JPH04293132A - Backup system for logic circuit - Google Patents

Abstract

PURPOSE:To back up the arbitrary logic circuit by a hardware equivalent to one logic circuit. CONSTITUTION:In the backup system in which a spare circuit 110 executes its function as proxy, when a fault is generated in one of plural logic circuits 101, this system is provided with a switching control means 102 to which an alarm signal is inputted from each logic circuit 101, and which designates the logical circuit 101 in which a fault is generated and sends out a switching instruction, and a replacing means 103 for replacing the designated logic circuit 101 and the spare circuit 110 in accordance with an input of the switching instruction, and the spare circuit 110 is provided with a control information store means 111 for storing control information corresponding to a function of each logic circuit 101, a programmable logical element 112 for setting the contained hardware, based on inputted control information, and an input means 113 for inputting the control information concerned to the programmable logical element 112 in accordance with the input of the switching instruction.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backup system for logic circuits. Logic circuits forming computer input/output control devices, image digital signal processing devices, and the like are required to have high reliability. Therefore, there is a need for a backup system that automatically switches to a backup circuit and restores the function of the logic circuit when an IC or signal line is damaged due to external factors such as overload due to noise.

0002

2. Description of the Related Art FIG. 5 shows the configuration of a conventional backup method. In FIG. 5, the image signal processing device includes three active printed circuit boards 51001 to 51003 each having a logic circuit with a different function, and three spare printed boards 51011 to 51 corresponding to these.
013 are connected in cascade.

These printed boards 510 are each equipped with a fault detection section 511, and the fault detection section 511 detects a fault in the logic circuit based on the output of the logic circuit of each printed board 510. It is configured to send an alarm signal to the monitoring circuit 520. Monitoring circuit 520
The system is configured to recognize a printed board in which a fault has occurred in response to the above-mentioned alarm signal, and to switch between the active system and the standby system by controlling a selector 512 provided on each printed board.

The above-mentioned monitoring circuit 520 normally instructs the selector 512 of each printed board 510 to select the input port A, and the monitoring circuit 520 normally instructs the selector 512 of each printed board 510 to select the input port A.
The configuration is such that the outputs of 10 are input to its own logic circuit. On the other hand, for example, in response to an alarm signal indicating that a failure has occurred in the printed board 51001, the monitoring circuit 520 instructs the selectors 512 of the printed boards 51002 and 51012 to select the output of the standby printed board 51011. As a result, the above-mentioned active printed board 51001 is separated, and the output of the backup printed board 51011 is instead input to the active printed board 51002 and the backup printed board 51012 at the subsequent stage.

[0005] In this way, conventionally, a faulty active printed board has been replaced with a corresponding standby printed board for backup.

[0006]

By the way, with the development of semiconductor manufacturing technology in recent years, measures have been taken to prevent damage to ICs and LSIs due to external factors. In this case, the probability that failures occur simultaneously on a plurality of active printed circuit boards 510 is extremely small. However, three printed boards 510
Since it is uncertain which one of 01 to 51003 will fail, it is necessary to provide a spare for each printed board, which increases the amount of hardware for the spare circuit and increases the circuit scale of the entire device. Costs were also rising.

On the other hand, programmable logic circuit elements (Prog.
rammable logic device below PL
(abbreviated as D) has been commercialized and is used as a method for developing and prototyping input/output devices, image signal processing devices, etc., and realizing high-mix, low-volume production. This type of PLD,
FP is a large-scale PLD with several thousand gates or more.
GA (Field programmable gat)
New products that integrate 20,000 gates have also been announced as e-arrays, such as the LC from XILINX in the United States.
A (Logic cell array)XC4000
There are series etc. Furthermore, since rewritable products have been realized, by using such FPGA elements, it is also possible to dynamically realize logic circuits with various functions.

An object of the present invention is to provide a backup method that enables backup of any one of a plurality of logic circuits using hardware corresponding to one logic circuit.

