JP2014130424A - Electronic apparatus, and device connection propriety determination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the device connection propriety determination considering the state of a USB device connected to a USB port of a USB host, when the USB host is switched from normal operation mode to power-saving mode.SOLUTION: When a new USB device is connected to a USB port 103-1 or 103-2, a USB host 10 measures and stores actual use current values of the USB device in normal operation mode and power-saving mode (U0, U1, U2, U3 or the like). When the normal operation mode is switched to the power-saving mode, the USB host 10 compares the usable current value in the power-saving mode in the USB port 103-1 or 103-2 with the actual use current value required in the power-saving mode of the USB device connected to the USB port 103-1 or 103-2, and determines the connection propriety of the UBS device.

Description

  The present invention relates to an electronic apparatus having a device connection port such as a USB port and a device connection possibility determination method.

  An electronic device having a USB port is referred to as a UBS host or simply a host, and a device connected to the USB port is referred to as a USB device or simply a device. Moreover, electric power and electric current are synonymous.

  In the USB host, the maximum use current of the USB port is determined, and a device exceeding this maximum use current cannot be connected. On the other hand, a set value of the maximum use current required for the USB device is determined, and the USB host can know the maximum use current of the connection destination device by referring to this set value. . Therefore, in the USB host, control is performed so that devices exceeding the maximum use current of the USB port are not connected by the set value of the maximum use current of the connection destination device.

  However, in general, the set value of the maximum use current of the device is estimated to be larger than the actual use current. In practice, the device does not always consume the maximum working current. Therefore, even if the set value of the maximum use current of the device exceeds the maximum use current of the USB port on the host side, it is not always possible to connect. If the determination of whether or not a USB device can be connected is performed based on the setting value of the maximum use current, it may occur that the device can be connected but cannot be connected.

  In order to solve this problem, for example, in Patent Document 1, when a device is connected to a USB port, the sum of the actual use currents of the devices connected to the port is detected, and the sum of the actual use currents and the port A technology that compares the maximum operating current and determines whether it can be connected by referring to the specified current value of the device to be connected (set value of the maximum operating current) if the total of the actual operating current does not exceed the maximum operating current of the port Is disclosed. Further, this Patent Document 1 discloses a technique for disconnecting a device having a low priority when the sum of actual use currents of devices connected to a port exceeds the maximum use current of the port.

  In recent years, USB 3.0 has newly appeared in the USB standard, and switching from USB 2.0, which is the conventional USB standard, to USB 3.0 is being promoted. In USB 3.0, the maximum value of the supply current is changed from 500 mA of USB 2.0 to 900 mA. Furthermore, in USB 3.0, the use of power saving (energy saving) is newly formulated. That is, in USB 2.0, only the normal activation mode (U0) and the suspend mode (U3) as the normal operation mode were used, but in USB 3.0, the two modes U1 and U2 are the link layers at the intermediate level between U0 and U3. It is adopted as an energy-saving mode that disconnects the physical layer. The U1 and U2 modes consume less power (current) than the U0 mode.

  On the other hand, in recent years, in an electronic device such as an image forming apparatus (MFP or the like), in order to increase the power saving effect, the electronic device can be switched from the normal power consumption mode to the standby power consumption mode or the power consumption further depending on the usage conditions. It has become common to adopt a method of switching to a low power consumption mode to be suppressed. Here, the standby power consumption mode and the low power consumption mode are collectively referred to as a power saving mode (energy saving mode).

  When the electronic device is switched to the energy saving mode, the power supplied to the USB device connected to the electronic device (host) also decreases. However, depending on the device, even when the host side is switched to the energy saving mode, there is a device that needs to be in the normal activation mode (U0), and a device that can be switched to the modes U1 to U3. However, in a device that needs to be in the normal startup mode even if the host side is in the energy saving mode, if the necessary power (current) is not supplied, the operation becomes unstable or becomes inoperable. On the other hand, in the U1-U3 mode, the power consumption may be smaller than that in the U0 mode. Therefore, when the host side switches to the energy saving mode, it is necessary to determine whether or not connection is possible according to the power consumed by the connected USB device.

