JP2001177543A - Device and system for bus connection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bus connection device capable of easily performing device recognition processing and a device connection system. SOLUTION: A connect detection part 26 detects whether or not USB peripheral equipment 20 is connected to an upstream side device by detecting the potential of the Vbus terminal 241 of an up port 24. A recognition detecting part 28 detects whether or not the equipment 20 is recognized by the upstream side device on the basis of data from the upstream side device, given from through a D positive terminal 24b and D negative terminal 24c. A switch part 32 substantially connects/disconnects the D positive terminal 24b, the D negative terminal 24c and a downstream side USB controller 22 by electronic switching processing. A switch controlling part 34 controls so as to perform processing that substantially disconnects the part 32 and subsequently resumes the part 32 to a connected state, when USB peripheral equipment 20 is decided as not recognized of the connection, on the basis of information obtained from both the detecting part 26 and 28 even though the equipment 20 is connected to the upstream side device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bus connection device and the like.
In particular, the present invention relates to a bus connection device configured to be connectable to another bus connection device via a bus line and to be recognized by the other bus connection device via the bus line.

[0002]

2. Description of the Related Art USB (Universal Serial Bus) is known as a standard for serial connection in computers (especially personal computers). Using the USB standard, for example, a personal computer and a peripheral device can be connected.

FIG. 5 is a drawing for explaining a conventional connection state between a USB host device (or USB hub, hereinafter the same) 2 such as a personal computer and a USB peripheral device 8 such as a keyboard.

[0004] The USB host device 2 has an upstream USB controller 4 and a down port 6.
The USB peripheral device 8 includes a downstream USB controller 10.
And an up port 12.

The down port 6 of the USB host device 2 and the U
The up port 12 of the SB peripheral device 8 is connected by a USB cable 14. Both ends of the USB cable 14 are formed in a connector shape (not shown) that can be connected to and detached from the down port 6 and the up port 12.

[0006] When the USB host device 2 and the USB peripheral device 8 are connected using the USB cable 14, the upstream USB of the USB host device 2 is connected via the USB cable 14.
Communication for device recognition is performed between the controller 4 and the downstream USB controller 10 of the USB peripheral device 8.

[0007] By this communication, the USB host device 2
Automatically recognizes what kind of device the USB peripheral device 8 is. When this operation is completed, normal data communication between the USB host device 2 and the USB peripheral device 8 becomes possible.

As described above, the use of the USB is convenient because various peripheral devices can be connected to a common port provided in a computer without distinction. Also, many peripheral devices can be connected to one computer via a hub. In addition, peripherals can be disconnected and reconnected without restarting the computer, which is advantageous.

[0009]

However, the conventional USB connection has the following problems. Conventional US
In the B connection, the USB cable 14 and each port 6,1
Although there is no problem in the physical connection with the device 2, the device recognition process is often not completed normally due to a slight shift in communication timing, the presence of external noise, and the like. In such a case, since the USB host device 2 does not recognize what kind of device the USB peripheral device 8 is, normal data communication between the two cannot be performed.

In such a case, the connector of the USB cable 14 is once connected to the down port 6 or the up port 1.
2 and then reinserted, the device recognition process may be performed normally. However, this complicates the operation. In particular, when the ports 6 and 12 are located on the back side of the device, it becomes difficult to connect and disconnect the connector. Further, since the number of times of removing and inserting the connector is increased more than necessary, the connector and each of the ports 6 and 12 may be damaged.

The present invention solves the above problems,
An object of the present invention is to provide a bus connection device and a device connection system that can easily perform device recognition processing.

[0012]

According to the first aspect of the present invention, there is provided a bus connection device, comprising: connection detection means for detecting whether the bus connection device is connected to another bus connection device via a bus line; Recognition detection means for detecting whether or not is recognized by another bus connection device via the bus line,
Based on the information obtained from the connection detecting means and the recognition detecting means, when it is determined that the bus-connected device is connected to another bus-connected device and recognized, the other bus-connected device and the bus-connected device If it is determined that the bus connection device is not recognized even though it is connected to another bus connection device, the other bus connection device and the bus connection device are temporarily connected. And a determination switching means for performing an electrical switching process for returning to the connection state after the connection state is temporarily disconnected.

