JPH10116248A - Two-way transfer method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the procedure by switching the transfer direction of data in the same mode and to drastically shorten the processing time for switching the direction of the data transfer without using any hardware. SOLUTION: After a host device 1 is connected to a terminal device 2 to a actuate an interface, a compatible mode M2 is switched to a high-speed switching mode M7 through a negotiation phase to enter a phase for forward transfer provided in it. When a multifunction terminal side is ready to receive, the forward transfer mode (block transfer mode) is entered and data transfer is carried out. When the multifuctional terminal makes a request to transfer data backward, a transfer direction switching phase is done in a short time and the reverse transfer is carried out. After the reverse transfer ends, the forward transfer mode is entered in a short time without performing any termination process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bidirectional data transfer method using a parallel interface between a host device and a terminal device, for example, between a personal computer and a multifunction terminal.

[0002]

2. Description of the Related Art Printers and facsimile machines have become more and more multifunctional, and have been operating while performing various bidirectional communications with a host device such as a personal computer. Devices having such a printer, facsimile machine function or copy function are collectively referred to as multifunctional terminals. For data transfer using a parallel interface between a conventional personal computer (PC) and a multifunction terminal, for example, a Centronics interface cable standardized by IEEE standard 1284 is used. In this standard, for two-way communication,
Data is transmitted and received by giving meaning to any signal line of the interface cable. In transfer mode,
There is a compatible mode for transferring data from the PC to the multi-function terminal (referred to as forward direction) and a nibble mode for transferring data from the multi-function terminal to the PC (referred to as reverse direction).

For example, in the compatible mode, data is transmitted by eight signal lines from pin 2 to pin 9, and in the nibble mode, data is transmitted by four bits using four lines of pins 11 to 13 and 32. By switching these modes, bidirectional data transfer is realized. The mode is switched by a method of inquiring of the presence or absence of the reverse transfer under the initiative of the PC.

[0004]

The conventional bidirectional transfer method as described above has the following problems to be solved. As the terminals become multifunctional, the amount of data in the reverse direction between the PC and the multifunctional terminal and the number of times of switching the data transfer direction increase dramatically. Here, for example, when the multi-function terminal has a facsimile modem function, since the length and interval of a signal at the time of communication are determined by the standard, the bidirectional transfer must be completed within a certain limited time. However, in the above method, the data transfer direction cannot be switched unless the transfer mode is changed through the termination mode to the negotiation mode when the host completes the forward transfer, so that a considerable processing time is required. Therefore, there is a problem that data transfer is not completed within a required time for realizing the function of the multi-function terminal. In addition, a mode called an ECP mode in which the transfer direction is changed within the same mode without terminating using special hardware built into the PC side is standardized in IEEE 1284, but since hardware is used, cost is reduced. There's a problem.

[0005]

The present invention employs the following structure to solve the above problems. In the present invention, a device such as a PC is referred to as a host device, and a device such as a multifunction terminal is referred to as a terminal device. <Configuration 1> Forward transfer mode for transferring data from a host device to a terminal device between a host device and a terminal device connected to each other via an interface, and conversely, data from the terminal device to the host device When there is a reverse transfer mode for transferring to any mode, and when shifting from one mode to another mode, the process of ending each mode once and shifting to another mode through a preset procedure is performed. In addition to the setting, a high-speed switching mode is provided separately from these modes, and the modes include a forward transfer mode and a reverse transfer mode. The terminal device performs a handshake with the higher-level device via the signal line of (1), and switches to the reverse transfer mode without terminating the high-speed switching mode. Bidirectional transfer wherein.