  In Patent Literature 1, when the host side is switched to the energy saving mode, it is not considered to control whether the connection is possible based on the actual use current of the connected device in the energy saving mode. For this reason, when the host side is switched to the energy saving mode, the necessary power is not supplied to a device or the like that needs to be in the normal startup mode, causing a problem that the operation becomes unstable or becomes inoperable.

  In the present invention, in an electronic device having a device connection port such as a USB port, when the electronic device is switched to the energy saving mode, whether or not the device can be connected in consideration of an actual use current in the energy saving mode of the connected device. Is to solve the above problems.

  The present invention relates to an electronic device that includes a device connection port, and in which the usable current value of the port changes in the normal operation mode and the power saving mode. Means for storing a current value, and a usable current value in the power saving mode of the port and an actual used current value required in the power saving mode of the device connected to the port when the mode is switched to the power saving mode. And a means for determining whether or not a device can be connected.

  According to the present invention, when an electronic device is switched to the energy saving mode, it is determined whether connection is possible or not by determining whether or not the device can be connected in consideration of the actual use current value in the energy saving mode of the connected device. Operation is guaranteed.

It is a hardware block diagram of the system which concerns on one Embodiment of this invention. It is a whole processing flow figure at the time of a new device connection. It is a detailed flowchart of the measurement process of the actual use electric current value of FIG. It is a detailed flowchart of the device connection availability determination process of FIG. It is a figure which shows the correspondence example of the power state of a USB host and a USB device. FIG. 11 is a detailed flowchart of device connection availability determination processing when the USB host shifts to an energy saving mode. It is a figure explaining the priority of a USB device. It is a figure which shows an example of the setting screen of a display part.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the embodiment, a system including an electronic device having a USB port and a USB device connected to the electronic device is targeted. However, the present invention is not limited to such a system. The present invention can be applied to a system that generally includes a device connection port and includes an electronic device that is in a normal operation mode and a power saving mode, and a device connected thereto.

  FIG. 1 is a diagram illustrating a hardware configuration of a system according to an embodiment of the present invention. In FIG. 1, reference numeral 10 denotes an electronic apparatus (hereinafter referred to as a USB host) having a USB port as a device connection port, 20 denotes a USB hub, and 30 denotes a USB device. The USB host 10 includes a main power supply device 101, a USB power supply unit 102, USB ports 103-1, 103-2, current measuring devices 104-1, 104-2, a CPU 105, a ROM 106, a RAM 107, a device controller 108, and an input unit. 109, a display unit 110, and the like.

  The main power supply apparatus 101 is a main power supply unit (PSU) that supplies power to each unit of the USB host 10, the USB device 30, and the like. The power supply amount of the main power supply device 101 varies depending on the normal operation mode and the power saving mode (energy saving mode) of the USB host 10. In the energy saving mode, for example, not only the electronic circuit of the control system but also the power of the fundamental power supply part is reduced. Thereby, energy saving with a large effect is realized by reducing the amount of power supply of the entire system.

  The USB power supply unit 102 receives power from the main power supply unit (PSU) 101 and supplies power to the USB device 30 via the USB hub 20 or directly through the USB ports 103-1 and 103-2. The power supplied from the USB power supply unit 102 to the USB device 30 varies according to the change in the power supply amount of the main power supply device 101.

  The USB ports 103-1 and 103-2 are host-side terminals for connecting the USB device 30 via the USB hub 20 or directly. In FIG. 1, the number of USB ports is two, but one or more may be used. Further, although three USB devices are connected to the USB hub 20, it is not necessary to have three USB devices.

  In the USB port, the current value (maximum value) that can be passed is limited. That is, the upper limit is 500 mA for USB 2.0 and 900 mA for USB 3.0. Within a range not exceeding the upper limit, one or a plurality of USB devices can be connected directly or via a USB hub to the USB port. In USB 3.0, two power saving modes (energy saving modes) U1 and U2 for disconnecting the link layer and the physical layer are added between the normal startup mode (normal operation mode) U0 and the suspend mode U3. . In the present embodiment, the USB ports 103-1 and 103-2, the USB hub 20, and the USB device 30 are assumed to conform to USB 3.0.

