JP2003309618A - Communication apparatus and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To dynamically select a receiving process suited to a protocol to be used. <P>SOLUTION: The communication method for transmitting and receiving data to/from an external unit connected through a digital interface at a receiving node (1) having communication means adaptable to a plurality of communication protocols comprises a step of discriminating a communication protocol the external unit utilizes (S103-S105), a step of switching over and setting a first mode for receiving the data sent from the external unit in an interruption system, and a second mode for receiving the data in a polling system according to the identified communication protocol in the identification step (S106, S107), and a step of controlling the communication means for receiving data in the set first or second mode. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to IEEE Std 1394-19.
The present invention relates to a communication device and a communication method having a digital interface compliant with 95 and related standards.

[0002]

2. Description of the Related Art IEEE Std 1394-1995 guarantees a certain band within a time period that is cyclically continuous and does not perform a retransmission procedure even when an error occurs. Although not guaranteed, there are two types of transfer modes called asynchronous transfer, which is a transfer mode that guarantees reliable data transfer by a retransmission procedure when an error occurs. Isochronous transfer is mainly used for transferring large-capacity moving image data found in digital video cameras and the like, and asynchronous transfer is mainly used for transferring to devices such as storage devices, printers, and scanners where data loss is not allowed. Since isochronous transfer has a higher priority in the transfer mode, asynchronous transfer uses a band that is not used in isochronous transfer. Also, in the asynchronous transfer, a retry protocol is provided that enables the packet to be retransmitted when the receiving node cannot receive the packet (busy state).

Asynchronous transfer includes write, read, and lock transactions, and when transferring a large amount of data that cannot be lost from a certain node, the node having the data actively transmits the data. A write transaction (transferring data with a request packet) or a read transaction (transferring data with a response packet) in which a node receiving the data tries to read the data is used.

Of these, when the packet transmitted by the write transaction is received by the receiving side node, it is necessary to consider at which timing the packet transmitted asynchronously is confirmed and the data is processed. In general, there are a case where an interrupt method is used in which an interrupt is generated and a received packet is confirmed each time a packet is received, and a case where a polling method is used in which packet reception is confirmed at a fixed cycle.

[0005]

However, in the above-mentioned conventional technique, while the protocol supported by the plurality of protocols existing on 1394 is limited, the reception processing method (interrupt method) suitable for the protocol to be used is provided. Or polling method), there was no problem. However, for example, in a printer device or the like, it is necessary to support a plurality of protocols in the future in order to meet printout requests from various devices from a PC to a non-PC (for example, a scanner and a digital camera). This is not limited to a printer device, but in the case of a printer device, for example, it is necessary to support SBP-2 in communication with a PC and DPP in communication with a non-PC. In that case, if the packet reception processing method is fixed to either one (either interrupt processing or polling processing is fixed), the following problems may occur.

1. In the interrupt method, the processing in the IEEE 1394 interface section is good, but the IEEE 13
When the controller that controls the 94 interface and the controller that controls the device itself are physically composed of one piece of hardware, an asynchronous interrupt that frequently occurs when an interrupt is received and processing is performed each time a packet is received. Occurrence of processing delays processing (for example, image processing or control of printing mechanism in the case of a printer) that should be performed by other than the interface. In the worst case, other processing may not be performed normally, or the packet itself may not be received if the other processing has a higher priority. That is, since the processing as a whole depends on the interface portion, it is necessary to design the system in consideration of the case where the processing time is imbalanced between the processing of the interface portion and other main processing.

2. The polling method is easier to design the entire system than the interrupt method, but if the polling interval is relatively shorter than the packet reception interval, useless processing occurs due to frequent periodic interrupts. On the contrary, if it is long, packets cannot be received and may be dropped (device busy due to FIFO full, or transmission of response packet to be transmitted after reception of request packet is delayed and split timeout occurs at the transmitting side node). Retransmission of packets (retry) from the transmitting node due to busy or split timeout causes wasteful packets to flow on the bus, which causes a problem that the band cannot be effectively used. Also, the polling period and the packet reception interval are not uniformly defined, and it is difficult to uniquely determine the optimum interval because the setting values differ depending on the performance and configuration of each device and the protocol adopted.

