripheral devices  118 , it is defined as self power mode. The hub function module  112  checks whether the bus power mode and the self power mode of the peripheral devices  118  are switched. 
     In step S 364 , the hub function module  112  enables the disabled port  108  connected to the added peripheral device  118  associated with the switched power supplying mode. Therefore, the dynamic power management system  100 A of the present invention performs the port status conversion based on the enabling or disabling status of the ports  108  for dynamically adjusting the status conversion associated with the supplying current of the ports  108 . It should be noted that the procedure of the port status conversion in  FIG. 3D  can be performed after the step S 314  in  FIG. 3A . 
     Based on the above descriptions, the dynamic power management system for universal serial bus (USB) hub and method thereof to perform the port status conversion based on the enabling or disabling the port status by using the power management module for dynamically adjusting the status conversion associated with the supplying current of the ports and to save the cost of the external power source, e.g. transformer, of the hub device. The dynamic power management system performs downgraded execution mode, upgraded execution mode and port status conversion based on power supplying capability of the power unit for dynamically adjusting the port status conversion. 
     As is understood by a person skilled in the art, the foregoing preferred embodiments of the present invention are illustrative rather than limiting of the present invention. It is intended that they cover various modifications and similar arrangements be included within the spirit and scope of the appended claims, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structure.