JP2004302778A - Interface device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To transmit information while suppressing power consumption without lowering a practical transfer rate. <P>SOLUTION: In the interface device for connecting equipment on the basis of specifications of USB or the like, a save mode setting processing part 14 receives the setting input of a save mode for forcibly suppressing the transfer of the connection to a full speed mode of low-speed transfer. A save mode handshake processing part 12 transmits the presence / absence of the setting of the save mode to the equipment which is the opposite side of the connection. By suppressing the transfer speed corresponding to the necessity of power consumption suppression and the amount of the information to be transmitted, practical degradation of the transfer rate is suppressed while suppressing the power consumption. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an interface device for connecting devices, and more particularly to an interface device capable of transmitting information while suppressing power consumption without substantially lowering a transfer speed.
[0002]
[Prior art]
The USB 2.0 specification defines a high speed mode (High Speed Mode) operating at 480 Mbps, and is upwardly compatible with conventional USB 1.0 and USB 1.1 (these conventional specifications are collectively referred to as USB 1.1 hereinafter). In order to obtain the performance, the specification of the full speed mode operating at 12 Mbps based on the conventional specification is also included.
[0003]
Also, some devices are compatible with USB 2.0 specifications, and are compatible with both high-speed mode and full-speed mode. Further, there are some which correspond to USB 1.1 and correspond to a full speed mode and a low speed mode. When the various devices are connected to the other device via a USB cable, the various devices are automatically determined based on the corresponding modes, and the mode used for information transmission is set.
[0004]
[Problems to be solved by the invention]
However, in the automatic determination, among the high-speed mode, the full-speed mode, and the low-speed mode, a mode which can be operated at the highest speed, which is supported by both connected devices, is set. Therefore, the high-speed mode is always selected between devices having the USB 2.0 high-speed mode.
[0005]
Here, since the high-speed mode has a transfer speed 40 times the theoretical value as compared with the full-speed mode, the operation clock frequency is high and the power consumption is considerably large.
[0006]
When a built-in battery is used as a power source in a mobile device such as a notebook personal computer, it is necessary to minimize power consumption. Further, depending on the use situation, there are cases where the transfer speed is sufficient in the full speed mode, the high speed mode is not required, and it is better to reduce the power consumption. In these cases, a high-speed mode that consumes a large amount of power is conventionally set.
[0007]
The USB specification defines a “suspend mode”. Although the power consumption can be suppressed by the suspend mode, information cannot be transmitted.
[0008]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and has as its object to provide an interface device capable of transmitting information while suppressing power consumption without substantially lowering a transfer rate. And
[0009]
[Means for Solving the Problems]
First, the present invention relates to an interface device for connecting devices having different operation modes of a high-speed transfer and a low-speed transfer, wherein a save mode for accepting a setting input for forcibly restricting the transfer of the connection to the low-speed transfer is provided. This object has been achieved by providing a setting processing section and a save mode handshake processing section for transmitting the presence / absence of the setting of the save mode to the other device of the connection. Here, the interface device may be for connecting a device in conformity with a publicly available specification.
[0010]
Also, the interface device may include a high speed mode corresponding to the high speed transfer, and a full speed mode compatible with USB 1.1 corresponding to the low speed transfer. 2.0, wherein the save mode handshake processing unit is adapted to perform a chirp handshake specified by USB 2.0 with respect to a counterpart device in the already established full speed mode. Performing a process to shift to the high speed mode, wherein at least one of the save mode setting processing unit and the save mode handshake processing unit performs the chirp when the save mode is set. Masking a chirp signal related to a handshake, the mask including: The present invention is applied to a widely used USB specification by suppressing the transfer speed in the low-speed transfer by maintaining the already established full-speed mode during the chirp handshake, and solving the problem. It is a solution.
[0011]
Further, the present invention can be applied to a USB device by using the interface device for a slave.
[0012]
Further, the present invention can be applied to the USB host side by using the interface device for the master.
[0013]
Hereinafter, the operation of the present invention will be briefly described.