The present invention has been made in view of the above problems, and it is an object of the present invention to dynamically select a reception process suitable for a protocol to be used.

[0009]

In order to achieve the above object, the communication device of the present invention is a communication device that supports a plurality of communication protocols for transmitting / receiving data to / from an external device connected via a digital interface. And switching means for switching and setting a first mode in which the data transmitted from the external device is received by an interrupt method and a second mode in which the data is transmitted by a polling method, and a first mode set by the switching means. In order to receive the data in the 1st or 2nd mode, it has a control means which controls the said communication means, The said switching means sets according to the communication protocol which the said external device utilizes.

Further, the communication method of the present invention in an apparatus having communication means corresponding to a plurality of communication protocols for transmitting / receiving data to / from an external apparatus connected through a digital interface is a communication protocol used by the external apparatus. And a communication mode determined in the determination step between a first mode in which an interrupt method is used to receive data transmitted from the external device and a second mode in which a polling method is used to receive data transmitted from the external device. ,
There is a switching step for setting, and a control step for controlling the communication means to receive data in the first or second mode set in the switching step.

[0011]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

First, an outline of the communication device 1 according to the present embodiment will be described with reference to FIG.

Reference numeral 2 is a serial bus that complies with IEEE Std 1394-1995 and related standards. 3 is IEEE
It is a digital interface (hereinafter, IEEE 1394 interface) compliant with Std 1394-1995 and standards related thereto. An IEEE 1394 driver 4 controls a transaction layer level function.
A printer unit 5 prints print data.

Reference numeral 6 is an SBP-2 control unit for performing control corresponding to SBP-2 among a plurality of protocols existing on IEEE1394. SBP-2 (Serial Bus
Protocol-2) is a transport protocol suitable for IEEE 1394, and provides a framework for a command set defined above. The structure between communicating devices is Initiator-Target (master-slav
It has the form of e) and is asymmetric. The host Initiator takes the initiative, and the connections are login and logout.
Done by In the present embodiment, the target device is the communication device 1, and therefore the target device. SBP-
Although the upper layer protocol is transferred on top of the two frameworks, since it is assumed to be a printer device, the upper layer is SCSIc or PPDT (Peer to Peer Data).
Transport) and other protocols and command sets are applied, and communication is performed with a PC that is a host. The host (PC), which is the Initiator, takes the initiative in communication, but the data transfer itself is performed by a read transaction from the Target device.

Reference numeral 7 is a D for performing control corresponding to DPP among a plurality of protocols that similarly exist on 1394.
It is a PP controller. DPP (Direct Print Protocol)
Is a protocol that enables printing directly from an image source device (such as a scanner or digital camera) without a host PC. Thin Session, Thin Transacti
It has a layered structure called on, and data transfer is performed by a write transaction from the image source device.

Reference numeral 8 is an application controller for controlling the function at the application layer level. The application controller 8 also analyzes commands for print data, performs image processing (correction processing and decompression processing) on print data, and controls the printer unit 5.

Reference numeral 9 denotes a reception processing control unit for switching between packet reception processing by a polling method and an interrupt method. The reception process is switched to one suitable for the communication protocol according to the judgment of the application 208. At that time, when the interrupt method is selected, the interrupt generated in the polling cycle is masked or the cyclic handler is deactivated. When selecting the polling method, mask interrupts when packets are received.

Next, with reference to the flow chart shown in FIG. 2, the processing procedure of the receiving method setting processing in the present embodiment will be described.

In step S201, the packet receiving process of the communication device 1 which receives the packet is initialized. As described above, the communication device 1 is a device capable of selecting whether to receive a packet by the interrupt method or the polling method. It also supports multiple protocols. Normally, the packet receiving process is initialized when the power of the device which is the communication device 1 is turned on and when a certain data transfer is completed. The polling cycle is
CPU or IEEE 1394 that controls the communication device 1
A hardware timer attached to the IEEE 1394 interface 3 that controls the interface is used.

