JP2003248558A - Method and device for data transfer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To markedly improve the efficiency of data transfer, to always secure a data transferring rate above a certain level and to carry out a high speed printing process by controlling the changeover of the desired transfer method according to communication state of a bus. <P>SOLUTION: The data transferring is executed by using a synchronized transfer method executing the synchronized transfer in which the data transferring rate is limited and a non synchronized transfer method executing the non synchronized transfer in which the data transfer rate is unlimited, analyzing communication state on a serial bus such as USB, IEEE1394 (the number of connected devices and the bus traffic, etc.), selecting the desired transfer method from the plurality of transfer methods (synchronized and non synchronized) according to the analyzed result and changing over to the selected desired transfer method. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, for example, when transmitting data from a host computer on the master side to an printing device on the slave side via an interface and printing the data, analyzes the communication system to determine a desired data transfer system. A data transfer method capable of switching control, and
Regarding the device.

[0002]

2. Description of the Related Art Currently, a personal computer (PC)
And SCSI (Smal
l Computer System Interfa
CE), RS-232C, Centronics, and various external buses exist. However, the external bus that has been used so far is a bus specialized for each peripheral device connected thereto, and has adopted a specific transfer method.

FIG. 8 shows a conventional example in which peripheral devices are connected using these external buses. An external bus 110 is connected between the host device 100 such as a personal computer and the peripheral device 200. Host device 10
A host external bus control unit 101 is provided at 0.

The host external bus control unit 101 includes a buffer 102, a data transfer unit 103, and a transceiver 10.
4 and a control unit 105 are provided.

The control unit 105 includes a control signal line 121, a data signal line 122 and an address signal line 123 of the system bus.
The buffer unit 102 and the data transfer unit 103 are controlled by a control procedure sent based on an instruction from the host device 100.

The data transferred to the printer, which is the peripheral device 200, via the external bus 110 is the data signal line 12
2 to the buffer 104.

The data transfer unit 103 generates a signal of the procedure described later, transmits / receives data to / from the peripheral device 200 from the transceiver 104 via the external bus 110,
The communication result is passed to the control unit 105 or the buffer 102.

In this prior art example, the host device 100
Although the host external bus control unit 101 on the side has been described in detail, the peripheral device external bus control unit 201 provided on the peripheral device 200 side that receives the data to be transferred also
It has the same configuration as the host external bus control unit 101.

FIG. 9 shows a conventional host external bus control unit 10.
1 and an example of a transfer procedure in the peripheral device external bus control unit 201.

Tx corresponds to the transmitting side, here the host external bus control unit 101, and Rx corresponds to the receiving side, the peripheral device external bus control unit 201.

First, a Token signal is transmitted from Tx to Rx, which means designation of a transmission partner and start of data transmission. Upon receiving this Token signal, the Rx becomes ready for reception and waits for data. The Tx continues to send a data signal (Data0 in the figure) to the Rx. After confirming the reception of the data, the Rx transmits an ACK signal indicating the successful reception to the Tx. This completes one data transfer.

When transmitting a quantity of data that cannot be transferred at one time, this procedure is repeated. It is generally used to add an error correction code to data, assuming that an error has occurred in the data transfer path. For example, Hamming code, RM (Reed Muller) code, BC
H (Bose Caudhuri Hocqueng
hem) code, convolutional code, CRC (Cyclic)
RedundancyCheck k) code, RS (Re
ed Solomon) code and the like.

As an example, when a CRC code is used,
It becomes possible for the receiving side to check whether or not an error has occurred in the data, and when it is judged that an error has occurred in the transmission of Data1, the NA changes to an ACK signal, which means a retransmission request.
Send K signal to Tx. When the NAK signal is received, it is determined that an error has occurred in data transfer, and Data is again
Send 1. When Data1 is received normally, Rx
Sends an ACK signal to Tx.

Even if an error occurs in this way, it is possible to transfer error-free data by using means such as retransmission.

According to such a sequence, output from the host device 100 to the printer as the peripheral device 200 connected to the outside is performed. The connection procedure between the host device 100 and the peripheral device 200 is generally performed by the same method.

[0016]

On the other hand, USB
(Universal Serial Bus), IE
In a new standard bus such as EE1394, a plurality of devices can be connected to one bus. Further, it is characterized in that the bus is synchronized with a cycle time of a frame, which is a constant time interval, and the bus is controlled in this cycle unit.

In such a new standard bus such as USB and IEEE1394, a plurality of devices are connected by time sharing the bus. Therefore, the standard provides several transfer modes for optimal data communication according to the characteristics of each device. The transfer modes are classified into synchronous transfer for supporting isochronous data (audio / video, input device) and asynchronous transfer for supporting aperiodic and large amount of data transfer. The characteristics of each of these transfers are as follows.