[0014]
The present invention provides, in an interface device for connecting a device, a save mode setting processing unit that receives a save mode setting input for forcibly restricting transfer of the connection to low-speed transfer. If the interface device has the USB 2.0 specification, for example, the save mode is a full speed mode as in the embodiment described later.
[0015]
Further, the interface device of the present invention includes a save mode handshake processing unit for transmitting the presence or absence of the setting of the save mode to the other device of the connection. By the save mode handshake, the above save mode is established with the partner device.
[0016]
In the case of the USB specification, a chirp handshake defined in the USB 2.0 specification may be used as the save mode handshake as in an embodiment described later. The chirp handshake first establishes a full-speed mode transfer, performs a process related to the chirp handshake on the other device in the full-speed mode, and transitions to the high-speed mode. Things. Therefore, by masking the chirp signal related to the chirp handshake, the full-speed mode (corresponding to the low-speed transfer of the present invention) to the high-speed mode (corresponding to the high-speed transfer of the present invention) during the chirp handshake. , So that the full-speed mode of the low-speed transfer can be continued.
[0017]
In the save mode, the transfer speed is forcibly suppressed to a low speed transfer. Further, if such a save mode is set according to the necessity of suppressing power consumption and the amount of information to be transmitted, a substantial decrease in transfer speed can be suppressed. In addition, the function of setting the save mode can be incorporated while maintaining the compatibility with the specification which is open to the public. Maintaining compatibility allows compliance with publicly available specifications.
[0018]
As described above, according to the present invention, information can be transmitted while suppressing power consumption without substantially lowering the transfer speed.
[0019]
It should be noted that the specifications of the interface device targeted by the present invention are not particularly limited. For example, as in an embodiment described later, the specification may be USB 2.0.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0021]
FIG. 1 is a circuit diagram showing a connection by an interface device according to an embodiment to which the present invention is applied.
[0022]
In this embodiment, the USB 2.0 specification is applied to both the host-side device and the device-side device. Therefore, it corresponds to the full speed mode and the high speed mode of the USB 2.0 specification. Conventionally, these devices are connected in a high-speed mode. In the present embodiment, the save mode of the present invention for suppressing power consumption is a full speed mode.
[0023]
In this figure, the left side is the host side such as a personal computer. The host side is a master interface device including at least a master USB transceiver 31 and an interface control unit 10 described later. The interface control unit 10 is for performing USB-related control, and is a USB driver program on the host side.
[0024]
Next, the right side in this figure is a device side such as an external storage device or a video capture device. The device side is a slave interface device including at least a slave USB transceiver 32 and an interface control unit 10 described later. The interface control unit 10 is for controlling USB, and corresponds to a USB driver program on the host side, and is a firmware on the device side. The host-side and device-side interface control units 10 have the same communication function, but specific contents are different from each other.
[0025]
The host-side interface device and the device-side interface device are connected to each other by a USB cable 20 composed of connectors CN1 and CN2 and a cable line. The signal lines D + and D− of the cable are connected to the ground GND by pull-down resistors RPD on the master side. On the slave side, the signal line D + is connected to the power supply VDD by a pull-up resistor RPU via a switch SWPU.
[0026]
The switch SWPU is turned on in the full-speed mode, and turned off in the high-speed mode.
[0027]
Next, FIG. 2 is a block diagram illustrating a configuration of the interface control unit 10 in the present embodiment.
[0028]
The interface control unit 10 controls USB, and controls the master USB transceiver 31 on the host side and controls the slave USB transceiver 32 on the device side. In the interface control unit 10, a save mode handshake processing unit 12 that performs a process related to the handshake of the dedicated protocol according to the present embodiment together with a process related to the chirp handshake specified by USB 2.0. have. In both the chirp handshake and the save mode handshake, a handshake is performed with a device to be connected in order to determine a USB transmission speed.
[0029]
The mode setting related hardware 16 is, for example, the above-described switch SWPU. On the device side, the switch SWPU is turned on in the full speed mode corresponding to the save mode of the present invention. The mode setting related hardware 16 is controlled by the save mode handshake processing unit 12.
