JP2004213392A - Usb device and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a USB device and a control method thereof capable of supporting a single operation of a plurality of kinds of storage media and improving a user convenience as well as saving power. <P>SOLUTION: The USB device comprises a bus switching means, a detection means, an auxiliary power unit and a power control means. The bus switching means controls a USB connection between a storage medium and a host so that they are physically engaged or disengaged. The detection means detects the storage medium that has been switched and engaged by the bus switching means. The auxiliary power unit is a power source capable of supplying power to the USB device in a system different from that for power supply for the bus. The power control means controls supply by power supply of the bus and the auxiliary power so that in the state before the storage medium is engaged, power supply inside is made only to a minimum functional block based on the detection result by the detection means. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a USB device and a method for controlling a USB device, and more particularly, to a USB device and a method for controlling a USB device that can be equipped with a support for a plurality of types of storage devices and can supply power stably.
[0002]
[Prior art]
[Patent Document 1] Japanese Patent Application Laid-Open No. 2000-29544 In recent years, many USB devices for external connection that support a plurality of types of storage media have been found. This is because with the spread of small portable devices such as digital cameras, the demand for compact USB devices capable of handling a plurality of types of storage media such as a memory stick and a compact flash (registered trademark) (hereinafter abbreviated as CF) as storage media has increased. . Some USB devices for external connection take a form in which power is supplied from a host (a system main body to which the USB device is connected), and omit a power supply circuit and a cable for AC / DC conversion. Since the current capacity that can be supplied to these USB devices by the host is limited (500 mV / 5 V according to the USB standard), the functions that can be realized within the current capacity of the USB device are naturally limited. For example, control of a plurality of types of storage media requires a large current, which is difficult to realize.
[0003]
Therefore, according to Patent Literature 1, a rechargeable battery device is provided in a USB device, and power is supplied from the battery device when the current is insufficient during the operation of the USB device.
[0004]
[Problems to be solved by the invention]
However, in Patent Document 1, power management is not conscious of power saving, and consideration is not given to a portable terminal or the like. Although each type of storage media supported operation independently, it could not support simultaneous operation. In addition, there is an inadequacy in coping with a usage exceeding a range of power supply capability supplied from a host via a USB interface.
[0005]
The present invention has been made to solve these problems. A USB device and a control of a USB device which can support independent operation of each of a plurality of types of storage media, can improve user-friendliness at the same time, and can save power. The aim is to provide a method.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, a plurality of types of storage media can be mounted to the host by USB connection, and communication between the mounted storage media and the host is performed, and bus power is supplied from the bus. The USB device of the present invention is operated by a bus switching means for controlling a USB connection between a storage medium and a host so that the USB connection can be joined or detached from hardware, and a storage device switched and mounted by the bus switching means. Detecting means for detecting the media, auxiliary power capable of supplying power to the USB device in a system separate from the bus power supply, and minimizing internal power supply based on the detection result by the detecting means before the storage medium is mounted. Power supply control means for controlling the supply by the bus power supply and the auxiliary power supply so as to perform only the It is characterized in that. Therefore, the power supply to the device is minimized until the storage medium is mounted, and the battery-powered personal computer can be driven for a long time by saving power, and the operation of each of a plurality of types of storage media can be supported independently. At the same time, user convenience can be improved and power consumption can be reduced.
[0007]
Further, it has a current value calculating means for calculating a required current capacity when a plurality of storage media are mounted. When the total current capacity obtained by the current value calculation means exceeds the supply of the bus power that can be supplied from the host, the power supply control means adds the supply power of the auxiliary power to the supply power of the bus power and supplies the power to the storage medium. If the power is less than the above, the supply by the bus power and the auxiliary power is controlled so that only the supply power of the bus power is sufficient. Therefore, even when a plurality of storage media are mounted and the power required for control is not sufficient to be supplied by the bus power supply from the host, the operation can be performed by using the auxiliary power supply together with the bus power supply, When the storage medium is not mounted, unnecessary power consumption of the host can be reduced.
[0008]
Further, by configuring the auxiliary power supply with a secondary battery, the USB device can be compactly configured. In addition, the provision of the charging means for charging the auxiliary power supply allows the host to use the USB interface to charge the auxiliary power supply, thereby facilitating charging. Further, the charging performed by the charging unit is performed using an excess current other than that supplied to the USB device when the total current capacity is lower than the supply power of the bus power supply that can be supplied from the host, or performed by the charging unit. Since the charging is performed when the storage medium is not mounted, the charging is automatically performed using the vacant current capacity of the bus power supply, so that the operation of the user can be omitted.
