JP2634962B2 - Logic circuit backup method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a logic circuit backup system. High reliability is required for a logic circuit constituting an input / output control device of a computer or a digital signal processing device for images. Therefore, when an IC or signal line is damaged due to an external factor such as overload due to noise, a backup method is required which automatically switches to a spare circuit and restores the function of the logic circuit.

[0002]

2. Description of the Related Art FIG. 5 shows a configuration of a conventional backup system. 5, the image signal processing apparatus, the three printed circuit board 510 _{01-510 03} of the active system which includes a logic circuit having a different function, three printed circuit boards of the standby system corresponding to each of these 510 _{11 to} 510 ₁₃ are connected in cascade.

Each of these printed boards 510 has a failure detection unit 511, and the failure detection unit 511
However, based on the output of the logic circuit of each printed circuit board 510, a failure of the logic circuit is detected, and an alarm signal is sent to the monitoring circuit 520. Monitoring circuit 52
Reference numeral 0 indicates a configuration in which a faulty printed board is recognized in accordance with the alarm signal described above, and the selector 512 provided on each printed board is controlled to switch between the active system and the standby system.

The above-described monitoring circuit 520 normally instructs the selector 512 of each printed circuit board 510 to select the input port A, and the active printed circuit board 5 in the preceding stage is respectively provided.
The configuration is such that ten outputs 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 510 ₀₁ , the monitoring circuit 520 instructs the selector 512 of the printed boards 510 ₀₂ and 510 ₁₂ to select the output of the standby printed board 510 _11. I do. As a result, the above-described active printed board 510 ₀₁ is cut off, and the output of the standby printed board 510 ₁₁ is input to the working printed board 510 ₀₂ and the standby printed board 510 ₁₂ at the subsequent stage. .

As described above, in the related art, a backup is made by replacing a faulty active printed board with a corresponding standby printed board.

[0006]

However, with the recent development of semiconductor manufacturing technology, measures have been taken to prevent ICs and LSIs from being damaged by external factors. In this case, the probability that a failure occurs simultaneously in a plurality of active printed boards 510 is extremely small. However, three printed boards 510
_Since it is uncertain which of _{01 to} 510 ₀₃ will cause a failure, it is necessary to provide a spare for each printed board, and the amount of hardware of the spare circuit becomes enormous, increasing the circuit scale of the entire device. , The cost was also high.

[0007] On the other hand, a programmable logic circuit element (Programmable element) that allows the user to freely program the circuit configuration at hand
Able logic device (hereinafter abbreviated as PLD) has been commercialized, and is used as a method for realizing development, trial production, and high-mix low-volume production of input / output devices and image signal processing devices. FPGA (Field programmable) which is a kind of this PLD and is a large-scale PLD having a scale of several thousand gates or more.
A new product that integrates 20,000 gates has been announced as a gate array. For example, LCA (Logic
cell array) XC4000 series. Also, since rewritable products have been realized, such FPG
With the use of the A element, logic circuits having various functions can be dynamically realized.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a backup system which can back up an arbitrary one of a plurality of logic circuits with hardware corresponding to one logic circuit.

[0009]

FIG. 1 is a block diagram showing the principle of the present invention. According to the present invention, when a failure occurs in any of the plurality of logic circuits 101 having different functions, the function of the corresponding logic circuit 101 is changed to the spare circuit 110.
In the backup method, a switching control unit 102 receives an alarm signal for notifying the occurrence of a failure from each of the plurality of logic circuits 101, specifies the failed logic circuit 101, and sends a switching instruction. A replacement unit that replaces the designated logic circuit and the spare circuit in response to the input of the switching instruction, wherein the spare circuit stores control information corresponding to the function of each of the plurality of logic circuits; Information storage means 111
And a programmable logic element 112 for setting the built-in hardware based on the input control information;
Input means 113 for selecting the corresponding control information from the control information storage means 111 in response to the input of the switching instruction and inputting the selected control information to the programmable logic element 112.

[0010]

According to the present invention, since the control information relating to the function of each logic circuit 101 is stored in the control information storage means 111, in response to a switching instruction from the switching control means 102, the input means 113 transmits the corresponding control information. Is input to the programmable logic element 112 so that any logic circuit 10
In response to the occurrence of a failure in No. 1, the function of the corresponding logic circuit 101 can be realized. Further, in response to the instruction from the switching control means 102, the replacement means 10
By replacing the corresponding logic circuit 101 with the spare circuit 110, the spare circuit 110 can substitute the function of the failed logic circuit 101.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 2 shows the configuration of an embodiment of an image signal processing apparatus to which the backup method of the present invention is applied. FIG.
In the image signal processing device, the current printed board 210
And ₁ to 210 _3, the preliminary printed board 220, a monitoring circuit 230 is configured by a selector 241 _{1 to 241 3.}

The above-mentioned working printed boards 210 _{1 to} 210 _1
3 is cascade-connected via selectors 241 ₁ and 241 ₂ , and is configured to transmit the output of the working printed board 210 ₃ via the selector 241 ₃ . The outputs of these active printed boards 210 are input to the corresponding input ports A of the selector 241. The input data to each active printed board 210 is also input to the spare printed board 220, and the output from the spare printed board 220 is input to the input port B of each selector 241.

