JPH08235126A - Duplex system of centralized type arbitration circuit - Google Patents

Abstract

PURPOSE: To provide a duplex system of the centralized arbitration circuit whose fault or malfunction hardly causes the whole system to malfunction or stop. CONSTITUTION: The centralized type arbitration circuit(ARBA) 141 compares the priority levels of respective devices 16 which send out requests to use a bus and sends a bus use permission ID. At this time, a centralized type arbitration circuit (ARBB) 142 sends an abnormality signal 22 to a monitor circuit 13 unless the decision that the ARBB 142 has made matches the decision that the ARBA 141 has made. The monitor circuit 13 activates a bus freezing signal immediately to freeze the operation of signals on the system bus 15 and sends out a reset/retry signal 19 to the ARBA 141 and ARBB 142 to make them retry to decide the priority levels. The monitor circuit 103 monitors the results of retrial decision making and restarts the operation on the system bus when the decision results have no problem.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duplication system of a centralized arbitration circuit having a function of arbitrating bus use in a computer device or an information processing device.

[0002]

Japanese Patent Laid-Open No. 59-79330 discloses an input / output bus, two input / output devices connected to the input / output bus, and the input / output bus connected to the two input / output devices. Is provided with two competing circuits for deciding which of the two input / output control devices is to be used, and control lines connected to these two competing circuits. A duplexing method of an input / output control device is disclosed in which one of the competing circuits is in an operating state and the other of the two competing circuits is in an inoperative state.

Japanese Patent Publication No. 41780/1990 discloses that
There is disclosed a system multiplex system including one bus arbitration circuit and a system monitoring circuit in which only one of the two bus arbitration circuits has a bus arbitration function. Also in this system multiplexing system, one of the two bus arbitration circuits is activated and the other of the two bus arbitration circuits is deactivated.

Thus, the centralized arbitration circuit is generally used alone at that time. Only a dual system of MPU (microprocessor unit) has been used for a system requiring high reliability.

Referring to FIG. 2, there is shown an example of a conventional MPU duplexing method. In this duplex system of MPU, MPU (microprocessor unit A)
11 and MPU (microprocessor unit B) 1
2 are connected in parallel to the system bus 15. MPU
A11 performs normal operation, MPU12 is MPUA
The execution state of 11 is monitored. MPUB12 is MPUA1
When the malfunction of 1 is detected, the MPU abnormal signal 17 is sent to the monitoring circuit 13 (the MPU abnormal signal 17 is activated). Upon receiving the MPU abnormal signal 17, the monitoring circuit 13 immediately sends the bus freeze signal 18 to the system bus 15 (activates the bus freeze signal 18) to immediately freeze the operation of the system bus 15, M
The reset / retry signal 19 is sent to the PUA 11 and the MPUB 12 (the reset / retry signal 19 is activated) to cause the MPUA 11 and the MPUB 12 to reset and retry (that is, restart) the internal circuit. As a result, when the MPU 12 no longer detects a malfunction of the MPU 11, the MPU 12 cancels sending of the reset / retry signal 19 to the MPU 11 and MPU 12 (inactivates the reset / retry signal 19) and monitors the MPU abnormality signal 17. The transmission to the circuit 13 is canceled (the MPU abnormality signal 17 is made inactive). When the MPU abnormal signal 17 is canceled, the control circuit 13 cancels the sending of the bus freeze signal 18 to the system bus 15 (inactivates the bus freeze signal 18) and restarts the operation of the system bus 15.

A plurality of bus devices 16 are connected to the system bus 15 in parallel. Each of the plurality of bus devices 16 includes a DMA (Direct Memory Access) controller, a main memory, an input device, an output device, and an input / output device (I / O) device.

Now, a plurality of bus devices 16 are connected to the system bus 1
Assume that 5 is used and the system bus 15 is arbitrated. The centralized arbitration circuit 14 includes a system bus 15 for each of the plurality of bus devices 16.
When the bus use request signal transmitted above is received, the priorities of the plurality of bus devices 16 are compared, and the current system bus 1
After sending the identification (ID) code of the bus device 16 having the highest priority among the bus devices 16 requesting the use of No. 5, to the system bus 15, a bus use permission signal is sent to the system bus 15 ( The bus device 1 having the highest priority among the bus devices 16 by activating the bus use permission signal)
6 is given permission to use the system bus 15.

The bus device 16 which has obtained permission to use the system bus 15 immediately sends a bus use signal to the system bus 15 (activates the bus use signal) to use the system bus 15.

Further, the other bus device 16 which has failed to use the system bus 15 inactivates the use request of the system bus 15, monitors the bus use signal, and waits until it becomes inactive.