[0009]
Further, according to the USB device control method as another invention, the USB connection between the storage medium and the host is controlled by a bus switching step of controlling the USB connection to be connectable or detachable by hardware, and a bus switching step, A bus power supply for detecting a mounted storage medium and a power supply for supplying only internal power to a minimum number of functional blocks based on a detection result of the detection step before the storage medium is mounted. And a power supply control step of controlling the supply of auxiliary power that can supply power to the USB device in a system different from the bus power supply. Therefore, the independent operation of each of the plurality of types of storage media can be supported, and at the same time, the usability of the user can be improved and the power can be saved.
[0010]
Further, the method includes a current value calculating step of calculating a required current capacity when a plurality of storage media are mounted. Then, when the total current capacity obtained in the current value calculation step in the power supply control step exceeds the supply of the bus power supply that can be supplied from the host, the supply power of the auxiliary power supply is supplied to the storage medium in addition to the supply power of the bus power supply. If it is less than the above, the supply by the bus power and the auxiliary power is controlled so that only the supply power of the bus power is sufficient. Therefore, even when a plurality of storage media are mounted and the power required for control is not sufficient to be supplied by the bus power supply from the host, the operation can be performed by using the auxiliary power supply together with the bus power supply, When the storage medium is not mounted, unnecessary power consumption of the host can be reduced.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
The USB device of the present invention detects a mounted storage medium which is switched by the bus switching means for controlling the USB connection between the storage medium and the host so that the USB connection can be connected or detached by hardware, and which is mounted. A detection unit, an auxiliary power supply that can supply power to the USB device in a system separate from the bus power supply, and an internal power supply into a minimum functional block based on a detection result by the detection unit before the storage medium is mounted. Power supply control means for controlling the supply by the bus power supply and the auxiliary power supply.
[0012]
【Example】
FIG. 1 is a block diagram showing a configuration of a USB device according to one embodiment of the present invention. In the figure, the USB device 100 of the present embodiment is assumed to be a USB device having a function of controlling a plurality of types of storage media 200, for example, a memory stick 201, a CF 202, a smart media 203, a PC card 204, an FDD 205, and the like. ing. The USB device 100 has a CPU 101 as a core, communicates with the host 300 through the USB interface unit 102 that supports a communication flow conforming to the USB standard, and transmits data to each of the storage control units 105 to 109. Send and receive.
The code ROM 103 holds firmware for operating the USB device 100 for each storage control. The RAM 104 has an area for executing firmware and an area for storing a firmware program downloaded from the code ROM 103 via the USB interface unit 102. Normally, the firmware program is moved from the ROM area to the RAM area in order to reduce the execution time of the firmware program. The memory stick control unit 105, the CF control unit 106, the smart media control unit 107, the PC card control unit 108, and the FDD control unit 109 correspond to the storage media 200 of the memory stick 201, the CF 202, the smart media 203, the PC card 204, and the FDD 205, respectively. It performs control and is connected to the bus switching control unit 110. The bus switching control unit 110 implements a connection to one of the plurality of types of storage media 200 and the USB interface unit 102 by hardware. The interface connector 111 is an interface connector of the storage media 200 of the memory stick 201, CF 202, smart media 203, PC card 204, and FDD 205, respectively, detects that each storage medium is mounted, and transmits the information to the USB interface unit 102. And a function of transmitting power to the power supply control unit 112. The power control unit 112 has a function of being supplied with power from the USB port 113 and individually supplying the functional blocks of the USB device 100 individually. The power control unit 112 has two power input lines so as to receive power supply from the USB port 113 and receive auxiliary power from the auxiliary power supply 115, and controls the power input lines. The auxiliary power supply 115 is configured as a secondary battery, and can be charged by the charge control unit 116. From the USB port 113, the power supply line is called bus power, and is specified by the USB standard to have a maximum of 500 mA. As shown in FIG. 2, the current capacity table 114 enumerates a list of current capacities required for controlling each storage medium, and refers to the information in the current capacity table to determine the necessary current capacities as USB devices. Has a mechanism to calculate the sum of
[0013]