  Current measuring devices 104-1 and 104-2 measure current values of USB ports 103-1 and 103-2, respectively. By measuring the current values of the USB ports 103-1 and 103-2, the actual use current value of the USB device 30 connected to the USB ports 103-1 and 103-2 directly or via the USB hub 20 is known. Can do.

  The CPU 105 controls each unit in the USB host 10 and executes predetermined processing. A program for processing by the CPU 105 is stored in the ROM 106. In the present embodiment, the CPU 105 functions as means for determining whether or not a device can be connected when a new USB device is connected or when the USB host 10 is switched to the energy saving mode.

  A ROM 106 is a non-volatile memory, and stores a program for processing by the CPU 105. The ROM 106 stores information necessary for processing by the CPU 105, a table, and the like. In this embodiment, the ROM 106 corresponds to a mode (any one of U0, U1, U2, U3, etc.) that can be taken by each USB device 30 for each power mode (normal operation mode, power saving mode, etc.) of the USB host 10. Remember the table. The ROM 106 stores the priority of each USB device 30. Further, the ROM 106 stores actual use current values in the normal operation mode and the power saving mode of each USB device 30 (U0, U1, U2, U3, etc.).

  A RAM 107 is a volatile memory and is used as a working memory for the CPU 105. The program in the ROM 106 is executed by the CPU 105 by being loaded into the RAM 107.

  The device controller 108 directly controls the USB device 30 via the USB ports 103-1 and 103-2 and the USB hub 20. For example, the device controller 108 controls whether or not the USB device 30 can be connected. If the connection is refused, the USB device 30 is turned off so that no current is supplied. The device controller 108 also controls the mode switching of the USB device 30. Further, the device controller 108 performs connection monitoring and recognition of the USB device 30.

  The input unit 109 includes an operation panel and operation buttons. The user uses this input unit 109 to set the priority of the USB device 30 and the energy saving mode.

  The display unit 110 is a liquid crystal display (LCD) or the like, and displays various setting screens and information. The input unit 109 and the display unit 110 may be configured integrally.

  Hereinafter, in the hardware configuration of FIG. 1, a device connection availability determination processing operation when a USB device is newly connected and a USB host is switched to the energy saving mode according to an embodiment of the present invention will be described. This is also a description of the processing operation of the device connection possibility determination method according to an embodiment of the present invention.

  First, with reference to FIG. 2 to FIG. 4, device connection availability determination processing operation when a new USB device is connected will be described.

  FIG. 2 is a diagram showing an overall processing flow when a USB device is newly connected. In the following, it is assumed that a USB device is newly connected to the USB hub 20. That is, it is assumed that a new USB device is connected to the USB port 103-1. In addition, the USB host 10 is set to the normal operation mode, and in the normal operation mode, all the USB devices are operated in the U0 mode.

  When the device controller 108 recognizes that a new USB device (hereinafter referred to as a new USB device) is connected to the USB port 103-1, the configuration information (device ID, vendor ID, etc.) of the new USB device is unique to the USB device. (Information set in (1)) is confirmed (step 1001). Then, the device controller 108 notifies the CPU 105 that the new USB device is connected and the configuration information of the new USB device.

  The CPU 105 checks whether the actual use current value of the new USB device (measurement result of the actual use current value when connected previously) is stored in the ROM 106 based on the device ID or the like (step 1002). The actual use current value of each mode (U0, U1, U2, U3, etc.) of the USB device already connected to the USB port 103-1 (hereinafter referred to as an already connected USB device) is an actual use current value measurement process described later. In the case where the new USB device is a device to be connected for the first time, the actual use current value of the device does not exist in the ROM 106.

  When the actual usage current value of the new USB device is already stored in the ROM 106 (the device has been connected before), the CPU 105 determines the actual usage current value of the new USB device and the existing USB device in the ROM 106 ( The determination as to whether or not a new USB device can be connected is immediately started using the U0 mode actual use current value (step 1003). On the other hand, if the actual use current value of the new USB device is not stored in the ROM 106, the CPU 105 measures the actual use current value of the new USB device (step 1004) and then determines whether or not the new USB device or the like can be connected again. Determination is started (step 1004).