The synchronous transfer has the following features.

A1) The data transfer rate is guaranteed to ensure isochronism.

A2) An upper limit is set for the data transfer rate so as not to consume too much bandwidth.

A3) In order to ensure isochronism, data retransmitting processing is not performed when transfer data is missing.

The asynchronous transfer has the following features.

B1) In order to send a large amount of data, the more data that can be transferred if the bandwidth is wide.

B2) Since the data transfer is assumed to be aperiodic, there is no guarantee of the data transfer rate.

B3) When the transfer data is missing, the data is supplemented by retransmitting the data.

However, some peripheral devices cannot be completely classified into the above two categories. For example, a printing device may be used.

In the case of a printing apparatus, data transfer is normally performed by asynchronous transfer because isochronism is not required. However, since the data transfer rate is not guaranteed, bus traffic will cause a delay in printing time.

Further, even if the synchronous transfer is assigned to the data transfer method, the transfer rate is limited, so that the printing time is delayed when an image of high quality and large size is transferred. . In particular, this is remarkable in a commercial printing apparatus that has a large print size and requires high image quality.

Therefore, an object of the present invention is to control the switching of a desired transfer method according to the communication mode of the bus.
It is to provide a data transfer method and an apparatus therefor capable of further improving the efficiency of data transfer.

Another object of the present invention is to provide a data transfer method and an apparatus thereof which can always secure a data transfer rate of a certain level or higher and can perform information processing such as high-speed printing. Especially.

[0031]

SUMMARY OF THE INVENTION The present invention executes a synchronous transfer method for executing a synchronous transfer with a limited data transfer rate, and an asynchronous transfer method with an unlimited data transfer rate. A data transfer method using an asynchronous transfer method, an analysis step of analyzing a communication form on a serial bus, and a selection step of selecting a desired transfer method from the transfer methods according to the analysis result. And a transfer method switching step of executing the data transfer by switching to the selected desired transfer method, thereby providing a data transfer method.

Here, the analysis step may analyze the number of the plurality of devices connected to the serial bus or the traffic of the serial bus.

In the selecting step, when the traffic of the serial bus is high, a data transfer method that secures a data transfer rate of a certain value or more is selected, and when the traffic of the serial bus is low, data transfer can be performed at high speed. The method may be selected.

In the selecting step, depending on the traffic of the serial bus, bulk transfer is performed when the bandwidth is vacant, and isochronous transfer is performed when the bandwidth is vacant, so that a transfer rate equal to or higher than a certain level is achieved. May be secured.

In the selecting step, an error correction code may be added to the transfer data when the synchronous transfer method is selected.

The switching of the data transfer method may be performed at the start of data transfer.

The switching of the data transfer method may be switched for each arbitrary transfer data unit.

The arbitrary transfer data unit may be data divided for each band area when transferring print output data.

The serial bus used for data transfer is a USB (Universal Serial Bu).
s) or IEEE 1394.

The present invention relates to a synchronous transfer method for executing a synchronous transfer with a limited data transfer rate and an asynchronous transfer method for executing an asynchronous transfer with an unlimited data transfer rate. An information processing device using, and an analysis unit for analyzing a communication form on a serial bus,
The information processing apparatus is configured by including a selecting unit that selects a desired transfer method from the transfer methods according to the analysis result.

The present invention is a system for controlling switching of data transfer between a master-side device and a plurality of slave-side devices via a serial bus, wherein the slave-side device comprises: 21. The information processing apparatus according to any one of claims 1 to 20, wherein the device on the master side includes a transfer method switching unit for executing a data transfer by switching to a desired transfer method selected and transferred by the device on the slave side. An information processing system is configured by providing the information processing system.

The present invention provides a synchronous transfer method for executing a synchronous transfer with a limited data transfer rate, and an asynchronous transfer method for executing an asynchronous transfer with an unlimited data transfer rate. Is a program that uses
The program is recorded on a computer-readable recording medium, and a step of analyzing a communication form on a serial bus, and a step of selecting a desired transfer method from the transfer methods according to the analysis result And a step of executing the data transfer by switching to the selected desired transfer method, thereby providing a data transfer control program.

The present invention is a medium in which a program for controlling switching of data transfer between a master-side device and a plurality of slave-side devices is recorded via a serial bus. In the computer, a synchronous transfer method for executing a synchronous transfer with a limited data transfer rate and an asynchronous transfer method for executing an asynchronous transfer with an unlimited data transfer rate are used. By analyzing the communication form on the serial bus, selecting a desired transfer method from the transfer methods according to the analysis result, and switching to the selected desired transfer method to execute data transfer, A medium on which a data transfer control program is recorded is provided.