[0030]
Next, the save mode setting processing unit 14 performs a process for setting a save mode according to the present invention. Specifically, the save mode is set by externally inputting the save mode setting and writing information to an internal register, or by operating a power saving switch to set the save mode. . Then, a signal is transmitted to the save mode handshake processing unit 12 based on the setting. The power saving switch is provided in the save mode setting processing unit 14.
[0031]
For example, in a recent OS (Operating System) for a personal computer, the power management of the computer is also performed, so that the save mode can be set as a part of the power management as in an embodiment described later. You may do so. Alternatively, as in an embodiment described later, a signal may be transmitted to the save mode setting processing unit 14 in response to a request from an application program of a personal computer, and the setting may be performed.
[0032]
Hereinafter, when describing the operation of the present embodiment, first, the chirp handshake of USB 2.0 will be described.
[0033]
When a USB 2.0 host and a device are connected by a USB cable, the host first establishes a connection between devices in a full-speed mode. Then, a chirp handshake is performed according to procedures A1 to A4 as listed below to establish a high-speed mode.
[0034]
A1. The device detects the “USB reset signal” sent from the host in the full speed mode. By this detection, the device notifies the host of the "K state" of the "high speed mode" in the full speed mode.
[0035]
A2. When the host detects the “K state”, it notifies the device of a “chirp signal” after the detection.
[0036]
A3. When the device detects the "chirp signal", the device turns off the switch SWPU to complete the preparation for the high-speed mode.
[0037]
A4. Thereafter, the high-speed mode is established on the host side and the device side.
[0038]
In the present embodiment, in such procedures A1 to A4 of the chirp handshake, the high-speed mode is prevented from being established (masked). If the high speed mode is not established, the save mode becomes the full speed mode. That is, the already established full speed mode will be continuously employed. Specifically, the transition to the high-speed mode is prevented by at least one of the following methods B1 and B2.
[0039]
B1. In the aforementioned procedure A1, the device does not notify the host of the "K state". Thus, the full speed mode can be set from the device side.
[0040]
B2. In the procedure A2, the host does not notify the device of the "chirp signal". This allows the host to set the full speed mode.
[0041]
When changing the already established high-speed mode or full-speed mode to another mode, the host side notifies the device side of a “USB reset signal” by some method. Just fine. When changing from the high-speed mode to the full-speed mode, the methods B1 and B2 are performed in the procedures A1 to A4 described above. When changing from the full-speed mode to the high-speed mode, a normal chirp handshake may be performed after the “USB reset signal” to establish the high-speed mode.
[0042]
In order to notify the above-mentioned “USB reset signal”, for example, the user may disconnect the USB cable once and then disconnect the device once. Alternatively, the mode may be forcibly shifted to the full-speed mode of low-speed transfer by a handshake of a dedicated protocol specific to the present embodiment as described later.
[0043]
In the method B1 described above, specifically, it is assumed that the user has selected and operated the save mode in the save mode setting processing unit 14 of the device by using the above-described power saving switch. Alternatively, it is assumed that a signal for selecting a save mode has been input to the save mode setting processing unit 14 from another control unit on the device side. In these cases, the above-mentioned method B1 is to set the save mode setting processing unit 14 on the device side so that the save mode handshake processing unit 12 does not notify the host side of the “K state”. Instruct 12. Then, the operation of the save mode handshake processing unit 12 is masked so as not to notify the “K state” to the host.
[0044]
In the method B2 described above, it is assumed that the user selects and operates the save mode in the save mode setting processing unit 14 on the host side by using the power saving switch. Alternatively, it is assumed that a signal for selecting a save mode has been input to the save mode setting processing unit 14 from another control unit on the host side. In this case, the operation of the save mode handshake processing unit 12 is masked so as not to notify the device side of the “chirp signal”.
[0045]
As described above, the high speed mode is originally set according to the USB 2.0 specification. In the present embodiment, the full speed mode of the save mode can be selected from the device side and the host side. I have.
[0046]
In the present embodiment, as described below, a handshake of a dedicated protocol unique to the present embodiment is performed between the host side and the device side, so that the full speed of the high-speed mode and the save mode is performed. -The mode is switched.
[0047]
Hereinafter, the processing of the above-described dedicated protocol handshake will be described.