  FIG. 3 is a diagram showing a detailed processing flow for measuring the actual use current value of the new USB device. When measuring the actual use current value of the new USB device, the USB host 10 side temporarily shifts to the device recognition mode.

  When shifting to the device recognition mode, the CPU 105 temporarily connects all USB devices (existing USB devices) connected to the current USB port 103-1 (USB hub 20) other than the new USB device through the device controller 108. Turn it off (step 2001). Next, the CPU 105 measures the actual use current value in each mode (U0, U1, U2, U3, etc.) of the normal operation mode and the power saving mode of the new USB device (step 2002). Specifically, the CPU 105 sequentially switches the new USB device to each mode of U0, U1, U2, and U3 through the device controller 108 to operate. At the same time, the CPU 105 instructs the current measuring device 104-1 to sequentially measure the actual use current value in each mode of the new USB device.

  Next, the CPU 105 stores the actual use current value of each mode of the new USB device measured by the current measuring device 104-1 in the ROM 106 (step 2003). The ROM 106 stores actual use current values in each mode (U0, U1, U2, U3, etc.) in association with USB device recognition information (device ID, etc.).

  Next, the CPU 105 turns off the connection of the new USB device once through the device controller 108 (step 2004), and returns the already connected USB device that has been previously connected off to the connection on again (step 2005).

  Thus, the device recognition mode for measuring the actual use current value in each of the normal operation mode and the power saving mode (U0, U1, U2, U3, etc.) of the new USB device is completed.

  With the measurement process of the actual use current value in FIG. 3, the actual use current value in the normal mode and the power saving mode of the USB device connected before is always held in the ROM 106. Depending on the storage capacity of the ROM 106, the data on the actual use current value may be deleted for a USB device that has been connected before but is not connected for a long time.

  FIG. 4 is a diagram illustrating a specific processing flow according to an embodiment of device connection availability determination processing when a new USB device is connected.

  The CPU 105 obtains configuration information (device ID, vendor ID, etc.) of the USB device already connected to the USB port 103-1 (USB hub 20) (device ID, vendor ID, etc.) through the device controller 108 (step 3001). ). Next, the CPU 105 reads the actual use current value (measurement result of the actual use current value at U0) of each connected USB device from the ROM 106 based on the device ID and the like (step 3002). Further, based on information (device ID and the like) of the new USB device already notified from the device controller 108, the CPU 105 actually uses the current value of the new USB device (measurement result of the actual current value used at U0). Are read from the ROM 106 (step 3003).

  Next, the CPU 105 calculates the sum of the actual use current values of the new USB device and the already connected USB device (step 1004), and uses the sum of the actual use current values as the maximum use assigned to the USB port 103-1. It is compared with the current value (the current value that can be used in the normal operation mode of the port) (step 3005). Note that the maximum usable current value of the USB ports 103-1 and 103-2 and the usable current value in the energy saving mode described later are stored in the ROM 106 in advance.

  If the sum of the actual use current values of the new USB device and the already connected USB device is less than or equal to the maximum use current value of the USB port 103, the CPU 105 permits connection of the new USB device (step 3006). The device connection availability determination process is terminated.

  On the other hand, if the sum of the actual use current values of the new USB device and the connected USB device exceeds the maximum use current value of the USB port 103-1, the CPU 105 compares the priorities of the new USB device and the connected USB device. (Step 3007). The priority will be described later. Here, if the priority of the new USB device is the lowest, the connection of the new USB device is rejected (step 3008), and the device connection possibility determination process is terminated. If the priority of the new USB device is not the lowest, the CPU 105 selects the USB device having the lowest priority from the already connected USB devices (step 3009), and rejects the selected USB device (step 3009). 3010).

  After step 3010, the process returns to step 3004. At this time, in step 3004, the total sum of the actual use current values (measurement results of the actual use current value of U0) between the new USB device and the already connected USB device other than the connection rejection target is calculated. The processing after step 3005 is the same as described above, and will be omitted.