[0044]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. <System Configuration> First, the overall configuration of this system will be described.

FIG. 1 shows a configuration example of a print system according to the present invention. This system includes a host device 300 on the master side, a plurality of inkjet printers 400 (hereinafter, referred to as printers) on the slave side, and an external bus 500.
, A host external bus control unit 600 and a peripheral device external bus control unit 700.

(Printer) The printer 400 is divided into a printer controller 410 having a peripheral device external bus controller 700 according to the present invention and a printer engine 420. Image data generated by the host device 300 is transferred to the printer 400 via the external bus 500 and the peripheral device external bus control unit 700, and print output processing is performed.

The printer controller 410 executes the following processes. a1) IF control processing with the external bus 500 used for communication with the host apparatus 300, a2) Interpretation processing of printer control commands (converted image data) transferred from the host apparatus 300, and bitmap data The generation process, a3) various image processes at the time of generating the bitmap data, a4) the operation of receiving a command from the user and transmitting a command to the printer engine 420 are mainly performed.

The printer engine 420 executes the following processes. b1) A process of receiving the bitmap data generated by the printer controller 410 and generating ejection timing data of the inkjet head, b2)
The printing process, b3) ink supply / recovery process to the inkjet head, b4) paper conveyance, motor control process in head operation, etc. are mainly performed.

Through the above processing, the printer 400 executes the printout of the image data received from the host device 300.

(Peripheral Device External Bus Control Unit) FIG. 2 shows a configuration example of the peripheral device external bus control unit 700 according to the present invention. First, the outline of the communication switching function of the present invention will be described. The peripheral device external bus control unit 700 analyzes the communication mode on the serial bus, and selects the desired transfer method from the synchronous transfer method and the asynchronous transfer method according to the analysis result. It has and. Here, the synchronous transfer method refers to a transfer method in which the upper limit of the data transfer rate is set and a fixed data transfer rate is guaranteed, and the asynchronous transfer method does not guarantee the data transfer rate. Instead, it refers to a transfer method that does not limit the data transfer rate.

In this case, when the synchronous transfer method is selected, an error correction code may be added to the transfer data.
The data transfer method may be switched at the start of data transfer, or may be switched for each arbitrary transfer data unit. The arbitrary transfer data unit may be data divided for each band area when transferring print output data. The serial bus used for data transfer is a bus to which a plurality of peripheral devices can be connected, and is a USB (Universal).
Serial Bus) or IEEE 1394 can be used.

Next, a specific configuration example of the communication switching function according to the present invention will be described. In this example, the host device 3
00 for data transfer between the
A case of using (Universal Serial Bus) will be described.

In FIG. 2, peripheral device external bus control unit 7
00 includes a USB transceiver 701, a serial interface engine 702, an endpoint buffer 703, a USB traffic monitoring unit 704, and a data transfer determination unit 705. Here, a USB is used as the external bus 500, and the configuration of each unit has the following functions.

The USB transceiver 701 is a driver,
It is composed of a receiver and drives and receives a USB data signal which is a differential signal.

Serial interface engine 702
Performs processing of the USB protocol layer. Specifically, S
YNC (Synchronization) detection, NRZI (Non-Return-to-Zero)
-Inverted: non-zero return inversion) encoding / decoding, bit stuffing / destuffing, C
RC (Cyclic Redundary Chec
k: Cyclic redundancy check) generation check, data serial
Perform parallel conversion.

The endpoint buffer 703 is a FIF.
It is composed of an O (First-In First-Out) buffer and communicates with the host device 300. in this case,
It has an asynchronous transfer buffer 703a, a synchronous transfer buffer 703b, and a data transfer method notification buffer 703c. The function of each of these buffers will be described later.

The USB traffic monitoring unit 704 analyzes the communication mode on the external bus 500 and monitors the number of connected devices and the bus traffic (communication amount).

The data transfer method determination unit 705 calculates the bandwidth consumption amount according to the analysis result by the USB traffic monitoring unit 704, that is, from the monitored bus traffic, and determines the optimum transfer method (synchronous method, asynchronous method). ) Is determined.

In USB, communication between the host device 300 and the printer 400 as a peripheral device is performed by the host device 3
The address of the target peripheral device is designated in the token packet from 00, and the transaction is transmitted to all the peripheral devices. On the peripheral device side, all received token packets must be completely decoded, and the address value in them must be decoded so that they will respond only when they are transferred to themselves. Therefore, the USB can also receive packets other than packets directed to itself, and can determine bus traffic and the number of connected devices. By the USB traffic monitoring unit 704,
It is possible to dynamically switch the transfer method by determining the bus traffic and the number of connected devices and switching the USB alternative setting according to the situation. Dynamic means that switching of the bus connection is performed as a continuous operation without being interrupted.