Therefore, when the judgment switching means judges that the bus connection device is not recognized despite being connected to the other bus connection device, the judgment switching means automatically connects the other bus connection device to the other bus connection device. An electrical switching process is performed in which the connection with the bus connection device is temporarily disconnected and then returned to the connection state again. For this reason, the device recognition process can be easily performed without disconnecting or connecting the connector.

According to a second aspect of the present invention, the bus line includes a line to be connected to a power supply of another bus connecting device, and the connection detecting means detects the potential of the line to connect the bus. It is characterized in that it is detected whether or not the device is connected to another bus-connected device via a bus line.

Therefore, by detecting the potential of the line which is not easily affected by external noise or the like, it is possible to easily and surely detect whether or not the bus connection device is connected to another bus connection device via the bus line. be able to.

According to a third aspect of the present invention, the bus line includes a line for performing data communication between the bus-connected devices, and the recognition detecting means determines the bus based on data given through the line. It is characterized in that it is detected whether or not the connected device is recognized by another bus connected device.

Therefore, it is possible to easily detect whether or not the bus-connected device has been recognized by another bus-connected device by using an existing line for performing data communication.

According to a fourth aspect of the present invention, the decision switching means substantially connects the bus line and the bus connection device depending on whether the line for performing data communication is forcibly fixed to a predetermined potential. A switch means for switching between a non-connected state and a connected state, and based on information obtained from the connection detecting means and the recognition detecting means,
Switch control means for controlling switching of the switch means.

Therefore, the bus line and the bus connection device can be easily disconnected from each other by using a simple method of forcibly fixing a line for performing data communication to a predetermined potential. Or in a connected state.

According to the USB device of the present invention, the USB device is detected by detecting the potential of the power supply terminal of the upstream port.
A connect detection unit that detects whether the B device is connected to another USB device, and the USB device is connected to another USB device based on data from the other USB device provided via a data terminal of the upstream port. The other USB device and the downstream USB controller are substantially disconnected by determining whether the data terminal of the upstream port is forcibly fixed to a predetermined potential or not by the recognition detection unit for detecting whether or not the USB device has been recognized. When it is determined that the USB device is connected to another USB device and recognized based on the information obtained from the switch unit and the connection detection unit and the recognition detection unit, the connection state of the switch unit is maintained. If it is determined that the USB device is not recognized in spite of being connected to another USB device, the switch unit is temporarily turned off and then turned on again. A switch control unit for controlling to perform a process of returning, characterized by comprising a.

Therefore, when it is determined that the downstream USB device is not recognized despite being connected to another USB device on the upstream side, another USB device is automatically detected.
An electrical switching process is performed in which the B device and the USB device are substantially temporarily disconnected and then returned to the connected state. For this reason, the USB device can be easily recognized without having to connect and disconnect the connector.

Further, by detecting the potential of the power supply terminal which is not easily affected by external noise or the like, the USB device can be connected to another U.S.
It is possible to easily and reliably detect whether or not a connection has been made to an SB device.

Further, it is possible to easily detect whether or not the USB device has been recognized by another USB device by using an existing data terminal for performing data communication.

Also, by using a simple method of forcibly fixing the data terminal of the upstream port to a predetermined potential,
The other USB device and the downstream USB controller can be easily switched to a substantially disconnected state or a connected state.

In the device connection system according to claim 6,
Connection detection means for detecting whether two functional devices are connected via a signal path, and recognition detection means for detecting whether one functional device is recognized by the other functional device via a signal path; Based on the information obtained from the connection detection means and the recognition detection means, when it is determined that two functional devices are connected and one device is recognized by the other device,
When the connection state of the two functional devices is maintained, and it is determined that one device is not recognized by the other device even though the two functional devices are connected, the two functional devices are substantially once And a determination switching means for performing an electrical switching process for returning to the connected state after the connection is disconnected.