[0048]
In the present embodiment, the dedicated protocol handshake is enabled by USB-based control transfer or bulk transfer.
[0049]
First, the processing of the dedicated protocol handshake by the control transfer of the USB specification will be described.
[0050]
FIG. 3 is a flowchart of a first example of a dedicated protocol handshake process by control transfer in the present embodiment.
[0051]
In the control transfer, when a response is required from the device side, a dedicated protocol of the host side and the device side is transferred as in the first example. The delivery is performed by a setup transaction, an in transaction, and an out transaction as described below.
[0052]
In this figure, a setup transaction is performed by packets 112 to 116. An in-transaction is performed by packets 122 to 126. Out-transactions are performed by packets 132 to 136.
[0053]
Here, the data packet denoted by reference numeral 114 is a packet A having a format including data D1 to D5 as shown in FIG.
[0054]
In the data D1 “0xc0” in the figure, the second “c” from the right indicates that this is a packet instructing to send data from the device side to the host side. Further, “ff” on the right side of “0xff” of the data D2 indicates that the packet A is a packet for transmitting a dedicated command for a dedicated protocol handshake. The data D3 is data indicating the content of the dedicated command, that is, the command type.
[0055]
As a response to the packet A, a data packet denoted by reference numeral 124 (packet B) is transmitted from the device to the host. In the packet B, data shorter than the data length shown in the data D5 of the packet A in FIG. 4 is sent back to the host.
[0056]
FIG. 5 is a flowchart of a second example of the dedicated protocol handshake process by control transfer in the present embodiment.
[0057]
In the case where a response from the device is not required in the control transfer, a dedicated protocol is transferred between the host and the device as in the second example. The delivery is performed by a setup transaction and an in-transaction as described below.
[0058]
In this figure, a setup transaction is performed by packets 162 to 166. An in-transaction is performed by packets 172 to 176.
[0059]
Here, the data packet denoted by reference numeral 164 is a packet A having the format shown in FIG. However, the command type of the data D3 is data indicating a command that does not require a response. The packet B is a “NULL packet”.
[0060]
In the setup transaction, when the device receives the data packet denoted by reference numeral 114 or 164, the save mode handshake processing unit 12 decodes the command. Then, when the device side needs a response as in the case of FIG. 3, the mode to be set is returned and necessary processing is performed. For example, the save mode handshake processing unit 12 sets a chirp handshake mask so as to set the full speed mode corresponding to the save mode of the present invention.
[0061]
Next, processing of the dedicated protocol handshake by the bulk transfer of the USB specification will be described.
[0062]
FIG. 7 is a flowchart of a dedicated protocol handshake process by bulk-out transfer in the present embodiment. FIG. 8 is a flowchart of a dedicated protocol handshake process by bulk-in transfer in the present embodiment.
[0063]
First, in the bulk-out transfer, an out-transaction is performed according to a protocol indicated by reference numerals 212 to 216 as shown in FIG. Alternatively, in bulk-in transfer, an in-transaction is performed according to a protocol indicated by reference numerals 242 to 246 as shown in FIG.
[0064]
In the case of bulk transfer, the degree of freedom of the data format increases. The host sends a command to the device by such a bulk-out transfer. Then, when a response to the command is required, the device sends the response to the host by such bulk-in transfer.
[0065]
As described above, according to the present embodiment, the present invention can be effectively applied.
[0066]
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, examples of the present invention according to the above-described embodiments will be described.
[0067]
First, in the first embodiment, the host side is a mobile device such as a notebook personal computer.
[0068]
For example, in recent years, an OS for a personal computer has also been designed to manage the power supply of the computer. In the case of a notebook personal computer, it depends on whether the battery is operating with an external AC power supply or the built-in battery. In order to suppress power consumption, the operating state of the computer is switched by lowering the operating clock of the CPU.
[0069]
In the present embodiment, when the power consumption is switched in such a manner as to be suppressed, a save mode setting is input to the save mode setting processing unit 14 as an instruction of the suppression, and the save mode setting processing unit 14 The save mode can be set by writing information to the above-described internal register. As a result, the full speed mode is set, and power consumption is suppressed.
