JP2538949B2 - Inter-system communication controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] Regarding a method of performing communication of fixed-length data between systems having different clocks, for example, via a communication control device, a data line for communication between the system and the communication control device is reduced. To receive fixed length data, for example, a counter that operates at the clock of the system that transmits the fixed length data is provided on the communication control device side, and the upper bits of the counter are set to the clock of the communication control device. The end of the transfer of the fixed length data is recognized by the signal synchronized with.

[Industrial applications]

The present invention can be applied to systems with different clocks, for example,
The present invention relates to a method for communicating fixed length data via a communication control device.

With the recent expansion of the data processing field and the increase in the processing amount by computers, there is no limit to the demand for improvement in the processing capacity of the computer system. For example, in a multiprocessor system including a plurality of processors, The construction shows one direction, but further, organically connecting a plurality of the multiprocessor systems,
There is a tendency to improve the processing capacity of the entire system.

In this case, it is necessary to effectively communicate between the multiprocessor systems.

On the other hand, as the computer system grows in size, the "variation" of the clocks distributed to each computer system increases, making it impossible to operate the entire system with one clock.

Therefore, when a plurality of multiprocessor systems as described above are connected to each other through, for example, a communication control device to construct one huge computer system, each of the multiprocessor systems and communication control devices must be The clock has to be independent.

Therefore, the communication between the multiprocessor systems becomes the communication between the systems having different clocks, and an effective communication system under such conditions is required.

Also, with the recent progress of high integration technology, the trend of high integration of logic devices is increasing, but it is general that the pin / gate ratio decreases as the integration degree of a logic block increases. . This is because the number of gates increases in proportion to the area of the integrated circuit, while the number of pins can increase only in proportion to the side length of the integrated circuit.

For this reason, it is necessary that the number of input / output terminals of each logic block constituting each computer system is as small as possible.

Therefore, also in the communication between the systems, it is required that the number of data lines and control lines used for the communication between the systems is as small as possible.

[Problems to be solved by conventional technology and invention]

FIG. 3 is a diagram for explaining a conventional inter-system communication method, (a) shows an example of normal inter-system communication by asynchronous, and (b) shows a case where clock synchronization is performed to improve throughput. Shows.

In the inter-system communication method shown in (a) and (b) of the figure, a specific command is transmitted from the system A 1 to the system B 3 via the communication control unit (CCP) 2, and the system B 3 transmits the command. Communication is performed by returning status (system status information, etc.) as response data to the command, but the command and status transferred at the time of intersystem communication are fixed length, and the transfer sequence is also It has the characteristic that it is a repetition of command status.

In such an inter-system communication method, the system
After issuing a command, A 1 waits for a response from the partner device (system B 3) for a certain period of time, or performs a parity check on the status byte to check the normal end for the command. There is.

Therefore, it is not necessary for the transmitting side to particularly recognize whether or not the receiving side has correctly received.

In this case, in the conventional system, in response to the transfer of fixed length data such as command transfer and status transfer, from the transmission side, that is, in the case of a command, system A
From 1 and in the case of status, the system B 3 sends a data transfer end notification signal to the communication control device (CCP) 2 which is the data receiving side. The end of data transfer was recognized by the transfer end notification signal.

However, in the case of (a) of this figure, the system
Since the data transfer is completely asynchronous between A 1 or system B 3 and the communication control device (CCP) 2, the communication control device (CCP) 2 side receives the received command or status from its own clock. Therefore, there was a problem that the throughput of intersystem communication was not improved.

In the case of (b), the transmission side clock is sent from the transmission side system A 1 or system B 3 to the communication control device (CCP) 2 and the reception side communication control device (CC)
In P) 2, since the command or status is received by the clock of the transmitting side, the throughput problem of intersystem communication is solved, but as in the case of (a), the communication control device (CCP) is used. Since the end of the data transfer is recognized by the data transfer end notification signal sent from the sending side on the second side, when the number of processors in system A 1 and system B 1 increases, the data There is a problem that the number of terminals for receiving the transfer end notification signal increases, which becomes a factor that hinders high integration on the communication control unit (CCP) 2 side.

In view of the above-mentioned conventional drawbacks, the present invention provides a method of performing fixed data communication between systems having different clocks, in which the communication data has a fixed length, and the data transfer sequence has a repeating pattern of "command" and "status". Focusing on that, without sending a data transfer end notification signal from the transmission side as in the conventional method, at high speed,
It is an object of the present invention to provide a communication method capable of recognizing the end of data (command, status, etc.) transfer.

