JP2003316718A - Usb device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a USB (universal serial bus) device capable of easily perform highly precise synchronization among a plurality of devices connected via USB. <P>SOLUTION: This device has a USB device function by which a plurality of devices are to be connected with USB standard network. The device is provided with a means for extracting frame data included in an SOF packet, a means for setting prescribed data becoming the comparison object of the frame data, a means for storing the prescribed data, and a means for comparing the extracted frame data with the stored data, and it is characterized in that, when the extracted frame data corresponds with the stored data, the operations of a plurality of devices are synchronized by performing a prescribed sequential processing. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a USB device capable of accurately synchronizing operations among a plurality of devices connected by USB.

[0002]

2. Description of the Related Art USB is a standard for transferring digital data at high speed, and is widely used mainly as an interface for connecting a PC and other peripheral devices. USB constitutes a tree-shaped bus, and the one with the only host function (hereinafter referred to as the host) is at the top, and the one with multiple device functions (hereinafter referred to as the device) is connected. With USB, the host is always in control, and the device can only do the transfers that the host requests.

The USB transfer is divided into frames every 1 millisecond, and an SOF having a frame value at the beginning of each frame.
Packets are sent by the host to all devices.
Then, control transfer, bulk transfer, interrupt transfer, and isochronous transfer are performed within the remaining frame time.

[0004]

In USB transfer, the host and the device perform one-to-one communication in all of control transfer, bulk transfer, interrupt transfer, and isochronous transfer, and the transfer can be performed simultaneously to a plurality of connected devices. There is no such thing as a broadcast. That is, when transferring the same content to a plurality of devices, the same transfer is repeated in order to each device.
Therefore, when a predetermined operation is to be synchronized between a plurality of devices, the transfer that signals the start of the operation must be performed individually, which causes a time lag and makes it difficult to perform highly accurate synchronization. was there.

An object of the present invention is to provide a USB device which can easily perform highly accurate tuning among a plurality of devices connected by USB.

[0006]

In order to solve the above-mentioned problems, a USB device of the present invention is a device having a USB device function connected to a plurality of USB standard networks,
Means for extracting frame data contained in the packet,
It has means for setting predetermined data to be compared with the frame data, means for storing the predetermined data to be compared, and means for comparing the extracted frame data with the stored data. When the frame data and the stored data match, a predetermined sequential process is performed to synchronize the operations of the plurality of devices.

Further, the USB device has means for comparing the extracted frame data with the stored data and setting the number of times of matching, and the extracted frame data and the stored data have a predetermined number of times. It is characterized in that the operations of a plurality of devices are synchronized by performing a predetermined sequential process when they match.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION First, referring to FIG.
An example will be described in which a plurality of devices are connected to a network and predetermined sequential processing is synchronized among a plurality of devices. FIG. 1 is a configuration diagram showing an embodiment of the present invention. Reference numeral 100 is a USB device of the present invention, and 101 is a USB device controller having a device function for USB connection as its component parts.
Reference numeral 02 is a CPU that controls the entire apparatus, 103 is a peripheral circuit including a storage circuit used by the CPU and a circuit that performs predetermined sequential processing, and 104 is a CPU 102 that extracts frame data each time the USB device controller receives an SOF packet. And a circuit for storing data to be compared with the frame data of the SOF packet. Two
00 is a USB device having the same configuration as the USB device 100 of the present invention. 10 is a device such as a PC having a USB host function, and U
The SB devices 100 and 200 are connected.

FIG. 2 is a block diagram of an SOF packet transmitted from the USB host 10 to the USB devices 100 and 200 every 1 millisecond, and 20 is an SOF packet composed of 24 bits, 21.
Is a PID that indicates the type of packet consisting of 8 bits, 2
2 is a frame number composed of 11 bits, and 23 is a CRC for confirming that the data composed of 5 bits is correctly received. Frame number 22 is 0-204
It can represent 7 milliseconds.

Next, the operation will be described. In order to synchronize the operations of the USB devices 100 and 200, the USB host 10 notifies the USB devices 100 and 200 of the frame number of the SOF which has the meaning of starting the operation. The control transfer is preferable for the transfer to be notified, but other transfer may be used. The USB device 100 is a USB device controller 101 and a CPU 102 that controls the USB device controller 101,
Control transfer from the host 10 is performed. CPU 102
Analyzes the transfer data and sets the frame number of the operation start SOF in the memory circuit 105. The frame number set here may be set from the USB host 10 as described above, or may be set by the USB device 100.