[0010]

Since the system using the conventional centralized arbitration circuit uses the centralized arbitration circuit 14 alone, when the centralized arbitration circuit 14 fails or malfunctions, the entire system becomes ineffective. It may malfunction or stop.

Therefore, it is an object of the present invention to provide a centralized arbitration circuit duplication method in which a failure or malfunction of the centralized arbitration circuit does not easily lead to malfunction or stop of the entire system.

[0012]

According to the present invention, there are provided a system bus; a plurality of units each connected to the system bus, and each sending a bus use request signal to the system bus when the system bus is used. A bus device connected to the system bus, receiving the bus use request signal from the system bus, and selecting the bus device having the highest priority among the bus devices currently requesting the use of the system bus. A first highest priority device selecting operation for selecting the first highest priority device, an identification code sending operation for sending the identification code of the first highest priority device to the system bus, and a bus use after the identification code sending operation. A bus use permission signal transmitting operation for transmitting a permission signal to the system bus;
A centralized arbitration circuit; a bus device which is connected to the system bus, receives the bus use request signal from the system bus, and has the highest priority among bus devices currently requesting the use of the system bus. A second highest-priority device selection operation for selecting as a second highest-priority device,
The identification code of the first highest priority device is received from the system bus, the identification code of the first highest priority device is compared with the identification code of the second highest priority device, and the first highest priority device If the identification code does not match the identification code of the second highest-priority device, an arbitration abnormality signal indicating arbitration abnormality is output, and the identification code of the first highest-priority device indicates that of the second highest-priority device. A second centralized arbitration circuit for performing a comparison operation for outputting a normal arbitration signal indicating normal arbitration when the identification code is matched; connected to the second centralized arbitration circuit and receiving the abnormal arbitration signal When a bus freeze signal is sent to the system bus and the arbitration normal signal is received, A monitoring circuit that does not send the bus freeze signal to the system bus; and each of the plurality of bus devices maintains the state at that time when the bus freeze signal is received from the system bus. Thus, a doubled system of the centralized arbitration circuit is obtained.

Further in accordance with the invention, the monitoring circuit is also connected to the first centralized arbitration circuit,
After the bus freeze signal is sent to the system bus, a retry signal is sent to the first and second centralized arbitration circuits, which provides a duplexing method of the centralized arbitration circuit.

Further, according to the present invention, when the first centralized arbitration circuit receives the retry signal, the first priority device selecting operation, the identification code sending operation, and the bus use permission signal sending operation. And the second centralized arbitration circuit performs the second highest-priority device selection operation and the comparison operation when receiving the retry signal. The scheme is obtained.

Further, according to the present invention, the monitoring circuit sends the retry signal to the first and second centralized arbitration circuits and then outputs the normal arbitration signal from the second centralized arbitration circuit. Upon receipt, after releasing the bus freeze signal to the system bus, causing the plurality of bus devices to resume operation, and after transmitting the retry signal to the first and second centralized arbitration circuits When the arbitration abnormality signal is received from the second centralized arbitration circuit, an arbitration down signal indicating arbitration down is output, thereby providing a dualized system of the centralized arbitration circuit.

According to the present invention, there is further provided a processor unit connected to the system bus and to the monitoring circuit, the processor unit comprising:
A duplexing system of a centralized arbitration circuit, characterized in that, when receiving the arbitration down signal, the plurality of bus devices, the first and second centralized arbitration circuits, and the monitoring circuit are brought down. To be

[0017]

Next, an embodiment of the present invention will be described with reference to the drawings.

Referring to FIG. 1, a duplexing method of a centralized arbitration circuit according to an embodiment of the present invention is shown in FIG.
Have similar parts indicated by similar reference numbers. FIG.
In the duplication method of the centralized arbitration circuit of the above, the first centralized arbitration circuit (ARBA) is used.
141 and the second centralized arbitration circuit (AR
BB) 142.

Each of the plurality of bus devices 16 or MPUA
When 11 sends a bus use request signal to the system bus 15, arbitration is performed.

First centralized arbitration circuit 14
1 is connected to the system bus 15 and the system bus 15
Received a bus use request signal from the system bus 15
A first highest priority device selecting operation for selecting the device having the highest priority among the devices requesting the use of the first highest priority device and the identification code of the first highest priority device. 15, an identification code sending operation to be sent to the system 15, and after the identification code sending operation, a bus use permission signal is sent to the system bus 1
Send to 5 (activate bus use permission signal)
The bus use permission signal transmission operation is performed.