[Means for solving problems]

FIG. 1 is a principle diagram of a communication system between systems having different clocks according to the present invention.

The above problems can be solved by a communication method between systems having different clocks configured as described below.

In the present invention, for example, a method of performing communication of fixed length data between a system A 1 and a system B 3 having different clocks via a communication control device (CCP) 2 and a communication control for receiving the fixed length data The fixed length data is transmitted to the device (CCP) 2 side by the clock of the system A 1 or system B 3 which transmits the fixed length data, and one word of the fixed length data is transmitted from the system A 1 or system B 3 of the transmitting side. A counter 21 that counts each time it is received, a synchronization circuit 23 that generates an output signal by synchronizing the output of the upper bits of the counter 21 with the clock of the system B 3, or the system A 1, and the progress of communication up to the present A preset signal circuit for recognizing the communication type to be performed next according to, and presetting the counter 21 by a value determined by the length of the fixed length data determined according to the communication type transmitted by the transmitting system A 1, or system B Provided, the output signal of the synchronization circuit 23 is configured to recognize the completion of the transfer of the fixed length data.

[Action]

That is, according to the present invention, for example, when communication is performed between the system A and the system B via the communication control device, when viewed from the communication control device side, a command (for example, 16 words Note that when the command is sent to the system B, status information (for example, 4 words) is returned from the system B, and the communication form is repeated. The control device performs a counting operation each time one word of data is received by the clock of the system A or system B on the data transmission side. For example, a 6-bit counter is provided, and when the power is turned on or a command is issued. , Or when the completion of reception of status data is recognized, the type of data to be received next is judged, and the data (command, or At the end of the transfer of (status), for example, a specific value in which the most significant bit of the counter is “1” is set.

More specifically, when the power is turned on, first, the data sent from the system A or the system B is a command. Therefore, for example, when the above 16 words are counted, the most significant bit is "0" 1. '0' in the decimal number is set in binary so that the transfer end of the command is extracted by synchronizing the most significant bit of the counter with the clock of the communication control device. Recognize the end of transfer.

Since it is known that the status will be sent after the command, at the end of the command transfer, when the four words of the status are counted, the most significant bit of the counter is "0" 1. So that, for example, the decimal number '12' is set in binary, and the transfer end of the status is extracted by synchronizing the most significant bit of the counter with the clock of the communication control device. Recognize the end of transfer.

Thereafter, the same process is repeated to recognize the type of the immediately preceding data, recognize the type of the next data, and determine the value to be set in the counter.

Since it functions in this way, it is possible to recognize the reception end of the received fixed length data without receiving the data transfer end notification signal from the data transmission side as in the conventional method, and the data line for communication. There is an effect that can be reduced.

〔Example〕

 Embodiments of the present invention will be described in detail below with reference to the drawings.

The above-mentioned FIG. 1 is a principle diagram of a communication system between systems having different clocks according to the present invention, and FIG. 2 is a block diagram showing an embodiment of the present invention. The counter 21 which operates on the transmitting side clock and the signal in which the most significant bit of the counter 21 is synchronized with the receiving side device clock are means necessary for carrying out the present invention. Note that the same reference numerals indicate the same object throughout the drawings.

The communication system between the systems having different clocks according to the present invention will be described below with reference to FIG. 1 while referring to FIG.

As described above, in the inter-system communication method to which the present invention is applied, when a command (16 words) that is fixed length data is sent from the system A 1 to the system B 3 via the communication control device (CCP) 2, From the system B 3, the status information of the system B 3 instructed by the command is changed to the status (4
Sent back to system A 1 as a word).

Therefore, the communication control device (CC
In P) 2, as described above, communication is performed in a repeating sequence of "command" and "status".

Focusing on this point, the present invention first loads a communication control table from a file storage device (not shown) into a storage device (not shown) when the power is turned on.

In the communication control table, it is assumed that the order in which communication is started among a plurality of systems A, B, ... Connected to the communication control device (CCP) 2 is set. . Further, this order can be dynamically changed by using a priority order determination circuit (priority circuit) or the like (not shown) even during communication.

Therefore, by referring to the contents of the communication control table, the communication control device (CCP) 2 can first recognize the system that sends the command first, for example, the system A 1, and then the system. The status is returned in response to the command of A 1, for example, system B 3 can be recognized, so every time the end of data transfer is recognized,
By referring to the communication control table, the system on the transmitting side can be known, the clock of the system can be selected, and the type of data to be transmitted can be recognized.

