JP3742367B2 - USB device and control method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a USB (Universal Serial Bus) device and a control method thereof, and more particularly to an improvement in a negotiation procedure executed immediately after a USB device is connected to a USB host. In the present application, a device such as a personal computer (PC) on the upstream side is collectively referred to as a “USB host”, and a device such as a PHS terminal on the downstream side as viewed from the USB host is collectively referred to as a “USB device”. The application target of the present invention is not limited to the USB connection between the PC and the PHS terminal.
[0002]
[Prior art]
USB is widely used as an interface means for connecting an external device to a PC. There are self-power and bus power in the drive power acquisition mode in the USB device. Self-power is drive power acquired from an internal battery or an external power supply (for example, commercial power supply) or drive by it. Bus power is drive power acquired from a USB host via a USB cable or drive by it. That is. For example, if a USB is adopted in a portable device having a built-in battery such as a PHS terminal, a mobile phone, etc., it is possible to use the self-power by the built-in battery or the bus power. In a device having an external power supply terminal, self-power obtained from an external power supply via an AC adapter or the like can also be used. Various proposals have been made on how to effectively use self-power and bus power. Applicable or related proposals include those described in Patent Documents 1 to 4 below.
[Patent Document 1]
Japanese Patent Laid-Open No. 11-305880 [Patent Document 2]
JP 2000-29544 A [Patent Document 3]
JP 2001-184146 A [Patent Document 4]
Japanese Patent Laid-Open No. 2002-7003
[Problems to be solved by the invention]
By the way, immediately after the USB device is connected to the USB host via the USB cable, the negotiation is executed between the USB host and the USB device. In this negotiation, information regarding the configuration (functional configuration) of the USB device, that is, configuration data is transmitted from the USB device to the USB host, and whether or not the USB connection with the configuration specified by the data is permitted. The determination is made on the USB host side, and the connection is permitted / denied depending on the result. The configuration data includes a required current value information (MaxPower) field indicating a current value required by the USB device. In principle, MaxPower is set so as to cover the current consumption of the USB device.
[0004]
In addition, when the USB host that has received the configuration data from the USB device cannot supply the current of the value specified by MaxPower as the bus power, the USB host rejects the connection based on the configuration. For example, when a USB host such as a PC and a USB device are connected via a single USB cable without going through a USB hub, the USB host and the USB device are connected to a self-powered hub (ie, an external power source via an AC adapter etc.) If the connection is made via a USB hub that has acquired drive power from the device, the connection is permitted even with a configuration of MaxPower = 500 mA. On the other hand, when a USB host and a USB device are connected via a bus power hub (that is, a USB hub obtained as the driving power with the bus power), the connection is permitted. The maximum configuration is MaxPower = 100 mA.
[0005]
Therefore, even if a USB device that transmits configuration data of MaxPower = 500 mA at the time of negotiation is connected to the USB host via the bus power hub, the USB connection is not permitted. The idea of avoiding this and allowing connection permission to be always obtained is to set MaxPower to 100 mA or less regardless of actual power consumption. However, when a connection permission is received according to such a configuration, an excess of the actual power consumption in the USB device is covered by self power with respect to the MaxPower equivalent value, that is, the bus power supplied from the USB host. As a result, the internal battery discharges or external power is consumed. If the USB device has neither a built-in battery nor an external power supply connection terminal, it cannot operate normally due to insufficient power.
[0006]
For this problem of connection success / failure depending on the type of hub, there have been only distribution measures such as distributing USB devices with a cautionary statement that may not work properly when using a hub. No effective technical measures have been taken to prevent this. In addition, a technique (refer to Patent Documents 1 and 2) that keeps the internal battery in the best possible state of charge by suppressing or charging the internal battery according to the detection value of the voltage and power (see Patent Documents 1 and 2). The technology of switching the self power / bus power (see Patent Documents 3 and 4), etc., helps to alleviate the problem by suppressing problems caused when connecting with a MaxPower value smaller than the actual power consumption equivalent value. However, this is not only a fundamental solution, but it cannot be realized without a function of detecting or predicting voltage or power. In addition, since those described in Patent Documents 1 and 2 are based on the premise that a battery is built in the USB device, they cannot be applied to a USB device that does not have a built-in battery.
[0007]
One of the objects of the present invention is to eliminate the problem of connection success / failure depending on the type of device group existing between the USB host and the USB device, for example, the hub type, by devising the control procedure.