  The CPU 105 sends a device connection availability determination result to the device controller 108. The device controller 108 turns on / off the USB port 103-1, that is, the new USB device or the already connected USB device in the USB hub 20 based on the device connection possibility determination result from the CPU 105.

  Next, the device connection availability determination processing operation when the power state of the USB host 10 is switched from the normal operation mode to the energy saving mode (power saving mode) will be described. Here, the USB device 103-1, that is, the USB device connected to the USB hub 20 will be described as an example.

  When the USB host 10 is switched from the normal operation mode to the energy saving mode, the maximum use current value assigned to the USB port 103-1 decreases. On the other hand, when the USB host 10 is switched to the energy saving mode, the USB device connected to the USB port 103-1 needs to be in the U0 mode or may be switched to the U1 to U3 mode. There is also.

  FIG. 5 shows a correspondence example of the power states of the USB devices connected to the USB host 10 and the USB port 103-1. Here, it is assumed that the power state of the USB host 10 includes a normal operation mode and energy saving modes A and B. The power consumption decreases in the order of the normal operation mode, the energy saving mode A, and the energy saving mode B. It is assumed that the USB devices connected to the USB port 103 are 1 to 3, all of which comply with USB 3.0 and the power state is any of the U0 to U3 modes. The power consumption decreases in the order of U0, U1, U2, and U3.

  Assume that the correspondence table of the power states of the USB devices connected to the USB host 10 and the USB port 103-1 as shown in FIG. As described above, the ROM 106 also stores actual use current values in the U0 to U3 modes of the respective USB devices connected to the USB port 103-1.

  Although not described in the description of the device connection possibility determination process when the USB device is newly connected, the CPU 105 refers to the correspondence table as shown in FIG. 5 and is in the normal operation mode of the USB port 10. Any USB device recognizes that it is in the U0 mode.

  FIG. 6 is a diagram illustrating a specific processing flow according to an embodiment of the device connection possibility determination process when the power state of the USB host 10 is switched from the normal operation mode to the energy saving mode (A or B in FIG. 5). is there.

  The CPU 105 acquires configuration information (device ID, vendor ID, etc.) of the USB device connected to the USB port 103-1 (hereinafter referred to as connected USB device) through the device controller 108 (step 4001). Next, the CPU 105 reads from the ROM 106 the actual use current value necessary for the USB host 10 in the energy saving mode for each connected USB device based on the device ID and the like (step 4002). For example, in the example of the correspondence table of FIG. 5, if the USB host 10 is in the energy saving mode A, the actual usage current value of U0 (measurement result of the actual usage current value at U0) for the USB device 1, the USB device For U2, the actual usage current value of U2 (measurement result of the actual usage current value at U2) is acquired, and for USB3, the actual usage current value of U1 (measurement result of the actual usage current value at U1) is acquired. Similarly, when the USB host 10 is in the energy saving mode B, the actual use current value of U1 (measurement result of the actual use current value at U1) for the USB device 1 and U3 for the USB devices 2 and 3 The actual use current value (measurement result of the actual use current value at U3) is acquired.

  Next, the CPU 105 calculates the sum of the actual use current values required in the energy saving mode of each connected USB device (step 4003), and calculates the sum of the current values in the energy saving mode of the USB port 103-1. It is compared with the usable current value (maximum usable current value in the energy saving mode) (step 4004). Then, the CPU 105 maintains the connection state for all the connected USB devices if the sum of the necessary current values of the connected USB devices in the energy saving mode is equal to or less than the usable current values in the energy saving mode of the USB port 103-1. Then (step 4005), the device connection possibility determination process is terminated.

  On the other hand, when the sum of the actual use current values required in the energy saving mode of the connected USB device exceeds the usable current value in the energy saving mode of the USB port 103-1, the CPU 105 The USB device with the lowest priority is selected (step 4006), and the selected USB device is rejected (step 4007). Then, the CPU 105 holds the information (device ID, vendor ID, etc.) of the rejected USB device in the RAM 107 (step 4008).