In this way, the sender system A 1, or system
Upon recognizing B 2 or the like, first, the clock of the selected system is sent to the counter 21 of the present invention, and a specific value is set in the counter 21 corresponding to the type of data sent.

In this example, since the counter 21 is composed of, for example, 5 bits, in the case of "CMD-in" in which the command of 16 words is transmitted, the binary number "00000" is set. Then, the status consisting of 4 words is sent out, "STAT
In the case of "US-in", the binary number "01100" is set.

In this state, each time one command or status is sent from the transmitting side, the counter 21 is added to the counter 21 by the clock of the data transferring side, and the register group 22 of the address indicated by the counter 21 is added. Function to write the transfer data.

As described above, since the counter 21 is composed of 5 bits, in the case of the above command, the most significant bit (MSD) of the counter 21 is "0" when 16 words are transferred.
It becomes "1", and the transfer end recognition signal can be obtained by synchronizing the signal of the most significant bit with the known synchronizing circuit 23 by the receiving side clock of the communication control device (CCP) 2.

Similarly, in the case of the status, the most significant bit of the counter 21 becomes "1" when the four words are received, so that the signal can be synchronized to obtain the transfer end recognition signal. .

Of course, the data (command / status) stored in the register group 22 is read by the clock on the receiving side.

In this embodiment, the system A 1 and the system B 3
The reception of fixed data (command / status) between the communication control device (CCP) 2 and the communication control device (CCP) 2 has been described as an example, but the system on the receiving side is not limited to the communication control device (CCP) 2. It goes without saying that other systems may be used.

However, the system on the receiving side needs to adopt a communication mode in which the type of fixed data transmitted from the transmitting side can be automatically recognized.

Further, in the above embodiment, the method of obtaining the transfer end recognition signal with the most significant bit using the 5-bit counter has been described, but the present invention is not limited to this system, and the counter with an arbitrary number of bits can be used. Needless to say, the transfer end recognition signal may be obtained from a specific bit position.

The communication system of the present invention can be applied to inter-system communication having such a communication form regardless of the type of the system that performs communication.

As described above, in the present invention, in a system for communicating fixed-length data between systems having different clocks, the system that receives the fixed-length data is provided with a counter that operates on the clock of the transmitting-side system to transmit the data. Each time the data from the side is received, the counter is counted up, and when all the data is received, a specific bit of the counter, for example, the most significant bit is configured to be '1',
The output signal of the higher-order bit is characterized in that a signal obtained by synchronizing the output signal of the receiving side system is used as a transfer end recognition signal.

〔The invention's effect〕

As described above in detail, the communication method between systems having different clocks according to the present invention is a method of performing fixed-length data communication between systems having different clocks, for example, a method of performing fixed-length data communication via a communication control device. A counter that operates at the clock of the system that transmits the fixed-length data is provided on the side of the communication control device that receives, and, for example, a signal obtained by synchronizing the most significant bit of the counter with the clock of the communication control device. Since the end of transfer of the fixed length data is recognized, as in the conventional method,
The reception end of the received fixed length data can be recognized without receiving the data transfer end notification signal from the data transmission side, and the data line for communication can be reduced.

[Brief description of drawings]

FIG. 1 is a principle diagram of a communication system between systems having different clocks according to the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a description of a conventional intersystem communication system. Fig. In the drawing, 1 is a system A, 2 is a communication controller (CCP), 3 is a system B, 21 is a counter, 22 is a register group, 23 is a synchronizing circuit, and is a transfer end recognition signal.

Claims (1)

(57) [Claims] 1. A clock of a system (1 or 3) for transmitting fixed length data in an intersystem communication control device (2) for controlling communication of fixed length data between systems (1, 3) having different clocks. And a counter (21) that counts each time one word of the fixed length data is received from the system (1 or 3) on the transmitting side, and outputs the upper bits of the counter (21) to the receiving system. The synchronization circuit (23) for generating an output synchronized with the clock (3 or 1) and the communication type to be performed next according to the progress of communication up to the present are recognized, and the transmission side system (1 or 3) ) Is provided with a preset signal circuit that presets the counter (21) with a value determined by the length of the fixed length data that is determined according to the communication type transmitted, and the fixed length is output by the output signal of the synchronization circuit (23). Data transfer Intersystem communication control apparatus characterized by being configured to recognize the end.