(Host Device) The host device 300 is provided with a host external bus control unit 600. The host external bus control unit 600 includes a switching transfer unit 601 and a transfer method storage unit 602.

The switching transfer unit 601 has a function of switching to the optimum transfer system selected and transferred by the peripheral device external bus control unit 700 and executing data transfer according to the switched transfer system.

The transfer method storage unit 602 includes the printer 400.
It has a function to temporarily store the transfer method transferred from.

Although the peripheral device external bus control unit 700 (USB controller) according to the present invention is provided in the printer controller 410 in this example, the present invention is not limited to this, and may be provided in the host device 300. . in this case,
The host device 300 has the communication switching function according to the present invention for all peripheral devices of different models to be connected, and when 100 printers of the same model, for example, the same printer, are connected, only the number of printers corresponding to the number of printers A communication switching function may be provided.

(USB) Here, the USB data transfer will be briefly described.

Data transfer basically consists of three packets,
It consists of token packet, data packet, and handshake packet. One data transfer composed of these three packets is called a transaction. A packet ID indicating the type of transaction, the address of the device (peripheral device 400) that is the target of data transfer, and the endpoint number are inserted in the token packet, and the peripheral device 400 and the host that match the information of this token packet. Data can be transferred to and from the device 300. This token packet is used by the host device 300.
Only can be generated. This is the host device 300
It means that you are managing bus access rights only. Transfer data is stored in the data packet. Stores information indicating whether the data transfer was completed normally or could not be completed normally.

There are three types of transactions, an in transaction, an out transaction, and a setup transaction. In transaction,
Data is transferred from the peripheral device 400 to the host device 300. In the out transaction, the host device 300
Data is transferred to the peripheral device 400 from the. In the setup transaction, it is used to transfer a command specified by the standard from the host device 300 to the peripheral device 400. These three transactions form a transfer called bulk transfer, control transfer, isochronous transfer, or interrupt transfer.

Bulk transfer is a sequence of in transactions or out transactions. The control transfer is a setup transaction only or a sequence of in-transactions and out-transactions following the setup transaction. Isochronous transfer is a sequence of in transactions or out transactions without handshake packets.
The interrupt transfer is one in-transaction.

These transfers are arranged in a period of 1 ms unit called a frame. This control is performed by the host external bus control unit 600. The start of the frame is notified by a special packet called an SOF (Start of Frame) packet. Of these, the bandwidth for isochronous transfer and interrupt transfer is secured in the frame. The bulk transfer is an asynchronous data transfer, and the control transfer is used to initialize the peripheral device external bus control unit 700 connected to the bus. Isochronous transfer is a synchronous transfer, and a data transfer amount per unit time is secured. However, unlike other transfers, data is not guaranteed only for isochronous transfer. It is used for interrupt processing because it is guaranteed that interrupt transfer will always be transferred at set times.

The above USB communication is performed between the host device 300 and the endpoint. The printer 400, which is a peripheral device, can have a plurality of end points and can be made into a unit called an interface by grouping the plurality of end points.

Further, the peripheral device can have a plurality of interfaces, and the plurality of interfaces can be grouped to form a device configuration. By defining these interfaces and device configurations, it is possible to flexibly support peripheral devices with complex functions.

<System Operation> Next, the operation of this system will be described. (Outline of Data Transfer) A data transfer system in which the present invention is applied to a data transfer system using USB will be described.

FIG. 3 shows a logical configuration of the peripheral device external bus control unit 700 shown in FIG. 2 according to the present invention. The peripheral device external bus control unit 700 includes an asynchronous transfer buffer 7
03a, a synchronous transfer buffer 703b, a data transfer method notification buffer 703c, and three logical communication paths used between these buffers and the host device 300.

Communication methods with the host device 300 on the logical communication path are interrupt transfer, bulk transfer, and bulk transfer, respectively.
Allocate isochronous transfers. Further, regarding the logical communication path, the communication path connecting the data transfer method notification buffer 703c and the host device 300 is the interface # 1, and the bulk transfer communication path is the interface # 2.
Also, the alternative setting # 0 and the communication path for isochronous transfer are set as the interface # 2 and the alternative setting # 1.

In the data transfer system to which the present invention is applied, prior to the data transfer, the data transfer system determination unit 705 determines whether to use bulk transfer or isochronous transfer, and the data transfer system notification buffer 703c uses the interface #. It is transmitted to the host device 300 by an interrupt transfer using 1. The host device 300 is
The alternative setting of the interface is switched according to the determination of the data transfer method determination unit 705.