  After the process of step 4008, it is confirmed whether all the connected USB devices have been selected. If there remains any unselected USB devices, the process returns to step 4003, and if not, the device connection availability determination process ends.

  Here, when returning to step 4003, in step 4003, for the remaining connected USB devices other than the connection rejection target, the sum of actual use current values required in the energy saving mode is calculated again. The processing after step 4004 is the same as described above, and will be omitted.

  The CPU 105 sends a device connection availability determination result to the device controller 108. The device controller 108 maintains the connection of all USB devices connected to the USB port 103-1, that is, the USB hub 20, or a part or all of the USB devices based on the device connection determination result from the CPU 105. Turn off the connection. In addition, about the USB device which maintains a connection, according to the electric power state required in the said energy saving mode, it switches to modes, such as U0 and U1, U2.

  Thereafter, when the USB host 10 returns to the normal operation mode, the CPU 105 checks whether there is information on the USB device whose connection is refused in the RAM 107 or the like. If there is information on the USB device whose connection has been rejected, the USB device information is sent to the device controller 108. In response to this, the device controller 108 reconnects the USB device.

  As described above, focusing on the USB device connected to the USB port 103-1 of the USB host 10 via the USB hub 20, when the USB device is newly connected and when the USB host 10 is switched to the power saving mode. Although the device connection availability determination process according to an embodiment of the present invention has been described, the same is basically true for a USB device connected to the USB port 103-2. However, since only one USB device is directly connected to the USB port 103-2, priority determination is unnecessary.

  When a new USB device (new USB device) is connected to the USB port 103-2, the CPU 105 assigns the actual use current value (measurement result of the actual use current value at U 0) of the new USB device to the USB port 103. Compared with the maximum operating current value (the current value that can be used in the normal operation mode of the port). If the actual usage current value of the new USB device is less than or equal to the maximum usage current value of the USB port 103-2, the connection of the new USB device is permitted and exceeds the maximum usage power value of the USB port 103-2. In case it refuses the connection.

  In addition, when the USB host 10 is switched from the normal operation mode to the energy saving mode, the CPU 105 uses the actual use current required in the energy saving mode of the USB device (connected USB device) connected to the USB port 103-2. The value (measurement result of actual use current value at U0, U1, U2 or U3) is compared with the usable current value of the USB port 103-2 in the energy saving mode. When the actual use current value of the connected USB device is equal to or less than the usable current value of the USB port 103-2, the connection state of the connected USB device is maintained and exceeds the usable current value of the USB port 103-2. In the case, the connection of the connected USB device is rejected.

  Next, the priority of the USB device will be described. FIG. 7 shows an example of priorities of USB devices according to an embodiment of the present invention. FIG. 7 is merely an example, and the present invention is not limited to this.

  In FIG. 7, reference numerals 1 to 6 are priority items. At priority 1, the priority of a specific class of devices is increased. For example, the priority order of devices such as an ID card reader and a fingerprint authentication device is increased. In priority 2, the priority is set by the actual use current value. For example, the priority of a device having a small actual use current value in the U0 mode is increased. With priority 3, the priority of a device with a specific vendor ID (such as a specific manufacturer) is increased. With priority 4, the priority of the device with the specific product ID (specific product) is increased. At priority 5, the priority is increased in descending order of device usage frequency. For priority 6, priority is set according to the version of the USB device. For example, among USB 3.0 and USB 2.0, USB 3.0 mainly has a high-speed communication and a large capacity storage device, so the priority of USB 2.0 devices is increased.

  A matrix in which priority numbers are set corresponding to the respective items is prepared in advance in the ROM 106 of the USB host 10 or the like. The CPU 105 automatically sets the priority order of the USB devices in the order of priority numbers based on the configuration information of the USB devices. In general, the priority numbers are in no particular order.

  In addition, by using the input unit 109 and the display unit 110, the user performs a predetermined input operation on the input unit 109 according to the setting screen displayed on the display unit 110 to set the priority order of the USB devices. But you can. This makes it possible to set a priority level that is convenient for the user. For example, by designating a specific device and setting a higher priority, the USB device required by the user can be operated even in the energy saving mode of the USB host.