<Structure 2> A forward transfer mode in which data is transferred from a higher-level device to a terminal device between a higher-level device and a terminal device connected to each other via an interface, and vice versa. There is a reverse transfer mode in which data is transferred to the higher-level device, and when shifting from any mode to another mode, the respective modes are temporarily terminated,
In addition to setting processing for shifting to another mode through a preset procedure, a high-speed switching mode is provided separately from these modes, and this mode includes a forward transfer mode and a reverse transfer mode. Immediately after operating in the reverse transfer mode, the host device masks all other tasks and interrupt processing, executes a handshake via a predetermined signal line configuring the interface, and ends the high-speed switching mode. A bidirectional transfer method characterized by switching to a forward transfer mode without performing.

<Structure 3> A forward transfer mode in which data is transferred from a higher-level device to a terminal device between a higher-level device and a terminal device connected to each other via an interface, and vice versa. There is a reverse transfer mode in which data is transferred to the higher-level device, and when shifting from any mode to another mode, the respective modes are temporarily terminated,
In addition to setting processing for shifting to another mode through a preset procedure, a high-speed switching mode is provided separately from these modes, and this mode includes a forward transfer mode and a reverse transfer mode. Immediately after operating in the forward transfer mode, the terminal device performs a handshake with the higher-level device via a predetermined signal line constituting the interface, and switches to the reverse transfer mode without terminating the high-speed switching mode. Immediately after operating in the reverse transfer mode, the higher-level device masks all other tasks and interrupt processing, executes a handshake via a predetermined signal line configuring the interface, and performs high-speed switching. A bidirectional transfer method characterized by switching to a forward transfer mode without terminating the mode.

<Structure 4> In structures 1 to 3, processing for shifting from the forward transfer mode to the reverse transfer mode via the negotiation phase, and shifting from the reverse transfer mode to the forward transfer mode via the termination phase is performed. When set, a process is set to shift from the forward transfer mode to the high-speed switching mode via the negotiation phase and to shift from the fast switching mode to the positive-direction transfer mode via the termination phase. Transfer method.

<Structure 5> In structures 1 to 3, both the host device and the terminal device execute the switching process between the forward transfer mode and the reverse transfer mode at the same time as the handshake. Characteristic bidirectional transfer method.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below using specific examples. <Specific Example 1> FIG. 1 is an explanatory diagram of a specific example of the bidirectional transfer method of the present invention. For example, a host device 1 such as a personal computer and a terminal device 2 are connected to a standard parallel interface 3 such as a Centronics interface cable.
, The bidirectional transfer processing as shown in this figure is performed. In this specific example, a multifunctional terminal having a facsimile function is used as the terminal device 2. This diagram is an operation based on IEEE1284, and operates in a compatible mode M1 when the power is turned on. The compatible mode M1 includes a forward transfer mode (a mode in which data is transferred from a higher-level device to a terminal device) M2 and an idle mode M3.

Conventionally, when shifting from such a forward transfer mode to another mode, a negotiation phase M4 is once performed. A conventionally prepared mode includes a reverse transfer nibble mode (mode for transferring data from a terminal device to a higher-order device) M6. Further, in the present invention,
The high-speed switching mode M7 is newly set. Then, when exiting any of the modes, the mode shifts to the compatible mode M1 via the termination phase M8. In the high-speed switching mode M7, both the forward transfer mode and the reverse transfer mode are included therein to speed up the switching between forward and reverse data transfer.

That is, in the conventional method, the nibble mode M6, which is the forward transfer mode, is changed from the forward transfer mode M2.
In the case of transition to, the operation is performed such that one mode is always exited via the negotiation phase M4 or the termination phase M8 and the other mode is entered.
The high-speed switching mode M7 supports both forward and reverse transfer modes in one mode. Specifically, the switching time is reduced by the host device 1 and the terminal device 2, for example, a personal computer and a multi-function terminal having a facsimile function facing each other in the interrupt processing. Note that the high-speed switching mode M7 is
Like the other nibble modes M6, the reason for returning to the compatible mode M1 via the termination phase M8 is to maintain consistency with the IEEE 1284 standard sequence.

