CN100390766C - Universal serial bus device and method for exchanging data with same - Google Patents

Abstract

A Universal Serial Bus (USB) device supports a Bulk-only transmission mode to exchange data with a USB host, and comprises a Bulk endpoint buffer for storing data received or sent by a Bulk endpoint (Bulk endpoint) and an interrupt endpoint buffer for storing data received or sent by an interrupt endpoint (interrupt endpoint); the method for realizing USB device includes storing partial data received or sent originally via batch end point by using interrupt end point buffer; a multiplexer (multiplexer) is then used to control the path of data exchange between the USB device and the USB host either to or from the USB host and the bulk endpoint buffer or the USB host and the interrupt endpoint buffer.

Description

Universal serial bus device and its method for data exchange

technical field

The present invention relates to a universal serial bus, in particular to a universal serial bus device and a data exchange method.

Background technique

Universal Serial Bus (USB) is a new interface technology for personal computer peripheral devices. The USB protocol has three versions: 1.0, 1.1 and 2.0. The communication speed is divided into 1.5Mbps, 12Mbps, 480Mbps, and can Connect up to 127 peripheral devices to the host computer at the same time, featuring fast, bidirectional, plug and play (PnP) and low price. The USB interface has been widely used in various electronic equipment, among which USB mass storage class equipment can be used in the design of portable storage devices and digital audio-visual products, so it is widely used, such as portable hard disk, fast Flash disk, digital camera, MP3 player, CD-ROM drive, etc.

The transmission specifications of USB mass storage devices include four independent sub-transmission specifications, among which the more commonly used ones are the bulk-only (Bulk-only) transmission mode and the control-bulk-interrupt (control-bulk-interrupt, CBI) transmission mode , the two define two basic methods for data transmission between the USB host end (host) and the device end (device) of the USB mass storage device. The Bulk-Only transmission method only uses bulk endpoints (Bulk Endpoint) for data transmission, while the CBI transmission method uses three types of endpoints: Control Endpoint, Bulk Endpoint, and Interrupt Endpoint. for data transfer.

The types of data packets transmitted between the USB host and the device include three types: common data (data), command block wrapper (CBW), and status packets (command status wrapper, CSW). CBW refers to the command packet sent from the USB host to the device. It consists of 31 bytes, and the commands contained in it generally use the SCSI command set. The USB device takes out and executes the corresponding command from the received CBW, transmits the specified data to the host computer and sends the CSW reflecting the execution status of the current command, which consists of 13 bytes. The USB host side can judge whether the operation is correct according to the CSW, so as to decide whether to continue to transmit data or perform error checking of data transmission.

When performing data transmission in bulk individual transmission, a general USB device only uses bulk endpoints for data transmission with the host. When data is sent from the USB host to the USB device, the data is first received by the bulk endpoint and then stored in the bulk endpoint buffer. And if data is to be sent from the USB device to the USB host, the data is first stored in the bulk endpoint buffer, and then sent through the bulk endpoint. In the bulk individual transfer method, since only bulk endpoints are used to transmit common data, CBW, and CSW, the buffers storing the data of bulk endpoints must be stored and cleared again and again, because these actions are quite time-consuming. , so that the speed of data transmission is delayed, and the performance of the USB system is reduced.

Contents of the invention

In view of this, the object of the present invention is to provide a method for realizing a universal serial bus (universal serial bus, USB) device, so as to solve the problems existing in the prior art. The USB device supports a bulk-only transfer method to exchange data with the USB host, and includes a bulk endpoint buffer to store data received or sent through the bulk endpoint (bulk endpoint), and also includes an interrupt endpoint buffer to Store data received or sent via the interrupt endpoint. In one embodiment, a method for implementing a USB device includes the following steps: using an interrupt endpoint buffer to store part of the data originally received or sent via the bulk endpoint. Then use a multiplexer (multiplexer) to control the path of data exchange between the USB device and the USB host is between the USB host and the bulk endpoint buffer or between the USB host and the interrupt endpoint buffer.