With the above device configuration, it is possible to dynamically switch the data transfer to the asynchronous transfer buffer 703a or the synchronous transfer buffer 703b.

(Example of Data Transfer Processing) An example in which the above-described data transfer method processing is applied to the printer 400 will be described. Here, a description will be given from the point where the user prints out by a predetermined application.

FIG. 4 is a flowchart showing the sequence from the application of the host device 300 to the print output.

When the user starts printing from the application (step S1), the printer driver is notified. The printer driver notifies the system of printer setting information such as paper size and print quality (step S2).

The operation system (OS) of the host device 300 requests the application to convert the data (step S3), and the application converts the print data into data of a predetermined format required by the operation system (step S4). Transfer to operating system.

The operation system stores the transferred data in the storage unit (step S5) and notifies the application of the end permission (step S6). The application receives this permission, ends the printing operation (step S7), and shifts to a state for accepting the next operation.

The operation system divides the stored data into a data amount (for each band area) of a size that can be processed by the printer driver, and transfers the data to the printer driver (step S8).

The printer driver performs image processing for generating image data optimum for the target printer from the received data (step S9). For example, color space conversion, color matching, raster size, edge enhancement,
For example, softness. For these processes, the optimum combination is selected according to the text area and the image area.

The image data generated as described above is converted into a printer control command (step S10), and is sent to the operating system together with a printer transmission request (step S11).

The operation system transfers the received printer control command to the host external bus controller 600 (step S12).

When the host external bus control unit 600 receives the printer control command from the operating system, it sends the external bus 500 to the peripheral device external bus control unit 700.
An inquiry is made as to the transfer method used for the printer control command transfer via (step S13).

The peripheral device external bus control unit 700 monitors the bus state by the traffic monitoring unit 704 (step S14). Then, when the transfer method inquiry is received from the host device 300, the data transfer method determination unit 705 determines the optimum transfer method according to the bus monitoring result, and notifies the host device 300 through the data transfer method notification buffer 703c. Yes (step S15).
Here, a method of switching the transfer method for each band area of the image data to be transferred has been described.

The host external bus control unit 600 switches the transfer system based on the notification of the optimum transfer system from the peripheral device external bus control unit 700 (step S16), and then sends a printer control command via the external bus 500. The data is transmitted to the peripheral device external bus control unit 700 (step S17). The peripheral device external bus control unit 700 receives the data and notifies the host external bus control unit 6 that the data transfer is completed.
00 is notified (step S18). Upon receiving this end notification, the host external bus control unit 600 notifies the system of the end of data transfer (step S19).

Upon receiving the data, the peripheral device external bus control unit 700 sends the data to the printer controller 410. The printer controller 410 receives the data, converts the data so that the printer 400 can interpret the data (step S20), and performs image processing for print output (step S21). Further, the image-processed data is transmitted to the printer engine 420 (step S22). The printer engine 420 controls each functional block so as to print out based on the reception.

When the host external bus control unit 600 notifies the operation system of the end of data transfer,
The transfer process described above is repeated until the band ends, that is, one page to be printed ends (step S2).
3). Further, the above-described operation is repeated for all pages requested to be printed (step S24).

When another device is connected to the external bus 500 by the above printing operation and the bus traffic is high, isochronous transfer is used to transfer the image data to the printer 400 at a certain transfer rate or more. Can be assigned automatically. Also, if the bus traffic is low, bulk transfer can automatically assign a high data transfer rate with maximum bandwidth usage.

(Transfer Method Determination Processing) FIG. 5 is a flowchart showing the data transfer method determination processing. Host external bus control unit 600 and peripheral device external bus control unit 700
The processing performed between and will be described.

Here, a method of switching the transfer method for each band area of the image data to be transferred is adopted. The method of notifying the host of the transfer method can be realized by using interrupt transfer. In interrupt transfer, the host sends a transfer request to the device at a constant polling interval to transfer data from the device. Since the polling interval can be specified from the device side, the explanation will be given here assuming that the polling interval is set every 50 frames.

The host external bus control unit 600 has 50 ms
Each time, the optimum transfer method requested by the data transfer method determination unit 705 of the peripheral device external bus control unit 700 in the peripheral device printer 400 is received (step S3).
1). The host external bus control unit 600 confirms the received optimum transfer method (step S32) and stores the requested transfer method in the request transfer method storage unit 602 (step S33).