Therefore, when the judgment switching means judges that the function device is not recognized in spite of being connected to another function device, the judgment switching means automatically sets:
An electrical switching process is performed in which the other functional device and the functional device are temporarily disconnected and then returned to the connected state. For this reason, the device recognition process can be easily performed without disconnecting or connecting the connector.

[0027]

FIG. 1 is a block diagram for explaining a configuration of a USB peripheral device 20 which is a USB device (bus connection device, one functional device) according to an embodiment of the present invention.

The USB peripheral device 20 is connected to another US on the upstream side.
U, which is a B device (other bus connection device, other functional device)
An up port 24 which is an upstream port for connecting to the SB host device 2 (see FIG. 2) and a downstream USB controller 22 connected to the up port 24 are provided.

The USB peripheral device 20 includes an up port 24
Data terminals D + terminal 24b and D- terminal 24
c. USB host device 2 and downstream USB
By communication with the controller 22, the USB peripheral device 2
0 is recognized by the USB host device 2.

The USB peripheral device 20 further includes a connect detection unit 26, a recognition detection unit 28,
0 is provided. The connection detection unit 26 detects whether or not the USB peripheral device 20 is connected to the USB host device 2 by detecting the potential of the Vbus terminal 24a that is the power terminal of the up port 24. Note that the up port 24 also has a GND terminal 24d as a power supply terminal. The GND terminal 24d is connected to the ground potential.

The recognition detection unit 28 detects the D
Based on data from the USB host device 2 given via the + terminal 24b and the D- terminal 24c, the USB
It detects whether the peripheral device 20 has been recognized by the USB host device 2.

The decision switching means 30 includes a switch section 32 (switch means) and a switch control section 34 (switch control means).

The switch unit 32 is provided with a D
The + terminal 24b and the D- terminal 24c are substantially disconnected from the downstream USB controller 22 by an electrical switching process.

The switch control section 34 is connected to the connection detection section 2
If it is determined that the USB peripheral device 20 is connected to the USB host device 2 and is recognized based on information obtained from the connection detection unit 6 and the recognition detection unit 28 (recognition detection unit), the switch unit If the USB peripheral device 20 is not recognized even though the USB peripheral device 20 is connected to the USB host device 2, the switch unit 32 is temporarily turned off once. Control is performed so as to perform processing for returning to the connection state after the state (disconnected state).

FIG. 2 shows the USB peripheral device 20 and the USB
2 is a diagram for explaining wiring of a connection device system including a host device 2.

The USB host device 2 has an upstream USB controller 4 and a down port 6.
The down port 6 has a Vbus terminal 6a and a GND terminal 6d as power supply terminals and a D + terminal 6 as a data terminal.
b and a D-terminal 6c.

In this embodiment, the Vbus terminal 6a
And GND terminal 6d are connected to +5 volts (power supply potential) and 0 volts (ground potential), respectively.

The D + terminal 6b and the D- terminal 6c are connected to the upstream USB controller 4. D + terminal 6
The b and D- terminals 6c are further connected to the ground potential via pull-down resistors R11 and R12, respectively. In this embodiment, the resistor R11,
R12 is 15 KΩ.

A down port 6 of the USB host device 2;
The up port 24 of the USB peripheral device 20 is connected by the USB cable 14 which is a bus line (signal path). The USB cable 14 includes a Vbus line 14a and a GND line 14d, which are lines to be connected to the power supply of the USB host device 2, and the USB host device 2
Line 14b and D- line 14c, which are lines for performing data communication between the USB device 20 and the USB peripheral device 20
It has.

Both ends of the USB cable 14 are formed in connector shapes (not shown) that can be connected to and detached from the down port 6 and the up port 24.

The USB peripheral device 20 includes a microcomputer section 40 and the above-described up port 24.
The microcomputer unit 40 is connected to the downstream US shown in FIG.
It corresponds to the B controller 22, the connection detection unit 26, the recognition detection unit 28, and the switch control unit 34.

The Vbus terminal 24a of the up port 24
It is connected to the input port 40a of the microcomputer section 40. The D + terminal 24b and the D− terminal 24c are connected to the input / output port 40 of the microcomputer unit 40, respectively.
c, 40d.