In another embodiment, the present invention provides a Universal Serial Bus (USB) device. The USB device supports bulk-only transmission for data exchange with a USB host. The USB device includes: a bulk endpoint buffer for storing data received from or sent to the USB host via a bulk endpoint (bulk endpoint); an interrupt endpoint buffer for storing data received via an interrupt endpoint (interrupt endpoint) The data received or sent from the USB host to the USB host; the multiplexer (multiplexer), coupled between the USB host and the bulk endpoint buffer and interrupt endpoint buffer, is used to control the data exchange between the USB device and the USB host The path is between the USB host end and the bulk endpoint buffer or between the USB host end and the interrupt endpoint buffer; and the microprocessor (micro-processor), coupled to the bulk endpoint buffer and the interrupt endpoint buffer, uses To perform data calculations and control the operation of all units in the USB device, and the microprocessor can control the multiplexer to guide the part of the data received or sent by the bulk endpoint to be stored in the interrupt endpoint buffer and passed through Interrupt endpoint buffer receive or transmit.

Description of drawings

1 is a block diagram of an embodiment of a USB device according to the present invention;

FIG. 2 shows a method for controlling a data path of a USB device according to the present invention.

[Brief explanation of labels]

100 ~ USB device;

104～control endpoint buffer;

106 ~ bulk endpoint buffer;

108～interrupt endpoint buffer;

110～microprocessor;

112～storage unit;

114～multiplexer;

116～path selection register;

Detailed ways

FIG. 1 is an embodiment of a USB device 100 according to the present invention. The USB device 100 supports both a bulk-only (Bulk-only) transfer method and a control-bulk-interrupt (CBI) transfer method. The USB device 100 includes three buffers, namely a control endpoint buffer (control endpoint buffer) 104, a batch endpoint buffer (bulk endpoint buffer) 106, and an interrupt endpoint buffer (interrupt endpoint buffer) 108. These three buffers 104, 106 and 108 are respectively used to store data received from the host or to be sent to the host by the control endpoint, bulk endpoint, and interrupt endpoint. The USB device 100 also includes a storage unit 112 for storing data, and a micro-processor (micro-processor) 110 for performing data calculations and controlling the entire USB device 100 including the storage unit 110 and buffers 104, 106, 108 operation.

The types of data packets transmitted between the USB host and the device have been described above, including three types: common data, command packets (CBW), and status packets (CSW). When performing data transmission in bulk individual transmission, the USB device 100 is different from traditional USB devices that only use bulk endpoints, but uses both bulk endpoints and interrupt endpoints for data transmission with the host. Since there are very few opportunities to use interrupt endpoints for data transmission in the traditional bulk individual transfer method, the present invention uses the interrupt endpoint buffer 108 to process and store command packets and status packets, and the bulk endpoint buffer 106 is dedicated to executing common data The processing and storage work of the USB device 100 can reduce the repeated clearing and storing of the bulk endpoint buffer 106 in the USB device 100, and improve the performance of the USB device 100.

The USB device 100 also includes a multiplexer 114 and a path selection register 116. The path selection bit is stored in the path selection register 116, and the microprocessor 110 can change the value of the path selection bit stored in the path selection register 116. is 0 or 1. When the value of the path selection bit stored in the path selection register 116 is 0, the data path will lead to the bulk endpoint buffer 106 from the multiplexer 114, and when the value of the path selection bit stored in the path selection register 116 When 1, the data path will lead from the multiplexer 114 to the interrupt endpoint buffer 108 . Therefore, when data is sent from the USB host to the USB device 100, the data first arrives at the multiplexer 114, and the multiplexer 114 can direct the data path to the bulk endpoint or The interrupt endpoint, after being received by the bulk endpoint or the interrupt endpoint, stores the data in the bulk endpoint buffer 106 or the interrupt endpoint buffer 108 respectively. And if the data is to be sent from the USB device 100 to the USB host, the data is first stored in the bulk endpoint buffer 106 or the interrupt endpoint buffer 108, and then sent to the multiplexer 114 via the bulk endpoint or the interrupt endpoint respectively for transmission to the USB host side. In addition, the routing register 116 can be a bit in a memory controlled by the microprocessor 110 .

FIG. 2 is an embodiment of a method 200 for controlling a data path of the USB device 100 according to the present invention. Firstly, in step 202 , the microprocessor 110 changes the value of the routing bit in the routing register 116 to 1, so as to direct the data path of the multiplexer 114 to the interrupt endpoint buffer 108 . At this time, if the USB host sends a command packet to the USB device 100 , the command packet can be directed to the interrupt endpoint buffer 108 for storage in step 204 . After the command packet is received, the value of the routing bit in the routing register 116 can be changed to 0 in step 206 so as to direct the data path of the multiplexer 114 to the bulk endpoint buffer 106 .