50 m from the printer 400 which is a peripheral device
Since the notification of the optimum transfer method is received every s, the transfer method storage unit 602 constantly updates the transfer method every 50 ms. When a data transfer request is received from the system, the transfer method stored in the transfer method storage unit 602 is read.
The data transfer is performed by switching to the transfer method according to the stored transfer method (step S34).

According to such a switching method, the transfer method can be determined from the state of the bus traffic immediately before the data transfer.

The data transfer method may be determined by simply comparing the data transfer amounts. That is, in the peripheral device external bus control unit 700, the traffic monitoring unit 7
According to 04, the bus traffic for 50 frames is monitored (step S41), and it is checked whether the bandwidth consumption amount is 20% or less (step S42).

When the bandwidth consumption is 20% or less, bulk transfer is used (step S43), and when the bandwidth consumption is 20% or more, isochronous transfer is used (step S4).
4).

FIG. 6 shows an example of the bandwidth consumption amount 801 in one frame of each transfer method at full speed. FIG. 7 shows an example of the bandwidth consumption amount 802 in one frame of each transfer method at low speed.

At the full speed shown in FIG. 6, as a result of monitoring bus traffic, 16 bulk transfers per frame (800 bulk transfers per 50 frames)
Bulk transfer can be used when there is a free bandwidth that can be used. If not, isochronous transfer can be used. As a method of calculating the available bandwidth, the number of times of each transfer method in one or more frames is counted, and the average bandwidth consumption amount other than itself in one frame of each transfer may be obtained.

Therefore, in the data transfer using the serial bus system such as USB or IEEE1394, a data transfer rate of a certain level or more is secured even when the bus traffic is high, and the data transfer can be performed at high speed when the bus traffic is low. Since the data transfer method is controlled to be switched, more efficient data transfer can be performed.

(Isochronous Transfer Data Error Correction Processing) In the above-described example, bulk transfer is used when the bandwidth is vacant and isochronous transfer is used when the bandwidth is small according to the bus traffic. We have realized a data transfer method that can ensure a transfer rate above a certain level. By adopting such a transfer method in the printer 400, it is possible to provide an apparatus that performs high-speed printing. In particular, it is effective for commercial printers such as large format printers and digital photo printers that require high-speed printing.

However, in the isochronous transfer, if there is an error in the transfer data, the resending of the data is not supported, and the print quality will be degraded. In particular, the commercial printer as described above, which requires high image quality, reduces the product value.

Therefore, in this example, in the flowchart of FIG. 5, it is checked whether or not the isochronous transfer is used (step S51), and if the isochronous transfer is used, an error correction code is added in the transfer data ( In step S52), error detection and correction processing may be performed on the peripheral device side when receiving data. By adding the error correction code only when the isochronous transfer is used, the data transfer can be performed more efficiently (step S5).
3).

As described above, it is possible to provide a high-speed peripheral device which can always expect a data transfer rate higher than a certain level.

The error correction code is generally a Hamming code, RM (Reed Muller) code, BCH.
(Bose Caudhuri Hocquengh
em) code, convolutional code, CRC (Cyclic R)
edundancy Check k) code, RS (Re
ed Solomon) code and the like.

The present invention is not limited to the above example, but various applications are possible. In this example, an ink jet printer is taken as an example, but the present invention can be applied to various peripheral devices such as LBP and storage devices that use serial communication for data transfer.

Further, in this example, the transfer method switching timing is described as an example in which the transfer method is switched for each band area unit, but for example, it may be switched for each page unit or for each print request.

Further, in this example, the full speed mode is taken as an example of the transfer speed, but the present invention can also be applied to the high speed mode, for example.

Even if the present invention is applied to a system composed of a plurality of devices (for example, host computer, interface device, reader, printer, etc.),
The present invention may be applied to a device including one device (for example, a small image processing device such as a PDA (personal information management) device, a copying machine, and a facsimile device).

It goes without saying that the present invention can also be applied to the case where it is achieved by supplying a program to a system or an apparatus. Then, a storage medium storing a program represented by software for achieving the present invention is supplied to a system or apparatus, and the computer (or CPU or M of the system or apparatus).
The effect of the present invention can also be enjoyed by the PU) 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.

As a storage medium for supplying the program code, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD
-R, magnetic tape, non-volatile memory card (IC memory card), ROM (mask ROM, flash EEP)
ROM etc.) can be used.

Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also the OS (operating system) running on the computer based on the instruction of the program code. It is needless to say that this also includes a case where the above) performs a part or all of the actual processing and the processing realizes the functions of the above-described embodiments.

Furthermore, after the program code read from the storage medium is written in the memory provided in the function expansion board inserted into the computer or the function expansion unit connected to the computer, based on the instruction of the program code, It goes without saying that a case where the CPU or the like included in the function expansion board or the function expansion unit performs some or all of the actual processing and the processing realizes the functions of the above-described embodiments is also included.