Next, a control operation of the present embodiment will be described with reference to FIG. 3 showing a control flow in the USB device of the present embodiment. First, when power is turned on to the host in FIG. 1 (step S101). At this time, only the circuit for detecting the attachment of the storage medium 200 of the power supply control unit 112 and the interface connector 111 of FIG. 1 is operated through the bus power, and the other blocks do not consume current. When various media are attached to the interface connector 111 (Step S102; YES), a media detection signal is notified to the power control unit 112 (Step S103), and based on the information, the power control unit 112 The required current capacity of the USB device 100 is calculated with reference to the current capacity of the target storage device 200 (step S104). For example, when the memory stick 201 and the PC card 204 are mounted, it is possible to calculate 100 mA + 200 mA + 300 mA = 600 mA from the current capacity table shown in FIG. Then, the power control unit 112 determines whether or not the total of the current capacities at this time exceeds the upper limit of the aforementioned USB standard of 500 mA (step S105). If the power is not supplied by the USB device 100 alone (step S106) and exceeds the power (step S105; YES), the auxiliary power from the auxiliary power supply 115 is also added to the bus power to supply the power to the USB device 100 (step S106). Step S107). As for the power supply, blocks unnecessary for driving the attached storage medium 200 are turned off, so that unnecessary current consumption can be suppressed. After that, the USB device 100 is initialized from the host 300 and becomes usable (Step S108). On the other hand, the charging of the auxiliary power supply 115 by the charging control unit 116 in FIG. 1 uses bus power. In particular, the surplus current is used when nothing is attached to the storage medium. It is determined whether or not the auxiliary power supply 115 is sufficiently charged (step S109). If it is not enough (step S109; NO), charging is performed using the pass power (step S110). S109; YES), the process proceeds to the initialization flow of the USB device 100 (step S108). Even after the initialization of the USB device 100 is completed, the mounting of the medium is constantly monitored (step S111). If a change occurs (step S111; YES), the process returns to step S102 as needed to confirm the type of the mounted medium. I do.
[0014]
It should be noted that the present invention is not limited to the above embodiment, and it goes without saying that various modifications and substitutions can be made within the scope of the claims.
[0015]
【The invention's effect】
As described above, a plurality of types of storage media can be mounted to the host by USB connection, perform communication between the mounted storage media and the host, and operate by supplying bus power from the bus. A USB device according to the present invention includes a bus switching unit that controls a USB connection between a storage medium and a host so that the USB connection can be joined or detached by hardware, and detects the mounted storage medium switched by the bus switching unit. Detection means, an auxiliary power supply that can supply power to the USB device in a system separate from the bus power supply, and a minimum functional block based on the detection result of the detection means by the internal power supply before the storage medium is mounted. Power supply control means for controlling the supply by the bus power supply and the auxiliary power supply. It is characterized in. Therefore, the power supply to the device is minimized until the storage medium is mounted, and the battery-powered personal computer can be driven for a long time by saving power, and the operation of each of a plurality of types of storage media can be supported independently. At the same time, user convenience can be improved and power consumption can be reduced.
[0016]
Further, it has a current value calculating means for calculating a required current capacity when a plurality of storage media are mounted. When the total current capacity obtained by the current value calculation means exceeds the supply of the bus power that can be supplied from the host, the power supply control means adds the supply power of the auxiliary power to the supply power of the bus power and supplies the power to the storage medium. If the power is less than the above, the supply by the bus power and the auxiliary power is controlled so that only the supply power of the bus power is sufficient. Therefore, even when a plurality of storage media are mounted and the power required for control is not sufficient to be supplied by the bus power supply from the host, the operation can be performed by using the auxiliary power supply together with the bus power supply, When the storage medium is not mounted, unnecessary power consumption of the host can be reduced.
[0017]
Further, by configuring the auxiliary power supply with a secondary battery, the USB device can be compactly configured. In addition, the provision of the charging means for charging the auxiliary power supply allows the host to use the USB interface to charge the auxiliary power supply, thereby facilitating charging. Further, the charging performed by the charging unit is performed using an excess current other than that supplied to the USB device when the total current capacity is lower than the supply power of the bus power supply that can be supplied from the host, or performed by the charging unit. Since the charging is performed when the storage medium is not mounted, the charging is automatically performed using the vacant current capacity of the bus power supply, so that the operation of the user can be omitted.