[0008]
[Means for Solving the Problems]
In order to achieve such an object, the control method according to the present invention includes: (1) Immediately after a USB device is connected to the USB host, a plurality of configuration data having different MaxPower values from the USB host. (2) The configuration data received from the USB device by the USB host includes whether or not the drive current corresponding to the MaxPower value can be supplied to the USB device. It is determined whether or not the USB connection with the specified configuration can be permitted. (3) Based on the MaxPower value in the configuration data related to the USB connection permitted by the USB host, the USB device uses the MaxPower value. The power corresponding to the specified obtainable current value The operation mode of the USB device is set so that the power consumption of the USB device does not exceed, and (4) after that, the USB host supplies drive current to the USB device with the obtainable current value as a limit. It is characterized by. The USB device according to the present invention includes (1) means for transmitting a plurality of types of configuration data having different MaxPower values to the USB host immediately after being connected to the USB host, and (2) the USB host. Means for setting the operation mode based on the MaxPower value in the permitted configuration data so that the power consumption does not exceed the power corresponding to the obtainable current value specified by the MaxPower value. (3) The operation is performed by the drive current supplied from the USB host up to the obtainable current value which is the drive current value corresponding to the MaxPower value in the configuration data permitted by the USB host. .
[0009]
One of the features of the present invention is that a plurality of types of configuration data having different MaxPower values are transmitted from the USB device during the negotiation. For example, MaxPower = 500 mA configuration data for requesting the maximum bus power and MaxPower = 100 mA configuration data for requesting the maximum bus power when the bus power hub is interposed are transmitted. In this way, if a plurality of types of configuration data having different MaxPower values are transmitted and negotiated, the probability that the USB device is permitted to connect increases. In particular, by setting the MaxPower value in at least one of the plurality of configuration data as a drive current (that is, a value of 100 mA or less) that can be acquired from the USB host when a bus power hub is interposed, Connection permission can be received regardless of the type of hub.
[0010]
If the present invention is implemented with the logic that negotiation is performed with another configuration data when the connection is rejected, and transmission of untransmitted configuration data is omitted when permission is obtained from the USB host, The present invention can be implemented without any modification to the processing procedure on the USB host side, that is, only the procedure modification on the USB device side. At this time, if the negotiation is performed in order from the configuration data having the largest MaxPower value, the USB device can be permitted by the maximum MaxPower, that is, the best configuration under the current connection environment.
[0011]
Another feature of the present invention is that the power consumption of the USB device does not exceed the power corresponding to the obtainable current value corresponding to the MaxPower value in the configuration permitted by the USB host. The operation mode is set. Examples of the operation form here include a communication speed and a clock speed. For example, when the present invention is applied to a USB device for communication whose communication speed can be variably set, if a configuration having a large MaxPower value is permitted, communication is performed at a high speed, and only a configuration having a small MaxPower value is used. By switching the communication speed such that communication is performed at a low speed if permission is not given, the operation load of the USB device and the power consumption are adapted to the bus power that can be acquired. Also, for example, the present invention is implemented in such a manner that a USB device is operated with a high-speed clock when a configuration with a large MaxPower value is granted, and with a low-speed clock when a configuration with a small MaxPower value is granted. It is also possible to do.
[0012]
Therefore, according to the present invention, since the possibility that the connection is permitted by the USB host is increased, the problem that the success or failure of the connection depends on the hub type can be alleviated / resolved. In particular, if negotiation is performed with configuration data in which the obtainable current value when the bus power hub is interposed is set to the MaxPower value, even when the USB device is connected to the USB host via the bus power hub, , Can receive connection permission. From the viewpoint of the user of the USB device, the usage form of the USB device will be expanded. In the present invention, since the USB operation mode, for example, the communication speed is set according to the MaxPower value in the permitted configuration data, there is almost no shortage of bus power with respect to power consumption in the USB device. Therefore, consumption of self-power, including taking out from the built-in battery, generally does not occur. Further, no power or voltage detection is required for this operation. The present invention can also be applied to a USB device that does not have a built-in battery.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following description, software or hardware is not clearly shown for some members or modules. This is simplified because a so-called person skilled in the art can appropriately determine whether they should be realized in software or hardware based on the disclosure of the present application. Even if the following description suggests realization by any of the software (hardware), there are some that can be realized by hardware (software). A so-called person skilled in the art will be able to make appropriate changes and modifications to the realization based on the disclosure of the present application.
[0014]
FIG. 1 shows the relationship between the USB host 10 and the USB device 20 in one embodiment of the present invention and the main configuration. In this embodiment, the USB host 10 is a PC having a downstream USB port, the USB device 20 is a PHS terminal having an upstream USB port, and the USB cable 30 is a cable for connecting the USB host 10 and the USB device 20. Yes, by connecting the upstream side terminal of the USB cable 30 to the USB port of the USB host 10 and the downstream side terminal to the USB port of the USB device 20, the connection state shown in FIG.