Each time the SOF frame data extraction circuit 104 receives an SOF packet from the USB host 10, it extracts the frame number and notifies the CPU 102 of that fact.
When the frame number of the operation start is set in the memory circuit 105, the CPU 102 compares the frame number extracted by the SOF frame data extraction circuit 104 with the frame number set in the memory circuit 105 every time the SOF packet is received. . The comparison operation by the CPU 102 is performed by the storage circuit 105.
It is not performed unless the frame number of the operation start is set in.

In the comparison operation of the CPU 102, when the frame number extracted by the SOF frame data extraction circuit 104 matches the frame number set in the storage circuit 105, the CPU 102 controls the peripheral circuit 103 to perform a predetermined sequence. Perform processing. At this time, the CPU 102 causes the storage circuit 10
The data set for No. 5 is erased so that the operation start frame number is not set. By doing so, the comparison operation of the CPU 102 is stopped, and it is guaranteed that the predetermined sequential processing is not performed in duplicate. On the other hand, when it is desired to duplicate the operations, the CPU 102 does not erase the data set in the storage circuit 105, and the CPU 102 may continue the comparison operation.

Although the above description is for the USB device 100, the same applies to the USB device 200. Therefore, if the same frame number of the SOF that starts a predetermined sequential operation is set in the storage circuit 105 for each of the USB devices 100 and 200, the USB devices 100 and 20
0 can perform predetermined sequential operations in synchronism.

In the above description, since the SOF frame number is 11 bits and can be expressed only for 0 to 2047 milliseconds, the time interval from the setting of the frame number in the memory circuit 105 to the start of a predetermined sequential operation. Up to 2
There is a limit of 048 milliseconds. Therefore, the memory circuit 10
When the frame number is set to 5, the number of times of comparison and coincidence is also set at the same time. This match count setting is also USB host 10
May be set by the USB device 100 or may be set by the USB device 100. The CPU 102 uses the SOF frame data extraction circuit 104
The number of times the extracted frame number matches the frame number set in the storage circuit 105 is counted, and when the number of matches reaches the set number, the peripheral circuit 103
Are controlled to perform predetermined sequential processing. At this time, CPU10
In No. 2, the data set in the memory circuit 105 is erased so that the operation start frame number and the number of coincidences are not set. By doing so, the comparison operation of the CPU 102 is stopped, and it is guaranteed that the predetermined sequential processing is not performed in duplicate. On the other hand, if you want to duplicate, CP
The U 102 does not erase the data set in the memory circuit 105, returns the counted number of coincidences to zero, and causes the CPU 102 to continue the comparison operation.

By doing so, it becomes possible to arbitrarily set the time interval from the setting of the frame number in the memory circuit 105 to the start of a predetermined sequential operation.

[0016]

As described above, according to the first aspect of the invention, it is possible to easily realize a highly accurate tuning operation between devices having a USB device function which are connected to a plurality of USB standard networks. it can.

According to the second aspect of the present invention, it is possible to freely set the time interval until the tuning operation is started.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of an SOF packet.

[Explanation of symbols]

Device with USB host function such as 10 PC 20 SOF packets 100, 200 USB device of the present invention 101, 201 USB device controller 102, 202 CPU 103, 203 peripheral circuits 104, 204 SOF frame data extraction circuit 105, 205 comparative frame data storage circuit

Claims (2)

[Claims] 1. An apparatus having a USB device function, which is connected to a plurality of USB standard networks, wherein a unit for extracting frame data included in an SOF packet and predetermined data to be compared with the frame data are set. When the extracted frame data and the stored data match, the extracted frame data and the stored data are compared, and the predetermined frame data to be compared is stored. A USB device that synchronizes the operations of multiple devices by performing predetermined sequential processing on. 2. The USB device has means for comparing the extracted frame data with the stored data and setting the number of times that they should match, and the extracted frame data and the stored data have a predetermined number of times. A USB device that synchronizes the operations of multiple devices by performing predetermined sequential processing when they match.