[0018]
Further, according to the USB device control method as another invention, the USB connection between the storage medium and the host is controlled by a bus switching step of controlling the USB connection to be connectable or detachable by hardware, and a bus switching step, A bus power supply for detecting a mounted storage medium and a power supply for supplying only internal power to a minimum number of functional blocks based on a detection result of the detection step before the storage medium is mounted. And a power supply control step of controlling the supply of auxiliary power that can supply power to the USB device in a system different from the bus power supply. Therefore, the independent operation of each of the plurality of types of storage media can be supported, and at the same time, the usability of the user can be improved and the power can be saved.
[0019]
Further, the method includes a current value calculating step of calculating a required current capacity when a plurality of storage media are mounted. Then, when the total current capacity obtained in the current value calculation step in the power supply control step exceeds the supply of the bus power supply that can be supplied from the host, the supply power of the auxiliary power supply is supplied to the storage medium in addition to the supply power of the bus power supply. If it is less than the above, the supply by the bus power and the auxiliary power is controlled so that only the supply power of the bus power is sufficient. Therefore, even when a plurality of storage media are mounted and the power required for control is insufficient to be supplied by the bus power supply from the host, the operation can be performed by using the auxiliary power supply together with the bus power supply, When the storage medium is not mounted, unnecessary power consumption of the host can be reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a USB device according to one embodiment of the present invention.
FIG. 2 is a diagram showing information of a current capacity table.
FIG. 3 is a flowchart illustrating a control operation in the USB device of the present embodiment.
[Explanation of symbols]
100; USB device, 101; CPU,
102; USB interface unit, 103; code ROM,
104; RAM, 105; Memory Stick control unit,
106; CF control unit, 107; smart media control unit,
108; PC card control unit; 109; FDD control unit;
110: bus switching control unit, 111: interface connector,
112: power supply control unit, 113: USB port, 114: current capacity table,
115; auxiliary power supply; 116; charging control unit; 200; storage medium;
201; memory stick, 202; CF,
203; smart media, 204; PC card, 205; FDD,
300; host.

Claims (8)

In a USB device, a plurality of types of storage media can be mounted to the host by USB connection, and communication between the mounted storage medium and the host is performed, and the USB device operates by supplying bus power from the bus.
Bus switching means for controlling a USB connection between the storage medium and the host so that the USB connection can be joined or detached by hardware;
Detecting means for detecting a storage medium switched and mounted by the bus switching means;
An auxiliary power supply capable of supplying power to a USB device in a separate system from the bus power supply;
Power supply control for controlling the supply of the bus power and the auxiliary power in order to supply the internal power to only the minimum function blocks based on the detection result by the detection means in a state before the storage medium is mounted. A USB device. When a plurality of storage media are mounted, the storage medium has a current value calculation unit for calculating a required current capacity, and the power supply control unit can supply the total current capacity obtained by the current value calculation unit from the host. The power supply of the auxiliary power supply is supplied to the storage medium in addition to the supply power of the bus power supply when the supply power of the bus power supply exceeds the supply power of the bus power supply. The USB device according to claim 1, wherein the USB device controls supply by an auxiliary power supply. The USB device according to claim 1, wherein the auxiliary power supply includes a secondary battery. The USB device according to claim 1, further comprising a charging unit that charges the auxiliary power. The charging performed by the charging unit is performed using an excess current other than that supplied to a USB device when the total current capacity is lower than the supply power of a bus power supply that can be supplied from the host. USB device. The USB device according to claim 5, wherein the charging performed by the charging unit is performed when the storage medium is not mounted. A plurality of types of storage media can be mounted to the host by USB connection, and communication between the mounted storage media and the host is performed, and a USB device that controls operation by supplying bus power from the bus is controlled. In the method,
A bus switching step of controlling a USB connection between the storage medium and the host so that the USB connection can be joined or detached by hardware;
A detecting step of detecting a storage medium switched and attached by the bus switching step;
In order to supply power internally only to the minimum function blocks based on the detection result of the detection step before the storage medium is mounted, the bus power supply, and a USB device in a different system from the bus power supply. A power control step of controlling the supply of the auxiliary power capable of supplying power to the USB device. A current value calculating step of calculating a required current capacity when a plurality of the storage media are mounted, wherein a total current capacity obtained by the current value calculating step in the power control step can be supplied from the host; The supply power of the auxiliary power supply is supplied to the storage medium in addition to the supply power of the bus power supply when the supply power of the bus power supply is exceeded, and the supply of the bus power supply and the auxiliary The method for controlling a USB device according to claim 7, wherein the supply by a power supply is controlled.

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