[0015]
Software such as a communication application 11 and a USB driver 12 is installed in the USB host 10, and USB hardware 13 including the above USB port is installed as hardware. In addition, the USB device 20 has a USB hardware 21 and a USB driver 22 mounted or installed in a complementary manner to the USB host 10, and communication control for controlling communication at 32 k / 64 k / 128 kbps in the PHS. Module 23, wireless unit 24 which is a circuit for performing wireless transmission / reception under the control of communication module 23, USB control module 25 for controlling the operation of communication control module 23 and CPU management module 26 based on the execution result of the initialization sequence, communication A CPU management module 26 that manages various members including the CPU included in the control module 23 is mounted or installed. In addition, although not shown, the USB device 20 can be provided with a battery and an external power connection terminal.
[0016]
As is generally known, in order to perform communication by a PC using a wireless line, a wireless communication device having a wireless communication function is connected to the PC for use, or a wireless device having an equivalent function is used. A communication card or board may be mounted on a PC for use. In this case, the data transmission is performed from the communication application on the PC to the communication control module on the wireless communication device via the hardware of the PC and the wireless communication device (including the above-described cards and boards, the same applies hereinafter) and the corresponding driver. The data is transferred, and the data is transmitted to the wireless line by the wireless communication circuit of the wireless communication device. Radio reception is the reverse flow. Also in the present embodiment, a configuration for performing communication according to this flow is adopted. That is, in a state where the USB device 20 is connected to the USB host 10 via the USB cable 30 and the initialization sequence described later is successfully completed and the USB connection is established, the communication application 11 on the USB host 10 is connected to the USB driver. The data is transferred to the USB driver 22 of the USB device 20 and thus to the communication control module 23 through the USB hardware 13 and 21, and the communication control module 23 transmits the data to the PHS wireless line through the wireless unit 24 according to a predetermined procedure. Data transmission is performed in the flow of sending. Data reception is the reverse of this (refer to the double arrow line “communication data” in the figure).
[0017]
In the drawing, the initialization sequence indicated by the double arrow line connecting the USB driver 12 and the USB driver 22 is a procedure executed immediately after the USB device 20 is connected to the USB host 10. Including the negotiation of the USB device 20. In the negotiation, configuration data is transferred from the USB driver 22 on the device side to the USB driver 12 on the host side. This configuration data is information indicating the configuration of the USB device 20, and includes a MaxPower field in which required current value information is set. The required current value information is information indicating a bus power current value necessary for the USB device 20 to operate normally and properly with bus power. Based on the configuration data including the MaxPower field, the host-side USB driver 12 determines whether or not USB connection may be permitted for the USB device 20 having a configuration generally specified by the configuration data. If the determination is “permitted”, the USB connection is established through a predetermined process (not described here), and communication according to the above-described procedure is possible. On the other hand, if a determination of “reject” is made, the USB connection is not established in the configuration. For example, if the MaxPower value in the configuration data exceeds the acceptable upper limit, it is determined as “rejected”.
[0018]
A characteristic difference of the present embodiment with respect to the above-described conventional technology is that, firstly, negotiation of the USB device 20 with respect to the USB host 10 is performed by sequentially transmitting a plurality of types of configuration data having different MaxPower values. . Second, the USB control module 25 communicates so that the power consumption in the USB device 20 remains below the power value corresponding to the acquirable current value based on the acquirable current value given as the MaxPower value related to the permitted configuration. By instructing the communication speed to the control module 23 and the clock speed to the CPU management module 26, the operation mode of the USB device 10 after the USB connection is established is determined or restricted.
[0019]
Specifically, in the present embodiment, configuration data for MaxPower = 500 mA for requesting the maximum bus power and configuration data for MaxPower = 100 mA for requesting the maximum bus power when the bus power hub is interposed are prepared. . In the initialization sequence, the USB driver 22 first negotiates with configuration data of MaxPower = 500 mA. If the result is “permitted”, the USB control module 25 determines that the obtainable current value from the bus power is 500 mA, and instructs the communication control unit 23 to perform communication at 64 kbps or 128 kbps. However, the CPU management module 26 is instructed to operate each part of the USB device 20 with a normal speed clock. Negotiation with configuration data of MaxPower = 100 mA is omitted.
[0020]
If the result of the negotiation based on the configuration data of MaxPower = 500 mA is “rejected”, the USB driver 22 plugs in in a pseudo manner according to its own judgment or according to an instruction from the USB control module 25, and after reconnection Negotiation is performed using configuration data of MaxPower = 100 mA. If the result is “permitted”, the USB control module 25 determines that the current value obtainable from the bus power is 100 mA, instructs the communication control module 23 to perform communication at 32 kbps, The CPU management module 26 is instructed to operate each part of the USB device 20 with a clock slower than the normal speed.