[0115]

As described above, according to the present invention,
A synchronous transfer method that executes a synchronous transfer with a limited data transfer rate and an asynchronous transfer method that executes an asynchronous transfer with an unlimited data transfer rate are used. The communication mode (number of connected devices, bus traffic, etc.) on the serial bus is analyzed, and the desired transfer method is selected from among multiple transfer methods (synchronous type, asynchronous type) according to the analysis result. Since the data transfer is executed by switching to the desired transfer method, it is possible to dynamically change the synchronous transfer when the bus traffic is high and the asynchronous transfer when the bus traffic is low according to the communication status of the bus. As a result, even if the bus traffic is high, a certain data transfer rate is secured, and if the bus traffic is low, high-speed data transfer is possible. Can be controlled switching to an appropriate data transfer method, it is possible to improve the efficiency of data transfer.

Further, according to the present invention, it is possible to provide a high-speed printing apparatus which can always expect a data transfer rate higher than a certain level by the switching control by the transfer method.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a configuration example of a print system that is an embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of a peripheral device external bus control unit provided in the printer on the slave side.

FIG. 3 is a flowchart showing a transfer process of a peripheral device external bus control unit.

FIG. 4 is an explanatory diagram showing a sequence from a host application to print output.

FIG. 5 is a flowchart showing data transfer and switching control processing in the system.

FIG. 6 is an explanatory diagram showing a bandwidth consumption amount in one frame of each transfer method at full speed.

FIG. 7 is an explanatory diagram showing a bandwidth consumption amount in one frame of each transfer method at a low speed.

FIG. 8 is a block diagram showing an outline of a conventional external bus control unit.

FIG. 9 is an explanatory diagram showing a conventional data transfer procedure.

[Explanation of symbols]

100 host device 101 Host external bus control unit 200 peripherals 201 Peripheral device External bus control unit 300 Host device 400 printer 410 Printer controller 420 printer engine 500 external bus 600 Host external bus controller 700 Peripheral device External bus control unit 701 USB transceiver 702 serial interface engine 703 Endpoint buffer 703a Asynchronous transfer buffer 703b Synchronous transfer buffer 703c Data transfer method notification buffer 704 Traffic monitoring unit 705 Data transfer method determination unit

Claims (37)