In step S202, a data transfer request from the transmission request node is accepted. At this time, it is understood which of the supported protocols the data transfer request was made. In this embodiment, SBP-2 and DPP are supported protocols.
Target. Only when the data transfer is SBP-2 or DPP (YES in step S203), the following procedure is taken. Otherwise (step S
If NO in 203), the setting process ends.

In step S204, the transfer request is Login.
Determine if done by. Login is SBP
It is an exclusive command at -2. In SBP-2, data transfer is performed by a read transaction from the communication device 1. The read transaction is a transfer mode in which the data in the transmission side node can be acquired at a predetermined timing of the communication device 1. That is, the reception side node transmits the request packet at a desired timing, and the transmission side node stores the data in the payload of the response packet and transmits it. If the protocol used by the device that has made the transfer request is SBP-2, that is, if the accepted command is Login, the process proceeds to step S207, and if not, the process proceeds to step S205.

In step S207, the transfer request is Login.
The polling method is selected in response to the command, that is, the data transfer using SBP-2. In SBP-2, since the request packet is transmitted at the timing of the communication device 1, it is considered that packet reception may not occur more than expected, so a polling method that does not impose a load on the system is selected. Here, since the polling method has already been selected as the packet reception process in the initial setting, the process is terminated without any particular change in the setting of the polling cycle. When changing the polling cycle in consideration of the protocol, the amount of data to be transferred, and other factors, the setting of the cycle is changed.

In step S205, the transfer request is Connec.
Determine if it was done by t Request. Conne
ct Request is a DPP connection command. In DPP, data transfer is performed by a write transaction from the sending node. The light transaction is
This is a transfer mode in which data in the sending node is sent out at a predetermined timing of the sending node. That is, the request packet having the data payload is transmitted at the timing of the transmitting node, the communication device 1 stores the request packet received asynchronously, and returns the response packet. The protocol used by the device that requested the transfer is D
If it is PP, that is, the received command is Connect
If the request is Request, the process proceeds to step S206. If not, for example, when a connection request of another unsupported protocol or isochronous transfer is used, the process ends.

In step S206, the interrupt method is selected as the processing method of the received packet, and it is set so as not to receive the periodic interrupt generated by the value set by the system timer or the user timer. That is, the factor of the periodic interrupt of polling is masked. Alternatively, deactivate the cyclic handler itself so that interrupts are not generated in the polling cycle. The selection of the interrupt method is to eliminate the possibility of dropping the received packet that may occur when the polling method is selected. This is because when the polling method is selected, the response to the received request packet (transmission of response packet) may be delayed from the value set in the split timeout register,
This is because there is a possibility that packets will not be able to be received as device busy because packets are accumulated in the FIFO. Therefore, here, the packet reception process by the asynchronous interrupt, which burdens the system, is selected, and the setting of the reception process is completed. Since it is known in step S205 that data transfer is performed by DPP, an interrupt method that facilitates asynchronous packet reception processing is selected and set.

As described above, according to this embodiment, it is possible to dynamically select the optimum receiving process for the communication protocol. As a result, when the interrupt method is selected, packet dropouts do not occur, and when the polling method is selected, the number of asynchronous interrupts in the interface is reduced, and processing other than communication that the device that is originally the receiving node should perform. Equalization with the time taken can be realized. It is also effective when implementing a number of new protocols that will be developed in the future.

The present invention is based on SBP-2 and DPP.
The present invention is not limited to the above, but can be applied to other communication protocols.

[0027]

Other Embodiments Another object of the present invention is to supply a storage medium (or recording medium) recording a program code of software for realizing the functions of the above-described embodiments to a system or apparatus, and to supply the system or apparatus. Alternatively, it is needless to say that it is also achieved by the computer (or CPU or MPU) of the device reading and executing the program code stored in the storage medium. in this case,
The program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) running on the computer based on the instructions of the program code. Needless to say, this also includes a case where a part or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing.