  Furthermore, the priority order of devices may be set not by a single priority information but by a plurality of priority information. In this case, for example, a point may be given as in the case of only one priority information, such as 2 in the case where one or two priority information overlaps.

FIG. 8 is a diagram illustrating an example of a setting screen displayed on the display unit 110.
FIG. 8A shows a setting screen for user confirmation for each USB device. The first line displays the product name for each port. The second line displays the ON / OFF setting of the device priority. With this priority setting, the priority of each device can be changed. The third line displays device details. By selecting this, USB device information such as configuration can be confirmed. The fourth line displays the energy saving mode setting screen. By selecting this, it is possible to set which energy saving mode of the device is applied to the energy saving mode of the USB host.

  FIG. 8B is an example of the detail setting screen on the fourth line in FIG. In the case of automatic, it is possible to make correspondence by having a unique setting in the USB host.

  FIG. 8C is a priority setting screen. By selecting this, by having the priority as shown in FIG. 7 in advance by the USB host, it is possible to switch on / off for each priority, and to set a combination of priorities. .

  As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment described so far. For example, the USB port and the USB device are compliant with USB 3.0, but may be compliant with USB 2.0. Also, the port and device need not be in USB format. As described above, the present invention is generally applicable to a system including a device connection port and an electronic device whose power state is switched between a normal operation mode and a power saving mode, and a device connected thereto.

  Further, in the description of the embodiment, the device connection determination is performed for each of a plurality of ports included in the electronic device. However, the plurality of ports are regarded as one port and connected to each port. It is also possible to perform device connection availability determination for all devices. Such an embodiment is also included in the present invention.

10 Electronic equipment (USB host)
20 USB hub 30 USB device 101 Main power supply device 102 USB power supply unit 103-1 and 103-2 USB port 104-1 and 104-2 Current measuring device 105 CPU
106 ROM
107 RAM
108 Device Controller 109 Input Unit 110 Display Unit

JP 2005-10981 A

Claims (7)

In an electronic device that includes a device connection port, and the usable current value of the port changes in a normal operation mode and a power saving mode,
Means for storing an actual use current value in a normal operation mode and a power saving mode of a device connected to the port;
When the mode is switched to the power saving mode, the usable current value of the port in the power saving mode is compared with the sum of the actual usage current values required in the power saving mode of the device connected to the port, Means for determining whether or not a device can be connected;
An electronic device comprising:   The electronic apparatus according to claim 1, further comprising means for measuring an actual use current value in a normal operation mode and a power saving mode of the device when a device is newly connected to the port.   When the device is newly connected to the port, the means for determining whether or not the device can be connected is a usable current value in the normal operation mode of the port, the device newly connected to the port, and the port. The electronic device according to claim 1, wherein whether or not the device can be connected is determined by comparing a total of actual use current values required in the normal operation mode of the device already connected to the device. Means for storing a priority of a device connected to the port;
The means for determining whether or not the device can be connected is characterized in that if the sum of the actual current values of the devices exceeds the available current value of the port, the device having a low priority is rejected. 4. The electronic device according to any one of items 1 to 3.   5. The electronic apparatus according to claim 1, wherein the port is a USB port, the device is a USB device, and conforms to USB 2.0 or USB 3.0. A device connection determination method in an electronic device comprising a device connection port, wherein the usable current value of the port changes in a normal operation mode and a power saving mode,
When a device is newly connected to the port, measuring the actual operating current value in the normal operation mode and the power saving mode of the device;
Storing actual measured current values in each measured mode;
When the mode is switched to the power saving mode, the usable current value of the port in the power saving mode is compared with the sum of the actual usage current values required in the power saving mode of the device connected to the port, Determining whether the device can be connected;
A method for determining whether or not a device can be connected.   When a device is newly connected to the port, the usable current value in the normal operation mode of the port, and the normal operation mode of the device newly connected to the port and the device already connected to the port The device connection availability determination method according to claim 6, further comprising a step of determining whether or not a device can be connected by comparing with a total of actual use current values required in step (7).

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