Hereinafter, the high-speed switching mode M according to the present invention will be described.
7 will be described in detail. FIG. 2 shows the IE
FIG. 3 is an explanatory diagram of assignment of interface signal lines conforming to EE1284 type B. This clarifies the signal name of each pin of the so-called Centronics interface, its logic, data transfer direction and function. Each signal name is described with the specified symbol. Hereinafter, the contents of the symbols in the drawings after FIG. 3 can be understood by referring to this figure.

FIG. 3 is an explanatory diagram of an interface signal line. Each of the above interface signal lines is used in the high-speed switching mode M7 as shown in FIG.
First, pins 1, 14, and 36 are used for initialization at the time of mode transition. Next, 11-pin, 12-pin, 13-pin
Pins and 32 pins are both used as data lines for reverse transfer. That is, in the nibble mode, the multifunction terminal is used to transfer data to the host PC. Eight pins from pin 2 to pin 9 are used as data lines for forward transfer. That is, in the compatible mode, it is used to transfer data from the host PC to the multi-function terminal.

FIG. 4 is a time chart for switching the transfer direction from the forward direction to the reverse direction in the high-speed transfer mode. FIGS. 5 and 6 show the contents of the reverse transfer mode and a time chart when the mode shifts to the forward transfer mode again. Hereinafter, FIG. 1 and FIGS.
, The method of the present invention will be described more specifically.

In accordance with IEEE 1284, when the power is turned on, the mode shifts to the compatible mode shown in FIG. The transition from the compatible mode to the high-speed switching mode of the present invention is also performed through the procedure of the negotiation phase determined by IEEE1284.
4

At the time of transition to the high-speed switching mode, forward transfer is possible, and 2-byte data is transferred by one falling and rising of nStrobe (e). The host sets an appropriate amount of data as one block, and executes transfer in this unit.

The host does not perform a busy check during the transfer of one block of data. When the transfer of one block of data is completed, it is checked whether the printer is busy. If the printer is busy, data transfer cannot be performed until the busy is released. XXkb of receive buffer remaining to be busy
yte or more. The remaining amount of the reception buffer for releasing the busy is YYkbyte or less. Busy (g) Busy
It is released by the signal Low. When it is desired to transmit data to the PC on the multi-function terminal side, (h) nFault giving a meaning of the data transmission request on the multi-function terminal side is set to Low (timing t
1). When the PC transmits data for one block in the forward direction, it monitors the nFault signal in (h), and when nFault = Low is detected, shifts to the reverse transfer mode.

The reverse transfer switching phase operates as follows. The multi-function terminal sets the nFault signal to Low at an arbitrary timing in the forward transfer phase or the block transfer end phase due to the presence of transmission data. The PC monitors nFault after the block transfer phase ends,
Is detected, the following transfer direction switching handshake is performed. The following operation is also performed when the PC simply wants to change the transfer direction to the opposite direction.

The host sends 1284 Active (nSelectIn)
Set to Low (timing t1) and set HostBusy (nAutoFd) to Hi
Set to gh to request termination from IEEE 1284 mode. Multifunctional terminals are PtrBusy (Busy) and nD
Set ataAvail (nFault) to High (timing t
2). The multi-function terminal inverts XFlag (Select) (timing t3) and sets PtrClk (nAck) to Low.

The host is HostClk (nStrob), 1284Ac
tive (nSelectin) is set to High (timing t4), and Host
Set Busy (nAutoFd) to Low. Multifunctional terminal, Pt
rBusy (Busy) is set to Low (timing t5).
Here, if the multi-function terminal does not change PtrBusy (Busy) to Low, the terminal can enter the termination of IEEE1284. The host sets HostBusy (nAutoFd) to High (timing t6). Multifunctional terminal, PtrBus
y is set to High (timing t7). At this time,
If there is reverse transmission data, PError and nFault
Set Low, if not, set High.