[0021]
Therefore, compared with the case where “permission” is obtained at MaxPower = 500 mA and the case where “permission” is obtained at MaxPower = 100 mA, the latter, which is a low-speed communication / low-speed clock, consumes less power, and this operating state. If so, the power consumption of the USB device 20 is usually less than 100 mA in terms of bus power. In other words, the former allows high-speed communication, and the latter allows low-speed communication. Even if there is a bus power hub, since “permission” will be obtained at MaxPower = 100 mA, at least the low-speed communication by the latter is guaranteed. In both the former and the latter, the power consumption in the USB device 20 is equal to or less than the power value corresponding to the “permitted” MaxPower value. Does not occur. Further, since the negotiation with the configuration data of MaxPower = 500 mA is executed before the negotiation with the configuration data of MaxPower = 100 mA, that is, the USB device 20 is executed in order from the one with the largest MaxPower value. Under the current connection environment, maximum MaxPower, that is, permission with the best configuration can be obtained. Such operations / advantages can be implemented / achieved by the USB driver 22 or the USB control module 25 on the USB device 20 side without particularly modifying the USB host 10 side.
[0022]
As described above, according to the present embodiment, the possibility that the connection is permitted by the USB host 10 is increased, so that the problem that connection success / failure is determined depending on the connection form including the hub type can be alleviated / resolved. That is, even if the connection is rejected in the conventional case, the USB connection is established and PHS communication is possible at a low speed. For the user of the USB device 20, it is not necessary to pay attention to whether the connected hub is self-powered or bus-powered, and the psychological burden on the user is reduced. In addition, since the communication speed and clock speed are set according to the MaxPower value in the permitted configuration data, there is almost no bus power shortage. Therefore, self-power consumption including taking out from the built-in battery is reduced. Mostly not. Even when the USB device 20 is operated with bus power for a long time for communication, the built-in battery does not run out. Further, no power or voltage detection is required for this operation. The present embodiment can also be adopted for a USB device that does not have a built-in battery.
[0023]
Further, since a PHS terminal is assumed here as the USB device 20, the communication speed and the clock speed are exemplified as the operation forms to be set according to the initialization sequence execution result. Depending on the type of the USB device 20, the operation form becomes another type. For example, when the present invention is applied to a USB connection type digital camera, resolution, liquid crystal backlight, communication speed, clock speed, and the like can be set.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a USB host and a USB device according to an embodiment of the present invention.
[Explanation of symbols]
10 USB host (PC), 11 communication application, 12, 22 USB driver, 13, 21 USB hardware, 20 USB device (PHS terminal), 23 communication control module, 24 wireless unit, 25 USB control module, 26 CPU management module 30 USB cable.

Claims (6)

Immediately after the USB device is connected to the USB host, a plurality of types of configuration data having different required current value information are transmitted to the USB host.
The configuration specified by the configuration data received from the USB device, including whether the USB host can supply a drive current corresponding to the required current value information to the USB device. Determine whether or not to allow USB connection by
Based on the required current value information in the configuration data related to the USB connection permitted by the USB host, the power consumption of the USB device exceeds the power corresponding to the obtainable current value specified by the required current value information. Set the operation mode of the USB device
Thereafter, the USB host supplies a drive current to the USB device with the obtainable current value as a limit. The control method according to claim 1,
The USB device is
The plurality of types of configuration data are transmitted to the USB device in order from the current value information indicating a larger current value,
A control method characterized by omitting transmission of configuration data when untransmitted configuration data remains when permission is obtained from the USB host. The control method according to claim 1 or 2, wherein the communication speed is set for a communication USB device capable of variably setting the communication speed.
A control method, wherein the operation mode is a communication speed in the USB device. The control method according to claim 1 or 2,
A control method, wherein the operation mode is a clock speed used in the USB device. The control method according to any one of claims 1 to 4,
A control method characterized in that at least one of the plurality of types of configuration data is configuration data using a drive current that can be obtained from the USB host when a bus power hub is interposed as its required current value information. . Means for transmitting a plurality of types of configuration data having different required current value information to the USB host immediately after being connected to the USB host;
Based on the required current value information in the configuration data permitted by the USB host, the operation mode is set so that the power consumption does not exceed the power corresponding to the obtainable current value specified by the required current value information. Means for setting;
With
A USB device that operates according to a drive current supplied from the USB host with a limit of an acquirable current value that is a drive current value corresponding to required current value information in configuration data permitted by the USB host. .

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