The D + terminal 24b is connected to a pull-up resistor R
21 to a Vbus terminal 24a. In this embodiment, the resistance R21 is 1.5K
Ω, which is lower (about 1/10) than the pull-down resistors R11 and R12.

The D + terminal 24b is connected to the diode D1.
Connected to the anode. The cathode of the diode D1 is connected to the output port 40b of the microcomputer unit 40.
It is connected to the. The diode D1 corresponds to the switch unit 32 shown in FIG.

In this embodiment, the USB peripheral device 20 is a bus-powered bus connection device.
Power is supplied from the Vbus terminal 6a and the GND terminal 6d of the USB host device 2 via the Vbus line 14a and the GND line 14d of the SB cable 14.

FIG. 3 shows the USB peripheral device 20 and the USB
1 shows a specific configuration example of a connection device system including a host device 2. In this example, the USB host device 2 (upstream-side bus connection device) is a computer (personal computer), and the USB peripheral device 20 (downstream-side bus connection device) is a keyboard. In this example, the USB host device 2 has two down ports. one,
This is the down port 6 described above. The USB hub 50 is connected to another down port 7 via a USB cable 71.

The down ports 50a, 5a of the USB hub 50
A printer 60, a scanner 62, a terminal adapter 64, and a USB hub 52 are connected to Ob, 50c, and 50d via USB cables 72, 73, 74, and 75, respectively.

The USB hub 50 corresponds to a downstream-side bus connection device in relation to the USB host device 2.
Printer 60, scanner 62, terminal adapter 6
4, in relation to the USB hub 52, corresponds to an upstream-side bus connection device.

The down ports 52a and 5a of the USB hub 52
A game pad 66 and a joystick 68 are connected to 2b via USB cables 76 and 77, respectively.

The USB hub 52 corresponds to a downstream bus connecting device in relation to the USB hub 50, but corresponds to an upstream bus connecting device in relation to the game pad 66 and the joystick 68.

In this example, a mouse 69 is connected to the USB peripheral device 20 via a USB cable 78. The USB peripheral device 20 has a built-in USB hub function, and the mouse 69 is connected via a down port (not shown) of the USB hub. Therefore, in relation to the mouse 69, the USB peripheral device 20 corresponds to an upstream bus connection device.

Next, based on FIG. 2 and FIG.
An operation when the B peripheral device 20 and the USB host device 2 are connected using the USB cable 14 will be described. FIG.
5 is a flowchart showing a processing procedure of the operation.

The upstream USB controller 4 of the USB host device 2 is connected to the D + terminal 6 b of the down port 6 and the D- terminal
The potential of the terminal 6c is monitored. As described above, since the D + terminal 6b and the D- terminal 6c are connected to the ground potential via the pull-down resistors R11 and R12, respectively, the downstream bus connection device is connected to the down port 6. Otherwise, the D + terminal 6b and the D- terminal 6
c Both terminals are at the ground potential.

While both the D + terminal 6b and the D- terminal 6c are at the ground potential, the upstream USB controller 4 does not start the recognition processing for the downstream bus-connected device.

Here, the up port 24 of the USB peripheral device 20 is connected to the down port 6 via the USB cable 14.
Is connected, the Vbus line 14 of the USB cable 14
The supply of electric power from the USB host device 2 to the USB peripheral device 20 is started via a and the GND line 14d.

When power supply to the USB peripheral device 20 is started, the microcomputer unit 40 of the USB peripheral device 20 starts. When the supply of power to the USB peripheral device 20 is started, a high potential (+5 volt, corresponding to logic “H”) is applied to the input port 40 a of the microcomputer unit 40.

When the input port 40a has a high potential, the microcomputer unit 40 of the USB peripheral device 20 determines that the upstream bus connecting device has been connected to the up port 24 (step S1).

When the supply of power to the USB peripheral device 20 is started, the output port 40b of the microcomputer section 40 is set to a high potential (+5 volts, corresponding to logic "H") unless otherwise specified. Is set. Thereby, data communication can be performed via the D + line of the USB cable 14.