[0009]

[Means for Solving the Problems] FIG. 1 is a block diagram of the principle of the present invention. In the present invention, when a failure occurs in any one of a plurality of logic circuits 101 each having a different function, the function of the corresponding logic circuit 101 is transferred to a backup circuit 110.
In the backup method acting on behalf of the logic circuit 101, a switching control means 102 receives an alarm signal from each of the plurality of logic circuits 101 to notify the occurrence of a fault, and sends a switching instruction to specify the logic circuit 101 in which the fault has occurred; A control system comprising a replacement means 103 for replacing a designated logic circuit 101 and a backup circuit 110 in response to input of a switching instruction, the backup circuit 110 storing control information corresponding to the function of each of the plurality of logic circuits 101. Information storage means 111
and a programmable logic element 112 that configures built-in hardware based on input control information.
It is characterized by comprising an input means 113 for selecting the corresponding control information from the control information storage means 111 and inputting it to the programmable logic element 112 in response to the input of a switching instruction.

0010

[Operation] In the present invention, since the control information regarding the function of each logic circuit 101 is stored in the control information storage means 111, the input means 113 inputs the corresponding control information in response to a switching instruction from the switching control means 102. By inputting into the programmable logic element 112, any logic circuit 101
If a failure occurs in the corresponding logic circuit 1,
It becomes possible to realize the functions of 01. Further, in response to an instruction from the switching control means 102 described above, the replacement means 103
However, by replacing the corresponding logic circuit 101 with the spare circuit 110, the function of the faulty logic circuit 101 can be replaced by the spare circuit 110.

[0011]

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings. FIG. 2 shows the configuration of an embodiment of an image signal processing device to which the backup method of the present invention is applied. Figure 2
In the image signal processing device, the current printed board 210
1 to 2103, a spare printed board 220, a monitoring circuit 230, and selectors 2411 to 2413.

[0012] The above-mentioned current printed boards 2101 to 21
03 are cascade-connected via selectors 2411 and 2412, and are configured to send out the output of the current printed board 2103 via the selector 2413. The outputs of these current printed circuit boards 210 are input to input ports A of the corresponding selectors 241, respectively. In addition, the input data to each active printed board 210 is also input to a spare printed board 220, and the output from this spare printed board 220 is transmitted to each selector 241.
is input to input port B of.

These selectors 2411 to 2413
form the replacement means 103, and each selector 241
Normally, the above-mentioned input port A is selected, and input port B is selected in response to an instruction input from the monitoring circuit 230. The three working printed boards 2101 to 2103 described above correspond to the logic circuit 101, and each includes a logic operation section 211 and a fault detection section 212. Here, the logic operation unit 2 provided in each of the currently used printed boards 2101 to 2103
11 have different functions, and the fault detection section 212 is configured to detect an abnormality in the operation of the corresponding logic operation section 211 and send an alarm signal to the above-mentioned monitoring circuit 230.

Various configurations can be considered for the configuration of this fault detection unit 212 depending on the functions of the corresponding logic operation unit 211. FIG. 2 shows the configuration of a failure detection unit 212 that performs abnormality detection by focusing on errors in time. In FIG. 3, the failure detection unit 212 includes two parity calculation units 310a and 310.
Parity calculation units 310a and 310b each calculate one parity bit from the input and output of the memory 301, and the exclusive OR gate 321 calculates both parity bits. The configuration is such that when it is determined that they do not match, a logic "1" is sent out as an alarm signal. For example, as shown in FIG.
01, and when reading data, this parity bit is also read out, inputted to the exclusive logic gate 321, and compared with the parity bit obtained by the parity calculation unit 310b. Further, in FIG. 3, the odd/even parity setting signal is a signal for determining whether the parity bit is set to odd parity or even parity.

In addition, in FIG. 2, a spare printed board 2
20 corresponds to a spare circuit 110, which includes a programmable logic element 112 and ROMs 2221 to 2223.
, a selector 223, and a multiplexer 224, and includes a programmable logic element 112 and a ROM 2221.
~2223 are interconnected via a bus.

The three ROMs 2221 to 222 mentioned above
3 corresponds to the control information storage means 111, and stores control information (described later) corresponding to the functions of the logic operation units 211 provided in the current printed circuit boards 2101 to 2103, respectively. Further, the selector 223 is
It corresponds to the input means 113, and the monitoring circuit 230
The configuration is such that a selection signal is input to one of these ROMs 222 in response to an instruction from the ROM 222 to enable reading.