Now, the firmware controlling the microprocessor 110 can analyze the command packet stored in the interrupt endpoint buffer 108 in step 208, and take out the SCSI command contained in the command packet; if the SCSI command represents that the USB host side requires to read a certain specific data, the microprocessor 110 can retrieve the data from the storage unit 112 and store the data in the bulk endpoint buffer 106 at step 210 . Since the value of the path selection bit is 0 at this time, the data path of the multiplexer 114 is to the bulk endpoint buffer 106 , so the data can be directly transmitted to the USB host through the bulk endpoint. On the contrary, if the SCSI command indicates that the USB host requires to write certain data, the USB device 100 must receive the data from the USB host. At this time, because the value of the path selection bit is 0, the data path of the multiplexer 114 is to the bulk endpoint buffer 106, so the USB host can directly transmit the data to the bulk endpoint and store it in the bulk endpoint buffer 106. . Therefore, the microprocessor 110 can extract the data from the bulk endpoint buffer 106 in step 210 and store it in the storage unit 112 .

Then, the microprocessor 110 may change the value of the path selection bit in the path selection register 116 to 1 in step 212 so as to direct the data path of the multiplexer 114 to the interrupt endpoint buffer 108 . Since the USB device 100 has finished executing the command packet received in step 206 in step 210 , the USB device 100 must respond to the host with a status packet to notify the USB host of the execution result of the command packet. At this time, the firmware controlling the microprocessor 110 can write the status packet into the interrupt endpoint buffer 108 in step 214 , so that the status packet can be directly sent from the interrupt endpoint buffer 108 to the USB host. At this point, the entire command processing flow between the USB host and the USB device 100 is completed. Finally, when the status packet is sent, the microprocessor 110 can change the value of the routing bit in the routing register 116 to 0 in step 216, so as to direct the data path of the multiplexer 114 to the bulk endpoint Buffer 106. The process of steps 202 to 216 can be repeated to continuously process the data transmission between the USB host and the USB device 100 .

If the value of the path selection bit in the path selection register 116 is 1, and the USB device 100 is storing a command packet or a status packet in the interrupt endpoint buffer 108, the USB host may also issue a request to be processed through the interrupt endpoint. interrupt command, resulting in contention for the interrupt endpoint buffer 108. At this time, you can choose to process the command of the interrupt endpoint first, store the command packet or status packet in the current interrupt endpoint buffer 108 separately, and change the value of the path selection bit to 0. After the command of the interrupt endpoint is processed, the command packet or status packet is stored back into the interrupt endpoint buffer 108, and the value of the path selection bit is changed to 1 to continue the processing of the command packet or status packet. It is also possible to choose to process the command packet or the status packet first, and first store the command of the interrupt endpoint separately, and then process the command of the interrupt endpoint after the command packet or status packet is processed.

To sum up, the USB device provided in the embodiment of the present invention can process and store command packets and status packets by using the buffer of the interrupt endpoint, so that the buffer of the bulk endpoint can be used exclusively to handle the transmission of ordinary data . Therefore, the buffer of the bulk endpoint does not need to constantly empty and move the data stored therein, thereby saving a lot of unnecessary execution operations and reducing unnecessary execution operations for the firmware program of the USB device. Therefore, the time required for data transmission between the USB device and the host can be reduced, thereby improving the performance of the USB device.

The foregoing has described several embodiments of the present invention. Those skilled in the art will appreciate that they may modify or use the embodiments of the present invention as a basis for their designs to achieve the same purpose or convenience as the embodiments described herein. Those skilled in the art should also understand that the above-mentioned equivalent structures do not go beyond the spirit and scope of the present invention. Belong to the protection scope of the present invention.

Claims (13)

1. a universal serial bus device carries out the method for exchanges data, the in batches independent transmission mode of this universal serial bus device support is to carry out exchanges data with the USB host end, and comprise that the bulk endpoint impact damper is to store the data via bulk endpoint received or sent, also comprise the interrupt endpoint impact damper storing, and the method that this realization universal serial bus device carries out exchanges data comprises the following steps: via the data that interrupt endpoint received or sent

Use this interrupt endpoint impact damper, former to store via partial data that this bulk endpoint received or sent; And

The utilization multiplexer is controlled the path of exchanges data between this universal serial bus device and this USB host end, makes it be to and between this USB host end and this bulk endpoint impact damper or between this USB host end and this interrupt endpoint impact damper.