[Claims] 1. A synchronous transfer method for executing a synchronous transfer with a limited data transfer rate, and an asynchronous transfer method for executing an asynchronous transfer with an unlimited data transfer rate are used. A data transfer method, comprising: an analysis step of analyzing a communication form on a serial bus; a selection step of selecting a desired transfer method from the transfer methods in accordance with the analysis result; A data transfer method, comprising: a transfer method switching step of switching to a transfer method and executing data transfer. 2. The data transfer method according to claim 1, wherein the analyzing step analyzes the number of the plurality of devices connected to the serial bus. 3. The data transfer method according to claim 1, wherein the analyzing step analyzes traffic of the serial bus. 4. The selecting step selects a synchronous data transfer method that secures a data transfer rate above a certain level when the serial bus traffic is high, and selects a data transfer rate when the serial bus traffic is low. 4. The data transfer method according to claim 3, wherein an asynchronous data transfer method with no limitation is selected. 5. The data transfer method according to claim 1, wherein the selecting step adds an error correction code in the transfer data when the synchronous transfer method is selected. . 6. The data transfer method is switched at the start of data transfer.
Data transfer method according to any one of. 7. The data transfer method according to claim 1, wherein the data transfer method is switched for each arbitrary transfer data unit. 8. The data transfer method according to claim 7, wherein the arbitrary transfer data unit is data divided for each band area when transferring print output data. 9. The serial bus used for data transfer is a USB (Universal Serial B).
9. The data transfer method according to claim 1, wherein bulk transfer is performed when the bandwidth is free, and isochronous transfer is performed when the bandwidth is low. 10. The serial bus used for data transfer is IEEE 1394, and performs asynchronous transfer when the bandwidth is free and performs isochronous transfer when the bandwidth is low. Item 9. The data transfer method according to any one of Items 1 to 8. 11. A synchronous transfer method for executing a synchronous transfer with a limited data transfer rate and an asynchronous transfer method for executing an asynchronous transfer with an unlimited data transfer rate are used. An information processing apparatus, comprising: analysis means for analyzing a communication form on a serial bus; and selection means for selecting a desired transfer method from the transfer methods according to the analysis result. Information processing device. 12. The information processing apparatus according to claim 11, wherein the analysis unit analyzes the number of the plurality of devices connected to the serial bus. 13. The information processing apparatus according to claim 11, wherein the analysis unit analyzes traffic on the serial bus. 14. The selecting means selects a synchronous data transfer method that secures a data transfer rate above a certain level when the serial bus traffic is high, and selects a data transfer rate when the serial bus traffic is low. 14. The information processing apparatus according to claim 13, wherein an asynchronous data transfer method in which is unlimited is selected. 15. The information processing apparatus according to claim 11, wherein the selecting means adds an error correction code in the transfer data when the synchronous transfer method is selected. . 16. The information processing apparatus according to claim 11, wherein the switching of the data transfer method is performed at the start of data transfer. 17. The information processing apparatus according to claim 11, wherein the transfer method of the data is switched for each arbitrary transfer data unit. 18. The information processing apparatus according to claim 17, wherein the arbitrary transfer data unit is data divided for each band area when transferring print output data. 19. The serial bus used for data transfer is USB, and bulk transfer is performed when the bandwidth is free, and isochronous transfer is performed when the bandwidth is low. Item 19. The information processing device according to any one of items 11 to 18. 20. The serial bus used for data transfer is IEEE 1394, and performs asynchronous transfer when the bandwidth is free and performs isochronous transfer when the bandwidth is low. 19. The information processing device according to any one of 11 to 18. 21. A system for performing switching control of data transfer between a master-side device and a plurality of slave-side devices via a serial bus, wherein the slave-side device is one of claims 11 to 20. The information processing apparatus according to any one of claims 1 to 3, wherein the device on the master side includes a transfer method switching unit that switches to a desired transfer method selected and transferred by the device on the slave side to execute data transfer. An information processing system characterized by the above. 22. A synchronous transfer method for executing a synchronous transfer with a limited data transfer rate and an asynchronous transfer method for executing an asynchronous transfer with an unlimited data transfer rate are used. A program, which is recorded on a computer-readable recording medium, and a step of analyzing a communication form on a serial bus, and a desired transfer from the transfer methods according to the analysis result. A data transfer control program comprising: a method of selecting a method; and a step of switching to the selected desired transfer method and executing data transfer. 23. The data transfer control program according to claim 22, wherein in the analysis, the number of the plurality of devices connected to the serial bus is analyzed. 24. The data transfer control program according to claim 22, wherein traffic of the serial bus is analyzed during the analysis. 25. In the selection, when the traffic of the serial bus is high, a synchronous data transfer method that secures a data transfer rate above a certain level is selected, and when the traffic of the serial bus is low, the data transfer rate is 25. The data transfer control program according to claim 24, wherein an unlimited asynchronous data transfer method is selected. 26. The data transfer control program according to claim 22, wherein when the synchronous transfer method is selected in the selection, an error correction code is added to the transfer data. . 27. The data transfer control program according to claim 22, wherein the switching of the data transfer method is performed at the start of data transfer. 28. The data transfer control program according to claim 22, wherein the data transfer method is switched for each arbitrary transfer data unit. 29. The data transfer control program according to claim 28, wherein the arbitrary transfer data unit is data divided for each band area when transferring print output data. 30. A medium recording a program for controlling switching of data transfer between a master-side device and a plurality of slave-side devices via a serial bus, wherein the control program is stored in a computer. A serial transfer method for executing a synchronous transfer with a limited data transfer rate and an asynchronous transfer method for executing an asynchronous transfer with an unlimited data transfer rate, The above communication form is analyzed, a desired transfer method is selected from the transfer methods according to the analysis result, and data transfer is executed by switching to the selected desired transfer method. A medium on which a data transfer control program is recorded. 31. The medium recording a data transfer control program according to claim 30, wherein the number of the plurality of devices connected to the serial bus is analyzed during the analysis. 32. The medium recording the data transfer control program according to claim 30, wherein the traffic of the serial bus is analyzed during the analysis. 33. In the selection, when the traffic of the serial bus is high, a data synchronous transfer method that secures a data transfer rate of a certain value or more is selected, and when the traffic of the serial bus is low, the data transfer rate is high. 33. The medium recording the data transfer control program according to claim 32, wherein an unlimited asynchronous data transfer method is selected. 34. The data transfer control program according to claim 30, wherein an error correction code is added to the transfer data when a synchronous transfer method is selected in the selection. The medium on which is recorded. 35. The medium recording the data transfer control program according to claim 30, wherein the switching of the data transfer method is performed at the start of data transfer. 36. The medium recording the data transfer control program according to claim 30, wherein the switching of the data transfer method is switched for each arbitrary transfer data unit. 37. The medium recording the data transfer control program according to claim 36, wherein the arbitrary transfer data unit is data divided into band areas when transferring print output data. .