On the other hand, when the supply of power to the USB peripheral device 20 is started, the potential of the D + terminal 6b of the down port 6 of the USB host device 2 is actuated by the action of the pull-up resistor R21 on the USB peripheral device 20 side. Is raised. The resistance values of the resistors R11 and R21 are set so that the logic level of the raised potential becomes “H”.

The upstream USB controller 4 of the USB host device 2 sends the D + terminal 6 b of the down port 6 or the D- terminal
When detecting that the logic level of the potential of the terminal 6c becomes “H”, the downstream USB controller (in this embodiment, the USB peripheral device) of the downstream bus connection device is connected via the D + terminal 6b and the D− terminal 6c. The microcomputer unit 40) of the device 20 is requested to start the recognition operation.

The microcomputer 40 of the USB peripheral device 20 that has received the request sends necessary information, for example, information indicating that it is a keyboard, via the D + terminal 24b and the D- terminal 24c.

The upstream USB controller 4 of the USB host device 2 determines what kind of bus connection device the USB peripheral device 20 is based on the information sent from the microcomputer section 40 of the USB peripheral device 20. Recognize. When the recognition processing is completed without any problem, the upstream USB controller 4 of the USB host device 2 sends a predetermined recognition completion signal to the D + terminal 6b and the D− terminal 6c.
Out via.

The microcomputer 40 of the USB peripheral device 20 monitors the recognition completion signal for a predetermined time (steps S2 and S4).

When the recognition completion signal is obtained during the predetermined time, it is determined that the recognition processing has been completed normally (step S2).

When the recognition processing is completed normally, normal communication processing is started between the USB host device 2 and the USB peripheral device 20 via the D + line 14b and the D- line 14c of the USB cable 14 (step S3). ).

On the other hand, when the recognition completion signal is not obtained during the predetermined time, that is, when the timeout occurs in step S4, the microcomputer unit 40 of the USB peripheral device 20 executes the reconnection processing described later. It is determined whether a predetermined number of times (for example, about three times) has been performed (step S5). At this point, since the reconnection process has not been performed yet, the process proceeds to step S6.

In step S6, a disconnect (disconnect) process is performed. Disconnect processing is US
This is performed by setting the output port 40b of the microcomputer unit 40 of the B peripheral device 20 to a low potential (ground potential, corresponding to logic "L"). Thereby, the USB cable 14
D + line 14b is forced to ground potential (predetermined potential,
(Corresponding to the logic level "L").

When the D + line 14b of the USB cable 14 has the ground potential, the D + terminal 6b of the down port 6 of the USB host device 2 has the ground potential. When the D + terminal 6b is fixed to the ground potential, the upstream USB controller 4
Determines that the bus connection device is not connected to the downstream side, and suspends the confirmation processing. That is, by performing the disconnection processing, the USB peripheral device 20 or the USB
This is the same state as removing the USB cable 14 from the host device 2.

The microcomputer unit 40 of the USB peripheral device 20 performs a reconnect (reconnect) process after continuing the disconnect state for a predetermined time (step S).
7).

The reconnect process is performed by returning the output port 40b of the microcomputer unit 40 of the USB peripheral device 20 to a high potential (+5 volt, corresponding to logic "H"). Thereby, the D + line 1 of the USB cable 14
4b, the D of the down port 6 of the USB host device 2
The logic level of the potential of the + terminal 6b becomes "H".

The upstream USB controller 4 of the USB host device 2 detects that the logic level of the potential of the D + terminal 6b of the down port 6 becomes "H", and starts the recognition process again.

Thereafter, steps S1, S2 and S4 to S7 are repeated until the recognition processing is completed normally. in this case,
When the number of reconnects reaches the predetermined number, the US
The B peripheral device 20 determines that it is an unknown device (device), and terminates the processing (step S8).

Note that step S1 in FIG. 4 corresponds to the connect detecting section 26 in FIG. Step S2 corresponds to the recognition detection unit 28. Steps S4 to S7 correspond to the switch control unit 34.

As described above, in this embodiment, U
Vbus terminal 24 of up port 24 of SB peripheral device 20
a of the USB peripheral device 20
Is detected whether the USB port is connected to the USB host device 2, and the D + terminal 24b and the D- terminal 24c of the up port 24 are detected.
USB peripheral device 20 is connected to the USB host device 2 based on data from the USB host device 2
It is detected whether or not it has been recognized.