Second centralized arbitration circuit 14
2 is connected to the system bus 15 and the system bus 15
Received a bus use request signal from the system bus 15
Second highest priority device selecting operation for selecting the device having the highest priority among the devices requesting to use the second highest priority device, and identifying the first highest priority device from the system bus 15. The code is received and the identification code of the first highest priority device is compared to the identification code of the second highest priority device, and the identification code of the first highest priority device matches the identification code of the second highest priority device. If not, the arbitration error signal 22 indicating the arbitration error is output (the arbitration error signal 22 is activated), and if the identification code of the first highest priority device matches the identification code of the second highest priority device, arbitration is performed. A comparison operation of outputting a normal arbitration signal indicating normality (making the arbitration abnormality signal 22 inactive) is performed.

As described above, the first centralized arbitration circuit 141 is set to the normal execution mode, and the second centralized arbitration circuit 142 is set to the monitoring mode for monitoring the operation of the centralized arbitration circuit 141.

The monitoring circuit 13 is connected to the second centralized arbitration circuit 142 via the OR gate 21 and receives the arbitration abnormality signal 22.
The bus freeze signal 18 is sent to the system bus 15. However, when the arbitration normal signal is received, the bus freeze signal 18 is not sent to the system bus 15.

Upon receiving the bus freeze signal 18 from the system bus 15, each of the plurality of bus devices 16 maintains the state at that time.

The monitoring circuit 13 is also connected to the first centralized arbitration circuit 141 via the AND gate 24, sends the bus freeze signal 18 to the system bus 15, and then outputs the reset / retry signal 19 to the first and the first. 2 centralized arbitration circuits 141 and 142. At this time, the AND gate 24 sends the reset / retry signal 19 to the first and second centralized arbitration circuits 141 and 142 while receiving the arbitration abnormality signal 22.

First centralized arbitration circuit 14
1 receives the reset / retry signal 19, performs the first priority device selection operation, the identification code transmission operation, and the bus use permission signal transmission operation, and the second centralized arbitration circuit 142 resets. / When receiving the retry signal 19, the second highest priority device selection operation and the comparison operation are performed.

The monitoring circuit 13 sends the reset / retry signal 19 to the first and second centralized arbitration circuits 1.
When the arbitration normal signal is received from the second centralized arbitration circuit 142 after being sent to the terminals 41 and 142 (when the arbitration abnormality signal 22 is made inactive), the bus freeze signal 18 is sent to the system bus 15. Release the bus device 16
To resume operation. Even after the reset / retry signal 19 is sent to the first and second centralized arbitration circuits 141 and 142, when the arbitration abnormality signal 22 is received from the second centralized arbitration circuit 142, the arbitration down signal indicating the arbitration down is generated. Output to MPUA11 and MPUB12.

One of MPUA11 and MPUB12 is
When the arbitration down signal is received, the plurality of bus devices 16, the first and second centralized arbitration circuits 141 and 142, and the monitoring circuit 13 are brought down.

It should be noted that the OR gate 21 outputs the MPU abnormal signal 1 as well as the arbitration abnormal signal 22.
7 is also passed to the monitoring circuit 13. Further, when the AND gate 25 receives the reset / retry signal 19 from the monitoring circuit 13 while receiving the MPU abnormality signal 17 from the MPUB 12, the AND / gate 25 resets the reset / retry signal 19 to MP.
It sends to 141 and 142 to UA11 and MPUB12.

The operation of the centralized arbitration circuit in the duplex system will be described below. In the duplex system of the centralized arbitration circuit, arbitration is performed when the MPUA 11 or the bus device 16 sends a bus use request signal requesting use of the system bus 15 to the system bus 15.

The centralized arbitration circuit 141 receives the bus use request signal transmitted on the system bus 15 and compares the priority levels of the MPUA 11 and the bus device 16.

As a result, the identification code of the device having the highest priority among the devices currently requesting the use of the system bus 15 is sent to the system bus 15, and the bus use permission signal is activated to activate the system bus 15. Give permission to use.

At this time, the centralized arbitration circuit 142 reads the identification code issued by the centralized arbitration circuit 141, and compares it with the result of priority determination by the centralized arbitration circuit 142 itself. If the determination result of the centralized arbitration circuit 141 is the same, the operation is continued as it is, but if the determination is different, the centralized arbitration circuit 142 is performed.
Sends an arbitration abnormality signal 22 to the monitoring circuit 13 to notify the arbitration circuit that an abnormality has occurred.

Upon receiving the arbitration abnormality signal 22, the monitoring circuit 13 immediately activates the bus freeze signal 18 to freeze (that is, stop) the operation of the signal on the system bus 15. At this time, when the bus freeze signal 112 becomes active, the MPU 11 and the bus device 16 maintain the state at that time for a certain time, and after this certain time, all the signal lines output on the system bus 15 are once It becomes inactive and waits until the bus freeze signal 18 becomes inactive.

The monitoring circuit 13 confirms that all the operations on the system bus 15 have stopped, and sends a reset / retry signal 19.