Furthermore, as the programmable logic element 112, a commercially available programmable logic IC may be used.
For example, LCA (Logic cell) is a programmable logic IC manufactured by Xilinx.
array) may be used. This IC is equipped with a plurality of internal logic blocks that can be individually defined and wiring sections that connect these internal logic blocks.By defining the combinational logic and connections of the internal logic blocks, the internal hardware can be controlled. It is configured to set the software. Therefore, when this IC is used as a programmable logic element 112, control information corresponding to the functions of each logic operation section 211 includes information defining the combinational logic of each of these internal logic blocks and information regarding connections between internal logic blocks. The information may be stored in the corresponding ROM 222.

[0018] Here, each company uses various product names (LCA, PAL, etc.) to name the programmable logic element, which can be confusing, so below,
As a general term for these, Programmable lo
PLD, which is an abbreviation for gic device, will be used, and it is also shown as PLD in FIG. 2. Further, the monitoring circuit 230 corresponds to the switching control means 102, and includes an alarm detection section 231 and a backup control section 23.
2, the alarm detection section 231 detects the faulty working printed board 210 in response to an alarm signal from each working printed board 210, and the backup control section 232 detects the faulty working printed board 210 according to the detection result. It is configured to output instructions to the selector 241 and the spare printed board 220 described above.

The operation of the backup method of the present invention will be explained below. For example, when a fault occurs in the current printed board 2101, the fault detection unit 212 provided in the current printed board 2101 sends an alarm signal to the monitoring circuit 230, and in response to this alarm signal, the alarm detection unit 231 The backup control unit 232 is notified that a failure has occurred on the current printed board 2101.

[0020] In response, the backup control unit 232
For the selector 223 of the spare printed board 220, the ROM 2221 corresponding to the current printed board 2101 is selected.
While instructing the PLD 112 to select the
Instructs to load control information. In response to this instruction, PL
The D112 reads control information corresponding to the function of the logic operation unit 211 of the current printed circuit board 2101 from the readable ROM 2221, defines the combinational logic of the internal logic blocks based on this control information, and defines the combinatorial logic of the internal logic blocks. Connect logic blocks using internal connections. As a result, the functions of the logic operation unit 211 provided in the current printed circuit board 2101 are realized by hardware on the PLD 112.

[0021] Also, at this time, the backup control unit 23
2 instructs the multiplexer 224 to select the input data corresponding to the currently used printed board 2101, and also selects the selector 2 corresponding to the currently used printed board 2101.
411 to select input port B. As a result, the output of the spare printed board 220 is input to the working printed board 2102, the working printed board 2101 is disconnected from the above-mentioned cascade connection, and the spare printed board 220 is replaced by the selector 2.
It is connected to the current printed circuit board 2102 via 411. In this way, the three selectors 2411 mentioned above
~2413, the function of the replacement means 103 is realized, and the current printed board 2101 is replaced by the spare printed board 22.
Replaced with 0.

As mentioned above, the spare printed board 220
By configuring a PC board with a PLD 112 and loading control information corresponding to a faulty working printed board 210 into the PLD 112, the corresponding working printed board 210 can be replaced with a spare printed board 220 and the function can be taken over. It becomes possible. As a result, the spare printed board 220
By using the hardware for one board provided as a backup board, it is possible to back up any one of the three currently used printed boards in case a failure occurs. Therefore, compared to the case where a spare printed board is provided for each of the currently used printed boards, the amount of hardware provided as a spare circuit can be significantly reduced, resulting in cost reduction and downsizing of the device. .

By the way, the part that is damaged due to overload due to noise etc. is only a small part of the logic operation section, so if the part of the logic operation section 211 including the damaged part can be replaced with a spare circuit, the current use There is no need to replace the entire printed board 210 with a spare circuit. Hereinafter, a method will be described in which a spare circuit 110 is built into each active printed board and a part of the function of the logic operation section is performed by a PLD.