These selectors 241 _{1 to} 241 ₃ are:
Forming a replacement means 103;
Normally, the input port A described above is selected and the monitoring circuit 23
The input port B is selected according to the input of an instruction from 0. The three working printed boards 21 described above.
0 _{1-210 3,} which corresponds to the logic circuit 101 is configured to include respectively a logical operation unit 211 and the fault detecting unit 212. Here, each working printed board 21
0 _1-210 logical operation section 211 provided in the ₃ has different functions, also detects each failure detector 212 of the operation of the corresponding logic operation unit 211 abnormalities, above monitoring circuit 230 Is configured to send an alarm signal.

Various configurations can be considered as the configuration of the fault detecting unit 212 according to the function of the corresponding logical operation unit 211. FIG. 3 shows a write / read to / from a memory included in the logical operation unit 211. 4 shows a configuration of a failure detection unit 212 that performs abnormality detection by focusing on an error at the time. In FIG. 3, the failure detection unit 212 includes two parity calculation units 310a and 310
b and an exclusive OR gate 321, and the parity calculation units 310 a and 310 b calculate one parity bit from the input and output of the memory 301, respectively. When it is determined that they do not match, a logic "1" is transmitted as an alarm signal. For example, as shown in FIG.
01, and when the data is read, the parity bit is also read, input to the exclusive logic gate 321, and compared with the parity bit obtained by the parity calculator 310b. In FIG. 3, the odd / even parity setting signal is a signal for determining whether the parity bit is odd parity or even parity.

In FIG. 2, a spare printed board 2
Reference numeral 20 denotes a spare circuit 110, which includes a programmable logic element 112 and ROMs 222 _{1 to} 222 _3.
, A selector 223, and a multiplexer 224, and the programmable logic element 112 and the ROMs 222 _1-
And 222 ₃ has a configuration which is interconnected via a bus.

The above-mentioned three ROMs 222 _{1 to} 222 ₃
Corresponds to the control information storage unit 111, and stores control information (described later) corresponding to the function of the logical operation unit 211 provided on each of the active printed boards 210 _{1 to} 210 ₃ . The selector 223 is equivalent to the input unit 113, and is configured to input a selection signal to any of these ROMs 222 in accordance with an instruction from the monitoring circuit 230 to make the ROM 222 readable.

As the programmable logic element 112, a commercially available programmable logic IC may be used.
For example, an LCA (Logic cell array) which is a programmable logic IC manufactured by Xilinx may be used. This IC includes a plurality of individually definable internal logic blocks and a connection portion connecting these internal logic blocks. By defining the combination logic and connection of the internal logic blocks, the internal hardware is defined. It is configured to set hardware. Therefore, when this IC is used as the programmable logic element 112, the control information corresponding to the function of each logic operation unit 211 includes information defining the combination logic of each of these internal logic blocks and connection between the internal logic blocks. The information corresponding to R
What is necessary is just to store it in OM222.

Here, as the names of the programmable logic elements, various product names (LCA, PAL, etc.) are used by the respective companies, and the names may be confusing.
PLD, which is an abbreviation of Programmable logic device, is used as a generic term for these, and in FIG.
Shown as D. Further, the monitoring circuit 230 corresponds to the switching control unit 102, and the alarm detection unit 231
And a backup control unit 232,
The alarm detection unit 231 detects the active printed board 210 in which a failure has occurred in response to the alarm signal from each of the active printed boards 210, and the backup control unit 232 causes the above-described selector 241 and the standby print board to respond in accordance with the detection result. It is configured to output an instruction for the plate 220.

The operation of the backup system according to the present invention will be described below. For example, when a failure occurs in the working printed circuit board 210 _1, the failure detection unit 212 provided in this working printed circuit board 210 _1, sends an alarm signal to the monitoring circuit 230, in response to this alarm signal, the alarm detector 23
1 notifies the backup control unit 232 that a failure has occurred in the active printed board 210 ₁ .

In response, the backup control unit 232
, To the selector 223 of the pre-printed board 220, corresponding to the working printed circuit board 210 ₁ ROM 222 ₁
And instructs the PLD 112 to load control information. In response to this instruction, PLD
112 reads the control information corresponding to the read enable state by the ROM 222 ₁ from the function of the working printed circuit board 210 _first logical operation section 211, based on the control information, as well as define the combinatorial logic of the internal logic block these Are connected using an internal connection. As a result, the function of the logical operation unit 211 provided on the active printed board 210 ₁ is realized on the PLD 112 by hardware.