The D + terminal 24b of the up port 24
And the USB host device 2 and the USB peripheral device 20 are substantially disconnected depending on whether or not the potential of at least one of the D- terminals 24c is forcibly set to a fixed potential (ground potential). ing.

Further, based on information as to whether the USB peripheral device 20 is connected to the USB host device 2 and information as to whether the USB peripheral device 20 has been recognized by the USB host device 2, the USB peripheral device 20 is connected. Is determined to be connected to and recognized by the USB host device 2,
If the USB host device 2 and the USB peripheral device 20 are substantially connected to each other, and it is determined that the USB peripheral device 20 is not recognized despite being connected to the USB host device 2, the USB host device 2 2 and the USB peripheral device 20 are temporarily disconnected and then returned to the connected state.

Therefore, the process of recognizing the USB peripheral device 20 can be easily performed without disconnecting or connecting the connector. Also, by detecting the potential of the Vbus terminal 24a, which is less susceptible to external noises, the US
Whether or not the B peripheral device 20 has been connected to the USB host device 2 can be easily and reliably detected. Further, existing D + terminals 24b and D-
Using the terminal 24c, the USB peripheral device 20
It can be easily detected whether or not the B host device 2 has recognized it.

In the above embodiment, the microcomputer 40 is used as the connection detecting means,
Although the configuration is such that the potential of the bus terminal 24a is monitored, the connection detecting means is not limited to this. For example,
It can be configured to monitor the potential of the GND terminal 24d.

In the above-described embodiment, the diode D1 is used as the switching means to switch whether or not the D + line 14b is forcibly set to the ground potential. However, the switching means is not limited to this. Not something. For example, it may be configured to switch whether or not the D-line 14c is forcibly set to the ground potential.

The switching means is not limited to a diode. As the switching means, for example, a switching element such as a transistor can be used. Further, in this case, between the D + terminal 24b and the input / output port 40c and / or the D− terminal 24c
A transistor may be inserted between the input and output port 40d. In this case, for example, the transistor is controlled by microcomputer unit 40, and conduction between D + terminal 24b and input / output port 40c and / or between D− terminal 24c and input / output port 40d is controlled.

In the above embodiment, the downstream USB controller 2 of the USB peripheral device 20 shown in FIG.
2. The case where the functions of the connection detection unit 26, the recognition detection unit 28, and the switch control unit 34 are configured using a microcomputer has been described as an example, but a part or all of the functions are configured by hardware logic. Is also good.

In the above embodiment, the USB peripheral device in which the D + terminal 24b is pulled up to +5 volts (power supply potential) via a resistor has been described as an example, but the present invention is not limited to this. Not something. For example, D
The present invention can be applied to a USB peripheral device in which the negative terminal 24c is pulled up to +5 volts (power supply potential) via a resistor. Further, the present invention can be applied to a USB peripheral device in which the D + terminal 24b is pulled up to a potential other than the power supply potential, for example, +3.3 volts via a resistor.

Further, in the above-described embodiment, a bus-powered USB peripheral device has been described as an example, but the present invention is not limited to this. For example, the present invention can be applied to a self-powered USB peripheral device having a self-power supply. Further, the present invention can be applied to a bus connection device other than the USB standard and a device connection system.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a USB peripheral device 20 which is a USB device according to an embodiment of the present invention.

FIG. 2 shows a USB peripheral device 20 and a USB host device 2
6 is a diagram for explaining wiring of a connection device system including the above.

FIG. 3 shows a USB peripheral device 20 and a USB host device 2
It is a figure which shows the example of a specific structure of the connection apparatus system containing a.

FIG. 4 is a flowchart for explaining an operation when the USB peripheral device 20 and the USB host device 2 are connected using the USB cable 14.

FIG. 5 is a diagram illustrating a conventional connection state between a USB host device 2 and a USB peripheral device 8.