After the above operation is completed, the process shifts to the host busy data available phase (FIG. 5). The subsequent transfer sequence shown in FIG. 5 in the reverse direction is the same as the IEEE1284 nibble mode, and a description thereof will be omitted. When the transfer in the reverse direction is completed for one block, the host enters the data available phase, and the presence or absence of a data transmission request from the PC is checked by referring to the signal (b) (at timing t in FIG. 6).
8). When a data transmission request is issued from the PC, the transfer direction is switched from the reverse direction to the forward direction.

The forward transfer switching phase operates as follows. In the reverse transfer state, it is possible to switch the transmission direction to the forward direction by starting the following handshake at the same timing as the transition to the termination phase of the nibble mode.

The host sends 1284 Active (nSelectIn)
Low (at timing t9), and set HostBusy (nAutoFd) to Hi.
Set to gh to request termination from IEEE 1284 mode. Multifunctional terminals are PtrBusy (Busy) and nD
Set ataAvail (nFault) to High (timing t1
0). The host inverts XFlag (Select) and sets PtrClk (nAc
k) is set to Low (timing t11).

The host is HostClk (nStrobe), 1284Ac
Set tive (nSelectln) to High and set HostBusy (nAutoFd) to Lo
w (timing t12). Multifunctional terminals are
Set PtrBusy (Busy) to Low (timing t1
3). The host sets HostBusy (nAutoFd) to High (timing t14). Multifunctional terminals are available on PtrBusy (Bus
y) is set to High, AckDataReq (PError) is set to Low, nDat
Set aAvail (nFault) to High (timing t1
5). After the above operation, the process proceeds to the next phase.

As described above, in this specific example, after the power is turned on, the high-speed switching mode is entered by negotiation from the compatible mode, and the phase for the forward transfer is entered. If the multi-function terminal can receive data, the transfer mode is the forward transfer mode (block transfer phase). If the multi-function terminal requests data transfer in the reverse direction, the nFault signal is set to low. The PC detects this at the end of the block transfer phase, performs a transfer direction switching phase, and performs data transfer in the reverse direction.

When the PC is not performing the block transfer, the PC is in the reverse idle state or the forward idle state. In either case, when the host busy data knot transitions from the idle state to the idle state, nF
Since ault is High, it can detect that nFault changes to Low level. For example, at timing t1 in FIG.
If nFault is High, the state shifts to the forward idle state. After that, when nFault changes to Low, an interrupt is generated and it is known that there is a transfer request in the reverse direction.

<Effect of Specific Example 1> As described above, the IEEE
By applying the above method without having hardware such as the 1284 ECP mode, a forward / reverse transfer mode is provided in one high-speed switching mode, and a forward / reverse direction or a reverse / forward direction is provided. Of the transfer direction can be realized without taking a complicated procedure standardized by IEEE 1284. IEEE128
In mode 4, negotiation is performed from the compatible mode and each transfer mode (forward transfer mode or reverse transfer mode)
Then, the transfer direction is changed. Therefore, the procedure has always been taken to shift to the termination phase, shift to the compatible mode again, and shift to another transfer mode after the negotiation phase. However, according to the present invention, since the data transfer direction can be switched in the same mode, the procedure is greatly shortened. In addition, since the processing time for switching the direction of data transfer can be greatly reduced without using hardware, a function of a multifunctional terminal, which could not be realized until now due to a problem with the switching processing time, can be realized.

<Example 2> In Example 2, reference is made to timings t1 to t7 in FIG. 4 and timings t9 to t15 in FIG. Here, the multifunctional terminal performs all the handshaking from timing t1 to t7 in FIG. 4 in the interrupt processing at the time of the phase shift so that the data transfer direction can be switched at a high speed. The PC masks all other tasks and interrupt processing from timing t9 in FIG. 5 and performs all handshaking for subsequent mode switching. In any case, after detecting nAck = High in (f), the mask of the other task and the interrupt is released. By doing so, the software on the PC side and the software on the multi-function terminal side can simultaneously perform the handshake for switching the data transfer, realizing a high-speed handshake.