Upon receipt of the reset / retry signal 19, the centralized arbitration circuits 141 and 142 reset the internal circuits, and the centralized arbitration circuit 142 deactivates the arbitration abnormality signal 22 to retry the determination of the priority. .

As a result of the retry, if the determination results of the centralized arbitration circuits 141 and 142 are the same, the bus use permission signal becomes active, and the monitoring circuit 13 sees this and deactivates the bus freeze signal 18. Then, the operation on the system bus 15 is restarted.

Even if the retries are retried, the determination results of the centralized arbitration circuits 141 and 142 differ again, and when the arbitration abnormality signal 22 becomes active again, M
The PUA 11 and the MPUB 12 are notified of the arbitration down, and one of the MPUA 11 and the MPUB 12 receives it and stops the entire system.

[0039]

As described above, according to the centralized arbitration circuit duplication system according to the present invention, the failure or malfunction of the centralized arbitration circuit is less likely to result in malfunction or stop of the entire system. A duplication method can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a duplex system of a centralized arbitration circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram of a duplexing method of a conventional MPU.

[Explanation of symbols]

 11 MPUA 12 MPUB 13 Monitoring Circuit 14 Centralized Arbitration Circuit 141 Centralized Arbitration Circuit 142 Centralized Arbitration Circuit 15 System Bus 16 Bus Device 17 MPU Abnormal Signal 18 Bus Freeze Signal 19 Reset / Retry Signal 21 OR Gate 22 Arbitration Abnormal Signal 24 AND Gate 25 AND gate

Claims (6)

[Claims] 1. A system bus; a plurality of bus devices, each connected to the system bus, each sending a bus use request signal to the system bus when the system bus is used; A first bus device which receives the bus use request signal from the system bus and selects the bus device having the highest priority among the bus devices currently requesting the use of the system bus as a first highest priority device; Of the first priority device, an identification code sending operation for sending the identification code of the first highest priority device to the system bus, and a bus for sending a bus use permission signal to the system bus after the identification code sending operation. A first centralized arbitration circuit for performing a use permission signal transmission operation; connected to the system bus, and requesting the bus use from the system bus A second highest priority device selecting operation for receiving a signal and selecting the bus device having the highest priority among the bus devices currently requesting the use of the system bus as the second highest priority device; An identification code of the first top priority device is received from the bus, the identification code of the first top priority device is compared with the identification code of the second top priority device, and the identification code of the first top priority device is received. Does not match the identification code of the second highest-priority device, an arbitration abnormality signal indicating an arbitration abnormality is output, and the identification code of the first highest-priority device is the second
And a second centralized arbitration circuit for performing a comparison operation for outputting an arbitration normal signal indicating normal arbitration when the identification code of the highest priority device is connected to the second centralized arbitration circuit. A bus freeze signal is sent to the system bus when an arbitration abnormality signal is received, and a monitor circuit that does not send the bus freeze signal to the system bus when the arbitration normal signal is received; Each of the bus devices of 1) maintains the state at that time when the bus freeze signal is received from the system bus, and the duplexing method of the centralized arbitration circuit. 2. The monitoring circuit is also connected to the first centralized arbitration circuit, and sends a retry signal to the first and second centralized arbitration circuits after transmitting the bus freeze signal to the system bus. The doubling method of the centralized arbitration circuit according to claim 1, characterized in that it is sent to a circuit. 3. When the first centralized arbitration circuit receives the retry signal, the first centralized arbitration circuit performs the first highest priority device selection operation, the identification code transmission operation, and the bus use permission signal transmission operation, and The dual centralized arbitration circuit according to claim 2, wherein, when the second centralized arbitration circuit receives the retry signal, the second centralized arbitration circuit performs the second highest priority device selection operation and the comparison operation. Method. 4. The bus when the monitoring circuit receives the arbitration normal signal from the second centralized arbitration circuit after sending the retry signal to the first and second centralized arbitration circuits. After releasing the freeze signal to the system bus to restart the operation of the plurality of bus devices and sending the retry signal to the first and second centralized arbitration circuits, 4. The duplexing method of the centralized arbitration circuit according to claim 3, wherein when the abnormal arbitration signal is received from the centralized arbitration circuit, an arbitration down signal indicating arbitration down is output. 5. A processor unit connected to the system bus and connected to the monitoring circuit, further comprising:
5. The processor unit, when receiving the arbitration down signal, causes the plurality of bus devices, the first and second centralized arbitration circuits, and the monitoring circuit to go down. A method of duplexing the centralized arbitration circuit described in. 6. The bus device according to claim 1, wherein each of the plurality of bus devices is one of a DMA controller, a main memory, an input device, an output device, and an input / output device. A duplicated method of the centralized arbitration circuit described in crab.