[Explanation of symbols]

 20: USB peripheral device 22: Downstream USB controller 24: Up port 24a: Vbus terminal 24b: D + terminal 24c: D- terminal 26: Connect detection Unit 28 Recognition detection unit 32 Switch unit 34 Switch control unit

Continuation of the front page (72) Inventor Kazuyoshi Takemura 2-1 Nissincho, Neyagawa-shi, Osaka Onkyo Corporation (72) Inventor Nao Yamamoto 2-1 Nissincho, Neyagawa-shi, Osaka Onkyo Corporation ( 72) Inventor Izumi Shimosako 2-1, Nisshinmachi, Neyagawa-shi, Osaka Onkyo Corporation F-term (reference) 5B014 EA04 HC02 HC06 HC07 5B061 FF01 QQ01 QQ06 5K032 BA04 DA04

Claims (6)

[Claims] A bus connection device configured to be connectable to another bus connection device via a bus line and to be recognized by another bus connection device via a bus line, wherein the bus connection device connects the bus line. Connection detection means for detecting whether or not the bus connection device is connected to another bus connection device, and recognition detection means for detecting whether or not the bus connection device is recognized by another bus connection device via a bus line, Based on the information obtained from the connection detecting means and the recognition detecting means, when it is determined that the bus-connected device is connected to another bus-connected device and recognized, the other bus-connected device and the bus-connected device When it is determined that the bus connection device is not recognized despite being connected to another bus connection device, the other bus connection device and the bus connection device are determined. Bus connection device, characterized by comprising a determination switching means for electrically switching process of returning again to the connected state after the sputum substantially disconnected, the. 2. The bus connection device according to claim 1, wherein the bus line includes a line to be connected to a power supply of the other bus connection device, and the connection detection unit detects a potential of the line. Detecting whether or not the bus-connected device is connected to another bus-connected device via a bus line. 3. The bus connection device according to claim 1, wherein the bus line includes a line for performing data communication between the bus connection devices, and the recognition detection unit operates via the line. Detecting whether or not the bus-connected device has been recognized by another bus-connected device based on given data. 4. The bus connection device according to claim 3, wherein the judgment switching means determines whether or not the line for performing the data communication is forcibly fixed to a predetermined potential and determines whether the bus line and the bus connection device are connected to each other. Switch means for switching between a substantially unconnected state and a connected state, and switch control means for controlling switching of the switch means based on information obtained from the connection detection means and the recognition detection means. And characterized by having. 5. An upstream port for connecting to another USB device on the upstream side, and a downstream US connected to the upstream port.
B controller, and the USB device communicates with another USB device via the data terminal of the upstream port and the downstream USB controller.
U configured so that the device can be recognized by other USB devices
In the SB device, a connection detection unit that detects whether or not the USB device is connected to another USB device by detecting the potential of the power supply terminal of the upstream port is provided through the data terminal of the upstream port. Other US
The USB device is connected to another U based on the data from the B device.
A recognition detection unit for detecting whether or not the USB device has been recognized, and whether or not the data terminal of the upstream port is forcibly fixed to a predetermined potential, substantially connects another USB device and the downstream USB controller. When it is determined that the USB device is connected to another USB device and recognized based on information obtained from the switch unit to be connected and the connection detection unit and the recognition detection unit, the connection state of the switch unit is changed. If it is determined that the USB device is not recognized even though the USB device is connected to another USB device, a process of temporarily turning off the switch unit and then returning to the connection state is performed. A USB controller, comprising: a switch control unit configured to perform control as described above. 6. A device connection system configured to connect two functional devices via a signal path and to allow at least one functional device to be recognized by the other functional device via the signal path. , A connection detecting means for detecting whether two functional devices are connected via a signal path, and a recognition detection for detecting whether one functional device is recognized by the other functional device via a signal path Means for connecting two functional devices when it is determined that two functional devices are connected and one device is recognized by the other device based on information obtained from the connection detecting device and the recognition detecting device. When the state is maintained, and it is determined that one device is not recognized by the other device even though the two functional devices are connected, the two functional devices are temporarily set to the substantially unconnected state. Device connection system characterized by comprising: a determination switching means, the again perform electrical switching process of returning the connection state after.