<Effect of Specific Example 2> The handshake for switching the data transfer direction on the PC side and the multi-function terminal side is performed simultaneously in a mutually closed process, thereby processing conventionally occurring at the time of handshake. Eliminate delays. Thereby, the transfer direction switching processing time can be reduced. In the specific example described above, the handshake is executed by the interrupt processing. However, if the host side and the terminal side face each other by monitoring a predetermined signal line, the handshake can be executed in a short time. May be used. Therefore,
For example, the signal line may be monitored by a dedicated CPU or a high-speed CPU such as a RISC, or may be monitored by other hardware.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a specific example of a two-way transfer method according to the present invention.

FIG. 2 is an explanatory diagram of assignment of interface signal lines conforming to IEEE1284 type B;

FIG. 3 is an explanatory diagram of an interface signal line.

FIG. 4 is a high-speed switching mode operation time chart (1).

FIG. 5 is a high-speed switching mode operation time chart (No. 2).

FIG. 6 is a high-speed switching mode operation time chart (3).

[Explanation of symbols]

 Reference Signs List 1 upper device 2 terminal device 3 parallel interface M1 compatible mode M4 negotiation phase M6 nibble mode M7 fast switching mode M8 termination phase

Claims (5)

[Claims] 1. A forward transfer mode for transferring data from a host device to a terminal device between a host device and a terminal device mutually connected via an interface, and conversely, data from the terminal device to a host device. When there is a reverse transfer mode for transferring data to the device, and when shifting from one mode to another,
Once each mode is completed, the process to shift to another mode through a preset procedure is set. In addition to these modes, a high-speed switching mode is provided, and a forward transfer mode is included in this mode. Immediately after operating in the forward transfer mode, the terminal device performs a handshake with respect to the higher-level device via a predetermined signal line constituting the interface, and ends the high-speed switching mode. A bidirectional transfer method characterized by switching to a reverse transfer mode without any change. 2. A forward transfer mode for transferring data from a higher-level device to a terminal device between a higher-level device and a terminal device connected to each other via an interface, and vice versa. When there is a reverse transfer mode for transferring data to the device, and when shifting from one mode to another,
Once each mode is completed, the process to shift to another mode through a preset procedure is set. In addition to these modes, a high-speed switching mode is provided, and a forward transfer mode is included in this mode. Immediately after operating in the reverse transfer mode, the higher-level device masks all other tasks and interrupt processing and executes a handshake via a predetermined signal line constituting the interface. And switching to the forward transfer mode without terminating the high-speed switching mode. 3. A forward transfer mode for transferring data from a host device to a terminal device between a host device and a terminal device connected to each other via an interface, and conversely, transferring data from the terminal device to a host device. When there is a reverse transfer mode for transferring data to the device, and when shifting from one mode to another,
Once each mode is completed, the process to shift to another mode through a preset procedure is set. In addition to these modes, a high-speed switching mode is provided, and a forward transfer mode is included in this mode. Immediately after operating in the forward transfer mode, the terminal device performs a handshake with respect to the higher-level device via a predetermined signal line constituting the interface, and ends the high-speed switching mode. In the reverse transfer mode, the host device immediately masks the other tasks and interrupt processing immediately after operating in the reverse transfer mode, and hands over the predetermined signal lines constituting the interface. A bidirectional transfer method characterized by performing a shake to switch to a forward transfer mode without terminating a high-speed switching mode. Law. 4. The process according to claim 1, wherein a process of shifting from the forward transfer mode to the reverse transfer mode via the negotiation phase and a shift from the reverse transfer mode to the forward transfer mode via the termination phase is set. Bidirectional transfer characterized by setting a process for shifting from the forward transfer mode to the high-speed switching mode via the negotiation phase, and for shifting from the fast switching mode to the positive-direction transfer mode via the termination phase. Method. 5. The apparatus according to claim 1, wherein both the host device and the terminal device execute a switching process between the forward transfer mode and the reverse transfer mode simultaneously with the handshake. Bidirectional transfer method.