At this time, the backup control unit 23
2, the selector 241 to the multiplexer 224, instructs the selection of the input data corresponding to the working printed circuit board 210 _1, which corresponds to the working printed circuit board 210 ₁
Instruct ₁ to select input port B. Thereby, the spare printed board 22 is added to the current printed board 210 _2.
0 is input, the current printed board 21
0 ₁ is disconnected from the above cascade, on behalf of, the preliminary printed board 220 is connected to the working printed circuit board 210 ₂ via the selector 241 _1. In this way, the function of the replacing means 103 is realized by the _three selectors 241 _{1 to} 241 3 described above, and the current printed board 210 ₁ is replaced with the spare printed board 220.

As described above, the spare printed board 220
Is provided with the PLD 112, and by loading the control information corresponding to the failed active printed board 210 into the PLD 112, the corresponding active printed board 210 can be replaced with the spare printed board 220 to perform the function instead. It becomes possible. Thereby, the spare printed board 220
With one piece of hardware provided as above, backup can be performed in response to a failure occurring in any one of the three working printed boards. Therefore, the amount of hardware provided as a spare circuit can be significantly reduced as compared with the case where a spare printed board is provided for each of the current printed boards, thereby reducing costs and miniaturizing the apparatus. .

Incidentally, the part damaged by overload due to noise or the like is only a small part of the logical operation unit. Therefore, if a part of the logical operation unit 211 including the damaged part can be replaced by a spare circuit, It is not necessary to replace the entire printed board 210 with a spare circuit. Hereinafter, a description will be given of a method in which the spare circuit 110 is incorporated in each working printed board, and a part of the function of the logical operation unit is substituted by the PLD.

FIG. 4 shows a configuration of an active printed circuit board to which the backup method of the present invention is applied. As shown in FIG.
The active printed circuit board divides the function of the logical operation unit 211 into four circuit blocks 410 _{1 to} 410 ₄ , and corresponds to each of the circuit blocks 410 and four failure detection units 411 _{1 to} 41 _1.
1 ₄ and each of the four input selector 412 _i1 ~411
_i4 and output-side selectors 412 _{o1 to} 411 _o4 are provided. Each input-side selector 412 _i converts the input data into a corresponding circuit block 410 and a spare circuit 110.
Is transmitted to any one of the above. Also,
The output side selector 412 _o is connected to the corresponding circuit block 41.
One of the data from 0 and the data from the spare circuit 110 is selected and output as the output data of the corresponding circuit block 410. in this case,
A spare circuit 110 is configured by providing control information storage means 111 including _four ROMs 421 _{1 to} 421 ₄ corresponding to the above-described circuit blocks 410 _{1 to} 410 _4, respectively.
Control information corresponding to each of the circuit blocks 410 described above may be stored.

In the same manner as in the above-described embodiment, 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 of the failure detecting units 411. This control information is stored in the P
What is necessary is just to load into LD112. Thereby, PLD1
The function of the circuit block 410 in which the failure has occurred is realized by 12.

At this time, the monitoring circuit 430 operates the input-side selector 41 corresponding to the corresponding circuit block 410.
It is sufficient to instruct 2 _i to transmit the input data to the PLD 112 and to instruct the output side selector 412 _o to select the output data of the PLD 112, and replace the failed circuit block 410 with the PLD 112. In this way, it is possible to back up each circuit block inside one printed board.

In this case, the PLD 112 having a scale corresponding to the function of one circuit block 410 may be prepared, so that the hardware provided as the spare circuit 110 is required as compared with the case where the entire working printed board is replaced with the entire printed board. The amount can be reduced, and further downsizing and cost reduction can be achieved.

[0028]

As described above, according to the present invention, control information corresponding to a failed logic circuit is input to a programmable logic element, and the function of the corresponding logic circuit is realized, whereby one logic circuit is realized. By using hardware equivalent to the above, it is possible to make a backup in response to the occurrence of a failure in any one of a plurality of logical circuits, so that the hardware of the spare circuit occupying the entire apparatus is reduced. Thus, the size and cost of the device can be reduced.

[Brief description of the drawings]

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

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

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

FIG. 4 is a configuration diagram of an embodiment of an active 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]

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

Claims (1)

(57) [Claims] When a failure occurs in one of a plurality of logic circuits (101) having different functions, the function of the corresponding logic circuit (101) is changed to a spare circuit (110).
In the backup method, an alarm signal for notifying the occurrence of a failure is input from each of the plurality of logic circuits (101), and the switching is performed by designating the failed logic circuit (101) and sending a switching instruction. Control means (102), and replacement means (103) for replacing a designated logic circuit (101) with the spare circuit (110) in response to the input of the switching instruction, wherein the spare circuit (110) is A control information storage means (111) for storing control information corresponding to the function of each of the plurality of logic circuits (101), and a programmable logic for setting built-in hardware based on the input control information An element (112) and corresponding control information are selected from the control information storage means (111) in response to the input of the switching instruction, and the program is enabled. Backup method of the logic circuit which is a configuration that includes an input means for input to the logic device (112) (113).