Further, after the program code read from the storage medium is written in the memory provided in the function expansion card inserted into the computer or the function expansion unit connected to the computer, based on the instruction of the program code. , The CPU provided in the function expansion card or the function expansion unit performs some or all of the actual processing,
It goes without saying that the processing includes the case where the functions of the above-described embodiments are realized.

When the present invention is applied to the above storage medium, the storage medium stores the program code corresponding to the flowchart shown in FIG. 2 described above.

[0030]

According to the present invention, it is possible to dynamically select a reception process suitable for the communication protocol used.

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of a communication device according to the present embodiment.

FIG. 2 is a flowchart showing a processing procedure of a reception processing setting processing according to the present embodiment.

[Explanation of symbols]

1 communication device 2 serial bus 3 IEEE 1394 interface 4 IEEE 1394 driver 5 Printer section 6 SBP-2 controller 7 DPP controller 8 Application controller 9 Reception processing control unit

Claims (23)

[Claims] 1. A communication means for transmitting / receiving data to / from an external device connected via a digital interface, the communication means being compatible with a plurality of communication protocols, and receiving data transmitted from the external device by an interrupt method. Switching means for switching and setting the first mode and the second mode performed by the polling method, and controlling the communication means to receive data in the first or second mode set by the switching means. The communication device is characterized in that the switching device performs setting according to a communication protocol used by the external device. 2. The communication device according to claim 1, wherein the interrupt method is masked when data is received in the second mode. 3. The switching means sets the first mode when performing data transfer by a write transaction from the external device, and sets the second mode when performing data transfer by a read transaction from the communication device. The communication device according to claim 1, wherein the communication device is set to the mode. 4. The communication device according to claim 1, wherein the switching unit determines a communication protocol according to a connection method of the external device to the communication device. 5. The switching means is configured such that the external device is Co.
5. The method according to claim 4, wherein the first mode is set when a connection is made by nnect Request, and the second mode is set when the external device makes a connection by a login command. Communication device. 6. The communication device according to claim 1, further comprising setting means for resetting a polling cycle in the second mode. 7. The communication device according to claim 1, wherein in the second mode, an OS system timer is used to measure a polling cycle. 8. When the first mode is set,
The communication device according to claim 7, wherein the polling method is deactivated. 9. The communication device according to claim 1, wherein in the second mode, a user-defined timer is used to measure a polling cycle. 10. The communication device according to claim 4, wherein the communication unit complies with IEEE 1394. 11. A communication method in a device having a communication means compatible with a plurality of communication protocols for transmitting / receiving data to / from an external device connected via a digital interface, the communication protocol being used by the external device. A determination step of determining, a first mode of performing reception of data transmitted from the external device by an interrupt method, and a second mode of performing a polling method are switched to the communication protocol determined by the determination step, A communication method comprising: a switching step of setting; and a control step of controlling the communication means to receive data in the first or second mode set in the switching step. 12. The communication method according to claim 11, wherein the interrupt method is masked when data is received in the second mode. 13. In the switching step, the first mode is set when data transfer is performed by a write transaction from the external device, and the second mode is set when data transfer is performed by a read transaction from the communication device. 2. The mode is set to 1.
The communication method according to 1 or 12. 14. The communication method according to claim 11, wherein in the switching step, the communication protocol is determined by a connection method of the external device to the communication device. 15. In the switching step, the first device is connected when the external device connects by a Connect Request.
15. The communication method according to claim 14, wherein the second mode is set when the external device connects by a login command. 16. The communication method according to claim 11, further comprising a setting step of resetting a polling cycle in the second mode. 17. The communication method according to claim 11, wherein in the second mode, an OS system timer is used to measure a polling cycle. 18. The communication method according to claim 17, wherein the polling method is deactivated when the first mode is set. 19. The communication method according to claim 11, wherein in the second mode, a user-defined timer is used to measure a polling cycle. 20. The communication method according to claim 14, wherein the communication unit complies with IEEE 1394. 21. A program executable by an information processing device, the information processing device executing the program comprising:
A program causing the communication device according to any one of claims 1 to 10 to function. 22. A program executable by an information processing device, having a program code for realizing the communication method according to claim 11. 23. A storage medium storing the program according to claim 21 or 22.