[0070]
In the present embodiment, the full-speed mode is set when the high-speed mode is originally set, so that the power consumption of the USB can be reduced while providing the use of the USB.
[0071]
Next, the second embodiment aims to reduce the power consumption by setting the high-speed mode only when a large amount of information is to be transferred by USB, and setting the full-speed mode otherwise. It is. This embodiment is also particularly effective on the host side for mobile devices such as notebook personal computers.
[0072]
In the present embodiment, for example, a device that is a video capture device on the device side and that can compress or uncompress information transferred by USB can be taken as an example.
[0073]
In the case of compression, the amount of information transferred by USB is suppressed, so that the transfer speed is sufficient even in the full speed mode of the save mode, and the power consumption can be suppressed by setting the save mode.
[0074]
Therefore, in the case of compression, the save mode setting is input to the save mode setting processing unit 14 as an instruction that the transfer speed may be low, and information is stored in the internal register of the save mode setting processing unit 14. Write. Thus, the save mode is set, and the full speed mode is set. Further, power consumption is suppressed.
[0075]
In the case of non-compression, since the amount of information transferred by USB is large, a high-speed mode can be set to provide stable use of the device.
[0076]
Next, the third embodiment is a case where information transfer by USB is performed intermittently, and the interruption time is relatively longer than the transfer time. In this embodiment, a high-speed mode is set when a large amount of information is transferred, and the performance is improved. On the other hand, when the information transfer is interrupted or the amount of information to be transferred is small, the power consumption can be suppressed by setting the save mode to the full speed mode.
[0077]
Specifically, when the amount of information to be transferred is small, a save mode setting is input to the save mode setting processing unit 14 as an instruction that the transfer speed may be low. As a result, the full speed mode of the save mode is set, and power consumption is suppressed.
[0078]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, information can be transmitted, suppressing power consumption, without lowering a substantial transfer speed.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a connection by an interface device according to an embodiment to which the present invention is applied; FIG. 2 is a block diagram showing a configuration of an interface control unit in the embodiment; FIG. 3 is a control transfer in the embodiment; FIG. 4 is a format diagram of a packet A of the dedicated protocol described above. FIG. 5 is a flowchart of a second example of a dedicated protocol handshake process by control transfer in the embodiment. FIG. 6 is a format diagram of the packet A of the dedicated protocol. FIG. 7 is a flowchart of a dedicated protocol handshake process by bulk-out transfer in the embodiment. FIG. 8 is a diagram of a dedicated protocol handshake process by bulk-in transfer in the embodiment. Floater DESCRIPTION OF SYMBOLS
DESCRIPTION OF SYMBOLS 10 ... Interface control part 12 ... Save mode handshake processing part 14 ... Save mode setting processing part 16 ... Mode setting related hardware 20 ... USB cable 31 ... Master USB transceiver 32 ... Slave USB transceiver

Claims (4)

In an interface device for connecting devices having different operation modes of high-speed transfer and low-speed transfer,
A save mode setting processing unit that receives a setting input for suppressing the transfer of the connection to the low-speed transfer forcibly,
An interface device comprising: a save mode handshake processing unit for transmitting the presence / absence of the save mode to the other device of the connection. The USB device according to claim 1, wherein the interface device includes a high speed mode corresponding to the high speed transfer and a full speed mode compatible with USB 1.1 corresponding to the low speed transfer. Compatible USB 2.0 specification,
The save mode handshake processing unit performs a process related to a chirp handshake specified by USB 2.0 with respect to a partner device in the already established full speed mode, and performs the high speed mode. To move to,
Furthermore, at least one of the save mode setting processing unit and the save mode handshake processing unit, when setting the save mode, masks a chirp signal related to the chirp handshake,
The interface apparatus according to claim 1, wherein the mask keeps the full-speed mode already established at the time of the chirp handshake, thereby suppressing a transfer rate to the low-speed transfer. The interface device according to claim 1 or 2,
An interface device, wherein the interface device is for a slave (for a device). The interface device according to claim 1 or 2,
An interface device, wherein the interface device is for a master (for a host).

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