FIG. 4 shows the configuration of a currently used printed board to which the backup method of the present invention is applied. As shown in Figure 4,
In the current printed circuit board, the function of the logic operation section 211 is divided into four circuit blocks 4101 to 4104, and four fault detection sections 4111 are installed corresponding to each circuit block 410.
~4114 and four input side selectors 412i1 each
~411i4 and output side selector 412o1~411
o4. Each input side selector 4
12i is a circuit block 410 corresponding to input data.
and the backup circuit 110. Further, the output side selector 412o is configured to select either the data from the corresponding circuit block 410 or the data from the backup circuit 110 and output it as the output data of the corresponding circuit block 410. In this case, the circuit blocks 4101 to 4101 described above
4104, four ROMs 4211 corresponding to each
The preliminary circuit 110 is configured by providing the control information storage means 111 consisting of the circuit block 41
Control information corresponding to each 0 may be stored.

In addition, the monitoring circuit 430 instructs the selector 422 of the backup circuit 110 to select the corresponding control information in response to the alarm signal from each failure detection section 411, in the same manner as in the above-described embodiment. This control information is
All you have to do is load it into the LD112. As a result, PLD1
12 realizes the function of the circuit block 410 in which the fault has occurred.

Furthermore, at this time, the monitoring circuit 430 selects the input side selector 41 corresponding to the corresponding circuit block 410.
2i to send the input data to the PLD 112, and the output side selector 412o to send the input data to the PLD 11.
2, and the circuit block 410 in which the failure has occurred is replaced with the PLD 112. In this way, it is possible to back up each circuit block within a single printed board.

In this case, since it is sufficient to prepare a PLD 112 of a size corresponding to the function of one circuit block 410, the amount of hardware provided as the spare circuit 110 is reduced compared to the case where the entire current printed board is replaced with the entire printed board. The amount can be reduced, and further miniaturization and cost reduction can be achieved.

[0028]

Effects of the Invention As explained above, the present invention enables one logic circuit to be integrated by inputting control information corresponding to a faulty logic circuit into a programmable logic element and realizing the function of the corresponding logic circuit. By using the equivalent hardware, it is possible to back up in case a failure occurs in any one of the multiple logic circuits, reducing the amount of spare circuit hardware that occupies the entire device. As a result, it is possible to reduce the size and cost of the device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the principle of the present invention.

FIG. 2 is a configuration diagram of an embodiment of an image signal processing device to which the backup method of the present invention is applied.

FIG. 3 is a detailed configuration diagram of a failure detection section.

FIG. 4 is a configuration diagram of an embodiment of a currently used printed board to which the backup method of the present invention is applied.

FIG. 5 is an explanatory diagram of a conventional backup method.

[Explanation of symbols]

101 Logic circuit 102 Switching control means 103 Replacement means 110 Preliminary circuit 111 Control information storage means 112 Programmable logic device (PLD) 113
Input means 210 Current printed board 211 Logic operation unit 212, 411, 511 Failure detection unit 220 Spare printed board 222, 421 ROM 223, 241, 412, 422, 512 Selector 224 Multiplexer 230, 430, 520 Monitoring circuit 231 Alarm detection unit 232 Backup control unit 301 Memory 310 Parity calculation unit 321 Exclusive OR gate 410 Circuit block 510 Printed board

Claims (1)

[Claims] Claim 1: When a failure occurs in one of a plurality of logic circuits (101) each having a different function,
The function of the corresponding logic circuit (101) is transferred to the spare circuit (110).
), an alarm signal for notifying the occurrence of a fault is input from each of the plurality of logic circuits (101), and a switching instruction is sent specifying the logic circuit (101) in which the fault has occurred. comprising a switching control means (102) and a replacement means (103) for replacing the designated logic circuit (101) and the preliminary circuit (110) in response to the input of the switching instruction;
110) is a control information storage means (110) for storing control information corresponding to each function of the plurality of logic circuits (101).
111) and a programmable logic element (111) that configures the built-in hardware based on input control information.
112), and input means (113) for selecting relevant control information from the control information storage means (111) and inputting it to the programmable logic element (112) in response to the input of the switching instruction. A backup method for logic circuits characterized by a configuration that is similar to that of a logic circuit.