2. universal serial bus device according to claim 1 carries out the method for exchanges data, its Central Plains comprises general data, order package and state package via the type of the data that this bulk endpoint received or sent, and described partial data is ordered the data of the type of the data of type of package and this state package for this.

3. universal serial bus device according to claim 1 carries out the method for exchanges data, and wherein the control in this path of this multiplexer is the value decision by a path selection bit.

4. universal serial bus device according to claim 1 carries out the method for exchanges data, also comprises the following steps:

When the data type of being transmitted between this universal serial bus device and this USB host end is general data, adjust this multiplexer so that this path leads to this bulk endpoint impact damper by this USB host end; And

When the data type of being transmitted between this universal serial bus device and this USB host end is order package or state package, adjust this multiplexer so that this path leads to this interrupt endpoint impact damper by this USB host end.

5. universal serial bus device according to claim 1 carries out the method for exchanges data, also comprises the following steps:

When this universal serial bus device receives the interruptive command of this interrupt endpoint of USB host end access, immediately the described partial data in this interrupt endpoint impact damper is stored separately, and empty this interrupt endpoint impact damper, to store this interruptive command; And

After treating that this interruptive command disposes, return and deposit described partial data to this interrupt endpoint impact damper, and the described partial data in this interrupt endpoint impact damper is handled in continuation.

6. universal serial bus device according to claim 1 carries out the method for exchanges data, also comprises the following steps:

When this universal serial bus device receives the interruptive command of this interrupt endpoint of USB host end access, this interruptive command is stored separately, continue to handle the described partial data in this interrupt endpoint impact damper; And

After treating that described partial data disposes, return and deposit this interruptive command to this interrupt endpoint impact damper, and continue to handle this interruptive command.

7. universal serial bus device, this universal serial bus device support in batches separately transmission mode comprise to carry out exchanges data with the USB host end:

The bulk endpoint impact damper is in order to store the data of receiving or be sent to this USB host end via bulk endpoint from this USB host termination;

The interrupt endpoint impact damper is in order to store the data of receiving or be sent to this USB host end via interrupt endpoint from this USB host termination; And

Multiplexer, be coupled between this USB host end and this bulk endpoint impact damper and this interrupt endpoint impact damper, in order to control the path of exchanges data between this universal serial bus device and this USB host end, make it be to and between this USB host end and this bulk endpoint impact damper or between this USB host end and this interrupt endpoint impact damper.

8. universal serial bus device according to claim 7, also comprise microprocessor, be coupled to this bulk endpoint impact damper and this interrupt endpoint impact damper, in order to carry out operation of data, and control the running of all unit in this universal serial bus device, and this this multiplexer of microprocessor may command formerly is stored among this interrupt endpoint impact damper via the partial data that this bulk endpoint received or sent to guide, and receives or send via this interrupt endpoint impact damper.

9. universal serial bus device according to claim 8, also comprise the routing working storage, be coupled between this multiplexer and this microprocessor, in order to store path selection bit, this multiplexer determines this path to lead to this bulk endpoint impact damper or this interrupt endpoint impact damper by this USB host end according to the value of this path selection bit, and this microprocessor can be changed the value of this path selection bit.

10. universal serial bus device according to claim 8, wherein when the data type of being transmitted between this universal serial bus device and this USB host end was general data, this microprocessor can adjust this multiplexer so that this path leads to this bulk endpoint impact damper by this USB host end; And when the data type of being transmitted between this universal serial bus device and this USB host end was order package or state package, this microprocessor can adjust this multiplexer so that this path leads to this interrupt endpoint impact damper by this USB host end.

11. universal serial bus device according to claim 8 also comprises storage element, is coupled to this microprocessor, in order to storage data.

12. universal serial bus device according to claim 8, wherein when this universal serial bus device receives the interruptive command of this interrupt endpoint of USB host end access, this microprocessor stores the described partial data in this interrupt endpoint impact damper immediately separately, and empty this interrupt endpoint impact damper, to store this interruptive command; And after treating that this interruptive command disposes, this microprocessor returns deposits described partial data to this interrupt endpoint impact damper, and continues to handle the described partial data in this interrupt endpoint impact damper.

13. universal serial bus device according to claim 8, wherein when this universal serial bus device receives the interruptive command of this interrupt endpoint of USB host end access, this microprocessor stores this interruptive command separately, and continues to handle the described partial data in this interrupt endpoint impact damper; And after treating that described partial data disposes, this microprocessor returns deposits this interruptive command to this interrupt endpoint impact damper, and continues to handle this interruptive command.

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